Note: Descriptions are shown in the official language in which they were submitted.
REPETITIVE PULSED ELECTRIC DISCHARGE APPARATUS FOR
DOWNHOLE FORMATION EVALUATION
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This is a divisional application of Canadian Patent Application
Serial No.
2,896,335 filed on December 18, 2013. It is to be understood that the
expression "the present
invention" or the like used in this specification encompasses not only the
subject matter of this
divisional application but that of the parent also.
[0002] This application claims priority to and the benefit of the
filing of U.S. Patent
Application Serial No. 61/738,837, entitled "Repetitive Pulsed Electric
Discharge Power
Generation and Control Apparatus and Method of Use", filed on December 18,
2012; U.S. Patent
Application Serial No. 61/739,172, entitled "Repetitive Pulsed Electric
Discharge Apparatus and
Method of Use", filed on December 19, 2012; U.S. Patent Application Serial No.
61/738,753,
entitled "Repetitive Pulsed Electric Discharge Instrumentation Apparatus and
Method of Use",
filed on December 18, 2012; U.S. Patent Application Serial No. 61/739,144,
entitled "Repetitive
Pulsed Electric Discharge Nutating Bit Apparatus and Method of Use", filed on
December 19,
2012; U.S. Patent Application Serial No. 61/740,812, entitled "Repetitive
Pulsed Electric
Discharge Drill Bit Apparatus and Method of Use", filed on December 21, 2012;
U.S. Patent
Application Serial No. 61/749,071, entitled "Apparatus and Method for
Producing Electromagnetic
Energy", filed on January 4, 2013; U.S. Patent Application Serial No.
61/739,187, entitled
"Repetitive Pulsed Electric Discharge Fluid Flow Control Apparatus and Method
of Use", filed on
December 19, 2012, and U.S. Patent Application Serial No. 61/905,060, entitled
"Repetitive
Pulsed Electric Discharge Apparatuses and Methods of Use", filed on November
15, 2013.
[0003] This application is related to U.S. Patent Application Serial
No. 13/346,452, filed
January 9, 2012, entitled "Apparatus arid Method for Supplying Electrical
Power to Electrocrushing
Drill", which is a continuation-in-part application and claims the benefit and
priority of U.S. Patent
Application Serial No. 12/502,977, filed July 14, 2009, entitled "Apparatus
and Method for
Electrocrushing Rock"; which is a continuation-in-part application and claims
priority of U.S. Patent
Application Serial No.11/479,346, filed June 29, 2006, entitled "Portable and
Directional
Electrocrushing Drill", and issuing on July 14, 2009, as U.S. Patent No.
7,559,378; which is a
continuation-in-part application and claims priority to U.S. Patent No.
7,527,108, entitled "Portable
Electrocrushing Drill", filed on February 22, 2006 and issued on May 5, 2009;
which is a
continuation-in-part application and claims priority to U.S. Patent No.
7,416,032, entitled "Pulsed
Electric Rock Drilling Apparatus", filed on August 19, 2005, and issued on
August 26, 2008; and
U.S. Patent No. 7,530,406, entitled "Method of Drilling Using Pulsed Electric
Drilling", filed
November 20, 2006, and issued on May 12, 2009, which claim priority to U.S.
Patent Application
- 1 -
Date Recue/Date Received 2023-06-06
Serial No.60/603,509, entitled "Electrocrushing FAST Drill and Technology,
High Relative Permittivity Oil, High
Efficiency Boulder Breaker, New Electrocrushing Process, and Electrocrushing
Mining Machine", filed on August
20, 2004. This application is also related to U.S. Patent Application Serial
No. 11/208,671 entitled "Pulsed
Electric Rock Drilling Apparatus," filed August 19, 2005, U.S. Utility
Application Serial No. 11/561,840 entitled
"Method of Drilling Using Pulsed Electric Drilling;" filed November 20, 2006;
U.S. Utility Application Serial No.
11/360,118 entitled "Portable Electrocrushing Drill;" filed February 22, 2006;
PCT Patent Application
PCT/US06/006502 entitled "Portable Electrocrushing Drill;" filed February 23,
2006; U.S. Utility Application
Serial No. 11/479,346 entitled "Method of Drilling Using Pulsed Electric
Drilling;" filed June 29, 2006; PCT
Patent Application PCT/US07/72565 entitled "Portable Directional
Electrocrushing Drill; filed June 29, 2007;
U.S. Utility Application Serial No. 11/561,852 entitled "Fracturing Using a
Pressure Pulse," filed November 20,
2006; U.S. Patent Application Serial No. 13/466,296 entitled "Pulsed Electric
Rock Drilling Apparatus with Non-
Rotating Bit and Directional Control", filed May 8, 2012, which is a
divisional of U.S. Patent Application Serial
No.12/198,868, entitled "Pulsed Electric Rock Drilling Apparatus with Non-
Rotating Bit and Directional Control",
filed on August 26, 2008, which is a continuation-in-part application of U.S.
Patent No. 7,416,032, entitled
"Pulsed Electric Rock Drilling Apparatus", filed on August 19, 2005 and issued
on August 26, 2008, and U.S.
Patent No, 7,530,406, entitled "Method of Drilling Using Pulsed Electric
Drilling", filed November 20, 2006 and
issued on May 12, 2009; which claim priority to Provisional Application Serial
No.60/603,509, entitled
"Electrocrushing FAST Drill and Technology, High Relative Permittivity Oil,
High Efficiency Boulder Breaker,
New Electrocrushing Process, and Electrocrushing Mining Machine", filed on
August 20, 2004. This application
is also related to U.S. Patent Application Serial No.11/208,579, entitled
"Pressure Pulse Fracturing System",
filed on August 19, 2005; U.S. Patent Application Serial No.11/208,766,
entitled "High Permittivity Fluid", filed
on August 19, 2005; and U.S. Patent No. 7,384,009, entitled "Virtual Electrode
Mineral Particle Disintegrator",
filed on August 19, 2005, and issued on June 10, 2008.
- 2 -
Date Recue/Date Received 2023-06-06
BACKGROUND OF THE INVENTION
Field of the Invention (Technical Field):
[0004] The present invention relates to an electrocrushing drill,
particularly a portable drill
that utilizes an electric spark, or plasma, within a substrate to fracture the
substrate. An embodiment
of the present invention comprises two pulsed power systems coordinated to
fire one after the other.
Description of Related Art:
[0005] Note that where the following discussion refers to a number of
publications by
author(s) and year of publication, because of recent publication dates certain
publications are not to
be considered as prior art vis-a-vis the present invention. Discussion of such
publications herein is
given for more complete background and is not to be construed as an admission
that such
publications are prior art for patentability determination purposes.
[0006] Processes using pulsed power technology are known in the art for
breaking mineral
lumps. Typically, an electrical potential is impressed across the electrodes
which contact the rock
from a high voltage electrode to a ground electrode. At sufficiently high
electric field, an arc or
plasma is formed inside rock from the high voltage electrode to the low
voltage or ground electrode.
The expansion of the hot gases created by the arc fractures the rock. When
this streamer connects
one electrode to the next, the current flows through the conduction path, or
arc, inside the rock. The
high temperature of the arc vaporizes the rock and any water or other fluids
that might be touching, or
are near, the arc. This vaporization process creates high-pressure gas in the
arc zone, which
expands. This expansion pressure fails the rock in tension, thus creating rock
fragments.
[0007] It is advantageous in such processes to use an insulating liquid
that has a high
relative permittivity (dielectric constant) to shift the electric fields in to
the rock in the region of the
electrodes.
[0008] Water is often used as the fluid for mineral disintegration
process. The drilling fluid
taught in U.S. Patent Serial No. 11/208,766 titled "High Permittivity Fluid"
is also applicable to the
mineral disintegration process.
(00091 Another technique for fracturing rock is the plasma-hydraulic
(PH), or electrohydraulic
(EH) techniques using pulsed power technology to create underwater plasma,
which creates intense
shock waves in water to crush rock and provide a drilling action. In practice,
an electrical plasma is
created in water by passing a pulse of electricity at high peak power through
the water. The rapidly
expanding plasma in the water creates a shock wave sufficiently powerful to
crush the rock. In such
a process, rock is fractured by repetitive application of the shock wave. U.S.
Patent No. 5,896,938,
to the present inventor, discloses a portable electrohydraulic drill using the
PH technique.
- 3 -
Date rogue/ Date received 2021-12-14
[0010] The rock fracturing efficiency of the electrocrushing process is
much higher than
either conventional mechanical drilling or electrohydraulic drilling. This is
because both of those
methods crush the rock in compression, where rock is the strongest, while the
electrocrushing
method fails the rock in tension, where it is relatively weak. There is thus a
need for a portable drill bit
utilizing the electrocrushing methods described herein to, for example,
provide advantages in
underground hard-rock mining, to provide the ability to quickly and easily
produce holes in the ceiling
of mines for the installation of roofbolts to inhibit fall of rock and thus
protect the lives of miners, and
to reduce cost for drilling blast holes. There is also a need for an
electrocrushing method that
improves the transfer of energy into the substrate, overcoming the impedance
of a conduction
channel in a substrate.
BRIEF SUMMARY OF THE INVENTION
[0011] One embodiment of the present invention comprises an apparatus for
controlling
power delivered to a down-hole pulsed power system in a bottom hole assembly.
The apparatus of
this embodiment preferably comprises a cable for providing power from a
surface to the pulsed power
system, a command charge switch disposed between an end of the cable and a
prime power system
on the surface. The command charge switch is fired on command to control when
power produced
by the primary power system is fed into the cable thereby controlling power
provided to the pulsed
power system in the bottom hole assembly. The bottom hole assembly preferably
comprises a non-
rotating drill bit. The pulsed power system comprises at least one capacitor
disposed near the drill
bit. The prime power system preferably produces a medium voltage DC power to
charge at least one
prime power system capacitor that is connected by the command charge switch to
the cable. The
command charge switch preferably controls when the medium voltage DC power on
the prime power
capacitor is switched on to the cable and transmitted to the pulsed power
system. The command
charge switch preferably controls a duration of a charge voltage on the pulsed
power system in the
bottom hole assembly. The command charge switch can control a voltage waveform
on the cable.
The prime power system preferably dampens cable oscillations. The prime power
system preferably
incorporates a diode ¨ resistor set to dampen cable oscillations.
[0012] Another embodiment of the present invention comprises a method for
controlling
power delivered to a pulsed power system using a command control switch. This
method comprises
disposing the pulsed power system in a bottom hole assembly, providing power
to the pulsed power
system via a cable, disposing a command charge switch between an end of the
cable and a prime
power system on the surface, and firing the command charge switch thereby
controlling when the
power produced by the prime power system is fed into the cable and controlling
the power delivered
to the pulsed power system in the bottom hole assembly. The bottom hole
assembly comprises a
non-rotating drill bit. The prime power system produces a medium voltage DC
power to charge at
- 4 -
Date rogue/ Date received 2021-12-14
least one prime power system capacitor that is connected to the cable by the
command charge
switch. The command control switch controlling when the medium voltage DC
power on the prime
power capacitor is switched on to the cable, controlling a duration of charge
voltage on the pulsed
power system in the bottom hole assembly, and controlling a voltage waveform
on the cable. The
pulsed power system dampening cable oscillations.
[0013] Yet another embodiment of the present invention comprises an
apparatus for
conducting electric current from a top-hole environment to a down-hole pulsed
power system in a
bottom hole assembly. This apparatus preferably comprises a drill pipe
comprising first and second
connectable sections, the drill pipe sections comprising a plurality of
embedded conductors, male
contacts disposed on the embedded conductors of a first connectable section,
female contacts
disposed on the embedded conductors of a second connectable section, the male
contacts and
female contacts capable of alignment, at least one drill pipe connector for
connecting the first
connectable section to the second connectable section to form at least a
portion of the drill pipe, the
connector isolating one embedded conductor from another conductor. The
apparatus can also
comprise additional connectable sections alternating between embedded
connectors comprising male
contacts and embedded connectors comprising female contacts. The drill pipe of
this embodiment is
preferably non-conductive except the embedded conductors and does not carry
mechanical high
torque loads. The connector of this embodiment preferably comprises a non-
rotating connector, such
as for example, a stab-type connector or a turnbuckle connector. The
conductors of this embodiment
comprise a conduction of current of at least about 1 amp average current. The
conductors can also
carry high-voltage current. For example, the current can be a voltage of at
least about 1 kV. The
apparatus of this embodiment can also comprise low voltage conductors for
carrying low-voltage data
signal. The low-voltage conductors can carry current at a voltage of about 1
to about 500 volts. The
low-voltage conductors are preferably isolated from the high voltage
conductors. The connectors can
optionally comprise disconnect devices. The connectors enable connection of
the drill pipe sections
without relative rotation to enable alignment of the electrical conductors. At
least a portion of the drill
pipe can comprise a dielectric material, a metallic material and/or a
combination of dielectric materials
and metallic materials. The apparatus can further comprise additional
connectable sections
alternating between embedded connectors comprising male contacts and embedded
connectors
comprising female contacts.
[0014] One embodiment of the present invention comprises a method of
conducting electric
current from a top-hole environment to a down-hole pulsed power system in a
bottom hole assembly.
The method preferably comprises providing a drill pipe comprising two or more
connectable sections
and a plurality of embedded conductors, disposing male electrical connectors
on the plurality of
embedded conductors of a first connectable section, disposing female
electrical connectors on the
plurality of embedded conductors of a second connectable section, aligning the
male electrical
- 5 -
Date rogue/ Date received 2021-12-14
connectors with the female electrical connectors, connecting the connectable
sections together using
at least one drill pipe connector, isolating the embedded conductors from each
other, and conducting
electrical current from a top-hole environment to a down-hole pulsed power
system in a bottom hole
assembly. Current is preferably conducted at about 1 amp average current. High-
voltage current can
be carried in at least some of the plurality of embedded conductors. The high-
voltage current is
preferably at least about 1 kV. Low-voltage current can also be carried in at
least some of the
plurality of embedded conductors. The embedded conductors are preferably
insulated. The
connectable sections are preferably connected without relative rotation. This
method can also
comprise alternating between embedded connectors comprising male contacts and
embedded
connectors comprising female contacts.
[0015] Another embodiment of the present invention is an apparatus for
providing power to
a down-hole pulsed power system, the apparatus comprising an above-ground
power supply, a
down-hole pulsed power system, and a cable directly connected to the above-
ground power supply
and the down-hole pulsed power system. The cable is optionally between
approximately 500 feet and
approximately 30,000 feet in length. The down-hole pulsed power system
preferably comprises one
or more capacitors which are directly charged from the power supply. The power
supply optionally
comprises a switching power supply, which preferably utilizes controlled high-
frequency current
pulses to progressively increase a voltage of the one or more capacitors and
preferably measures the
voltage and adjusting the current to achieve a desired end state voltage on
the capacitors. The power
supply preferably comprises a DC power supply, and preferably comprises both a
separate second
cable for monitoring the capacitor voltage to control the end state voltage
and a high voltage probe for
monitoring the capacitor voltage, the probe located in the down-hole and
transmitting control signals
to the surface via the separate second cable. The power supply optionally
comprises an AC power
supply, in which case the apparatus preferably further comprises a rectifier
in the down-hole pulsed
power system and a separate second cable for monitoring voltage and/or
transmitting voltage
monitoring data at a different frequency along the second cable. The apparatus
preferably further
comprises above-ground voltage control circuitry for receiving voltage data
from the capacitors and
controlling a current output and/or voltage output from the power supply.
[0016] Another embodiment of the present invention is a method for
providing power to a
down-hole pulsed power system, the method comprising directly charging one or
more capacitors in a
down-hole pulsed power system from an above-ground power supply. The method
preferably further
comprises connecting a cable between the above-ground power supply and the
down-hole pulsed
power system. The power supply optionally comprises a switching power supply
in which case the
method preferably further comprises utilizing controlled high-frequency
current pulses to
progressively increase a voltage of the one or more capacitors and preferably
further comprises
measuring the voltage and adjusting the current to achieve a desired end state
voltage on the
- 6 -
Date recue / Date received 2021-12-14
capacitors. The power supply preferably comprises a DC power supply in which
case the method
further comprises monitoring the capacitor voltage to control the end state
voltage, transmitting
control signals to the surface via a signal cable, or alternatively
transmitting control signals to the
surface on the power cable as an AC signal superimposed on the DC power
current, preferably by
inductively coupling the control signals into the power cable down-hole and
inductively extracting the
control signals from the power cable at the surface. The power supply
optionally comprises an AC
power supply in which case the method comprises rectifying the AC power down-
hole and monitoring
voltage and/or transmitting voltage monitoring data at a different frequency
along a signal cable. The
method preferably further comprises receiving voltage data from the capacitors
and controlling a
current output and/or voltage output from the power supply.
[0017] Yet another embodiment of the present invention is a method for
providing power to
a down-hole pulsed power system, the method comprising transmitting microwaves
from an above-
ground microwave transmitter to a down-hole microwave receiver and charging
one or more
capacitors in a down-hole pulsed power system. The method preferably further
comprises providing a
microwave bandwidth sufficient for transmitting both data and bower to the
down-hole pulsed power
system. The method preferably further comprises transmitting data back to the
surface using a down-
hole low power transmitter. The method preferably further comprises using a
metallic drill pipe used
to provide drilling fluid as a microwave waveguide, thereby minimizing losses
and improving power
transmission. The method preferably further comprises using a drilling fluid
comprising a property
selected from the group consisting of non-conductive, non-aqueous, insulating,
and dielectric.
[0018] Another embodiment of the present invention is an electrocrushing
drill bit comprising
one or more high voltage electrodes surrounded by a current return structure
comprising a plurality of
circumferential openings for facilitating removal of drilling debris from the
drill bit. The drill bit
preferably comprises a plurality of rod shaped high voltage electrodes
arranged in at least a portion of
a circle. The high voltage electrodes optionally surround one or more rod
shaped central current
return electrodes, which optionally are arranged in at least a portion of a
circle concentric with the
high voltage electrodes. The current return structure optionally comprises a
current return ring which
is preferably sufficiently strong to structurally support a drill string. The
current return structure
optionally comprises a plurality of rod shaped circumferential current return
electrodes located at an
outer rim of the drill bit and the circumferential openings comprise spaces
between the circumferential
current return electrodes. The circumferential current return electrodes are
preferably concentric with
a plurality of high voltage electrodes arranged in at least a portion of a
circle. The drill bit may
optionally further comprise a central current return electrode located
approximately at a center of the
circle. The drill bit may optionally comprise a wall connecting the
circumferential current return
electrodes, the wall preferably thinner than a diameter of each the
circumferential current return
electrode and disposed so that the wall extends radially outwardly as far as
or beyond the
- 7 -
Date rogue/ Date received 2021-12-14
circumferential current return electrode, thereby longitudinally extending an
outer wall of the drill bit,
but does not extend past the circumferential current return electrodes
radially inwardly. The height of
the wall is preferably shorter than a length of the circumferential current
return electrodes. The wall
and the circumferential current return electrodes are preferably manufactured
together to form a
single structure. The wall optionally comprises a plurality of additional
openings to facilitate removal
of drilling debris from the drill bit. The circumferential current return
electrodes preferably comprise a
cross-sectional shape selected from the group consisting of circle, ellipse,
wedge, and airfoil. The
drill bit optionally comprises a single high voltage electrode surrounded by a
plurality of
circumferential current return electrodes and optionally comprises a plurality
of channels running
longitudinally along an outer surface of the drill bit to facilitate transport
of drilling debris up and out of
a drilling hole,
[00191 The current return structure optionally partially covers a bottom
face of the drill bit,
the current return structure comprising one or more bottom openings along the
bottom face, wherein
one or more of the high voltage electrodes is disposed within each the bottom
opening. The drill bit
preferably comprises a channel at approximately a center of the bottom face
for flowing drilling fluid
into the bit. The current return structure preferably comprises a solid
portion disposed near the
channel, thereby forcing at least some of the flowing drilling fluid to flow
radially from the channel
toward and around each the high voltage electrode. The flowing drilling fluid
preferably sweeps
drilling debris and bubbles in the fluid created by operation of the
electrodes out of the drill bit. The
high voltage electrodes are optionally rod shaped and arranged to form at
least a portion of a circle
centered on a center of the bottom face. Each the high voltage electrode is
preferably compressible
and/or extends out from the bottom face. Two or more of the high voltage
electrodes are optionally
electrically connected to form one or more sets of connected electrodes, each
set powered by a
separate pulsed power system. Preferred operation of one or more of the sets
over one or more
other of the sets preferably results in directional control of the drill bit.
The electrodes in each set are
optionally mechanically linked to move together. Each bottom opening is
preferably sector-shaped or
substantially triangular. The high voltage electrodes are optionally
substantially triangular or sector
shaped and are circumferentially arranged around a center of the bottom face,
each high voltage
electrode oriented so that one of its vertices is pointing toward the center.
The drill bit is preferably
connected to a bottom hole assembly via a rotational Joint and a motor for
nutating the drill bit.
Nutation of the drill bit preferably results in more uniform drilling despite
non-uniform electric field
distributions produced by the high voltage electrodes.
MOM The present invention is also a method for imaging a formation
ahead of an
electrocrushing drill bit, the method comprising providing a current pulse to
a conducting loop
disposed on or in an electrocrushing drill bit assembly, thereby generating a
pulsed magnetic field
which penetrates the formation ahead of the drill bit. Providing the pulse
preferably comprises
- 8 -
Date rogue/ Date received 2021-12-14
operating a pulsed power circuit operating at tens of kilovolts and a few
kiloamps and a separate
pulsed power subsystem generating the current pulse. The separate pulsed power
subsystem
preferably uses the same power source, instrumentation, charging system, and
control system used
during operation of the electrocrushing drill bit. The conducting loop is
optionally oriented so that a
plane of the conducting loop is either perpendicular to or parallel to the
axis of the drill bit assembly.
Providing a current pulse preferably comprises using current from one or more
electrocrushing
electrodes during operation of the electrocrushing drill bit. The conducting
loop is preferably
connected in series or in parallel with the one or more electrocrushing
electrodes. The method
optionally further comprises changing phasing of current through each of a
plurality of current loops,
thereby steering a maxima of the produced magnetic field through the
formation.
[0021] The present invention is also an apparatus for imaging a formation
ahead of an
electrocrushing drill bit, the apparatus comprising: a current pulse source
and a conducting loop
disposed on or in an electrocrushing drill bit assembly for generating a
magnetic field which
penetrates the formation ahead of the drill bit. The current pulse source
preferably comprises a
separate pulsed power subsystem which preferably uses the same power source,
instrumentation,
charging system, and control system used during operation of the
electrocrushing drill bit and
preferably comprises a pulsed power circuit operating at tens of kilovolts and
a few kiloamps. The
current pulse source optionally also powers one or more electrocrushing
electrodes, in which case
the conducting loop is optionally connected in series or in parallel with the
one or more
electrocrushing electrodes. The plane of the conducting loop is optionally
oriented substantially
perpendicular or parallel to the axis of the electrocrushing drill bit
assembly. The apparatus optionally
comprises a plurality of conducting loops having different orientations. The
apparatus preferably
further comprises one or more sensors for sensing the magnetic field.
[0022] The present invention is also a method for operating an
electrocrushing drill, the
method comprising sending a signal from a control and data acquisition system
on the surface to fire
one or more pulsed power systems driving one or more electrodes of an
electrocrushing drill bit;
ceasing transmitting data from a downhole data acquisition and communication
system to the surface
controller; producing a firing pulse to fire the one or more pulsed power
systems; the downhole data
acquisition and communication system acquiring data produced by the firing
step; and transmitting
the data to the control and data acquisition system after completion of the
firing pulse. The data
preferably comprises one or more parameters selected from the group consisting
of peak current,
peak voltage, spiker current, spiker voltage, sustainer current, sustainer
voltage, drill geophysical
location, average power consumption of the drill, temperature of circuit
pulsed power components
and fluid systems, fluid flow pressure at one or more downhole locations,
fluid flow rate, ambient
temperature, and ambient pressure. The ceasing and firing steps are optionally
performed
simultaneously. The signal is preferably sent over a direct connection between
the control and data
- 9 -
Date rogue/ Date received 2021-12-14
acquisition system and the data acquisition and downhole communication system.
The transmitting
step preferably comprises transmitting the data sufficiently fast to enable a
drill operator to protect
against a blowout, enabling the operator to slow progress of the bit before a
blowout occurs. The data
acquisition and communication system preferably stores the data until
completion of the firing pulse.
[0023] The present invention is also an apparatus for operating an
electrocrushing drill, the
apparatus comprising a control and data acquisition system on the surface for
sending a firing pulse
to fire one or more pulsed power systems driving one or more electrodes of an
electrocrushing drill
bit; a downhole data acquisition and communication system for acquiring and
storing data from one or
more downhole sensors during the firing pulse; a direct connection between the
control and data
acquisition system and the downhole data acquisition and communication system;
wherein the
downhole data acquisition and communication system is configured to transmit
the data over the
direct connection to the control and data acquisition system after completion
of the filing pulse. The
direct connection comprises a cable, or conductors embedded in pipe, or a
fiber optic connection.
The downhole data acquisition and communication system connects to the cable
through a rotating
interface at the center of a cable reel or through a side entry sub so,
thereby enabling the cable to run
on the outside and/or partially inside of a drill pipe. The downhole data
acquisition and
communication system is preferably located near a top of a bottom hole
assembly. The sensors are
preferably selected from the group consisting of packaged MEMS gyroscope
device, solid-state ring
laser gyroscope, fiber optic gyroscope, temperature sensor, pressure sensor, B-
dot probe, resistive
probe, capacitive probe, probe utilizing optical effects, current transformer,
E-dot probe, rotating flow
meter, capacitive flow meter, inductive flow meter, venturi-type meter, and
rotational pump speed
sensor. A connection between the one or more downhole sensors and the downhole
data acquisition
and communication system is preferably shielded from noise, preferably
comprising a coaxial cable, a
fiber optic link, RF data transmission, and/or direct laser data transmission.
[00241 The present invention is also a method for cooling an
electrocrushing drill, the
method comprising flowing a first portion of a fluid stream adjacent to high
power electrical
components and using a second portion of the fluid stream to sweep drilling
debris and bubbles out
from an electrocrushing bit. The method preferably further comprises
controlling a flow velocity of the
first portion. The method preferably further comprises combining the first
portion and the second
portion to form a merged flow. The method preferably further comprises flowing
the second portion
and/or the merged flow radially outward from the center of the bit. The
present invention is also an
apparatus for cooling an electrocrushing bit, the apparatus comprising one or
more conduits for
receiving a first portion of a fluid flow; one or more plenums or passages in
fluid connection with the
one or more conduits, the one or more plenums in thermal contact with or
enclosing one or more high
power electrical components; and one or more channels for flowing a second
portion of the fluid flow
to an electrocrushing bit. The apparatus preferably further comprises a
controller for controlling a
- 10 -
Date rogue/ Date received 2021-12-14
flow velocity of the first portion. The apparatus preferably further comprises
a flow diverter
shield for protecting the components from direct flow of the second portion.
The apparatus
preferably further comprises one or more tubes disposed in the one or more
plenums or
passages for enclosing electrical lines. The apparatus preferably further
comprises a flow
combiner for combining the first portion and the second portion.
[0026] Further scope of applicability of the present invention will be
set forth in part
in the detailed description to follow, taken in conjunction with the
accompanying drawings,
and in part will become apparent to those skilled in the art upon examination
of the following,
or may be learned by practice of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0026] The accompanying drawings, which are incorporated into, and form
a
part of, the specification, illustrate one or more embodiments of the present
invention and,
together with the description, serve to explain the principles of the
invention. The drawings
are only for the purpose of illustrating one or more preferred embodiments of
the invention
and are not to be construed as limiting the invention. In the drawings:
[0027] Fig. 1 shows an end view of a coaxial electrode set for a
cylindrical bit of
an embodiment of the present invention;
[0028] Fig. 2 shows an alternate embodiment of Fig. 1;
[0029] Fig. 3 shows an alternate embodiment of a plurality of coaxial
electrode sets;
[0030] Fig. 4 shows a conical bit of an embodiment of the present
invention;
[0031] Fig. 5 is of a dual-electrode set bit of an embodiment of the
present invention;
[0032] Fig. 6 is of a dual-electrode conical bit with two different cone
angles of an
embodiment of the present invention;
[0033] Fig. 7 shows an embodiment of a drill bit of the present
invention wherein one
ground electrode is the tip of the bit and the other ground electrode has the
geometry of a great
circle of the cone;
[0034] Fig. 8 shows the range of bit rotation azimuthal angle of an
embodiment of the
present invention;
[0036] Fig. 9 shows an embodiment of the drill bit of the present
invention having
radiused electrodes;
[0036] Fig. 10 shows the complete drill assembly of an embodiment of the
present
invention;
[0037] Fig. 11 shows the reamer drag bit of an embodiment of the present
invention;
11
Date recue / Date received 2021-12-14
[0038] Fig. 12 shows a solid-state switch or gas switch controlled high
voltage pulse
generating system that pulse charges the primary output capacitor of an
embodiment of the present
invention;
[0039] Fig. 13 shows an array of solid-state switch or gas switch
controlled high voltage
pulse generating circuits that are charged in parallel and discharged in
series to pulse-charge the
output capacitor of an embodiment of the present invention;
[0040] Fig. 14 shows a voltage vector inversion circuit that produces a
pulse that is a
multiple of the charge voltage of an embodiment of the present invention;
[0041] Fig. 15 shows an inductive store voltage gain system to produce
the pulses needed
for the FAST drill of an embodiment of the present invention;
[0042] Fig. 16 shows a drill assembly powered by a fuel cell that is
supplied by fuel lines and
exhaust line from the surface inside the continuous metal mud pipe of an
embodiment of the present
invention;
[0043] Fig. 17 shows a roller-cone bit with an electrode set of an
embodiment of the present
invention;
[0044] Fig. 18 shows a small-diameter electrocrushing drill of an
embodiment of the present
invention;
[0045] Fig. 19 shows an electrocrushing vein miner of an embodiment of
the present
invention;
[0046] Fig. 20 shows a water treatment unit useable in the embodiments of
the present
invention;
[0047] Fig. 21 shows a high energy electrohydraulic boulder breaker
system (NEES) of an
embodiment of the present invention;
[0048] Fig. 22 shows a transducer of the embodiment of Fig. 22;
[0049] Fig. 23 shows the details of the an energy storage module and
transducer of the
embodiment of Fig. 22;
[0050] Fig. 24 shows the details of an inductive storage embodiment of
the high energy
electrohydraulic boulder breaker energy storage module and transducer of an
embodiment of the
present invention;
[0051] Fig. 25 shows the embodiment of the high energy electrohydraulic
boulder breaker
disposed on a tractor for use in a mining environment;
[0052] Fig. 26 shows a geometric arrangement of the embodiment of
parallel electrode gaps
in a transducer in a spiral configuration;
[0053] Fig. 27 shows details of another embodiment of an electrohydraulic
boulder breaker
system;
[0054] Fig. 28 shows an embodiment of a virtual electrode electrocrushing
process;
- 12 -
Date rogue/ Date received 2021-12-14
[0055] Fig. 29 shows an embodiment of the virtual electrode
electrocrushing system
comprising a vertical flowing fluid column;
[0056] Fig. 30 shows a pulsed power drilling apparatus manufactured and
tested in
accordance with an embodiment of the present invention;
[0057] Fig. 31 is a graph showing dielectric strength versus delay to
breakdown of the
insulating formulation of the present invention, oil, and water;
[0058] Fig. 32 is a schematic of a spiker-sustainer circuit
[0059] Fig. 33(a) shows the spiker pulsed power system and the sustainer
pulsed power
system; and Fig. 33(b) shows the voltage waveforms produced by each;
[0060] Fig. 34 is an illustration of an inductive energy storage circuit
applicable to
conventional and spiker-sustainer applications;
[0061] Fig. 35 is an illustration of a non-rotating electrocrushing bit
of the present invention;
[0062] Fig. 36 is a perspective view of the non-rotating electrocrushing
bit of Fig. 35;
[0063] Fig. 37 illustrates a non-rotating electrocrushing bit with an
asymmetric arrangement
of the electrode sets;
[0064] Fig. 38 is an illustration of a bottom hole assembly of the
present invention; and
[0065] Fig. 39 illustrates the bottom hole assembly in a well.
[0066] Fig. 40 is a close-up side cutaway view of an embodiment of the
present invention
showing a portable electrocrushing drill stem with a drill tip having
replaceable electrodes;
[0067] Fig. 41 is a close-up side cutaway view of the drill stem of Fig.
39 incorporating the
insulator, drilling fluid flush, and electrodes;
[0068] Fig. 42 is a side cutaway view of the preferred boot embodiment of
the
electrocrushing drill of the present invention;
[0069] Fig. 43 is a side view of an alternative electrocrushing mining
drill system of the
present invention showing a version of the portable electrocrushing drill in a
mine in use to drill holes
in the roof for roofbolts;
[0070] Fig. 44 is a side view of an alternative electrocrushing mining
drill system of the
present invention showing a version of the portable electrocrushing drill to
drill holes in the roof for
roofbolts and comprising two drills capable of non-simultaneous or
simultaneous operation from a
single pulse generator box;
[0071] Fig. 45 is a view of the embodiment of Fig. 40 showing the
portable electrocrushing
drill support and advance mechanism;
[0072] Fig. 46 is a close-up side cut-way view of an alternate embodiment
of the drill stem;
[0073] Fig. 47A shows an electrode configuration with circular shaped
electrodes;
[0074] Fig. 47B shows another electrode configuration with circular
shaped electrodes;
[0075] Fig. 47C shows another electrode configuration with circular
shaped electrodes;
- 13 -
Date rogue/ Date received 2021-12-14
[0076] Fig. 47D shows a combination of circular and convoluted
electrodes;
[0077] Fig. 47E shows convoluted shaped electrodes;
[0078] Fig. 48 shows a multi-electrode set drill tip for directional
drilling;
[0079] Fig. 49 shows a multi-electrode set drill showing internal circuit
components and a
flexible cable;
[0080] Fig. 50 shows a multi-electrode set drill showing internal circuit
components, a
flexible cable, and a pulse generator;
[0081] Fig. 51 shows a command charge system for electrocrushing drilling
of rock;
[0082] Fig. 52 shows a section of dielectric pipe having embedded
conductors; and
[0083] Fig. 53 shows a pulsed power system comprising a breaker and diode
place in series
with a cable in order to stop cable oscillations.
[0084] Fig. 54A shows a simplified schematic of an electrical circuit for
powering an
embodiment of the electrocrushing apparatus of the present invention using a
command charge
system.
[0085] Fig. 54B shows a simplified schematic of an electrical circuit for
powering an
embodiment of the electrocrushing apparatus of the present invention using a
direct charge system.
[0086] Fig. 55 shows a schematic of an embodiment of the instrumentation,
communication,
and control subsystem of the present invention.
[0087] Fig. 56 shows a flow diverter for splitting the flow of drilling
fluid in embodiments of
the present invention.
[0088] Fig. 57 shows a cross section of a bottom hole assembly of the
present invention
showing electrical components and cooling paths therein.
[0089] Fig. 58 shows a tiltable drilling apparatus comprising a mud
motor.
[0090] Fig. 59A shows a pie-segment drill bit that comprises radial fluid
flow useful for
directional control.
[0091] Figs. 59B, 59C, and 59D are respectively a perspective view, a
bottom view, and a
top perspective view of the drill bit of Fig. 59A.
[0092] Fig. 60 shows a drill bit comprising a pie shaped current return
structure and rod
shaped electrodes.
[0093] Fig. 61 shows nutation motion of the drill bit of Fig. 35.
[0094] Fig. 62 shows the magnetic field B around the conductor flowing
current.
[0096] Fig. 63 shows the magnetic field created by current flowing in a
loop.
[0096] Fig. 64 shows the magnetic field produced by a multiplicity of
current loops arranged
in a solenoid or coil.
[0097] Fig. 65 illustrates an embodiment of the present invention
comprising an
electromagnetic repetitive pulsed electric drill.
- 14 -
Date rogue/ Date received 2021-12-14
[00981 Fig. 66 shows an electromagnetic repetitive pulsed electric drill
comprising a current
loop for projecting a magnetic field along the axis of the drill system.
[0099] Fig. 67 shows an electromagnetic repetitive pulsed electric drill
comprising a current
loop for projecting a magnetic field transverse to the axis of the drill
system.
[00100) Fig. 68 shows an embodiment of a rod-type electrocrushing bit
comprising a
continuous ground ring.
[00101] Fig. 69 shows an embodiment of a rod-type electrocrushing bit
comprising a plurality
of circumferential ground rods.
[00102] Fig. 70A shows an embodiment of a rod-type electrocrushing bit
comprising a
plurality of circumferential ground rods integrated with a rod wall.
[00103] Fig. 70B is a bottom view of the bit shown in Fig. 70A.
[00104] Fig. 71 shows an embodiment of a rod-type electrocrushing bit
comprising flow
channels.
[00105) Fig. 72 is a photograph of an embodiment of a drill bit of the
present invention
comprising a current return ring having a plurality of openings which
surrounds a single rod shaped
high voltage electrode.
DETAILED DESCRIPTION OF THE INVENTION
[00106) The present invention provides for pulsed power breaking and
drilling apparatuses
and methods. A pulsed power breaking and drill apparatus is also known as a
repetitive pulsed
electric discharge apparatus. As used herein, "drilling" is defined as
excavating, boring into, making a
hole in, or otherwise breaking and driving through a substrate. As used
herein, "bit" and "drill bit' are
defined as the working portion or end of a tool that performs a function such
as, but not limited to, a
cutting, drilling, boring, fracturing, or breaking action on a substrate
(e.g., rock). As used herein, the
term "pulsed power" is that which results when electrical energy is stored
(e.g., in a capacitor or
inductor) and then released into the load so that a pulse of current at high
peak power is produced.
"Electrocrushing" ("EC") is defined herein as the process of passing a pulsed
electrical current
through a mineral substrate so that the substrate is "crushed" or "broken".
Electrocrushino Bit
[00107) An embodiment of the present invention provides a drill bit on
which is disposed one
or more sets of electrodes. In this embodiment, the electrodes are disposed so
that a gap is formed
between them and are disposed on the drill bit so that they are oriented along
a face of the drill bit. In
other words, the electrodes between which an electrical current passes through
a mineral substrate
(e.g., rock) are not on opposite sides of the rock. Also, in this embodiment,
it is not necessary that all
electrodes touch the mineral substrate as the current is being applied. In
accordance with this
- 16 -
Date rogue/ Date received 2021-12-14
embodiment, at least one of the electrodes extending from the bit toward the
substrate to be fractured
and may be compressible (i.e., retractable) into the drill bit by any means
known in the art such as, for
example, via a spring-loaded mechanism.
[001081 Generally, but not necessarily, the electrodes are disposed on the
bit such that at
least one electrode contacts the mineral substrate to be fractured and another
electrode that usually
touches the mineral substrate but otherwise may be close to, but not
necessarily touching, the
mineral substrate so long as it is in sufficient proximity for current to pass
through the mineral
substrate. Typically, the electrode that need not touch the substrate is the
central, not the
surrounding, electrode.
[00109] Therefore, the electrodes are disposed on a bit and arranged such
that
electrocrushing arcs are created in the rock. High voltage pulses are applied
repetitively to the bit to
create repetitive electrocrushing excavation events. Electrocrushing drilling
can be accomplished, for
example, with a flat-end cylindrical bit with one or more electrode sets.
These electrodes can be
arranged in a coaxial configuration.
[00681 The electrocrushing (EC) drilling process does not require
rotation of the bit. The
electrocrushing drilling process is capable of excavating the hole out beyond
the edges of the bit
without the need of mechanical teeth. In addition, by arranging many electrode
sets at the front of the
bit and varying the pulse repetition rate or pulse energy to different
electrode sets, the bit can be
steered through the rock by excavating more rock from one side of the bit than
another side. The bit
turns toward the electrode sets that excavate more rock relative to the other
electrode sets.
[00691 Fig. 1 shows an end view of such a coaxial electrode set
configuration for a
cylindrical bit, showing high voltage or center electrode 108, ground or
surrounding electrode 110,
and gap 112 for creating the arc in the rock. Variations on the coaxial
configuration are shown in Fig.
2. A non-coaxial configuration of electrode sets arranged in bit housing 114
is shown in Fig. 3. Figs.
2-3 show ground electrodes that are completed circles. Other embodiments may
comprise ground
electrodes that are partial circles, partial or compete ellipses, or partial
or complete parabolas in
geometric form.
[00701 For drilling larger holes, a conical bit may be utilized,
especially if controlling the
direction of the hole is important. Such a bit may comprise one or more sets
of electrodes for
creating the electrocrushing arcs and may comprise mechanical teeth to assist
the electrocrushing
process. One embodiment of the conical electrocrushing bit has a single set of
electrodes, may be
arranged coaxially on the bit, as shown in Fig. 4. In this embodiment, conical
bit 118 comprises a
center electrode 108, the surrounding electrode 110, the bit case or housing
114 and mechanical
teeth 116 for drilling the rock. Either, or both, electrodes may be
compressible. The surrounding
electrode may have mechanical cutting teeth 109 incorporated into the surface
to smooth over the
rough rock texture produced by the electrocrushing process. In this
embodiment, the inner portion of
- 16 -
Date rogue/ Date received 2021-12-14
the hole is drilled by the electrocrushing portion (i.e., electrodes 108 and
110) of the bit, and the outer
portion of the hole is drilled by mechanical teeth 116. This results in high
drilling rates, because the
mechanical teeth have good drilling efficiency at high velocity near the
perimeter of the bit, but very
low efficiency at low velocity near the center of the bit. The geometrical
arrangement of the center
electrode to the ground ring electrode is conical with a range of cone angles
from 180 degrees (flat
plane) to about 75 degrees (extended center electrode).
[0071] An alternate embodiment is to arrange a second electrode set on
the conical portion
of the bit. In such an embodiment, one set of the electrocrushing electrodes
operates on just one
side of the bit cone in an asymmetrical configuration as exemplified in Fig. 5
which shows a dual-
electrode set conical bit, each set of electrodes comprising center electrode
108, surrounding
electrode 110, bit case or housing 114, mechanical teeth 116, and drilling
fluid passage 120.
[00721 The combination of the conical surface on the bit and the
asymmetry of the electrode
sets results in the ability of the dual-electrode bit to excavate more rock on
one side of the hole than
the other and thus to change direction. For drilling a straight hole, the
repetition rate and pulse
energy of the high voltage pulses to the electrode set on the conical surface
side of the bit is
maintained constant per degree of rotation. However, when the drill is to turn
in a particular direction,
then for that sector of the circle toward which the drill is to turn, the
pulse repetition rate (and/or pulse
energy) per degree of rotation is increased over the repetition rate for the
rest of the circle. In this
fashion, more rock is removed by the conical surface electrode set in the
turning direction and less
rock is removed in the other directions (See Fig. 8, discussed in detail
below).
Because of the conical shape of the bit, the drill tends to turn into the
section where greater amount of
rock was removed and therefore control of the direction of drilling is
achieved.
[0073] In the embodiment shown in Fig. 5, most of the drilling is
accomplished by the
electrocrushing (EC) electrodes, with the mechanical teeth serving to smooth
the variation in surface
texture produced by the electrocrushing process. The mechanical teeth 116 also
serve to cut the
gauge of the hole, that is, the relatively precise, relatively smooth inside
diameter of the hole. An
alternate embodiment has the drill bit of Fig. 5 without mechanical teeth 116,
all of the drilling being
done by the electrode sets 108 and 110 with or without mechanical teeth 109 in
the surrounding
electrode 110.
[0074] Alternative embodiments include variations on the configuration of
the ground ring
geometry and center-to-ground ring geometry as for the single-electrode set
bit. For example, Fig. 6
shows such an arrangement in the form of a dual-electrode conical bit
comprising two different cone
angles with center electrodes 108, surrounding or ground electrodes 110, and
bit case or housing
114. In the embodiment shown, the ground electrodes are tip electrode 111 and
conical side ground
electrodes 110 which surround, or partially surround, high voltage electrodes
108 in an asymmetric
configuration.
- 17 -
Date rogue/ Date received 2021-12-14
[0075] As shown in Fig. 6, the bit may comprise two or more separate cone
angles to
enhance the ability to control direction with the bit. The electrodes can be
laid out symmetrically in a
sector of the cone, as shown in Fig. 4 or in an asymmetric configuration of
the electrodes utilizing
ground electrode 111 as the center of the cone as shown in Fig. 6. Another
configuration is shown in
Fig. 7A in which ground electrode 111 is at the tip of the bit and hot
electrode 108 and other ground
electrode 110 are aligned in great circles of the cone. Fig. 7B shows an
alternate embodiment
wherein ground electrode 111 is the tip of the bit, other ground electrode 110
has the geometry of a
great circle of the cone, and hot electrodes 108 are disposed there between.
Also, any combination
of these configurations may be utilized.
[0076] It should be understood that the use of a bit with an asymmetric
electrode
configuration can comprise one or more electrode sets and need not comprise
mechanical teeth. It
should also be understood that directional drilling can be performed with one
or more electrode sets.
[0077] The electrocrushing drilling process takes advantage of flaws and
cracks in the rock.
These are regions where it is easier for the electric fields to breakdown the
rock. The electrodes
used in the bit of the present invention are usually large in area in order to
intercept more flaws in the
rock and therefore improve the drilling rate, as shown in Fig. 4. This is an
important feature of the
invention because most electrodes in the prior art are small to increase the
local electric field
enhancement.
[0078] Fig. 8 shows the range of bit rotation azimuthal angle 122 where
the repetition rate or
pulse energy is increased to increase excavation on that side of the drill
bit, compared to the rest of
the bit rotation angle that has reduced pulse repetition rate or pulse energy
124. The bit rotation is
referenced to a particular direction relative to the formation 126, often
magnetic north, to enable the
correct drill hole direction change to be made. This reference is usually
achieved by instrumentation
provided on the bit. When the pulsed power system provides a high voltage
pulse to the electrodes
on the side of the bit (See Fig. 5), an arc is struck between one hot
electrode and one ground
electrode. This arc excavates a certain amount of rock out of the hole. By the
time the next high
voltage pulse arrives at the electrodes, the bit has rotated a certain amount,
and a new arc is struck
at a new location in the rock. If the repetition rate of the electrical pulses
is constant as a function of
bit rotation azimuthal angle, the bit will drill a straight hole. If the
repetition rate of the electrical pulses
varies as a function of bit rotation azimuthal angle, the bit will tend to
drift in the direction of the side of
the bit that has the higher repetition rate. The direction of the drilling and
the rate of deviation can be
controlled by controlling the difference in repetition rate inside the high
repetition rate zone azimuthal
angle, compared to the repetition rate outside the zone (See Fig. 8). Also,
the azimuthal angle of the
high repetition rate zone can be varied to control the directional drilling. A
variation of the invention is
to control the energy per pulse as a function of azimuthal angle instead of,
or in addition to, controlling
the repetition rate to achieve directional drilling.
- 18 -
Date rogue/ Date received 2021-12-14
FAST Drill System
[0079] Another embodiment of the present invention provides a drilling
system/assembly
utilizing the electrocrushing bits described herein and is designated herein
as the FAST Drill system.
A limitation in drilling rock with a drag bit is the low cutter velocity at
the center of the drill bit. This is
where the velocity of the grinding teeth of the drag bit is the lowest and
hence the mechanical drilling
efficiency is the poorest. Effective removal of rock in the center portion of
the hole is the limiting
factor for the drilling rate of the drag bit. Thus, an embodiment of the FAST
Drill system comprises a
small electrocrushing (EC) bit (alternatively referred to herein as a FAST bit
or FAST Drill bit)
disposed at the center of a drag bit to drill the rock at the center of the
hole. Thus, the EC bit
removes the rock near the center of the hole and substantially increases the
drilling rate. By
increasing the drilling rate, the net energy cost to drill a particular hole
is substantially reduced. This
is best illustrated by the bit shown in Fig. 4 (discussed above) comprising EC
process electrodes 108
and 100 set at the center of bit 118, surrounded by mechanical drag-bit teeth
116. The rock at the
center of the bit is removed by the EC electrode set, and the rock near the
edge of the hole is
removed by the mechanical teeth, where the tooth velocity is high and the
mechanical efficiency is
high.
[0080] As noted above, the function of the mechanical drill teeth on the
bit is to smooth off
the tops of the protrusions and recesses left by the electrocrushing or plasma-
hydraulic process.
Because the electrocrushing process utilizes an arc through the rock to crush
or fracture the rock, the
surface of the rock is rough and uneven. The mechanical drill teeth smooth the
surface of the rock,
cutting off the tops of the protrusions so that the next time the
electrocrushing electrodes come
around to remove more rock, they have a larger smoother rock surface to
contact the electrodes.
[0081] The electrocrushing bit comprises passages for the drilling fluid
to flush out the rock
debris (i.e., cuttings) (See Fig. 5). The drilling fluid flows through
passages inside the electrocrushing
bit and then out] through passages 120 in the surface of the bit near the
electrodes and near the
drilling teeth, and then flows up the side of the drill system and the well to
bring rock cuttings to the
surface.
[0082] The electrocrushing bit may comprise an insulation section that
insulates the
electrodes from the housing, the electrodes themselves, the housing, the
mechanical rock cutting
teeth that help smooth the rock surface, and the high voltage connections that
connect the high
voltage power cable to the bit electrodes.
[0083] Fig. 9 shows an embodiment of the FAST Drill high voltage
electrode 108 and ground
electrodes 110 that incorporate a radius 176 on the electrode, with electrode
radius 176 on the rock-
facing side of electrodes 110. Radius 176 is an important feature of the
present invention to allocate
- 19 -
Date recue / Date received 2021-12-14
the electric field into the rock. The feature is not obvious because
electrodes from prior art were
usually sharp to enhance the local electric field.
[0084] Fig. 10 shows an embodiment of the FAST Drill system comprising
two or more
sectional components, including, but not limited to: (1) at least one pulsed
power FAST drill bit 118;
(2) at least one pulsed power supply 136; (3) at least one downhole generator
138; (4) at least one
overdrive gear to rotate the downhole generator at high speed 140; (5) at
least one downhole
generator drive mud motor 144; (6) at least one drill bit mud motor 146; (7)
at least one rotating
interface 142; (8) at least one tubing or drill pipe 147 for the drilling
fluid; and (9) at least one cable
148. Not all embodiments of the FAST Drill system utilize all of these
components. For example, one
embodiment utilizes continuous coiled tubing to provide drilling fluid to the
drill bit, with a cable to
bring electrical power from the surface to the pulsed power system. That
embodiment does not
require a down-hole generator, overdrive gear, or generator drive mud motor,
but does require a
downhole mud motor to rotate the bit, since the tubing does not turn. An
electrical rotating interface is
required to transmit the electrical power from the non-rotating cable to the
rotating drill bit.
[0085] An embodiment utilizing a multi-section rigid drill pipe to
rotate the bit and conduct
drilling fluid to the bit requires a downhole generator, because a power cable
cannot be used, but
does not need a mud motor to turn the bit, since the pipe turns the bit. Such
an embodiment does not
need a rotating interface because the system as a whole rotates at the same
rotation rate.
[0086] An embodiment utilizing a continuous coiled tubing to provide mud
to the drill bit,
without a power cable, requires a down-hole generator, overdrive gear, and a
generator drive mud
motor, and also needs a downhole motor to rotate the bit because the tubing
does not turn. An
electrical rotating interface is needed to transmit the electrical control and
data signals from the non-
rotating cable to the rotating drill bit.
[0087] An embodiment utilizing a continuous coiled tubing to provide
drilling fluid to the drill
bit, with a cable to bring high voltage electrical pulses from the surface to
the bit, through the rotating
interface, places the source of electrical power and the pulsed power system
at the surface. This
embodiment does not need a down-hole generator, overdrive gear, or generator
drive mud motor or
downhole pulsed power systems, but does need a downhole motor to rotate the
bit, since the tubing
does not turn.
[0088] Still another embodiment utilizes continuous coiled tubing to
provide drilling fluid to
the drill bit, with a fuel cell to generate electrical power located in the
rotating section of the drill string.
Power is fed across the rotating interface to the pulsed power system, where
the high voltage pulses
are created and fed to the FAST bit. Fuel for the fuel cell is fed down tubing
inside the coiled tubing
mud pipe.
[0089] An embodiment of the FAST Drill system comprises FAST bit 118, a
drag bit reamer
150 (shown in Fig. 11), and a pulsed power system housing 136 (Fig. 10).
- 20 -
Date recue / Date received 2021-12-14
[0090] Fig. 11 shows reamer drag bit 150 that enlarges the hole cut by
the electrocrushing
FAST bit, drag bit teeth 152, and FAST bit attachment site 154. Reamer drag
bit 150 is preferably
disposed just above FAST bit 118. This is a conical pipe section, studded with
drill teeth, that is used
to enlarge the hole drilled by the electrocrushing bit (typically, for
example, approximately 7.5 inches
in diameter) to the full diameter of the well (for example, to approximately
12.0 inches in diameter).
The conical shape of drag bit reamer 150 provides more cutting teeth for a
given diameter of hole,
thus higher drilling rates. Disposed in the center part of the reamer section
are several passages.
There is a passage for the power cable to go through to the FAST bit. The
power cable comes from
the pulsed power section located above and/or within the reamer and connects
to the FAST drill bit
below the reamer. There are also passages in the reamer that provide oil flow
down to the FAST bit
and passages that provide flushing fluid to the reamer teeth to help cut the
rock and flush the cuttings
from the reamer teeth.
[0091] Preferably, a pulse power system that powers the FAST bit is
enclosed in the
housing of the reamer drag bit and the stem above the drag bit as shown in
Fig. 10. This system
takes the electrical power supplied to the FAST Drill for the electrocrushing
FAST bit and transforms
that power into repetitive high voltage pulses, usually over 100 kV. The
repetition rate of those pulses
is controlled by the control system from the surface or in the bit housing.
The pulsed power system
itself can include, but is not limited to:
[0092] (1) a solid state switch controlled or gas-switch controlled
pulse generating system
with a pulse transformer that pulse charges the primary output capacitor
(example shown in Fig. 12);
[0093] (2) an array of solid-state switch or gas-switch controlled
circuits that are charged in
parallel and in series pulse-charge the output capacitor (example shown in
Fig. 13);
[0094] (3) a voltage vector inversion circuit that produces a pulse at
about twice, or a
multiple of, the charge voltage (example shown in Fig. 14);
[0095] (4) An inductive store system that stores current in an inductor,
then switches it to the
electrodes via an opening or transfer switch (example shown in Fig. 15); or
[0096] (5) any other pulse generation circuit that provides repetitive
high voltage, high
current pulses to the FAST Drill bit.
[0097] Fig. 12 shows a solid-state switch or gas switch controlled high
voltage pulse
generating system that pulse charges the primary output capacitor 164, showing
generating means
156 to provide DC electrical power for the circuit, intermediate capacitor
electrical energy storage
means 158, gas, solid-state, or vacuum switching means 160 to switch the
stored electrical energy
into pulse transformer 162 voltage conversion means that charges output
capacitive storage means
164 connecting to FAST bit 118.
- 21 -
Date recue / Date received 2021-12-14
[0098] Fig. 13 shows an array of solid-state switch or gas switch 160
controlled high voltage
pulse generating circuits that are charged in parallel and discharged in
series through pulse
transformer 162 to pulse-charge output capacitor 164.
[0099] Fig. 14 shows a voltage vector inversion circuit that produces a
pulse that is a
multiple of the charge voltage. An alternate of the vector inversion circuit
that produces an output
voltage of about twice the input voltage is shown, showing solid-state switch
or gas switching means
160, vector inversion inductor 166, intermediate capacitor electrical energy
storage means 158
connecting to FAST bit 118.
[00100] Fig. 15 shows an inductive store voltage gain system to produce
the pulses needed
for the FAST Drill, showing the solid-state switch or gas switching means 160,
saturable pulse
transformers 168, and intermediate capacitor electrical energy storage means
158 connecting to the
FAST bit 118.
[00101] The pulsed power system is preferably located in the rotating
bit, but may be located
in the stationary portion of the drill pipe or at the surface.
[00102] Electrical power for the pulsed power system is either generated
by a generator at
the surface, or drawn from the power grid at the surface, or generated down
hole. Surface power is
transmitted to the FAST drill bit pulsed power system either by cable inside
the drill pipe or
conduction wires in the drilling fluid pipe wall. In one embodiment, the
electrical power is generated
at the surface, and transmitted downhole over a cable 148 located inside the
continuous drill pipe 147
(shown in Fig.11).
[00103] The cable is located in non-rotating flexible mud pipe
(continuous coiled tubing).
Using a cable to transmit power to the bit from the surface has advantages in
that part of the power
conditioning can be accomplished at the surface, but has a disadvantage in the
weight, length, and
power loss of the long cable.
[00104] At the bottom end of the mud pipe is located the mud motor which
utilizes the flow of
drilling fluid down the mud pipe to rotate the FAST Drill bit and reamer
assembly. Above the pulsed
power section, at the connection between the mud pipe and the pulsed power
housing, is the rotating
interface as shown in Fig. 10. The cable power is transmitted across an
electrical rotating interface at
the point where the mud motor turns the drag bit. This is the point where
relative rotation between
the mud pipe and the pulsed power housing is accommodated. The rotating
electrical interface is
used to transfer the electrical power from the cable or continuous tubing
conduction wires to the
pulsed power system. It also passes the drilling fluid from the non-rotating
part to the rotating part of
the drill string to flush the cuttings from the EC electrodes and the
mechanical teeth. The pulsed
power system is located inside the rigid drill pipe between the rotating
interface and the reamer. High
voltage pulses are transmitted inside the reamer to the FAST bit.
- 22 -
Date recue / Date received 2021-12-14
[00105] In the case of electrical power transmission through conduction
wires in rigid rotating
pipe, the rotating interface is not needed because the pulsed power system and
the conduction wires
are rotating at the same velocity. If a downhole gearbox is used to provide a
different rotation rate for
the pulsed power/bit section from the pipe, then a rotating interface is
needed to accommodate the
electrical power transfer.
[00106] In another embodiment, power for the FAST Drill bit is provided
by a downhole
generator that is powered by a mud motor that is powered by the flow of the
drilling fluid (mud) down
the drilling fluid, rigid, multi-section, drilling pipe (Fig. 10). That
mudflow can be converted to
rotational mechanical power by a mud motor, a mud turbine, or similar
mechanical device for
converting fluid flow to mechanical power. Bit rotation is accomplished by
rotating the rigid drill pipe.
With power generation via downhole generator, the output from the generator
can be inside the
rotating pulsed power housing so that no rotating electrical interface is
required (Fig. 10), and only a
mechanical interface is needed. The power comes from the generator to the
pulsed power system
where it is conditioned to provide the high voltage pulses for operation of
the FAST bit.
[00107] Alternatively, the downhole generator might be of the
piezoelectric type that provides
electrical power from pulsation in the mud. Such fluid pulsation often results
from the action of a mud
motor turning the main bit.
[00108] Another embodiment for power generation is to utilize a fuel cell
in the non-rotating
section of the drill string. Fig. 16 shows an example of a FAST Drill system
powered by fuel cell 170
that is supplied by fuel lines and exhaust line 172 from the surface inside
the continuous metal mud
pipe 147. The power from fuel cell 170 is transmitted across the rotating
interface 142 to pulsed
power system 136, and hence to FAST bit 118. The fuel cell consumes fuel to
produce electricity.
Fuel lines are placed inside the continuous coiled tubing, which provides
drilling fluid to the drill bit, to
provide fuel to the fuel cell, and to exhaust waste gases. Power is fed across
the rotating interface to
the pulsed power system, where the high voltage pulses are created and fed to
the FAST bit.
[00109] As noted above, there are two primary means for transmitting
drilling fluid (mud) from
the surface to the bit: continuous flexible tubing or rigid multi-section
drill pipe. The continuous
flexible mud tubing is used to transmit mud from the surface to the rotation
assembly where part of
the mud stream is utilized to spin the assembly through a mud motor, a mud
turbine, or another
rotation device. Part of the mudflow is transmitted to the FAST bits and
reamer for flushing the
cuttings up the hole. Continuous flexible mud tubing has the advantage that
power and
instrumentation cables can be installed inside the tubing with the mudflow. It
is stationary and not
used to transmit torque to the rotating bit. Rigid multi-section drilling pipe
comes in sections and
cannot be used to house continuous power cable, but can transmit torque to the
bit assembly. With
continuous flexible mud pipe, a mechanical device such as, for example, a mud
motor, or a mud
turbine, is used to convert the mud flow into mechanical rotation for turning
the rotating assembly.
- 23 -
Date recue / Date received 2021-12-14
The mud turbine can utilize a gearbox to reduce the revolutions per minute. A
downhole electric
motor can alternatively be used for turning the rotating assembly. The purpose
of the rotating power
source is primarily to provide torque to turn the teeth on the reamer and the
FAST bit for drilling. It
also rotates the FAST bit to provide the directional control in the cutting of
a hole. Another
embodiment is to utilize continuous mud tubing with downhole electric power
generation.
[00110] In one embodiment, two mud motors or mud turbines are used: one
to rotate the bits,
and one to generate electrical power.
[00111] Another embodiment of the rigid multi-section mud pipe is the use
of data
transmitting wires buried in the pipe such as, for example, the Intelipipe
manufactured by Grant
Prideco. This is a composite pipe that uses magnetic induction to transmit
data across the pipe
joints, while transmitting it along wires buried in the shank of the pipe
sections. Utilizing this pipe
provides for data transmission between the bit and the control system on the
surface, but still requires
the use of downhole power generation.
[00112] Another embodiment of the FAST Drill is shown in Fig. 17 wherein
rotary or roller-
cone bit 174 is utilized, instead of a drag bit, to enlarge the hole drilled
by the FAST bit. Roller-cone
bit 174 comprises electrodes 108 and 110 disposed in or near the center
portion of roller cone bit 174
to excavate that portion of the rock where the efficiency of the roller bit is
the least.
[00113] Another embodiment of the rotating interface is to use a rotating
magnetic interface to
transfer electrical power and data across the rotating interface, instead of a
slip ring rotating interface.
[00114] In another embodiment, the mud returning from the well loaded
with cuttings flows to
a settling pond, at the surface, where the rock fragments settle out. The mud
then cleaned and
reinjected into the FAST Drill mud pipe.
Electrocrushinq Vein Miner
[00115] Another embodiment of the present invention provides a small-
diameter,
electrocrushing drill (designated herein as "SED") that is related to the hand-
held electrohydraulic drill
disclosed in U.S. Patent No. 5,896,938 (to a primary inventor herein).
However, the SED is
distinguishable in that the electrodes in the SED are spaced in such a way,
and the rate of rise of the
electric field is such, that the rock breaks down before the water breaks
down. When the drill is near
rock, the electric fields break down the rock and current passes through the
rock, thus fracturing the
rock into small pieces. The electrocrushing rock fragmentation occurs as a
result of tensile failure
caused by the electrical current passing through the rock, as opposed to
compressive failure caused
by the electrohydraulic (EH) shock or pressure wave on the rock disclosed in
U.S. Patent No.
5,896,938, although the SED, too, can be connected via a cable from a box as
described in the '938
patent so that it can be portable. Fig. 18 shows a SED drill bit comprising
case 206, internal insulator
208, and center electrode 210 which is preferably movable
- 24 -
Date recue / Date received 2021-12-14
(e.g., spring-loaded) to maintain contact with the rock while drilling.
Although case 206 and internal
insulator 208 are shown as providing an enclosure for center electrode 210,
other components
capable of providing an enclosure may be utilized to house electrode 210 or
any other electrode
incorporated in the SED drill bit. Preferably, case 206 of the SED is the
ground electrode, although a
separate ground electrode may be provided. Also, it should be understood that
more than one set of
electrodes may be utilized in the SED bit. A pulsed power generator as
described in other
embodiments herein is linked to said drill bit for delivering high voltage
pulses to the electrode. In an
embodiment of the SED, cable 207 (which may be flexible) is provided to link a
generator to the
electrode(s). A passage, for example cable 207, is preferably used to deliver
water down the SED
drill.
[00116) This small-diameter electrocrushing drill embodiment is
advantageous for drilling in
non-porous rock. Also, this embodiment benefits from the use concurrent use of
the high permittivity
liquid discussed herein.
[001171 Another embodiment of the present invention is to assemble several
individual small-
diameter electrocrushing drill (SED) drill heads or electrode sets together
into an array or group of
drills, without the individual drill housings, to provide the capability to
mine large areas of rock. In
such an embodiment, a vein of ore can be mined, leaving most of the waste rock
behind. Fig. 19
shows such an embodiment of a mineral vein mining machine herein designated
Electrocrushing Vein
Miner (EVM) 212 comprising a plurality of SED drills 214, SED case 206, SED
insulator 208, and
SED center electrode 210. This assembly can then be steered as it moves
through the rock by
varying the repetition rate of the high voltage pulses differentially among
the drill heads. For
example, if the repetition rate for the top row of drill heads is twice as
high but contains the same
energy per pulse as the repetition rate for the lower two rows of drill heads,
the path of the mining
machine will curve in the direction of the upper row of drill heads, because
the rate of rock excavation
will be higher on that side. Thus, by varying the repetition rate and/or pulse
energy of the drill heads,
the EVM can be steered dynamically as it is excavating a vein of ore. This
provides a very useful tool
for efficiently mining just the ore from a vein that has substantial deviation
in direction.
[00118] In another embodiment, a combination of electrocrushing and
electrohydraulic (EH)
drill bit heads enhances the functionality of the by enabling the
Electrocrushing Vein-Miner (EVM) to
take advantage of ore structures that are layered. Where the machine is mining
parallel to the layers,
as is the case in mining most veins of ore, the shock waves from the EH drill
bit heads tend to
separate the layers, thus synergistically coupling to the excavation created
by the electrocrushing
electrodes. In addition, combining electrocrushing drill heads with plasma-
hydraulic drill heads
combines the compressive rock fracturing capability of the plasma-hydraulic
drill heads with the
tensile rock failure of the electrocrushing drill heads to more efficiently
excavate rock.
- 26 -
Date rogue/ Date received 2021-12-14
[00119] With the EVM mining machine, ore can be mined directly and
immediately
transported to a mill by water transport, already crushed, so the energy cost
of primary crushing and
the capital cost of the primary crushers is saved. This method has a great
advantage over
conventional mechanical methods in that it combines several steps in ore
processing, and it greatly
reduces the amount of waste rock that must be processed. This method of this
embodiment can also
be used for tunneling.
[00120] The high voltage pulses can be generated in the housing of the
EVM, transmitted to
the EVM via cables, or both generated elsewhere and transmitted to the housing
for further
conditioning. The electrical power generation can be at the EVM via fuel cell
or generator, or
transmitted to the EVM via power cable. Typically, water or mining fluid flows
through the structure of
the EVM to flush out rock cuttings.
[00121] If a few, preferably just three, of the electrocrushing or plasma-
hydraulic drill heads
shown in Fig. 19 are placed in a housing, the assembly can be used to drill
holes, with directional
control by varying the relative repetition rate of the pulses driving the
drill heads. The drill will tend to
drift in the direction of the drill head with the highest pulse repletion
rate, highest pulse energy, or
highest average power. This electrocrushing (or electrohydraulic) drill can
create very straight holes
over a long distance for improving the efficiency of blasting in underground
mining, or it can be used
to place explosive charges in areas not accessible in a straight line.
Insulating Drilling Fluid
[00122] An embodiment of the present invention also comprises insulating
drilling fluids that
may be utilized in the drilling methods described herein. For example, for the
electrocrushing process
to be effective in rock fracturing or crushing, it is preferable that the
dielectric constant of the
insulating fluid be greater than the dielectric constant of the rock and that
the fluid have low
conductivity such as, for example, a conductivity of less than approximately
10-6 mho/cm and a
dielectric constant of at least approximately 6.
[00123] Therefore, one embodiment of the present invention provides for an
insulating fluid or
material formulation of high permittivity, or dielectric constant, and high
dielectric strength with low
conductivity. The insulating formulation comprises two or more materials such
that one material
provides a high dielectric strength and another provides a high dielectric
constant. The overall
dielectric constant of the insulating formulation is a function of the ratio
of the concentrations of the at
least two materials. The insulating formulation is particularly applicable for
use in pulsed power
applications.
[00124] Thus, this embodiment of the present invention provides for an
electrical insulating
formulation that comprises a mixture of two or more different materials. In
one embodiment, the
formulation comprises a mixture of two carbon-based materials. The first
material may comprise a
- 26 -
Date rogue/ Date received 2021-12-14
dielectric constant of greater than approximately 2.6, and the second material
may comprise a
dielectric constant greater than approximately 10Ø The materials are at
least partly miscible with
one another, and the formulation has low electrical conductivity. The term
"low conductivity' or "low
electrical conductivity", as used throughout the specification and claims
means a conductivity less
than that of tap water, that may be lower than approximately 10-5 mho/cm, and
may be lower than
10-6 mho/cm. The materials are substantially non-aqueous. The materials in the
insulating
formulation are non-hazardous to the environment, may be non-toxic, and may be
biodegradable.
The formulation exhibits a low conductivity.
[00125] In one embodiment, the first material comprises one or more
natural or synthetic oils.
The first material may comprise castor oil, but may comprise or include other
oils such as, for
example, jojoba oil or mineral oil.
[001261 Castor oil (glyceryl triricinoleate), a triglyceride of fatty
acids, is obtained from the
seed of the castor plant. It is nontoxic and biodegradable. A transformer
grade castor oil (from
CasChem, Inc.) has a dielectric constant (i.e., relative permittivity) of
approximately 4.45 at a
temperature of approximately 22 C (100 Hz).
[001271 The second material comprises a solvent, one or more carbonates,
and/or may be
one or more alkylene carbonates such as, but not limited to, ethylene
carbonate, propylene
carbonate, or butylene carbonate. The alkylene carbonates can be manufactured,
for example, from
the reaction of ethylene oxide, propylene oxide, or butylene oxide or similar
oxides with carbon
dioxide.
[001281 Other oils, such as vegetable oil, or other additives can be added
to the formulation
to modify the properties of the formulation. Solid additives can be added to
enhance the dielectric or
fluid properties of the formulation.
[001291 The concentration of the first material in the insulating
formulation may range from
between approximately 1.0 and 99.0 percent by volume, between approximately
40.0 and 95.0
percent by volume, between approximately 65.0 and 90.0 percent by volume,
and/or between
approximately 75.0 and 85.0 percent by volume.
[001301 The concentration of the second material in the insulating
formulation may range
from between approximately 1.0 and 99.0 percent by volume, between
approximately 5.0 and 60.0
percent by volume, between approximately 10.0 and 35.0 percent by volume,
and/or between
approximately 15.0 and 25.0 percent by volume.
[001311 Thus, the resulting formulation comprises a dielectric constant
that is a function of the
ratio of the concentrations of the constituent materials. The mixture for the
formulation of one
embodiment of the present invention is a combination of butylene carbonate and
a high permittivity
castor oil wherein butylene carbonate is present in a concentration of
approximately 20% by volume.
This combination provides a high relative permittivity of approximately 15
while maintaining good
- 27 -
Date rogue/ Date received 2021-12-14
insulation characteristics. In this ratio, separation of the constituent
materials is minimized. At a ratio
of below 32%, the castor oil and butylene carbonate mix very well and remain
mixed at room
temperature. At a butylene carbonate concentration of above 32%, the fluids
separate if undisturbed
for approximately 10 hours or more at MOM temperature. A property of the
present invention is its
ability to absorb water without apparent effect on the dielectric performance
of the insulating
formulation.
[00132] An embodiment of the present invention comprising butylene
carbonate in castor oil
comprises a dielectric strength of at least approximately 300 kV/cm (I psec),
a dielectric constant of
approximately at least 6, a conductivity of less than approximately 10'5
mho/cm, and a water
absorption of up to 2,000 ppm with no apparent negative effect caused by such
absorption. More
preferably, the conductivity is less than approximately 10-6 mho/cm.
[00133] The formulation of the present invention is applicable to a number
of pulsed power
machine technologies. For example, the formulation is useable as an insulating
and drilling fluid for
drilling holes in rock or other hard materials or for crushing such materials
as provided for herein.
The use of the formulation enables the management of the electric fields for
electrocrushing rock.
Thus, the present invention also comprises a method of disposing the
insulating formulation about a
drilling environment to provide electrical insulation during drilling.
[00134] Other formulations may be utilized to perform the drilling
operations described herein.
For example, in another embodiment, crude oil with the correct high relative
permittivity derived as a
product stream from an oil refinery may be utilized. A component of vacuum gas
crude oil has high
molecular weight polar compounds with 0 and N functionality. Developments in
chromatography
allow such oils to be fractionated by polarity. These are usually cracked to
produce straight
hydrocarbons, but they may be extracted from the refinery stream to provide
high permittivity oil for
drilling fluid.
[00135] Another embodiment comprises using specially treated waters. Such
waters include,
for example, the Energy Systems Plus (ESP) technology of Complete Water
Systems which is used
for treating water to grow crops. In accordance with this embodiment, Fig. 20
shows water or a
water-based mixture 128 entering a water treatment unit 130 that treats the
water to significantly
reduce the conductivity of the water. The treated water 132 then is used as
the drilling fluid by the
FAST Drill system 134. The ESP process treats water to reduce the conductivity
of the water to
reduce the leakage current, while retaining the high permittivity of the
water.
High Efficiency Electrohydraulic Boulder Breaker
[00136] Another embodiment of the present invention provides a high
efficiency
electrohydraulic boulder breaker (designated herein as "HEEB") for breaking up
medium to large
boulders into small pieces. This embodiment prevents the hazard of fly rock
and damage to
- 28 -
Date rogue/ Date received 2021-12-14
surrounding equipment. The HEEB is related to the High Efficiency
Electrohydraulic Pressure Wave
Projector disclosed in U.S. Patent No. 6,215,734 (to the principal inventor
herein).
[00137] Fig. 21 shows the HEEB system disposed on truck 181, comprising
transducer 178,
power cable 180, and fluid 182 disposed in a hole. Transducer 178 breaks the
boulder and cable 180
(which may be of any desired length such as, for example, 6-15 m long)
connects transducer 178 to
electric pulse generator 183 in truck 181. An embodiment of the invention
comprises first drilling a
hole into a boulder utilizing a conventional drill, filling the hole is filled
with water or a specialized
insulating fluid, and inserting HEEB transducer 178 into the hole in the
boulder. Fig. 22 shows HEEB
transducer 178 disposed in boulder 186 for breaking the boulder, cable 180,
and energy storage
module 184.
[00138] Main capacitor bank 183 (shown in Fig. 21) is first charged by
generator 179 (shown
in Fig. 21) disposed on truck 181. Upon command, control system 192 (shown in
Fig. 21 and
disposed, for example, in a truck) is closed connecting capacitor bank 183 to
cable 180. The
electrical pulse travels down cable 180 to energy storage module 184 where it
pulse-charges
capacitor set 158 (example shown in Fig. 23), or other energy storage devices
(example shown in
Fig. 25).
[00139] Fig. 23 shows the details of the HEEB energy storage module 184
and transducer
178, showing capacitors 158 in module 184, and floating electrodes 188 in
transducer 178.
[00140] Fig. 24 shows the details of the inductive storage embodiment of
HEEB energy
storage module 184 and transducer 178, showing inductive storage inductors 190
in module 184, and
showing the transducer embodiment of parallel electrode gaps 188 in transducer
178. The
transducer embodiment of parallel electrode gaps (Fig. 24) and series
electrode gaps (Fig. 23) can
reach be used alternatively with either the capacitive energy store 158 of
Fig. 3 or the inductive
energy store 190 of Fig. 24.
[00141] These capacitors/devices are connected to the probe of the
transducer assembly
where the electrodes that create the pressure wave are located. The capacitors
increase in voltage
from the charge coming through the cable from the main capacitor bank until
they reach the
breakdown voltage of the electrodes inside the transducer assembly. When the
fluid gap at the tip of
the transducer assembly breaks down (acting like a switch), current then flows
from the energy
storage capacitors or inductive devices through the gap. Because the energy
storage capacitors are
located very close to the transducer tip, there is very little inductance in
the circuit and the peak
current through the transducers is very high. This high peak current results
in a high energy transfer
efficiency from the energy storage module capacitors to the plasma in the
fluid. The plasma then
expands, creating a pressure wave in the fluid, which fractures the boulder.
- 29 -
Date recue / Date received 2021-12-14
[001421 The HEEB system may be transported and used in various
environments including,
but not limited to, being mounted on a truck as shown in Fig. 21 for transport
to various locations,
used for either underground or aboveground mining applications as shown in
Fig. 25, or used in
construction applications. Fig. 25 shows an embodiment of the HEEB system
placed on a tractor for
use in a mining environment and showing transducer 178, power cable 180, and
control panel 192.
[001431 Therefore, the HEEB does not rely on transmitting the boulder-
breaking current over
a cable to connect the remote (e.g., truck mounted) capacitor bank to an
electrode or transducer
located in the rock hole. Rather, the HEEB puts the high current energy
storage directly at the
boulder. Energy storage elements, such as capacitors, are built into the
transducer assembly.
Therefore, this embodiment of the present invention increases the peak current
through the
transducer and thus improves the efficiency of converting electrical energy to
pressure energy for
breaking the boulder. This embodiment of the present invention also
significantly reduces the amount
of current that has to be conducted through the cable thus reducing losses,
increasing energy transfer
efficiency, and increasing cable life.
[001441 An embodiment of the present invention improves the efficiency of
coupling the
electrical energy to the plasma into the water and hence to the rock by using
a multi-gap design. A
problem with the multi-gap water spark gaps has been getting all the gaps to
ignite because the
cumulative breakdown voltage of the gaps is much higher than the breakdown
voltage of a single
gap. However, if capacitance is placed from the intermediate gaps to ground
(Fig. 23), each gap
ignites at a voltage similar to the ignition voltage of a single gap. Thus, a
large number of gaps can
be ignited at a voltage of approximately a factor of 2 greater than the
breakdown voltage for a single
gap. This improves the coupling efficiency between the pulsed power module and
the energy
deposited in the fluid by the transducer. Holes in the transducer case are
provided to let the pressure
from the multiple gaps out into the hole and into the rock to break the rock
(Fig. 23).
[001453 In another embodiment, the multi-gap transducer design can be used
with a
conventional pulsed power system, where the capacitor bank is placed at some
distance from the
material to be fractured, a cable is run to the transducer, and the transducer
is placed in the hole in
the boulder. Used with the HEEB, it provides the advantage of the much higher
peak current for a
given stored energy.
1001461 Thus, an embodiment of the present invention provides a transducer
assembly for
creating a pressure pulse in water or some other liquid in a cavity inside a
boulder or some other
fracturable material, said transducer assembly incorporating energy storage
means located directly in
the transducer assembly in close proximity to the boulder or other fracturable
material. The
transducer assembly incorporates a connection to a cable for providing
charging means for the
energy storage elements inside the transducer assembly. The transducer
assembly includes an
- 30 -
Date rogue/ Date received 2021-12-14
electrode means for converting the electrical current into a plasma pressure
source for fracturing the
boulder or other fracturable material.
[001471 The transducer assembly may have a switch located inside the
transducer assembly
for purposes of connecting the energy storage module to said electrodes. In
the transducer
assembly, the cable is used to pulse charge the capacitors in the transducer
energy storage module.
The cable is connected to a high voltage capacitor bank or inductive storage
means to provide the
high voltage pulse.
[001481 In another embodiment, the cable is used to slowly charge the
capacitors in the
transducer energy storage module. The cable is connected to a high voltage
electric power source.
[001491 In an embodiment of the present invention, the switch located at
the primary
capacitor bank is a spark gap, thyratron, vacuum gap, pseudo-spark switch,
mechanical switch, or
some other means of connecting a high voltage or high current source to the
cable leading to the
transducer assembly.
[001501 In another embodiment, the transducer electrical energy storage
utilizes inductive
storage elements.
[001511 Another embodiment of the present invention provides a transducer
assembly for the
purpose of creating pressure waves from the passage of electrical current
through a liquid placed
between one or more pairs of electrodes, each gap comprising two or more
electrodes between
which current passes. The current creates a phase change in the liquid, thus
creating pressure in the
liquid from the change of volume due to the phase change. The phase change
includes a change
from liquid to gas, from gas to plasma, or from liquid to plasma.
[001521 In the transducer, more than one set of electrodes may be arranged
in series such
that the electrical current flowing through one set of electrodes also flows
through the second set of
electrodes, and so on. Thus, a multiplicity of electrode sets can be powered
by the same electrical
power circuit.
[001531 In another embodiment, in the transducer, more than one set of
electrodes is
arranged in parallel such that the electrical current is divided as it flows
through each set of
electrodes (Fig. 24). Thus, a multiplicity of electrode sets can be powered by
the same electrical
power circuit
[001541 A plurality of electrode sets may be arrayed in a line or in a
series of straight lines.
[001551 In another embodiment, the plurality of electrode sets is
alternatively arrayed to form
a geometric figure other than a straight line, including, but not limited to,
a curve, a circle (Fig. 24), or
a spiral. Fig. 26 shows a geometric arrangement of the embodiment comprising
parallel electrode
gaps 188 in the transducer 178, in a spiral configuration.
- 31 -
Date rogue/ Date received 2021-12-14
[001561 The electrode sets in the transducer assembly may be constructed
in such a way as
to provide capacitance between each intermediate electrode and the ground
structure of the
transducer (Fig. 23).
[001571 In another embodiment, in the plurality of electrode sets, the
capacitance of the
intermediate electrodes to ground is formed by the presence of a liquid
between the intermediate
electrode and the ground structure.
[001581 In another embodiment, in the plurality of electrode sets, the
capacitance is formed
by the installation of a specific capacitor between each intermediate
electrode and the ground
structure (Fig. 23). The capacitor can use solid or liquid dielectric
material.
[001591 In another embodiment, in the plurality of electrode sets,
capacitance is provided
between the electrode sets from electrode to electrode. The capacitance can be
provided either by
the presence of the fracturing liquid between the electrodes or by the
installation of a specific
capacitor from an intermediate electrode between electrodes as shown in Fig.
27. Fig. 27 shows the
details of the HEEB transducer 178 installed in hole 194 in boulder 186 for
breaking the boulder.
Shown are cable 180, the floating electrodes 188 in the transducer and liquid
between the electrodes
196 that provides capacitive coupling electrode to electrode. Openings 198 in
the transducer which
allow the pressure wave to expand into the rock hole are also shown.
[001603 In an embodiment of the present invention, the electrical energy
is supplied to the
multi-gap transducer from an integral energy storage module in the multi-
electrode transducer.
[001611 In another embodiment, in the multi-electrode transducer, the
energy is supplied to
the transducer assembly via a cable connected to an energy storage device
located away from the
boulder or other fracturable material.
Virtual Electrode Electro-Crushing Process
[001621 Another embodiment of the present invention comprises a method for
crushing rock
by passing current through the rock using electrodes that do not touch the
rock. In this method, the
rock particles are suspended in a flowing or stagnant water column, or other
liquid of relative
permittivity greater than the permittivity of the rock being fractured. Water
may be used for
transporting the rock particles because the dielectric constant of water is
approximately 80 compared
to the dielectric constant of rock which is approximately 3.5 to 12.
[001631 In one embodiment, the water column moves the rock particles past
a set of
electrodes as an electrical pulse is provided to the electrodes. As the
electric field rises on the
electrodes, the difference in dielectric constant between the water and the
rock particle causes the
electric fields to be concentrated in the rock, forming a virtual electrode
with the rock. This is
illustrated in Fig. 28 showing rock particle 200 between high voltage
electrodes 202 and ground
- 32 -
Date rogue/ Date received 2021-12-14
electrode 203 in liquid 204 whose dielectric constant is significantly higher
than that of rock particle
200.
[00164] The difference in dielectric constant concentrated the electric
fields in the rock
particle. These high electric fields cause the rock to break down and current
to flow from the
electrode, through the water, through the rock particles, through the
conducting water, and back to
the opposite electrode. In this manner, many small particles of rock can be
disintegrated by the
virtual electrode electrocrushing method without any of them physically
contacting both electrodes.
The method is also suitable for large particles of rock.
[00165] Thus, it is not required that the rocks be in contact with the
physical electrodes and
so the rocks need not be sized to match the electrode spacing in order for the
process to function.
With the virtual electrode electrocrushing method, it is not necessary for the
rocks to actually touch
the electrode, because in this method, the electric fields are concentrated in
the rock by the high
dielectric constant (relative permittivity) of the water or fluid. The
electrical pulse must be tuned to the
electrical characteristics of the column structure and liquid in order to
provide a sufficient rate of rise
of voltage to achieve the allocation of electric field into the rock with
sufficient stress to fracture the
rock.
[00166] Another embodiment of the present invention, illustrated in Fig.
29, comprises a
reverse-flow electro-crusher wherein electrodes 202 send an electrocrushing
current to mineral (e.g.,
rock) particles 200 and wherein water or fluid 204 flows vertically upward at
a rate such that particles
200 of the size desired for the final product are swept upward, and whereas
particles that are
oversized sink downward.
[00167] As these oversized particles sink past the electrodes, a high
voltage pulse is applied
to the electrodes to fracture the particles, reducing them in size until they
become small enough to
become entrained by the water or fluid flow. This method provides a means of
transport of the
particles past the electrodes for crushing and at the same time
differentiating the particle size.
[00168] The reverse-flow crusher also provides for separating ash from
coal in that it provides
for the ash to sink to the bottom and out of the flow, while the flow provides
transport of the fine coal
particles out of the crusher to be processed for fuel.
Industrial Applicability
[00169] The invention is further illustrated by the following non-
limiting example(s).
Example 1:
[00170] An apparatus utilizing FAST Drill technology in accordance with
the present invention
was constructed and tested. Fig. 30 shows FAST Drill bit 118, the drill stem
216, the hydraulic motor
218 used to turn drill stem 216 to provide power to mechanical teeth disposed
on drill bit
- 33 -
Date recue / Date received 2021-12-14
118, slip ring assembly 220 used to transmit the high voltage pulses to the
FAST bit 118 via a power
cable inside drill stem 216, and tank 222 used to contain the rocks being
drilled. A pulsed power
system, contained in a tank (not shown), generated the high voltage pulses
that were fed into the slip
ring assembly. Tests were performed by conducting 150 kV pulses through drill
stem 216 to the
FAST Bit 118, and a pulsed power system was used for generating the 150 kV
pulses. A drilling fluid
circulation system was incorporated to flush out the cuttings. The drill bit
shown in Fig. 4 was used to
drill a 7 inch diameter hole approximately 12 inches deep in rock located in a
rock tank. A fluid
circulation system flushed the rock cuttings out of the hole, cleaned the
cuttings out of the fluid, and
circulated the fluid through the system.
Example 2:
[00171] A high permittivity fluid comprising a mixture of castor oil and
approximately 20% by
volume butylene carbonate was made and tested in accordance with the present
invention as follows.
1. Dielectric Strength Measurements.
[00172] Because this insulating formulation of the present invention is
intended for high
voltage applications, the properties of the formulation were measured in a
high voltage environment.
The dielectric strength measurements were made with a high voltage Marx bank
pulse generator, up
to 130 kV. The rise time of the Marx bank was less than 100 nsec. The
breakdown measurements
were conducted with 1-inch balls immersed in the insulating formulation at
spacings ranging from
0.06 to 0.5 cm to enable easy calculation of the breakdown fields. The delay
from the initiation of the
pulse to breakdown was measured. Fig. 31 shows the electric field at breakdown
plotted as a
function of the delay time in microseconds. Also included are data from the
Charlie Martin models for
transformer oil breakdown and for deionized water breakdown (Martin, T. H., A.
H. Guenther, M
Kristiansen J. C. Martin on Pulsed Power" Lernunn Press, (1996)).
[00173] The breakdown strength of the formulation was substantially
higher than transformer
oil at times greater than 10 sec. No special effort was expended to condition
the formulation. It
contained dust, dissolved water and other contaminants, whereas the Martin
model is for very well
conditioned transformer oil or water.
2. Dielectric Constant Measurements.
[00174] The dielectric constant was measured with a ringing waveform at
20 kV. The ringing
high voltage circuit was assembled with 8-inch diameter contoured plates
immersed in the insulating
formulation at 0.5-inch spacing. The effective area of the plates, including
fringing field effects, was
calibrated with a fluid whose dielectric constant was known (i.e., transformer
oil). An aluminum block
was placed between the plates to short out the plates so that the inductance
of the circuit could be
- 34 -
Date recue / Date received 2021-12-14
measured with a known circuit capacitance. Then, the plates were immersed in
the insulating
formulation, and the plate capacitance was evaluated from the ringing
frequency, properly accounting
for the effects of the primary circuit capacitor. The dielectric constant was
evaluated from that
capacitance, utilizing the calibrated effective area of the plate. These tests
indicated a dielectric
constant of approximately 15.
3. Conductivity Measurements.
[001751 To measure the conductivity, the same 8-inch diameter plates used
in the dielectric
constant measurement were utilized to measure the leakage current. The plates
were separated by
2-inch spacing and immersed in the insulating formulation. High voltage
pulses, ranging from 70-
150kV were applied to the plates, and the leakage current flow between the
plates was measured.
The long duration current, rather than the initial current, was the value of
interest, in order to avoid
displacement current effects. The conductivity obtained was approximately 1
micromho/cm [1X104
(ohm-ora)).
4. Water Absorption.
[001761 The insulating formulation has been tested with water content up
to 2000 ppm
without any apparent effect on the dielectric strength or dielectric constant.
The water content was
measured by Karl Fisher titration.
5. Enemy Storage Comparison.
[001771 The energy storage density of the insulating formulation of the
present invention was
shown to be substantially higher than that of transformer oil, but less than
that of deionized water.
Table 1 shows the energy storage comparison of the insulating formulation, a
transformer oil, and
water in the 1 sec and 10 sec breakdown time scales. The energy density (in
Joules/cm) was
calculated from the dielectric constant (C.00) and the breakdown electric
field (End ¨ kV/cm). The
energy storage density of the insulating formulation is approximately one-
fourth that of water at 10
microseconds. The insulating formulation did not require continuous
conditioning, as did a water
dielectric system. After about 12 months of use, the insulating formulation
remained useable without
conditioning and with no apparent degradation.
- 36 -
Date rogue/ Date received 2021-12-14
Tablet Comparison of Energy Storage Density
Time; 1 psec Time; 10 psec
Fluid Dielectic kV/ Energy kV/c Energy
Constant cm Density m Density
Insulating 15 380 9.59E-02 325 7.01E-02
formulation
Trans. Oil 2.2 500 2.43E-02 235 5.38E-03
Water 80 600 1.27E+00 280 2.78E-01
Energy density = 1/2* C * Co*Ebd *Ebd j/cm's
6. Dielectric Properties.
[00178] A summary of the dielectric properties of the insulating
formulation of the present
invention is shown in Table 2. Applications of the insulating formulation
include high energy density
capacitors, large-scale pulsed power machines, and compact repetitive pulsed
power machines.
Table 2. Summary of Formulation Properties
Dielectric = 380 kV/cm (1 psec)
Strength
Dielectric = 15
Constant
Conductivity = le-6 mho/cm
Water absorption = up to 2000 ppm with no apparent ill effects
Spiker ¨ Sustainer
[00179] Another embodiment of the present invention comprises two pulsed
power systems
coordinated to fire one right after the other.
[00180] Creating an arc inside the rock or other substrate with the
electrocrushing (EC)
process potentially comprises a large mismatch in impedance between the pulsed
power system that
provides the high voltage pulse and the arc inside the substrate. The
conductivity of the arc may be
quite high, because of the high plasma temperature inside the substrate, thus
yielding a low
impedance load to the pulsed power system requiring high current to deposit
much energy. In
contrast, the voltage required to overcome the insulative properties of the
substrate (break down the
substrate electrically) may be quite high, requiring a high impedance circuit
(high ratio of voltage to
current). The efficiency of transferring energy from the pulsed power system
into the substrate can
be quite low as a consequence of this mismatch.
- 36 -
Date rogue/ Date received 2021-12-14
[001811 The first pulsed power system, comprising a spiker, may create a
high voltage pulse
that breaks down the insuiative properties of the substrate and may create an
arc channel in the
substrate. It is designed for high voltage but low energy, at high impedance.
The second pulsed
power system, comprising a sustainer, is designed to provide high current into
the arc, but at low
voltage, thus better matching the impedance of the arc and achieving much more
efficient energy
transfer.
[001821 Fig. 32 illustrates a schematic of the spiker sustainer circuit in
operation. The spiker
circuit is charged to a high voltage. A switching apparatus subsequently
connects the spiker circuit to
an electrode set that provides an electric field to the fracturable substrate.
The high voltage pulse
from the spiker circuit exceeds the dielectric strength of the fracturable
substrate and creates a
conductive channel comprising as plasma channel in the fracturable substrate.
[001831 The sustainer circuit comprises a blocker that prevents the high
voltage pulse from
the spiker circuit from conducting into the sustainer circuit. After a
conductive channel is established,
a switch on the sustainer circuit connects the sustainer circuit to an
electrode set that in turn is
connected to the fracturable substrate. The stored energy in the sustainer
circuit then flows through
the conductive channel in the fracturable substrate, depositing energy into
the fracturable substrate to
create fractures, and finally fracturing or breaking the substrate.
[001841 The spiker-sustainer circuit is used in electrocrushing rock or
any other fracturable
medium or substrate.
[001851 The switch used in the spiker may include liquid and gas switches,
solid state
switches, and metal vapor switches.
[001861 The blocker used with the sustainer may include solid-state
diodes, liquid and gas
diodes, or high voltage chervil switches, including liquid and gas switches,
solid state switches, and
metal vapor switches.
[001871 Electrode sets connect the high voltage pulse from the spiker and
the high current
pulse from the sustainer into the substrate. The electrode sets comprise a
single electrode set or a
plurality of electrode sets disposed on the substrate, and the electrode sets
may operate off a single
spiker circuit or off a single sustainer circuit.
[001881 The spiker-sustainer circuit may comprise a plurality of circuits,
at least one of which
initiates a conductive channel and at least one of which provides the energy
into the conductive
channel.
[001891 The spiker-sustainer circuit alternately may comprise plurality of
spikers operating a
plurality of electrode sets operating with a single sustainer.
[001901 Fig. 33A illustrates spiker pulsed power system 230 and sustainer
pulsed power
system 231, both connected to center electrode 108 and to surrounding
electrode 110, both
electrodes in contact or near substrate 106. Fig 33B illustrates a typical
voltage waveform produced
- 37 -
Date rogue/ Date received 2021-12-14
by spiker 230 and sustainer 231, the high voltage narrow pulse waveform
produced by spiker 230
and the lower voltage, typically a longer duration waveform, produced by
sustainer 231. Typical
voltages for spiker 230 may range from approximately 50 to 700 kV, and/or
range from approximately
100 to 500 kV. Typical voltages produced by sustainer 231 may range from
approximately 1 to 150
kV and/or may range from approximately 10 to 100 kV. A wide variety of
switches and pulsed power
circuits can be used for either spiker 230 or sustainer 231 to switch the
stored electrical energy into
the substrate, including but not limited to solid state switches, gas or
liquid spark gaps, thyratrons,
vacuum tubes, and solid state optically triggered or self-break switches (see
Figs. 12 ¨ 15). The
energy can be stored in either capacitors 158 and 164 (see Figs. 12 ¨ 14) or
inductors 168 (see Fig.
15) and 166 (see Fig. 34).
[00191] Fig. 34 illustrates an inductive energy storage circuit
applicable to conventional and
spiker-sustainer applications, illustrating switch 160 initially closed,
circulating current from generating
means current source 156 through inductor 166. When the current is at the
correct value, switch 160
is opened, creating a high voltage pulse that is fed to FAST bit 118.
[00192] The high voltage can be created through pulsed transformer 162
(see Fig. 12) or
charging capacitors in parallel and adding them in series (see Fig. 14) or a
combination thereof (see
Fig. 13).
[00193] The spiker-sustainer pulsed power system can be located downhole
in the bottom
hole assembly, at the surface with the pulse sent over a plurality of cables,
or in an intermediate
section of the drill string.
Non-rotating electrocrushing (EC) FAST bit
[00194] Fig. 35 illustrates non-rotating electrocrushing FAST bit 118,
showing center
electrode 108 of a typical electrode set and surrounding electrode 110
(without mechanical teeth
since the bit does not rotate).
[00195] Fig. 36 illustrates a perspective view of the same typical FAST
electrocrushing non-
rotating bit, more clearly showing the center grouping of electrode sets on
the non-conical part of the
bit and the side electrode sets located on the conical portion of the bit. An
asymmetric configuration
of the electrode sets is another embodiment providing additional options for
bit directional control, as
illustrated in Fig. 37.
[00196] The non-rotating bit may be designed with a plurality of
electrocrushing electrode
sets with the sets divided in groups of one or more electrode sets per group
for directional control.
For example, in Fig. 35, the electrocrushing electrode sets may be divided
into four groups: the
center three electrode sets as one group and the outer divided into three
groups of two electrode sets
each. Each group of electrode sets is powered by a single conductor. The first
electrode set in a
group to achieve ignition through the rock or substrate is the one that
excavates. The other electrode
- 38 -
Date recue / Date received 2021-12-14
sets in that group do not fire because the ignition of the first electrode set
to ignite causes the voltage
to drop on that conductor and the other electrode sets in that group do not
fire. The first electrode set
to ignite excavates sufficient rock out in front of it that it experiences an
increase in the required
voltage to ignite and a greater ignition delay because of the greater arc path
through the rock,
causing another electrode set in the group to ignite first.
[001971 The excavation process may be self-regulating and all the
electrode sets in a group
may excavate at approximately the same rate. The nine electrode sets shown in
Fig. 35 may require
four pulsed power systems to operate the bit. Alternatively, the nine
electrode sets in the bit of Fig.
35 are each operated by a single pulsed power system, e.g. requiring nine
pulsed power systems to
operate the bit. This configuration may provide precise directional control of
the bit compared to the
four pulsed power system configuration, but at a cost of greater complexity.
[001981 Directional control may be achieved by increasing the pulse
repetition rate or pulse
energy for those conical electrode sets toward which it is desired to turn the
bit. For example, as
illustrated in Fig. 35, either the pulse repetition rate or pulse energy are
increased to that group of
electrode sets compared to the other two groups of conical electrode sets to
turn towards the pair of
electrodes mounted on the conical portion of the bit as shown at the bottom of
Fig. 36. The bottom
electrode sets subsequently excavate more rock on that side of the bit than
the other two groups of
conical electrode sets and the bit preferably tends to turn in the direction
of the bottom pair of
electrode sets. The power to the center three electrode sets preferably
changes only enough to
maintain the average bit propagation rate through the rock. The group of
center electrodes do not
participate in the directional control of the bit.
(00199) The term "rock" as used herein is intended to include rocks or any
other substrates
wherein drilling is needed.
(00200) The two conical electrode sets on the bottom and the bottom center
electrode may all
participate in the directional control of the bit when nine pulsed power
systems are utilized to power
the non-rotating bit with each electrode set having its own pulsed power
system.
(00201) Another embodiment comprises arranging all the electrocrushing
electrode sets in a
conical shape, with no a fiat portion to the bit, as shown in Figure 6.
[002021 Fig. 36 illustrates a perspective view of the same typical FAST
electrocrushing non-
rotating bit, more clearly illustrating the center grouping of electrode sets
on the non-conical part of
the bit and the side electrode sets located on the conical portion of the bit.
[002031 Fig. 37 illustrates a typical FAST electrocrushing non-rotating
bit with an asymmetric
arrangement of the electrode sets. Another embodiment comprising a non-
rotating bit system
utilizing continuous coiled tubing to provide drilling fluid to the non-
rotating drill bit, comprising a cable
to preferably bring electrical power from the surface to the downhole pulsed
power system, as shown
in Fig. 37.
- 39 -
Date rogue/ Date received 2021-12-14
[00204] Bottom hole assembly 242, as illustrated in Figs. 38 and 39,
comprises FAST
electrocrushing bit 118, electrohydraulic projectors 243, drilling fluid pipe
147, power cable 148, and
pulsed power subsystem 244 that may comprise the pulsed power system and other
components of
the downhole drilling assembly (not shown).
[00205] The cable may be located inside the continuous coiled tubing, as
shown in Fig. 37 or
outside. This embodiment does not comprise a down-hole generator, overdrive
gear, or generator
drive mud motor or a bit rotation mud motor, since the bit does not rotate.
Another embodiment
utilizes segmented drill pipe to provide drilling fluid to the non-rotating
drill bit, with a cable either
outside or inside the pipe to bring electrical power and control signals from
the surface to the
downhole pulsed power system.
[00206] In another embodiment, part of the total fluid pumped down the
fluid pipe is diverted
through the backside electrohydraulic projectors/electrocrushing electrode
sets when in normal
operation. The fluid flow rate required to clean the rock particles out of the
hole is greater above the
bottom hole assembly than at the bottom hole assembly, because typically the
diameter of the fluid
pipe and power cable is less than the diameter of the bottom hole assembly,
requiring greater
volumetric flow above the bottom hole assembly to maintain the flow velocity
required to lift the rock
particles out of the well.
[00207] Another embodiment of the present invention comprises the method
of backwards
excavation. Slumping of the hole behind the bit, wherein the wall of the well
caves in behind the
bottom hole assembly, blocking the ability of the bottom hole assembly to be
extracted from the well
and inhibiting further drilling because of the blockage, as shown in Fig. 38,
can sometimes occur. An
embodiment of the present invention comprises the electrical-driven excavation
processes of the
FAST drill technology. An embodiment of the present invention comprises the
application of the
electrocrushing process to drilling. A combination of the electrohydraulic or
plasma-hydraulic process
with electrocrushing process may also be utilized to maximize the efficacy of
the complete drilling
process. The electrohydraulic projector may create an electrical spark in the
drilling fluid, not in the
rock. The spark preferably creates an intense shock wave that is not nearly as
efficient in fracturing
rock as the electrocrushing process, but may be advantageous in extracting the
bit from a damaged
well. A plurality of electrohydraulic projectors may be installed on the back
side of the bottom hole
assembly to preferably enable the FAST Drill to drill its way out of the
slumped hole. At least one
electrocrushing electrode set may comprise an addition to efficiently excavate
larger pieces of rock
that have slumped onto the drill bottom hole assembly. An embodiment of the
present invention may
comprise only electrocrushing electrode sets on the back of the bottom hole
assembly, which may
operate advantageously in some formations.
[00208] Fig. 38 illustrates bottom hole assembly 242 comprising FAST
electrocrushing bit
118, electrohydraulic projectors 243, drilling fluid pipe 147, power cable
148, and pulsed power
-40 -
Date recue / Date received 2021-12-14
subsystem 244 that may contain the pulsed power system (not shown) and other
components of the
downhole drilling assembly. Fig. 38 illustrates electrohydraulic projectors
243 installed on the back of
bottom hole assembly 242. Inside the bottom hole assembly a plurality of
switches (not shown) may
be disposed that may be activated from the surface to switch the electrical
pulses that are sent to the
electrocrushing non-rotating bit and are alternately sent to power the
electrohydraulic
projectors/electrocrushing electrode sets disposed on the back side of the
bottom hole assembly. The
spiker-sustainer system for powering the electrocrushing electrode sets in the
main non-rotating bit
may improve the efficiency of the electrohydraulic projectors disposed at the
back of the bottom hole
assembly. Alternately, an electrically actuated valve diverts a portion of the
drilling fluid flow pumped
down the fluid pipe to the back electrohydraulic projectors/ electrocrushing
electrode sets and flushes
the slumped rock particles up the hole.
[00209] In another embodiment of the present invention, electrohydraulics
alone or
electrohydraulic projectors in conjunction with electrocrushing electrode sets
may be used at the back
of the bottom hole assembly. The electrohydraulic projectors are especially
helpful because the high
power shock wave breaks up the slumped rock behind the bottom hole assembly
and disturbs the
rock above it. The propagation of the pressure pulse through the slumped rock
disturbs the rock,
providing for enhanced fluid flow through it to carry the rock particles up
the well to the surface. As
the bottom hole assembly is drawn up to the surface, the fluid flow carries
the rock particles to the
surface, and the pressure pulse continually disrupts the slumped rock to keep
it from sealing the hole.
One or more electrocrushing electrode sets may be added to the plurality of
projectors at the back of
the bottom hole assembly to further enhance the fracturing and removal of the
slumped rock behind
the bottom hole assembly.
[00210] In another embodiment of the present invention comprising the
FAST drill, a cable
may be disposed inside the fluid pipe and the fluid pipe may comprise a
rotatable drill pipe.
Mechanical teeth 116 may be installed on the back side of the bottom hole
assembly and the bottom
hole assembly may be rotated to further assist the
electrohydraulic/electrocrushing projectors in
cleaning the rock from behind the bottom hole assembly. The bottom hole
assembly is rotated as it is
pulled out while the electrohydraulic projectors/electrocrushing electrode
sets are fracturing the rock
behind the bottom hole assembly and the fluid is flushing the rock particles
up the hole.
[00211] Fig. 39 shows bottom hole assembly 242 in the well with part of
the wall of the well
slumped around the top of the drill and drill pipe 147, trapping the drill in
the hole with rock fragments
245.
[00212] Embodiments of the present invention described herein may also
include, but are not
limited to the following elements or steps:
[00213] The invention may comprise a plurality of electrode sets disposed
on the bit. The
pulse repetition rate as well as the pulse energy produced by the pulsed power
generator is variably
- 41 -
Date recue / Date received 2021-12-14
directed to different electrode sets, thus breaking more substrate from one
side of the bit than another
side, thus causing the bit to change direction. Thus, the bit is steered
through the substrate;
[002141 The electrode sets comprise groups of arranged sets. The electrode
sets are
connected with a single connection to the pulsed power generator for each
group of arranged set
[002151 The present invention comprises a single connection provided from
the pulsed power
generator to each electrode set disposed on the bit. The present invention
comprises a single
connection provided from the pulsed power generator to some of the electrode
sets disposed on the
bit. The remaining electrode sets are arranged into one or a plurality of
groups with a single
connection to the pulsed power generator for each group.
[002161 The present invention comprises a plurality of electrode sets
disposed on the drill bit.
The pulse repetition rate or pulse energy is applied differently to different
electrode sets on the bit for
the purpose of steering the bit from the differential operation of the
electrode sets.
[002171 The present invention comprises a plurality of electrode sets
arranged in groups.
The pulse repetition rate or pulse energy is applied differently to different
groups of electrode sets for
the purpose of steering the bit from the differential operation of electrode
sets.
[002181 The present invention comprises a plurality of electrode sets
arranged along a face of
the drill bit with symmetry relative to the axis of the direction of motion of
the drill bit.
[002191 Additionally, the present invention comprises a plurality of
electrode sets arranged
along a face of the drill bit with some of the electrode sets not having
symmetry relative to the axis of
the direction of motion of the drill bit.
[002201 The arrangement of the electrode sets comprises conical shapes
comprising axes
substantially parallel to the axis of the direction of motion of the drill
bit. Additionally, the arrangement
of the electrode sets comprises conical shapes comprising axes at an angle to
the axis of the
direction of motion of the drill bit Additionally, the arrangement of the
electrode sets comprises a flat
section perpendicular to the direction of motion of the drill bit in
conjunction with a plurality of conical
shapes comprising axes substantially oriented to the axis of the direction of
motion of the drill bit.
(00221) The present invention comprises providing electrode sets arranged
into groups with a
single connection to a voltage and current pulse source for each group.
[002221 The present invention comprises providing a single connection to a
voltage and
current pulse source for each electrode set on the bit. Alternately, the
present invention comprises
providing a single connection to a voltage and current pulse source for each
of some of the electrode
sets on the bit while arranging the remaining electrode sets into at least one
group with a single
connection to a voltage and current pulse source for each group.
[00223] The present invention comprises tuning the current pulse to the
substrate properties
so that the substrate is broken beyond the boundaries of the electrode set.
- 42 -
Date rogue/ Date received 2021-12-14
[002241 The present invention comprises providing a power conducting means
comprising a
cable for providing power to a FAST drill bottom hole assembly. The cable is
disposed inside a fluid
conducting means for conducting drilling fluid from the surface to the bottom
hole assembly.
Alternately, the cable is disposed outside a fluid conducting means
[002251 The present invention comprises a bottom hole assembly comprising
a drill bit, a
connector for connecting the drill bit to the pulsed power generator, and a
transmitter for transmitting
the drilling fluid to the bit, and a housing.
[002261 The present invention comprises a bottom hole assembly comprises
at least one
electrohydraulic projector installed on a side of the bottom hole assembly not
in the direction of
drilling. The present invention comprises a bottom hole assembly comprising at
least one
electrocrushing electrode set installed on a side of the bottom hole assembly
not in the direction of
drilling.
[002271 The present invention comprises a switch disposed in the bottom
hole assembly for
switching the power from the pulsed power generator from at least one of the
bit electrode sets to the
electrocrushing electrode set or electrohydraulic projector.
[002281 The present invention further comprises a valve in the bottom hole
assembly for
diverting at least a portion of the drilling fluid from the bit to the
electrocrushing electrode set or
electrohydraulic projector.
(002291 The present invention comprises a cable disposed inside the fluid
pipe, with the fluid
pipe comprising a rotatable drill pipe, and mechanical cutting teeth installed
on the back side of the
bottom hole assembly so the bottom hole assembly can be rotated to clean the
rock from behind the
bottom hole assembly.
[002301 The present invention comprises a method of drilling backwards out
of a damaged or
slumped or caved in well, the method utilizing at least one electrohydraulic
projector installed on a
side of the bottom hole assembly not in the direction of drilling. The present
invention further
comprises creating a pressure wave propagating backwards in the well, i.e.
opposite the direction of
drilling, to assist in cleaning the substrate particles out of a damaged or
slumped or caved-in well,
utilizing at least one electrohydraulic projector installed on a side of the
bottom hole assembly not in
the direction of drilling. The present invention comprises a method of
drilling backwards out of a
damaged or slumped or caved-in well utilizing at least one electrocrushing
electrode set installed on a
side of the bottom hole assembly not in the direction of drilling.
(002311 The present invention comprises a switch disposed in the bottom
hole assembly for
switching the power from the pulsed power generator from at least one of the
bit electrode sets to the
electrocrushing electrode set or electrohydraulic projector. The present
invention further comprises a
valve disposed in the bottom hole assembly to divert at least a portion of the
drilling fluid from the bit
to the electrocrushing electrode set or electrohydraulic projector.
- 43 -
Date rogue/ Date received 2021-12-14
[002321 The present invention comprises a method of creating a backwards
flow of drilling
fluid in the well (i.e. opposite to the direction of drilling) to assist in
cleaning the substrate particles out
of a damaged or slumped or caved-in well, further utilizing a valve in the
bottom hole assembly to
divert at least a portion of the drilling fluid from the bit to the back of
the bottom hole assembly.
[002331 The present invention further comprises a method of balancing the
fluid flow through
the bit, around the bottom hole assembly and through the well, diverting at
least a portion of the
drilling fluid in the bottom hole assembly from the bit to the back of the
bottom hole assembly during
normal drilling operation. The present invention further comprises a method of
cleaning the substrate
out of a damaged or slumped or caved-in well and enabling the bottom hole
assembly to drill
backwards to the surface by further providing a mechanical cutter installed on
the back side of a
rotatable bottom hole assembly and drill string, and rotating the bottom hole
assembly to clean the
substrate from behind the bottom hole assembly.
[002341 The present invention comprises a method of utilizing at least one
initial high voltage
pulse to overcome the insulative properties of the substrate, followed by
providing at least one high
current pulse from a different source impedance from the initial pulse or
pulses, thus providing
sufficient energy to break the substrate.
[002351 The present invention comprises utilizing a pulse transformer for
creating high
voltage pulses and high current pulses. The present invention alternately
comprises creating high
voltage pulses and high current pulses by charging capacitors in parallel and
adding them in series or
a combination of parallel and series. The high voltage pulses and the high
current pulses use
electrical energy stored in either capacitors or inductors or a combination of
capacitors and inductors.
[002361 The present invention comprises providing a pulsed power system
comprising a
pulsed power generator for providing at least one initial high voltage pulse
to overcome the insulative
properties of the substrate, comprising a spiker, followed by at least one
high current pulse to provide
the energy to break the substrate, comprising a sustainer.
[00237] The present invention comprises a spiker-sustainer pulsed power
system comprising
solid state switches, gas or liquid spark gaps, thyratrons, vacuum tubes,
solid state optically triggered
switches, and self-break switches. The spiker-sustainer pulsed power system
comprises capacitive
energy storage, inductive energy storage, or a combination of capacitive
energy storage and
inductive energy storage. The spiker-sustainer pulsed power system creates the
high voltage pulse
by a pulse transformer or by charging capacitors in parallel and adding them
in series or a
combination of capacitive energy storage and inductive energy storage.
[00238] The spiker-sustainer pulsed power system is located downhoie in a
bottom hole
assembly, at the surface with the pulse sent over one or a plurality of
cables, or in an intermediate
section of the drill string. The cable is disposed inside a fluid conducting
apparatus for conducting
- 44 -
Date rogue/ Date received 2021-12-14
drilling fluid from the surface to the bottom hole assembly. The cable is
alternately disposed outside
a fluid conducting apparatus for conducting drilling fluid from the surface to
the bottom hole assembly.
[00239] The preceding examples can be repeated with similar success by
substituting the
generically or specifically described compositions, biomaterials, devices
and/or operating conditions
of this invention for those used in the preceding examples.
[00240] Although the invention has been described in detail with
particular reference to these
preferred embodiments, other embodiments can achieve the same results.
Variations and
modifications of the present invention will be obvious to those skilled in the
art and it is intended to
cover all such modifications and equivalents. .
[00241] As used in the specification and claims herein, the terms "a",
"an", and "the" mean
one or more.
[00242] An embodiment of the present invention provides a drill bit on
which is disposed one
or more sets of electrodes. In this embodiment, the electrodes are disposed so
that a gap is formed
between them and are disposed on the drill bit so that they are oriented along
a face of the drill bit. In
other words, the electrodes between which an electrical current passes through
a mineral substrate
(e.g., rock) are not on opposite sides of the rock. Also, in this embodiment,
it is not necessary that all
electrodes touch the mineral substrate as the current is being applied. In
accordance with this
embodiment, at least one of the electrodes extending from the bit toward the
substrate to be fractured
and may be compressible (i.e., retractable) into the drill bit by any means
known in the art such as, for
example, via a spring-loaded mechanism.
[00243] The preferred embodiment of the present invention (see Figs. 48-
50) comprises a
drill bit with multiple electrode sets arranged at the tip of the drill stem,
each electrode set being
independently supplied with electric current to pass through the substrate. By
varying the repetition
rate of the high voltage pulses, the drill changes direction towards those
electrode sets having the
higher repetition rate. Thus the multi-electrode set drill stem is steered
through the rock by the control
system, independently varying the pulse repetition rate to the electrode sets.
[00244] To accomplish the control of the electrode sets independently, a
multi-conductor
power cable is used with each electrode set connected, either separately or in
groups, to individual
conductors in the cable. A switch is used at the pulse generator to
alternately feed the pulses to the
conductors and hence to the individual electrode sets according to the
requirements set by the control
system. Alternatively, a switch is placed in the drill stem to distribute
pulses sent over a single-
conductor power cable to individual electrode sets. Because the role of each
electrode set is to
excavate a small amount of rock, it is not necessary for the electrode sets to
operate simultaneously.
-45 -
Date recue / Date received 2021-12-14
A change in direction is achieved by changing the net amount of rock excavated
on one side of the bit
compared to the other side.
[00245] To further enhance the transmittal of power from the pulse
generator to the rock,
individual capacitors are located inside the drill stem, each connected,
individually or in groups, to the
individual electrode sets. This enhances the peak current flow to the rock,
and improves the power
efficiency of the drilling process. The combination of capacitors and
switches, or other pulse forming
circuitry and components such as inductors, are located in the drill stem to
further enhance the power
flow into the rock.
[00246] Accordingly, an embodiment of the present invention provides a
drill bit on which is
disposed one or more sets of electrodes. In this embodiment, the electrodes
are disposed so that a
gap is formed between them and are disposed on the drill bit so that they are
oriented along a face of
the drill bit. In other words, the electrodes between which an electrical
current passes through a
mineral substrate (e.g., rock) are not on opposite sides of the rock. Also, in
this embodiment, it is not
necessary that all electrodes touch the mineral substrate as the current is
being applied. In
accordance with this embodiment, at least one of the electrodes extending from
the bit toward the
substrate to be fractured and may be compressible (i.e., retractable) into the
drill bit by any means
known in the art such as, for example, via a spring-loaded mechanism.
[00247] Generally, but not necessarily, the electrodes are disposed on the
bit such that at
least one electrode contacts the mineral substrate to be fractured and another
electrode that usually
touches the mineral substrate but otherwise may be close to, but not
necessarily touching, the
mineral substrate so long as it is in sufficient proximity for current to pass
through the mineral
substrate. Typically, the electrode that need not touch the substrate is the
central, not the
surrounding, electrode.
[00248] Therefore, the electrodes are disposed on a bit and arranged such
that
electrocrushing arcs are created in the rock. High voltage pulses are applied
repetitively to the bit to
create repetitive electrocrushing excavation events. Electrocrushing drilling
can be accomplished, for
example, with a flat-end cylindrical bit with one or more electrode sets.
These electrodes can be
arranged in a coaxial configuration.
[00249] Generally, but not necessarily, the electrodes are disposed on the
bit such that at
least one electrode contacts the mineral substrate to be fractured and another
electrode that usually
touches the mineral substrate but otherwise may be close to, but not
necessarily touching, the
mineral substrate so long as it is in sufficient proximity for current to pass
through the mineral
substrate. Typically, the electrode that need not touch the substrate is the
central, not the
surrounding, electrode.
[00250] Therefore, the electrodes are disposed on a bit and arranged such
that
electrocrushing arcs are created in the rock. High voltage pulses are applied
repetitively to the bit to
- 46 -
Date rogue/ Date received 2021-12-14
create repetitive electrocrushing excavation events. Electrocrushing drilling
can be accomplished, for
example, with a flat-end cylindrical bit with one or more electrode sets.
These electrodes can be
arranged in a coaxial configuration.
[002511 An embodiment of the present invention incorporating a drill bit
as described herein
thus provides a portable electrocrushing drill that utilizes an electrical
plasma inside the rock to crush
and fracture the rock. A portable drill stem is preferably mounted on a cable
(preferably flexible) that
connects to, or is integral with, a pulse generator which then connects to a
power supply module. A
separate drill holder and advance mechanism is preferably utilized to keep the
drill pressed up
against the rock to facilitate the drilling process. The stem itself is a
hollow tube preferably
incorporating the insulator, drilling fluid flush, and electrodes. Preferably,
the drill stem is a hard
tubular structure of metal or similar hard material that contains the actual
plasma generation
apparatus and provides current return for the electrical pulse. The stem
comprises a set of
electrodes at the operating end. Preferably, the drill stem includes a
capacitor to enhance the current
flow through the rock. These electrodes are typically circular in shape but
may have a convoluted
shape for preferential arc management. The center electrode is preferably
compressible to maintain
connection to the rock. The drill tip preferably incorporates replaceable
electrodes, which are field
replaceable units that can be, for example, unscrewed and replaced in the
mine. Alternatively, the
pulse generator and power supply module can be integrated into one unit. The
electrical pulse is
created in the pulse generator and then transmitted along the cable to the
drill stem and preferably to
the drill stem capacitor. The pulse creates an arc or plasma in the rock at
the electrodes. Drilling
fluid flow from inside the drill stem sweeps out the crushed material from the
hole. The system is
preferably sufficiently compact so that it can be manhandled inside
underground mine tunnels.
[002521 When the drill is first starting into the rock, it is highly
preferable to seal the surface of
the rock in the vicinity of the starting point when drilling vertically. To
accomplish this, a fluid
containment or entrapment component provided to contain the drilling fluid
around the head of the
drill to insulate the electrodes. One illustrative embodiment of such a fluid
containment component of
the present invention comprises a boot made of a flexible material such as
plastic or rubber. The
drilling fluid flow coming up through the insulator and out the tip of the
drill then fills the boot and
provides the seal until the drill has progressed far enough into the rock to
provide its own seal. The
boot may either be attached to the tip of the drill with a sliding means so
that the boot will slide down
over the stem of the drill as the drill progresses into the rock or the boot
may be attached to the guide
tube of the drill holder so that the drill can progress into the rock and the
boot remains attached to the
launch tube.
[002531 The fluid used to insulate the electrodes preferably comprises a
fluid that provides
high dielectric strength to provide high electric fields at the electrodes,
low conductivity to provide low
leakage current during the delay time from application of the voltage until
the arc ignites in the rock,
- 47 -
Date rogue/ Date received 2021-12-14
and high relative permittivity to shift a higher proportion of the electric
field into the rock near the
electrodes. More preferably, the fluid comprises a high dielectric constant,
low conductivity, and high
dielectric strength. Still more preferably, the fluid comprises having an
electrical conductivity less
than 104 mho/cm and a dielectric constant greater than 6. The drilling fluid
further comprises having
a conductivity less than approximately 10-4 mho/cm and a dielectric constant
greater than
approximately 40 and including treated water.
[00254] The distance from the tip to the pulse generator represents
inductance to the power
flow, which impeded the rate of rise of the current is flowing from the pulse
generator to the drill. To
minimize the effects of this inductance, a capacitor is installed in the drill
stem, to provide high current
flow in to the rock plasma, to increase drilling efficiency.
[002551 The cable that carries drilling fluid and electrical power from
the pulse generator to
the drill stem is fragile. If a rock should fall on it or it should be run
over by a piece of equipment, it
would damage the electrical integrity, mash the drilling fluid line, and
impair the performance of the
drill. Therefore, this cable is preferably armored, but in a way that permits
flexibility. Thus, for
example, one embodiment comprises a flexible armored cable having a corrugated
shape that is
utilized as a means for advancing the drill into the hole when the drill hole
depth exceeds that of the
stem.
[002563 Preferably, a pulse power system that powers the bit provides
repetitive high voltage
pulses, usually over 30 kV. The pulsed power system can include, but is not
limited to:
(1) a solid state switch controlled or gas-switch controlled pulse generating
system with a
pulse transformer that pulse charges the primary output capacitor;
(2) an array of solid-state switch or gas-switch controlled circuits that are
charged in parallel
and in series pulse-charge the output capacitor;
(3) a voltage vector inversion circuit that produces a pulse at about twice,
or a multiple of, the
charge voltage;
(4) An inductive store system that stores current in an inductor, then
switches it to the
electrodes via an opening or transfer switch; or
(5) any other pulse generation circuit that provides repetitive high voltage,
high current
pulses to the drill bit.
[002571 The present invention substantially improves the production of
holes in a mine. In an
embodiment, the production drill could incorporate two drills operating out of
one pulse generator box
with a switch that connects either drill to the pulse generator. In such a
scenario, one operator can
operate two drills. The operator can be setting up one drill and positioning
it while the other drill is in
operation. At a drilling rate of 0.5 meter per minute, one operator can drill
a one meter deep hole
approximately every four minutes with such a set up. Because there is no
requirement for two
operators, this dramatically improves productivity and substantially reduces
labor cost.
- 48 -
Date rogue/ Date received 2021-12-14
[002581 Turning now to the figures, which describe non-limiting
embodiments of the present
invention that are illustrative of the various embodiments within the scope of
the present invention,
Fig. 40 shows the basic concept of the drilling stem of a portable
electrocrushing mining drill for
drilling in hard rock, concrete or other materials. Pulse cable 10 brings an
electrical pulse produced
by a pulse modulator (not shown in Fig. 40) to drill tip 11 which is enclosed
in drill stem 12. The
electrical current creates an electrical arc or plasma inside the rock between
drill tip 11 and drill stem
12. Drill tip 11 is preferably compressible to maintain contact with the rock
to facilitate creating the
arc inside the rock. A drilling fluid delivery component such as, but not
limited to, fluid delivery
passage 14 in stem 12 feeds drilling fluid through electrode gap 15 to flush
debris out of gap 15.
Drilling fluid passages 14 or other fluid in stem 12 are fed by a drilling
fluid line 16 embedded with
pulse cable 10 inside armored jacket 17. Boot holder 18 is disposed on the end
of drill stem 12 to
hold the boot (shown in Fig. 42) during the stetting of the drilling process.
Boot 23 is used to capture
drilling fluid flow coming through gap 15 and supplied by drilling fluid
delivery passage 14 during the
starting process. As the drill progresses into the rock or other material,
boot 23 slides down stem 12
and down armored jacket 17.
[002591 Fig. 41 is a close-up view of tip 11 of portable electrocrushing
drill stem 12, showing
drill tip 11, discharge gap 15, and replaceable outer electrode 19. The
electrical pulse is delivered to
tip 11. The plasma then forms inside the rock between tip 11 and replaceable
outer electrode 19.
Insulator 20 has drilling fluid passages 22 built into insulator 20 to flush
rock dust out of the base of
insulator 20 and through gap 15. The drilling fluid is provided into insulator
20 section through drilling
fluid delivery line 14.
[002601 Fig. 42 shows drill stem 12 starting to drill into rock 24. Boot
23 is fitted around drill
stem 12, held in place by boot holder 18. Boot 23 provides means of containing
the drilling fluid near
rock surface 24, even when drill stem 12 is not perpendicular to rock surface
24 or when rock surface
24 is rough and uneven. As drill stem 12 penetrates into rock 24, boot 23
slides down over boot
holder 18.
[002611 Fig. 43 shows an embodiment of the portable electrocrushing mining
drill utilizing drill
stem 12 described in Figs. 40-42. Drill stern 12 is shown mounted on jackleg
support 25, that
supports drill stem 12 and advance mechanism 26. Armored cable 17 connects
drill stem 12 to pulse
generator 27. Pulse generator 27 is then connected in turn by power cable 28
to power supply 29.
Armored cable 17 is typically a few meters long and connects drill stem 12 to
pulse generator 27.
Armored cable 17 provides adequate flexibility to enable drill stem 12 to be
used in areas of low roof
height Power supply 29 can be placed some long distance from pulse generator
27. Drilling fluid
inlet line 30 feeds drilling fluid to drilling fluid line 16 (not shown)
contained inside armored cable 17.
A pressure switch (not shown) may be installed in drilling fluid line 16 to
ensure that the drill does not
operate without drilling fluid flow.
- 49 -
Date rogue/ Date received 2021-12-14
[002621 Fig. 44 shows an embodiment of the subject invention with two
drills being operated
off single pulse generator 27. This figure shows drill stem 12 of operating
drill 31 having progressed
some distance into rock 24. Jack leg support 25 provides support for drill
stem 12 and provides
guidance for drill stem 12 to propagate into rock 24. Pulse generator 27 is
shown connected to both
drill stems 12. Drill 32 being set up is shown in position, ready to start
drilling with its jack leg 25 in
place against the roof. Power cable 28, from power supply 29 (not shown in
Fig. 44) brings power to
pulse generator 27. Drilling fluid feed line 30 is shown bringing drilling
fluid into pulse generator 27
where it then connects with drilling fluid line 16 contained in armored cable
17. In this embodiment,
while one drill is drilling a hole and being powered by the pulse generator,
the second drill is being set
up. Thus one man can accomplish the work of two men with this invention.
[002631 Fig. 45 shows jack leg support 25 supporting guide structure 33
which guides drill 12
into rock 24. Cradle or tube guide structure 33 holds drill stem 12 and guides
it into the drill hole.
Guide structure 33 can be tilted at the appropriate angle to provide for the
correct angle of the hole in
rock 24. Fixed boot 23 can be attached to the end of guide tube 33 as shown in
Fig. 45. Advance
mechanism 26 grips the serrations on armored cable 17 to provide thrust to
maintain drill tip 11 in
contact with rock 24. Note that advance mechanism 26 does not do the drilling.
It is the plasma
inside the rock that actually does the drilling. Rather, advance mechanisms 26
keeps drill tip 15 and
outer electrode 19 in close proximity to rock 24 for efficient drilling. In
this embodiment, boot 23 is
attached to the uppermost guide loop rather than to drill 12. In this
embodiment, drill 12 does not
utilize boot holder 18, but rather progresses smoothly through boot 23 into
rock 24 guided by the
guide loops that direct drill 12.
[002641 Fig. 46 shows a further embodiment wherein the drilling fluid line
is built into drill stem
12. Energy is stored in capacitor 13, which is delivered to tip 11 by
conductor 34 when the electric
field inside the rock breaks down the rock, creating a path for current
conduction inside the rock. The
low inductance created by the location of the capacitor in the stem
dramatically increases the
efficiency of transfer of energy into the rock. The capacitor is pulse charged
by the pulse generator
27. Center conductor 34 is surrounded by capacitor 13, which then is nested
inside drill stem 12
which incorporates drilling fluid passage 14 inside the stem wall. In this
embodiment, drill tip 11 is
easily replaceable and outer conductor 19 is easily replaceable. An
alternative approach is to use
slip-in electrodes 19 that are pinned in place. This is a very important
feature of the subject invention
because it enables the drill to be operated extensively in the mine
environment with the high
electrode erosion that is typical of high energy, high power operation.
[00265] Figs. 47A-470 show different, though not limiting, embodiments of
the electrode
configurations useable in the present invention. Figs. 47A, 478, and 47C show
circular electrodes,
Fig. 47E shows convoluted shape electrodes (the outer electrodes are
convoluted), and Fig. 47D
- 60 -
Date rogue/ Date received 2021-12-14
shows a combination thereof. Fig. 46 shows a coaxial electrode oonfiguration.
For longer holes or
for holes with a curved trajectory, the multi-electrode set drill tip is used.
[002661 Fig. 48 shows an embodiment of multi-electrode set drill tip 130
for directional drilling,
showing high-voltage electrodes 132, inter-electrode insulator 133, and ground
return electrodes 131
and 135. Figure 49 shows the multi-electrode set embodiment of the drill
showing a plurality of
electrode sets 130, mounted on the tip of drill stem 49, capacitors 40,
inductors 41, and switch 42 to
connect each of the electrode sets to flexible cable 43 from the pulse
generator (not shown). Figure
50 shows multi-conductor cable 44 connecting electrode sets 130 and capacitors
40 and inductors 41
to diverter switch 42 located in pulse generator assembly 45.
[002671 The operation of the drill is preferably as follows. The pulse
generator is set into a
location from which to drill a number of holes. The operator sets up a jack
leg and installs the drill in
the cradle with the advance mechanism engaging the armored jacket and the boot
installed on the tip.
The drill is started in its hole at the correct angle by the cradle on the
jack leg. The boot has an offset
in order to accommodate the angle of the drill to the rock. Once the drill is
positioned, the operator
goes to the control panel, selects the drill stem to use and pushes the start
button which turns on
drilling fluid flow. The drill control system first senses to make sure there
is adequate drilling fluid
pressure in the drill. If the drill is not pressed up against the rock, then
there will not be adequate
drilling fluid pressure surrounding the drill tips and the drill will not
fire. This prevents the operator
from engaging the wrong drill and also prevents the drill from firing in the
open air when drilling fluid is
not surrounding the drill tip. The drill then starts firing at a repetition
rate of several hertz to hundreds
of hertz. Upon a fire command from the control system, the primary switch
connects the capacitors,
which have been already charged by the power supply, to the cable. The
electrical pulse is then
transmitted down the cable to the stem where it pulse charges the stem
capacitor. The resulting
electric field causes the rock to break down and causes current to flow
through the rock from
electrode to electrode. This flowing current creates a plasma which fractures
the rock. The drilling
fluid that is flowing up from the drill stem then sweeps the pieces of crushed
rock out of the hole. The
drilling fluid flows in a swirl motion out of the insulator and sweeps up any
particles of rock that might
have drifted down inside the drill stem and flushes them out the top. When the
drill is first starting, the
rock particles are forced out under the lip of the boot. When the drill is
well into the rock then the rock
particles are forced out along the side between the drill and the rock hole.
The drill maintains its
direction because of its length. The drill should maintain adequate
directional control for
approximately 4-8 times its length depending on the precision of the hole.
[00268) While the first drill is drilling, the operator then sets up the
other jack-leg and
positions the second drill. Once the first drill has completed drilling, the
operator then selects the
second drill and starts it drilling. While the second drill is drilling, the
operator moves the first drill to a
- 51 -
Date rogue/ Date received 2021-12-14
new location and sets it up to be ready to drill. After several holes have
been drilled, the operator will
move the pulse generator box to a new location and resume drilling.
[002691 The following further summarizes features of the operation of the
system of the
present invention. An electrical pulse is transmitted down a conductor to a
set of removable
electrodes where an arc or plasma is created inside the rock between the
electrodes. Drilling fluid
flow passes between the electrodes to flush out particles and maintain
cleanliness inside the drilling
fluid cavity in the region of the drilling tip. By making the drill tips
easily replaceable, for example,
thread-on units, they can be easily replaced in the mine environment to
compensate for wear in the
electrode gap. The embedded drilling fluid channels provide drilling fluid
flow through the drill stem to
the drill tip where the drilling fluid flushes out the rock dust and chips to
keep from clogging the
interior of the drill stem with chips and keep from shorting the electrical
pulse inside the drill stem near
the base of the drill tip.
[002701 Mine water is drawn into the pulse generator and is used to cool
key components
through a heat exchanger. Drilling fluid is used to flush the crushed rock out
of the hole and maintain
drilling fluid around the drill tip or head. The pulse generator box is
hermetically sealed with all of the
high voltage switches and cable connections inside the box. The box is
pressurized with a gas or
filled with a fluid or encapsulated to insulate it. Because the pulse
generator is completely sealed,
there is no potential of exposing the mine atmosphere to a spark from it. The
drill will not operate and
power will not be sent to the drill stem unless the drilling fluid pressure
inside the stem is high enough
to ensure that the drill tip is completely flooded with drilling fluid. This
will prevent a spark from
occurring in air at the drill tip. These two features should prevent any
possibility of an open spark in
the mine.
[002711 There is significant inductance in the circuit between the pulse
generator and the drill
stem. This is unavoidable because the drill stem must be positioned some
distance away from the
pulse generator. Normally, such an inductance would create a significant
inefficiency in transferring
the electrical energy to the plasma. Because of the inductance, it is
difficult to match the equivalent
source impedance to the plasma impedance. The stem capacitor greatly
alleviates this problem and
significantly increases system efficiency by reducing inductance of the
current flow to the rock.
[002721 By utilizing multiple drills from a single pulse generator, the
system is able to increase
productivity and reduce manpower cost. The adjustable guide loops on the jack
leg enable the drill to
feed into the roof at an angle to accommodate the rock stress management and
layer orientation in a
particular mine.
[002731 The embodiment of the portable electrocrushing mining drill as
shown in Fig. 5, can
be utilized to drill holes in the roof of a mine for the insertion of roof
bolts to support the roof and
prevent injury to the miners. In such an application, one miner can operate
the drill, drilling two holes
at a rate much faster than a miner could drill one hole with conventional
equipment. The miner sets
- 62 -
Date rogue/ Date received 2021-12-14
the angle of the jack leg and orients the drill to the roof, feeds the drill
stem up through the guide
loops and through the boot to the rock with the armored cable engaged in the
advance mechanism.
The miner then steps back out of the danger zone near the front mining face
and starts the drill in
operation. The drill advances itself into the roof by the advance mechanisms
with the cuttings, or
fines, washed out of the hole by the drilling fluid flow. During this drilling
process, the miner then sets
up the second drill and orients it to the roof, feeds the drill stem through
the boot and the guide loops
so that when the first drill is completed, he can then switch the pulse
generator over to the second
drill and start drilling the second hole.
[00274] The same drill can obviously be used for drilling horizontally, or
downward. In a
different industrial application, the miner can use the same or similar dual
drill set-up to drill horizontal
holes into the mine face for inserting explosives to blow the face for
recovering the ore. The
embodiment of drilling into the roof is shown for illustration purposes and is
not intended as a
limitation.
[00275) The application of this drill to subsurface drilling is shown for
illustration purposes
only. The drill can obviously be used on the surface to drill shallow holes in
the ground or in boulders.
[002761 In another embodiment, the pulse generator can operate a plurality
of drill stems
simultaneously. The operation of two drill stems is shown for illustration
purposes only and is not
intended to be a limitation.
[002771 Another industrial application is the use of the present invention
to drill inspection or
anchoring holes in concrete structures for anchoring mechanisms or steel
structural materials to a
concrete structure. Alternatively, such holes drill in concrete structures can
also be used for blasting
the structure for removing obsolete concrete structures.
[00278) It is understood from the description of the present invention
that the application of
the portable electrocrushing mining drill of present invention to various
applications and settings not
described herein are within the scope of the invention. Such applications
include those requiring the
drilling of small holes in hard materials such as rock or concrete.
[002791 Thus, a short drill stem length provides the capability of
drilling deep holes in the roof
of a confined mine space. A flexible cable enables the propagation of the
drill into the roof to a depth
greater than the floor to roof height. The electrocrushing process enables
high efficiency transfer of
energy from electrical storage to plasma inside the rock, thus resulting in
high overall system
efficiency and high drilling rate.
[002801 The invention is further illustrated by the following non-limiting
example.
Example 3:
- 63 -
Date rogue/ Date received 2021-12-14
[002811 The length of the drill stem was fifty cm, with a 5.5 meter long
cable connecting it to
the pulse modulator to allow operation in a one meter roof height. The drill
was designed to go three
meters into the roof with a hole diameter of approximately four cm. The
drilling rate was
approximately 0.6 meters per minute, at approximately seven to ten holes per
hour.
[002821 The drill system had two drills capable of operation from a single
pulse generator.
The drill stem was mounted on a holder that located the drill relative to the
roof, maintained the
desired drill angle, and provided advance of the drill into the roof so that
the operator was not
required to hold the drill during the drilling operation. This reduced the
operators exposure to the
unstable portion of the mine. While one drill was drilling, the other was
being set up, so that one man
was able to safely operate both drills. Both drills connected to the pulse
generator at a distance of a
few meters. The pulse modulator connected to the power supply which was
located one hundred
meters or more away from the pulse generator. The power supply connected to
the mine power.
[002831 The pulse generator was approximately sixty cm long by sixty cm in
diameter, not
including roll cage support and protection handles. Mine drilling fluid was
used to cool key
components through a heat exchanger. Drilling fluid was used to flush out the
cuttings and maintain
drilling fluid around the drill head. The pulse generator box was hermetically
sealed with all of the
high voltage switches and cable connections inside the box. The box was
pressurized with an inert
gas to insulate it. Because the pulse generator was completely sealed, there
was no potential of
spark from it.
[002841 The drill would not operate and power would not be sent to the
drill unless the drilling
fluid pressure inside the stem was high enough to ensure that the drill tip
was completely flooded with
drilling fluid. This prevented a spark from occurring erroneously at the drill
tip. The boot was a stiff
rubber piece that fit snugly on the top of the drill support and was used to
contain the drilling fluid for
initially starting the drilling process. Once the drill started to penetrate
into the rock, the boot slipped
over the boot holder bulge and slid on down the shaft. The armored cable was
of the same diameter
or slightly smaller than the drill stem, and hence the boot slid down the
armored cable as the drill
moved up into the drill hole.
Command Charge System for Electrocrushinq Drilling of Rock
[002851 Referring to Fig. 51, one embodiment of the present invention
comprises command
charge system 500 for electrocrushing drilling of rock. Command charge system
500 comprises
cable 510, which preferably provides power from the surface to the pulsed
power system (not shown)
located in bottom hole assembly 512, where the pulsed power system produces
high voltage pulses
used for electrocrushing drilling. The pulsed power system of this embodiment
of the present
invention preferably comprises a drill bit (not shown), generator 520 linked
to the drill bit via cable 510
for delivering high voltage pulses down-hole and at least one set of at least
two electrodes disposed
- 64 -
Date rogue/ Date received 2021-12-14
on, near or in the drill bit defining therebetween at least one electrode gap.
The drill bit preferably
does not rotate. The capacitors and switches of the pulsed power system are
preferably located in
bottom hole assembly 512 close to the nonrotational drill bit.
[002861 In order to precisely control the timing of the firing electrodes
by the pulsed power
system, and to minimize the dwell time of high voltage on the pulsed power
system, command charge
switch 514 is located between end 516 of cable 510 and prime power system 518
at the surface of
the ground. Command charge switch 514, as illustrated in Fig. 51, is
preferably fired on command
and serves to control when the power produced by prime power system 518 is fed
into cable 510 and
hence into the pulsed power system in bottom hole assembly 512. Prime power
system 518
preferably takes power from the grid or from generator 520 and transforms that
power to produce a
power suitable for injection to cable 510. Preferably, prime power system 518
produces medium
voltage DC power that is used to charge a set of capacitors in prime power
system 518. Command
charge switch 514 then controls when that voltage on the prime power
capacitors is switched on to
cable 510, and hence is transmitted to the pulsed power system located in
bottom hole assembly
512. In one embodiment of the present invention, the use of command charge
switch 514 provides
the ability to control the duration of charge voltage on the pulsed power
system in bottom hole
assembly 512. It also preferably provides the ability to control the voltage
waveform on cable 510. In
addition, the prime power system incorporates a cable oscillation damping
function, such as a diode
and resistor set (not shown), to dampen cable oscillations created by the
operation of the bottom hole
assembly. The command charge system is equally applicable to downhole
configurations where
composite pipe with embedded conductors is utilized to transmit power to the
bottom hole assembly,
instead of a cable. Referring to Fig. 53, in one embodiment of the present
invention, diode 513 is
placed in series with cable 510 to stop cable oscillations. Breaker 515 is
also included in this
embodiment of the present invention.
Composite Pipe for Pulsed Power System
[002871 One of the challenges with utilizing a pulsed power system
encased in a bottom hole
assembly to drill wells utilizing an electrocrushing process is transmitting
electrical power to the
bottom hole assembly. Conventional technology typically utilizes a cable
running alongside the drill
pipe or running inside the drill pipe to transmit electrical power to the
bottom hole assembly.
However, utilizing the cable alongside the drill pipe creates a cable
management problem with the
cable potentially getting pinched between the drill pipe and the wall of the
hole. There is also the
problem of ensuring that the cable is spooled out at the same rate that drill
pipe is added to the hole,
and the stretch of the cable must also be accounted for to make sure the cable
does not get bunched
up at the bottom of the hole. If the cable is running inside the drill pipe,
then it must be broken into
sections to accommodate screwing on different sections of drill pipe. Each
connection between the
- 66 -
Date rogue/ Date received 2021-12-14
sections of the cable is a potential problem area for failure of the
connection, or failure of insulation in
the connection. Embodiments of the present invention comprise an apparatus and
method for
transmitting power to the bottom hole assembly without a cable, thereby
eliminating any cable
management issues associated with conventional technology. An embodiment of
the present
invention comprises a method for conducting electrical power and
communications signals from a
surface to a downhole device.
[00288] An embodiment of the present invention combines the functions of
transmitting power
to the bottom hole assembly and conducting drilling fluid to the bottom hole
assembly. Referring to
Figure 62, this embodiment comprises drill pipe 522 having conductors 524
embedded in the wall of
drill pipe 522. There are preferably two types of conductors, a high voltage
conductor for carrying
high voltage power to the bottom hole assembly for drilling operation and a
low voltage conductor for
carrying command and control signals down to the bottom hole assembly and for
returning
instrumentation signals to the surface. The signals preferably include, but
are not limited to, pulsed
power performance and operation instrumentation signals, thermal management
instrumentation
signals, and/or geophysical instrumentation signals. Drill pipe 522 of this
embodiment is preferably
made of a dielectric material, which serves as an insulation medium.
Conductors 524 preferably have
insulation disposed around them and are then preferably embedded in the
dielectric material of drill
pipe 522 to provide further insulation. The dielectric material also provides
structural integrity for the
drill pipe, provides containment for the pressure of the drilling fluid and
also provides mechanical
integrity to maintain functionality in the harsh drilling environment.
[00289] Embodiments of the present invention comprise embedding wires in
the body of a
pipe, preferably a non-conductive drill pipe, to conduct electric current and
collect data from a top-
hole environment to a down-hole bottom hole assembly. The high voltage wires
preferably carry
current at a voltage of at least about 1 kV. The pipe preferably does not
carry mechanical high torque
loads. The pipe sections preferably use connectors that do not require the
pipe to rotate on
assembly, more preferably non-rotating stab-type or buckle-type connectors,
and most preferably
turnbuckle connectors to enable alignment of electrical connectors 528 and 530
to each other.
Turnbuckle connectors utilize right-hand thread 532 on drill pipe 522 that
mates with the right-hand
thread portion of drill pipe turnbuckle connector 526. Drill pipe connector
526 also has left-hand
screw threads that mate with left-hand screw threads 534 on the other section
of drill pipe 522. This
enables drill pipe sections 522 to be connected without relative rotation,
providing for alignment of
electrical connectors 528 and 530. The high voltage electrical connectors also
provide for the
conduction of current at least 1 amp average current. The drill pipe assembly
of this embodiment
also comprises a provision for wires for carrying low-voltage data signals to
collect various data from
down-hole. Types of collected data can include but is not limited to
operational voltage and current of
components of the pulsed power system, data as to the geophysical location of
the bottom hole
- 66 -
Date rogue/ Date received 2021-12-14
assembly, other geophysical instrumentation data such as pressure and
temperature of the downhole
environment, and bottom hole assembly thermal management data. The drill pipe
assembly of this
embodiment also comprises a provision for wires for carrying low-voltage power
to operate the
instrumentation, control, cooling, and switch functions in the bottom hole
assembly. The low-voltage
data signal wires and low-voltage power wires are preferably isolated from the
high voltage wires.
The low voltage wires operate in a voltage of about 1 to 500 V or more.
[00290] The connectors for the high voltage power wires preferably provide
long lifetimes for
many connect - disconnect cycles while providing a long lifetime conducting
high current. The high
voltage connectors are sufficiently separated from each other in the drill
pipe construction to provide
adequate voltage isolation at the interface between pipe sections. The pipe
wall is preferably of
sufficient thickness and of appropriate dielectric materials to provide
adequate dielectric insulation
between high voltage lines. Thicknesses can range from about 0.1 inches to
about 1.0 inches or
more. Dielectric materials can include but are not limited to fiberglass,
polyurethane, PEEK, and
carbon fiber composite.
[00291] In one embodiment of the present invention, the bit of the bottom
hole assembly does
not rotate, in other words, it is nonrotational. In this embodiment, the drill
pipe does not have to
transmit torque to the bottom hole assembly. This simplifies the drill pipe
and the electrical
connections. The drill pipe sections of this embodiment preferably connect
with a stab-type or
buckle-type or click-type connection or most preferably a turnbuckle
connection so the drill pipe
sections do not have to rotate relative to each other during connection. The
electrical connections
can then easily be aligned during pipe section connection. The nonrotating
connection greatly
simplifies the design of the high voltage connections, enabling high voltage
insulation integrity to be
maintained with the pipe connected. The stab-type connection is not required
to be sufficiently robust
to support rotational torque, because the pipe does not rotate.
[00292] Referring to Fig. 52, one embodiment of the present invention
comprises drill pipe
522 having embedded conductors or wires 524. turnbuckle drill pipe connector
526, male electrical
contacts 528, and female electrical contacts 530. Male electrical contacts 528
preferably mate with
female electrical contacts 530. Drill pipe section 522 preferably comprises
right-hand threads 532
that mate with the right-hand threads of the turnbuckle connector 526 and left-
hand threads 534 of
drill pipe 522 that mate with left-hand threads on turnbuckle connector 526.
As turnbuckle connector
526 is rotated, it draws both drill pipe sections together without relative
rotation between them, thus
facilitating alignment of electrical connectors 528 and 530.
[002931 In another embodiment of the present invention, sections of drill
pipe can be cast as
single units, with the conductors embedded in the dielectric wall material
during the casting process.
By using a nonmetallic insulating dielectric material for the pipe, the
material can help insulate the
high voltage conductors. The conductors are preferably cast with an initial
layer of insulation on the
- 67 -
Date rogue/ Date received 2021-12-14
conductors to help manage the insulation function better, or the conductors
can be cast bare into the
pipe wall, with the insulating dielectric material of the pipe providing the
full insulation function. In yet
another embodiment of the present invention, conductors are insulated with
high temperature
insulators, such as ceramic insulators, and cast directly into the wall of
steel or aluminum drill pipe. In
yet another embodiment of the present invention, the drill pipe itself is a
hybrid drill pipe with one or
more layers of dielectric material and one or more layers of metallic material
to provide additional
structural strength. In such a hybrid drill pipe, the wires are preferably
cast into a dielectric material
layer, but may optionally be cast into a metallic material layer.
Repetitive Pulsed Electric Discharge Apparatus
[002941 Embodiment of the present invention a repetitive pulsed electric
discharge apparatus
comprises one or more pulsed power subsystems, a drill bit, and one or more
additional subsystems.
The subsystems are preferably within a bottom hole assembly (BHA) of the
repetitive pulsed electric
discharge apparatus. The bottom hole assembly is located down in a hole or
well and is the
assembly that drills in the hole or well. The one or more subsystems within
the bottom hole assembly
preferably fall into four categories: pulsed power, fluid flow management,
structures, and control, data
acquisition and communication. There are also additional and optional
subsystems. For example,
there is a subsystem that connects the BHA to the surface and there are
subsystems at the surface
that provide for the operation of the BHA. Each of these systems and
subsystems are discussed
below.
Pulsed Power Subsystem
[002951 In an embodiment of the present invention high voltage pulses are
applied
repetitively to the bit to create repetitive electrocrushing excavation
events. A pulsed power system
can include, but is not limited to:
(1) a solid state switch controlled or gas-switch controlled pulse generating
system with a
pulse transformer that pulse charges the primary output capacitor;
(2) an array of solid-state switch or gas-switch controlled circuits that are
charged in parallel
and in series pulse-charge the output capacitor;
(3) a voltage vector inversion circuit that produces a pulse at about twice,
or a multiple of, the
charge voltage;
(4) An inductive store system that stores current in an inductor, then
switches it to the
electrodes via an opening or transfer switch; and/or
(5) any other pulse generation circuit that provides repetitive high voltage,
high current pulses
to a drill bit.
- 68 -
Date rogue/ Date received 2021-12-14
[002961 In embodiments of the present invention, a bottom hole assembly
comprises one or
more of the following: a bit, one or more electrohydraulic projectors, a
drilling fluid pipe, a power
cable, one or more electrocrushing electrode sets, a connector for connecting
the drill bit to the
pulsed power generator, and/or a housing that may comprise the pulsed power
system and other
components of the pulsed power electric discharge apparatus.
(002971 In an embodiment of the present invention a repetitive pulsed
electric discharge
apparatus comprises a pulsed power subsystem, preferably within a bottom hole
assembly (BHA)
located down in a hole for drilling in the hole or well. The power is
preferably generated topside with
an electric generator, such as, for example, a diesel electric generator, or
is taken directly from a
power source, such as, for example, a power grid or a portable nuclear
reactor. The electrical power
is then fed into a power supply that converts the line power, for example,
three phase 480 volt power,
into a voltage range more suitable for the bottom hole assembly. The voltage
range can be about 5 --
50 kV DC, as an example. This voltage can be fed downhole over one or more
cables or over one or
more drill pipes with embedded conductors to the bottom hole assembly.
Alternatively, as described
above, electrical power can be fed to a command charge system which stores
electrical energy, and
then transmits the electrical energy in a pulse to the bottom hole assembly
when the drilling event is
about to be initiated. The command charge system preferably comprises one or
more energy storage
components, for example, capacitors or inductors, switches for creating the
pulse and transmitting it
to the cable, a transformer for changing the voltage of the pulse, components
for damping cable
oscillations, combinations thereof or the like. The command charge system also
optionally includes
one or more heaters and/or one or more triggers for the switches. The command
charge system or
power conditioning system preferably connects to interface hardware that
connects to the cable or
embedded conductor drill pipe, which is attached at the other end to the top
of the bottom hole
assembly. In a non-limiting example, if cable is used, then electrical power
for the downhole bottom
hole assembly connects to the cable reel through a rotating interface at the
center of the reel This
enables the cable to be unreeled and propagate down the hole with the drill
string. Alternatively, the
cable may connect to the bottom hole assembly through a side entry sub so that
the cable can run on
the outside of the drill pipe. If an embedded conductor drill pipe is
utilized, the conductors preferably
connect directly to mating conductors at the top of the bottom hole assembly.
Alternatively or in
addition the drill can be powered by a downhole power source, by a downhole
alternator or generator
powered by mud turbine.
(002981 The cable and/or embedded conductor drill pipe then transmits a
pulse or DC power
down the hole and connects to the pulsed power system in the bottom hole
assembly, which
preferably comprises capacitors and/or storage inductors which store the
electrical energy transmitted
from the surface. Upon command, switches connect the stored energy either
directly to the drill bit
and/or through transformers to the drill bit and/or through similar voltage
multiplying pulsed power
- 69 -
Date rogue/ Date received 2021-12-14
circuits to create a high voltage pulse at the drill bit. In some
circumstances, a splicer - sustainer
circuit can be used which creates a high voltage pulse separately from a main
drilling pulse.
Housekeeping power for the bottom hole assembly, for example, power for switch
heaters or
conditioners, instrumentation, switch triggers, and/or data acquisition and
transmission systems, is
preferably about 12-480 V, DC-800 Hz, and more preferably 120 volt 400 Hz
power. This
housekeeping power is also transmitted down the cable and/or embedded
conductor drill pipe to the
bottom hole assembly.
[002991 Subsystems and components involved in the pulsed power section of
the bottom hole
assembly can include, but are not limited to, a capacitor and/or inductive
energy storage subsystem,
one or more switches along with corresponding switch heaters and/or
conditioners and the
corresponding switch triggers, and one or more high voltage connection
subsystems that connect the
high voltage output to the drill bit. Other subsystems and components of a
bottom hole assembly can
include but are not limited to transformers and/or Marx banks and/or other
voltage multiplication
systems within the bottom hole assembly that create the high voltage pulse
that is then transmitted to
the drill bit by the high voltage connection and wiring system.
Instrumentation, Communication and Control Subsystem
[003001 Referring to Fig. 55, some embodiments of an instrumentation,
communication and
control subsystem of the present invention comprise a topside or surface
system 800 for a repetitive
pulsed electric discharge apparatus that comprises a primary power generation
and conditioning
apparatus and a command charge pulse generation and control apparatus. The
topside system
preferably interconnects with cable 810 and/or an embedded conductor drill
pipe. The topside
system also preferably interconnects with a command control and
instrumentation system.
Additionally, the command control and instrumentation system is preferably
located on the surface,
and preferably is a computer or programmable logic controller (PLC)-based. The
command control
and instrumentation system provides command signals to the power supply to
tell the power supply
when to turn on and when to turn off. The command control and instrumentation
system also
preferably comprises the command charge system that accepts the power from the
power supply,
stores it in a capacitor or inductive energy storage, and then sends the power
in a pulse to the bottom
hole assembly to initiate a drilling event. The command control and
instrumentation system
preferably comprises switch triggers that turn on the switches in the bottom
hole assembly. The
command control and instrumentation system also preferably controls the
direction of the drill by
controlling the relative firing frequency of the sets of electrodes of a drill
bit, in order to keep the drill
moving in the desired direction. The command control and instrumentation
system preferably
controls the relative firing frequency of electrode sets by controlling the
relative firing frequency of the
switches connected to the corresponding electrode sets.
- 60 -
Date rogue/ Date received 2021-12-14
[003011 The command control and instrumentation system preferably acquires
data from the
downhole instrumentation systems to assess the location of the drill in
physical space. For example,
the command control and instrumentation system preferably communicates with a
microchip-
packaged MEMS gyroscope device, a solid-state ring laser gyroscope, or a fiber
optic gyroscope, as
part of an inertial navigation system, to assess a relative motion of the
drill system and hence
determine the location of a drill system in three-dimensional space to enable
precise control of the
drilling trajectory of the drilling system. The command control and
instrumentation system also
preferably assesses the health and performance of the pulsed power system by
measuring the peak
voltage and peak current produced during the drilling cycle, the average power
consumption of the
drill related to drilling rate, the temperature of circuit pulsed power
components and fluid systems,
fluid pressure at several locations in the bottom hole assembly (to assess the
condition of the internal
flow of structures and to assess the internal flow rate inside the bottom hole
assembly), and other
parameters. The command control and instrumentation system also preferably
provides bottom hole
environmental data, including but not limited to fluid pressure and
temperature external to the bottom
hole assembly using pressure and temperature transducers, which are
transmitted to the command
control and instrumentation system at the surface via the data acquisition and
communication system.
[003021 A downhole control, instrumentation, data acquisition, and
communication system
preferably provides for the control of the pulsed power system, the
directional control and drilling rate
of the drill itself, the acquisition of performance data for various
subsystems in the BHA, and the
communication of that data with a topside control and instrumentation system.
The system of this
embodiment comprises one or more digital data storage components that acquire
data from one or
more instrumentation probes and transducers disposed in the bottom hole
assembly. The system
stores the data collected by the probes and transducers, and then one or more
data transmission
components transmit the data to the surface over one or more instrumentation
conductors or fiber-
optic cables of the downhole cable or the instrumentation conductors or fiber-
optic cables of the
embedded conductor drill pipe as an AC signal superimposed on the DC power
current. The data
transmission occurs either according to a programmed schedule, continuously,
or upon command
from the control system located on the surface.
[003031 The connection between the bottom hole assembly and the TCI is
preferably a direct
connection, e.g. via a cable, which enables high data rate transmission.
Conventional (non-EC) drills
cannot accommodate a direct connection due to rotation of the drill bit. This
enables near-
instantaneous acquisition of geophysical data, which greedy increases safety
of the drilling. For
example, if the drill enters a high pressure gas region, a pressure sensor can
relay that information to
the TCI, which can immediately slow the drilling rate and take precautions
against a blowout.
[00304] Topside control and instrumentation (7CI) system 800 preferably
creates control
signals to drive the power supply, the command charge system, and the switch
triggers in the bottom
- 61 -
Date rogue/ Date received 2021-12-14
hole assembly. The TCI system provides command signals to the power supply to
signal to the
power supply when to turn on and when to turn off, thereby also controlling
drilling rate. The TCI
system also provides command signals to one or more switches in a command
charge system to
accept power from the power supply, store the energy in a capacitor or
inductive energy storage, and
then, on command, send the energy in a pulse to the bottom hole assembly to
initiate a drilling event.
The TCI system comprises switch triggers that turn on the switches in the
bottom hole assembly. The
TCI system can also controls the direction of the drill by controlling the
relative firing frequency of the
sets of electrode of a drill bit, in order to keep the drill moving in the
desired direction. For example,
the TCI system controls the relative firing frequency of electrode sets by
controlling the relative firing
frequency of the switches connected to particular electrode sets.
[00305] The TCI system preferably acquires data from the bottom hole data
acquisition and
communication system to assess the performance of the bottom hole pulsed power
and fluid systems
820 and to display key data to an operator. The control signals from the TCI
system are preferably
fed down the cable or the embedded conductor drill pipe to the bottom hole
assembly and hence to
one or more switch triggers in the bottom hole assembly. The control signals
are also fed to the
power supply and the command charge system. Various pulsed power, fluid
temperature, and
geophysical sensors are fed to the downhole control instrumentation, data
acquisition and
communication system at the top of the bottom hole assembly and/or fed
directly over cable or fiber
optic links to the topside control and instrumentation system where the
function, health, and
performance of the BHA is assessed, along with its physical location in space
and the properties of
the environment the bottom of the well.
[00306] In another embodiment of the present invention, a pulsed power
electric discharge
apparatus comprises a pulsed power system packaged in a bottom hole assembly
that operates
downhole at varying depths and temperatures. The pulsed power electric
discharge apparatus also
incorporates data communication with a surface apparatus. The pulsed power
electric discharge
apparatus comprises a data acquisition and transmission apparatus that
acquires data as to the
operating performance and environment of the pulsed power electric discharge
apparatus and
transmits that data to a surface control and instrumentation apparatus. This
data acquisition and
transmission apparatus preferably: 1) controls the direction of a drill of the
pulsed power electric
discharge apparatus while drilling to optimize the intersection of desired
formation features; 2)
provides information to the operator as to bottom hole temperature and
pressure conditions; 3)
provides diagnostics on the condition of the pulsed power system in case of an
anomaly in drilling
rate or a potential malfunction; and 4) maintains a running assessment of the
performance of the
pulsed power system for future maintenance.
[00307] The bottom hole assembly presents a challenge for instrumenting
pulsed power
signals. The space within the bottom hole assembly is typically confined
because of the necessity for
- 62 -
Date rogue/ Date received 2021-12-14
drilling a small diameter hole. The operating temperatures and pressures can
be high because of the
downhole environment. In addition, there is significant vibration and shock
from the drilling action
itself. Packaging and selecting pulsed power instrumentation for the bottom
hole assembly can be
different from selecting and packaging pulsed power instrumentation for a
conventional pulsed power
system because of these factors.
[003081 Geophysical instrumentation incorporated into the bottom hole
assembly can include,
but is not limited to measurement of ambient temperature, measurement of
ambient pressure near
the bottom hole assembly, and determination of the location of the bottom hole
assembly in a three-
dimensional space.
[003091 Data transmitted from one or more sensors in the bottom hole
assembly is
transferred to a data acquisition and communication apparatus preferably
located near a top of the
bottom hole assembly. On command, this data is transmitted to a surface
instrumentation and control
system via a cable and/or fiber optic links to the surface.
[003101 Pulsed current in the pulsed power system, for example, the
current used to operate
a drill bit, is typically measured by current transformers, B-dot probes,
resistive probes, capacitive
probes, or probes utilizing optical effects to determine current or the
derivative of current. B-dot
probes measure the time changing magnetic field produced by the current and
integrate that
information to provide a measurement of current An advantage of a B-dot probe
is that it does not
require physical connection to a high current circuit, thus avoiding a
significant installation issue. In
an embodiment of the present invention, data from one or more current
transformers and/or B-dot
current probes is transmitted to a bottom hole assembly data acquisition and
communication
apparatus and then to a surface instrumentation and control system. Continuous
AC current is
preferably measured utilizing similar probes. Continuous DC current is
preferably measured with
resistive probes.
[00311) In embodiments of the present invention, pulsed voltage in a
pulsed power system is
measured with one or more resistive probes and/or one or more capacitive
probes. These probes are
connected to the component utilizing or providing the high voltage. In another
embodiment of the
present invention, one or more E-dot probes are used to measure the time
changing electric field,
which is integrated to yield the time changing voltage. An advantage of an E-
dot probe is that it does
not require physical connection to the high voltage component, thus avoiding a
significant insulation
issue. Yet another variation of the E-dot probe is to integrate the probe into
a pulse transformer so
that the probe measures the output voltage from the transformer, but without
requiring physical
connection to the high voltage components. In an embodiment of the present
invention, pulsed
voltage is measure using one or more E-dot probes and/or one or more resistive
probes and/or one
or more capacitive probes or combinations thereof.
- 63 -
Date rogue/ Date received 2021-12-14
[003121 An issue with any pulsed power instrumentation is noise on the
data connection
wiring to the instrumentation, induced by fast rising voltages and currents in
the pulsed power system.
In the bottom hole assembly, the connection between the pulsed power
instrumentation probes and
the data acquisition and communication apparatus is preferably shielded from
noise by a coaxial
cable or by a fiber optic link or by RF data transmission or by direct laser
data transmission or
combinations thereof or the like.
[003131 In addition to the pulsed power instrumentation, characteristics
of the bottom hole
assembly flow system are also preferably measured. This can include but is not
limited to
measurements of flow pressure at key points in the system, from which can be
deduced the flow rate
through the system. In some circumstances, it is appropriate to measure the
flow velocity directly,
either by rotating flow meters or by capacitive or inductive meters or venturi-
type meters.
Embodiments of the present invention comprise one or more flow meters and/or
one or more
capacitive meters and/or inductive meters and/or venturi-type meters for
measuring flow rate and flow
pressure. In an embodiment of the present invention a venture-type meter is
used to measure flow
rate and flow pressure. In an alternative embodiment of the present invention,
a flow rate is
measured by measuring the RPM of a pump, particularly a positive displacement
pump.
[003141 A data acquisition and communication apparatus (DAC) is preferably
located at the
top of the bottom hole assembly, to maximize the distance from the drill bit.
The DAC preferably
acquires data from one or more various probes, including one or more pulsed
power system
instrumentation probes and geophysical instrumentation probes and bottom hole
assembly fluid
dynamics probes, and can store that information until an inter-pulse period,
when the DAC can
transmit the data to the surface with minimal interference from the operation
of the pulsed power
system. Specifically, embodiments of the pulsed electrocrushing drill of the
present invention fire the
drill bit at a rate of approximately 100 pulses per second, with approximately
10 msec between each
pulse. Due to noise problems, it is preferable that data is not transmitted
during the firing of the bit.
Thus, when a signal is sent from the surface to fire an EC pulse, the DAC is
turned off and/or ceases
transmission of data prior to or simultaneous with the initiation of the
pulse. Each firing pulse
produces data, such as peak current, peak voltage, striker current and
voltage, and sustainer current
and voltage, which is acquired by the DAC; the data is then sent to the TCI
after the firing pulse is
completed. The data enables the system to monitor the performance of the
drill. If the
communication with the surface is over a fiber optic link, then the DAC can
transmit data to the
surface continuously.
Direct Charqinq Embodiments
[003151 In some embodiments of the present invention a power supply
located on the surface
is connected directly to the pulsed power system located in the downhole
bottom hole assembly.
- 64 -
Date rogue/ Date received 2021-12-14
without the use of the command charge system. This direct charging system is
advantageous
because for command charge systems it is difficult to manage ground swings. A
comparison of
representative embodiments of the two configurations is shown in Fig. 54. Fig.
54A shows a
simplified circuit for a command charge system. Power supply 600 connects to
the command charge
system which comprises command charge capacitor 610 and command charge switch
620 for
providing power through cable 630 from the surface to the bottom hole
assembly, which comprises at
least one spiker circuit 640 (some embodiments have three spiker circuits,
also called striker circuits)
and sustainer circuit 650 which, via magnetic diode 660 provide pulsed power
to drill bit 670 as
described above. The cable may also connect to the sustainer circuit capacitor
through an isolation
inductor (not shown). Fig. 548 shows a direct charge system, in which power
supply 700 provides
power through cable 710 from the surface to the bottom hole assembly, which
comprises at least one
spiker circuit 720 (some embodiments have three spiker circuits) and sustainer
circuit 730 which, via
magnetic diode 740 provide pulsed power to drill bit 750 as described above.
In alternative
embodiments of either system, primary output capacitor 760 can be replaced by
the equivalent self-
capacitance of the bit, connection structure and other components, which can
all be designed to
provide the equivalent function of the primary output capacitor.
[003161 In some embodiments a switching power supply which utilizes
controlled high-
frequency current pulses to progressively increase the voltage of the
capacitors in the bottom hole
assembly, while constantly measuring the charge voltage on those capacitors so
as to adjust the
current to achieve the desired end state voltage, may be used. This control
methodology is suitable
for long cable distances, for example 10,000 feet, (typically from
approximately 500 feet to
approximately 30,000 feet) between the power supply and the capacitors located
in the bottom hole
assembly.
(003171 Alternatively a DC power supply (preferably on the surface) may be
utilized to charge
the capacitors, preferably while monitoring the capacitor voltage on a
separate cable to control the
end state voltage. In this embodiment a high voltage probe utilized for
monitoring the capacitor
voltage could be located in the bottom hole assembly, with only control
signals going to the surface.
The control signals could alternatively be transmitted to the surface on the
power cable as an AC
signal superimposed on the DC power current. Such control signals can be
inductively coupled into
the power cable in the bottom hole assembly and then extracted inductively
from the power cable at
the surface.
(003181 Another embodiment is to locate an AC power supply on the surface
and transmit the
voltage across the cable as an AC waveform and then rectify it in the bottom
hole assembly, utilizing
a separate cable for monitoring voltage or, alternatively, transmitting
voltage monitoring data at a
different frequency along the same cable.
- 66 -
Date rogue/ Date received 2021-12-14
[003191 The power supply, together with voltage control circuitry that
receives voltage data
from the downhole bottom hole assembly capacitors and controls the current
and/or voltage output
from the power supply, is preferably on the surface. The primary power for the
power supply may be
an on-site generator, but it can alternatively comprise electrical power from
the electric power utility
grid or any suitable source of electrical power.
Data Transmission
[003201 The cable or the conductive drill pipe utilized to transmit power
to the RePED bottom
hole assembly also preferably comprises data transmission wires. Coupling
between the data
transmission wires and the main power wires would likely introduce electrical
noise into the data
stream. This is especially true with the command charge system because of the
higher current
involved in pulse charging the bottom hole assembly (BHA). An advantage of the
direct charge
system is that, while the average current will be the same between the two,
the direct charge system
will be charging at the average current whereas the command charge system will
have a peak current
about twice the average current. The higher peak current of the command charge
system may
induce more noise into the data lines than the direct charge system.
[003211 Using a switching power supply direct charge system utilizes high
frequency
chopping of the power in order to control the state of charge, and hence the
voltage on the capacitors
being charged. That high frequency chopping may induce noise on the data
lines. However, because
it is high frequency, it is much easier to shield then a large low-frequency
pulse. In addition, over
long cable runs it is difficult to control voltage at the capacitor when using
a switching power supply.
A direct current (DC) power supply does not produce any high frequency noise
and provides the
charging of the BHA without inducing noise on the data lines. This is
advantageous over a switching
power supply.
[003221 Another embodiment of the present invention comprises a
transmitter, preferably a
microwave transmitter, located at the top of a well and a receiver, preferably
a microwave receiver,
located at the top of a bottom hole assembly in the well. The transmitter and
receiver preferably
transmit power to the bottom hole assembly without the use of a cable or a
drill pipe with embedded
conductors. The bandwidth of a signal, preferably a microwave signal,
preferably provides for data
transmission down the hole to the bottom hole assembly, in addition to power
transmission. A low-
power transmitter installed on the bottom hole assembly preferably transmits
data back to the
surface. For microwave charging, the resonant frequency of the metallic drill
pipe used to conduct
drilling fluid to the bottom hole assembly is preferably appropriately matched
to the frequency of the
microwave system (e.g., a transmitter and a receiver), so that the drill pipe
functions as a waveguide
for the microwave system to minimize losses and improve power transmission to
the bottom hole
assembly.
- 66 -
Date rogue/ Date received 2021-12-14
[003231 In typical drilling operations, the drilling fluid is aqueous,
which being conductive will
short the microwave field, thereby blocking microwave charging of the bottom
hole assembly.
However, embodiments of the present invention utilize a non-aqueous insulating
or dielectric drilling
fluid, as described above, which is compatible with microwave charging.
Fluid Flow Subsystem
[003241 In some embodiments of the invention, a fluid flow subsystem
preferably comprises
one or more pumps at the surface that pump drilling fluid through a drill pipe
down to the bottom hole
assembly. At the top end of the bottom hole assembly, a portion of the
drilling fluid is preferably
diverted by a flow diverter. The diverted portion of drilling fluid preferably
cools the high power
electrical components. The remaining drilling fluid preferably flows around
flow dividers to the drill bit.
The drilling fluid flow is then directed through the drill bit, preferably
through a flow combiner and
through channels in the drill bit where it pushes out bubbles and rock
cuttings. Unlike embodiments
of the present invention which split the fluid flow into a cooling portion and
a clearing portion in order
for the fluid to perform both functions, conventional (non-EC) drills
typically don't require cooling, and,
conversely, well-logging tools don't require bubbles or rock cuttings to be
removed. Referring to Fig.
35, the drilling fluid preferably flows radially from the center of the bit
out towards to the exterior of the
bit. The drilling fluid then flows around the bottom hole assembly and up to
the surface. At the top,
the drilling fluid preferably flows from the well to a settling pond, where
cuttings settle out. The used
drilling fluid and cuttings are then preferably transferred to a solids
control system where the solids
are removed from the drilling fluid. In an alternative embodiment, the
drilling fluid can also be
transferred to a water extraction system where excess water is removed from
the drilling fluid.
[003251 The BHA preferably has significant fluid flow through the
assembly. The primary
purposes of this fluid flow are to stabilize the well in the rock formation
and to sweep the cuttings out
of the hole. In some embodiments, high flow rates accomplish the cutting sweep-
out function. In
addition to these functions of the fluid flow, there are number other
functions for the fluid flow within
the BHA. For example, one function is to clear fluid bubbles out of a bit
electrode area. Such
bubbles are created by the electrocrushing drilling action of the bit. A flow
structure is preferably
designed into the bit to direct the flow through the bit electrodes and
through the surrounding
structure to ensure efficient sweep-out of the bubbles created by the drilling
action.
(00326] In the embodiment shown in Figs. 56-57, fluid enters (from the
right) and flows
through bottom hole assembly (BHA) tube 920, preferably cooling the
electronics components and
pulsed power components within the BHA. The flow system preferably comprises a
flow diverter to
divert a predetermined amount of flow, for example, about 10% or more, of the
total flow, through the
electronics components and pulsed power components in order to prevent erosion
of the
components. The diverted flow, henceforth referred to as cooling flow, flows
through one or more low
- 67 -
Date rogue/ Date received 2021-12-14
speed flow choke tubes 930 disposed in sustainer section transition insulator
925, then into one or
more plenums or passages 950 which direct the flow around and over or adjacent
to various
electronics and/or pulsed power components, such as sustainer capacitor 960,
to cool them. These
components preferably comprise cooling structures that provide thermal
connection with the cooling
flow to cool the components. Channels and flow structures disposed in one or
more mounting
structures for the pulsed power and electronic components preferably maximize
the cooling
effectiveness of the cooling flow around the components. The remainder of the
flow flows through one
or more high speed flow channels 940 to the drill bit. High voltage power
lines 965 and signal and
housekeeping power lines 980 preferably extend through BHA tube 920 and are
preferably disposed
in tubes which mate to other sections of the drill to prevent direct contact
with the fluid. Spacer 970
preferably separates high voltage lines 965 and holds sustainer capacitor 960
in place.
[003271 An optional flow diverter shield (not shown) protects one or more
pulsed power
components from too much fluid flow, which can cause erosion. One or more
components are
preferably used to divert the cooling flow into the pulsed power and
electronic sections of the bottom
hole assembly. One or more other components then preferably merge the cooling
flow with a main
fluid flow near the drill bit. The flow system of this embodiment merges the
cooling flow and the main
flow in the bit area to maximize the effectiveness of the total flow in
clearing bubbles out of the bit.
The flow velocities of the fluid flow in this embodiment are preferably
controlled and correlate with
component temperature rise and cooling effectiveness to further optimize the
cooling flow and its
cooling function. Instrumentation and sensors are used to control the flow
velocities and correlate the
velocities with component temperature rise. Data from one or more sensors is
transmitted to the data
collection acquisition system (DCAS) which then transmits the data to the
surface control and
instrumentation system.
[003281 Referring to Fig. 58, in another embodiment of the present
invention, a repetitive
pulsed electric discharge apparatus comprises derrick 825, drill stem 830,
bottom hole assembly
(BHA) 840 disposed on the drill stem and tilt mechanism 850. Mud motor 860 and
mechanical bit 870
are preferably disposed under BHA 840. Extension pipe 880 is preferably
disposed on the bottom of
mechanical bit 870. At an opposite end of extension pipe 860, a repetitive
pulsed electric discharge
(RePED) bit 890 is preferably disposed. Extension pipe 880 preferably houses
the pulsed power
system cable so it can connect to ReF'ED bit 890. The apparatus of this
embodiment extends beyond
a mechanical bit to drill out only a center of a hole. In this embodiment, mud
motor 860 drives
mechanical bit 870. BHA 840 sits above mechanical bit 870 and cables and
fluids run to repetitive
electric pulsed discharge bit 890. Tilt mechanism 850 is preferably installed
above BHA 840 to tilt
BHA 840 and one or more bits. (For example, both mechanical bit 870 and
repetitive pulsed electric
discharge bit 890 can be tilted if both are used.) Repetitive pulsed electric
discharge bit 890 can be,
- 68 -
Date rogue/ Date received 2021-12-14
but does not need to be, steerable since the entire section tilts. In a
preferred embodiment, the
repetitive pulsed electric discharge apparatus comprises one spiker.
Drill Bit Design for Directional Control
[00329] In order to efficiently excavate or drill a hole using a pulsed
power drilling with an
electrocrushing process, there is preferably an electric field distribution at
the rock face produced by
the electrocrushing process. There is also a fluid flow to sweep the rock
particles and bubbles out of
the electrode region. Embodiments of the present invention as illustrated in
Fig. 59 comprise a drill
bit, preferably comprising a pie-segment current return structure, that
comprises radial fluid flow, in
conjunction with linear flow, to sweep the bubbles and rock particles out of
the electrode region as
quickly as possible with a predetermined fluid flow rate. As used throughout
the specification and
claims, the term "current return" element means an element which may be
grounded and at a ground
voltage or instead which may be electrically connected to the ground point but
not at the ground
voltage due to voltage drops between the element and the ground point (for
example due to a long
electrical connection). In the specification, the term "ground" may in some
places be used
interchangeable with the term "current return".
[00330] Figs. 59A-59D illustrate an embodiment of a drill bit comprising
a plurality of high
voltage electrodes 900 nestled in current return structure 910. Current return
structure 910 preferably
provides structural strength and integrity to the bit. In this embodiment,
fluid flows into the bit at 903
near the inner tips of high voltage electrodes 900, and then flows across the
rock face and out
openings or slots 905 in the outer rim of the surrounding ground ring (current
return structure 910).
The fluid thus preferably flows onto the rock surface around high voltage
electrodes 900 and out the
openings or slots in ground ring or current return structure 910. Some of the
fluid may also escape
onto the rock surface through the face of the bit around electrodes 900,
especially if an electrode is
extended out from the bit face. Each of the high voltage electrodes 900 is
preferably compressible
and extends out of the plane of the drawing into the rock as the rock is
excavated. In addition to
sweeping rock particles out of the electrode region, the fluid also must sweep
away bubbles created
by an arc (typically in regions 908); if not removed, the next arc could short
through such a bubble.
Such bubbles are typically not produced by a conventional (non-EC) drill, and
even if they are they do
not affect the drilling process for such a drill.
[00331] In this embodiment, pairs of electrodes are preferably connected
together to provide
three sets of electrodes, each set of electrodes being operated by a separate
pulsed power system.
This embodiment enables directional control of the bit, by one pulsed power
system operating at a
lower repetition rate than the other two, thus causing the bit and associated
bottom hole assembly to
steer towards this lower repetition rate electrode set. This embodiment of
tying one or more high
voltage electrodes together to provide electrode sets for directional control
can optionally be extended
- 69 -
Date recue / Date received 2021-12-14
to eight electrodes (four electrode sets of two electrodes each) or nine
electrodes (three electrode
sets of three electrodes each) or other combinations to achieve the desired
drilling rate and
directional control performance characteristics.
[00332] In the embodiment illustrated in Fig. 59, each high voltage
electrode 900 preferably
extends independently out of the bit and into the rock as the rock is
excavated. In another
embodiment of the present invention, a plurality of electrodes can be
mechanically linked to move as
a set instead of individually. In yet another embodiment, all of the
electrodes in a bit can electrically
be tied together, for those circumstances where the added complexity of
directional drilling is not
needed, thus requiring only one pulsed power system instead of a plurality of
pulsed power systems.
In another embodiment of the present invention, a drill bit comprises a
central electrode that may or
may not be electrically tied to one of the other electrodes or electrode sets
to provide more effective
excavation of the center portion of the bit.
[00333] In yet another embodiment of the bit, one or more of the high
voltage electrodes can
each be divided into two or more smaller high voltage electrodes without
having to modify the current
return structure. By having two separate assemblies of high voltage
electrodes, for example, greater
control can be achieved over the electric field distributions of a particular
high voltage electrode or
high voltage electrode set relative to the ground ring. That, in turn, can
result in greater drilling
effectiveness. For example, in Fig. 59, each of the six high voltage
electrodes 900 can be divided
into two electrodes, with those two electrodes (instead of the original one)
disposed in each wedge-
shaped opening of current retum structure 910, resulting in a total of twelve
electrodes for the bit.
The division of the electrodes can occur along a radial line and/or a
circumferential line, depending on
which configuration gives the most desirable electric field distribution. If
along a circumferential line,
the resulting design can have, for example, six smaller electrodes arrayed
near the center of the bit,
followed by six more electrodes arrayed closer to the circumference of the
bit, for a total of twelve
electrodes. As long as portions of a split electrodes are fed from the same
circuit (i.e. same voltage),
no insulator between them is necessary. Using split electrodes is advantageous
because the
resulting fluid passages between the electrodes improves the fluid flow, and
thus improves the ability
of the fluid to remove rock debris and bubbles. In addition, drilling
effectiveness is increased,
because excavation is typically increased at the electrode corners due to the
electric field distribution,
and two or more electrodes split from a single electrode have more corners
than the single electrode
does.
[00334] In another embodiment, the bottom view of which is shown in FIG.
60, each opening
in current return structure 910 accommodates a plurality of rod shaped
electrodes 915. As shown,
these may be arranged to form a circle centered on the center of the bit face.
- 70 -
Date recue / Date received 2021-12-14
Nutation of Drill Bit
[00335] In some embodiments of the present invention, it may be
beneficial to rotate the bit
with mechanical cutters to provide a more accurate cutting of the gauge of the
hole. In such an
embodiment, mechanical cutters can be arrayed along a periphery of the bit to
provide mechanical
cutting of an outer wall of a hole, thereby providing a smoother hole. In
other embodiments, the bit
can be rotated or nutated back and forth without mechanical cutters, to
provide a more rapid and
even excavation of the hole.
[00336] One of the issues observed in drilling tests with drilling
systems is difficulty with
completely clearing the hole because of nonuniformity in the excavation
process. As the drill
propagates through the rock, the non-uniformities in the rock may cause a lip
or ledge on the outer
rim of the rock hole that prevents the propagation of the drill through the
hole. This non-uniformity in
the excavation of the hole can be created by the non-uniformity in the
drilling process caused by the
physical structure of a drill bit. In order to solve the non-uniformity in the
drilling process, an
embodiment of the present invention comprises turning the drill bit
approximately 100 to
approximately 45 back and forth around an axis of the bit that is aligned to
the direction of drilling.
This nutation motion causes various segments of the drill bit to contact
different sections of the hole
rim that then cause the non-uniformities in the hole rim to be excavated by
different segments of the
drill bit. The nutation motion preferably enables the bit to completely clear
the hole and propagate
through the formation.
[00337] Referring to Fig. 61, in one embodiment of the present invention
the nutation motion
is accomplished by providing a rotational joint at a bit-bottom hole assembly
interface. The joint
preferably comprises a slip ring, preferably an oil-insulated slip ring, to
handle or accommodate the
four circuits that are required to feed power to bit 118. In an alternative
embodiment, conductors,
preferably flexible conductors, are used to accommodate the nutation of the
bit. A motor, preferably
electrically and/or fluid driven, turns the bit back and forth to clear any
non-uniformities at rim of bit
118. Electrodes 108 are preferably designed to accommodate the nutational
motion of the bit.
[00338] In an alternative embodiment, the bit rotates approximately 100
to approximately 45
back and forth around a point at the end of the bottom hole assembly so that
the axis of rotation is
substantially perpendicular to the axis of propagation. This embodiment
preferably provides a means
of physically changing the drilling direction by changing the orientation of
the bit.
[00339] Unlike grinding drill bits which require rotation or nutation in
order to provide the
physical mechanism for drilling rock, EC bits do not require motion to drill.
For EC bits, nutation
smoothes out nonuniformities resulting from the EC process itself on non-
uniform rock or from
discontinuities in the electrode structure. For example, if the bit pictured
in Fig. 59 is used, a portion
of the rock will be situated under current return structure 910 rather than an
electrode 900; nutation of
the bit to bring electrode 900 over that portion of the rock enables it to be
drilled.
- 71 -
Date recue / Date received 2021-12-14
Structural Subsystem
[003401 The structure of the bottom hole assembly preferably protects the
internal
subsystems from damage from the rock well environment, provides rigidity to
control alignment of the
internal subsystems and fluid flow systems, provides for easy disconnection of
the overall assembly
into subassemblies that can be easily transported, and provides for the
connection of the bottom hole
assembly to drill pipe for fluid flow and cable and/or embedded drill pipe for
power and
communications connections. The structure preferably comprises a steel tube
that protects the
internal components from impact or abrasion with the rock wall of the well.
The tube also provides
rigidity for the bottom hole assembly to maintain alignment of the components.
Special connectors
are preferably provided to enable the connection of different sections of the
bottom hole assembly.
The connectors also maintain structural strength and rigidity while providing
for reliable connections
of the pulsed power and other circuits from one section to the next.
[003411 Materials selected for the bottom hole assembly tubing structure
provide an overall
structural integrity of the system. The preferred materials for the bottom
hole assembly tubing
structure include but are not limited to steel drill pipe, high strength alloy
steel tubing, high-strength
metallic tubing of various metal alloys including steel and aluminum, high-
strength composite metallic
tubing of metal and nonmetal constituents, and high-strength abrasion
resistant composite tubing
incorporating carbon fiber, glass fiber, carbon nanotube structures, Kevlar
fibers, other high-strength
fibers and the like, or combinations thereof. The specific design of the
structure of the bottom hole
assembly preferably meets predetermined design requirements for the downhole
well environment.
In a non-limiting example, a bottom hole assembly structure can be made from 8
3/8" OD drill pipe in
four approximately 20-30 foot sections for a total overall length of about 90-
110 feet. Each section of
drill pipe is preferably connected to the other with a turnbuckle,
incorporating left-hand and right-hand
threads, so that alignment can be maintained of high voltage conductors
between the sections of drill
pipe without relative rotation. The turnbuckle enables the two sections of
drill pipe to be rigidly
fastened to each other with screw threads without relative rotation of the two
sections of drill pipe.
This enables the electrical conductors from one drill pipe to be connected to
the other drill pipe
without relative rotation, which would cause twisting and distortion of the
conductors. The bit is
preferably connected to the bottom hole assembly structure using a similar
turnbuckle.
Pulsed Magnetic Fields for Downhole Characterization
[003421 Embodiments of the present invention are directed to a drill and
system for drilling
that utilizes a pulsed source of electromagnetic energy downhole. A pulsed
power breaking and drill
apparatus is also known as a repetitive pulsed electric discharge apparatus.
The variant of the
pulsed electric drill system designed to produce pulsed magnetic and
electromagnetic fields is
- 72 -
Date rogue/ Date received 2021-12-14
referred to as the electromagnetic (EM) pulsed electric drill. Pulsed electric
drilling technology is
suited to provide such a source of electromagnetic energy because in certain
systems the pulsed
power system is already deployed downhole. The system enables electromagnetic
evaluation of a
formation downhole, even while drilling. The term "loop" is meant to include a
circular or non-circular
configuration, and a loop may be nearly closed or only partially closed. For
example, a conductor
configuration in the form of a square is encompassed in the definition of
loop. A configuration that is
only half of a square or half of a circle is also encompassed in the
definition of loop. The term "loop"
also means a coil or plurality of loops. Formation evaluation as described
herein can be performed in
minerals and mining exploration, oil and gas deposits, oil and gas
exploration, water exploration,
geophysical exploration, geologic formations and exploration, subsurface
mapping, and the like.
[00343] Referring to Fig. 65, one embodiment of the present invention
comprises an EM
pulsed electric drill used for electrohydraulic or electrocrushing drilling.
Bottom hole assembly 242,
electrocrushing bit 118, electrohydraulic projectors 243, drilling fluid pipe
147, power cable 148, and
pulsed power subsystem 244 comprise the pulsed power system and other
components of the
downhole drilling assembly (not shown). The drill can be powered by a downhole
power source, by a
downhole alternator or generator powered by mud turbine, or from the surface
by a cable or drill pipe
with embedded conductors. The arc produced by the drill either in the rock or
in the drilling fluid
creates a magnetic field around the arc as shown in Fig. 62. This magnetic
field can then be used for
formation evaluation and gas pocket detection ahead of the drill, with the
appropriate sensors, such
as disclosed in U.S. Patent Application No. 8,390,471. Using a pulsed electric
drill system to produce
the desired EM pulse is advantageous, because the infrastructure (such as
power feed, charging
scheme, control system, instrumentation, etc.) is already in place. Preferably
all that is required is an
additional circuit to produce the pulse (e.g. if either one or three spiker
circuits are employed by the
drill, the pulse circuit would be the second or fourth circuit, respectively).
A opposed to the high
voltage (e.g. approximately 150 kV) spiker circuits, the pulse circuit
preferably operates at relatively
low voltage (e.g. tens of kilovolts) and medium current (e.g. a few kiloamps).
[00344] Embodiments of the present invention comprises an EM pulsed
electric drill having
an additional pulsed power subsystem added to bottom hole assembly 242 to
create a pulsed
magnetic field by conducting pulsed current through a conductor formed in a
loop. The pulsed power
electromagnetic subsystem 244 preferably has energy storage and source
impedance characteristics
that are different from the electrocrushing or electrohydraulic pulsed power
systems in the pulsed
electric drill. The same charging system that is utilized for the rest of the
pulsed electric drill bottom
hole assembly pulsed power system can also be used for the EM pulsed power
subsystem. The
same control system that is utilized to control the pulsed electric drill can
also be used to control
subsystem 244. Subsystem 244 can then be used to drive current through one or
more magnetic
- 73 -
Date recue / Date received 2021-12-14
coils or loops to produce the desired electromagnetic pulsed field. The loop
can be constructed with
a specific configuration and oriented in a particular direction to provide a
pulsed magnetic field with
the desired configuration and orientation in space.
[00345] For example, the conductor can be physically constructed as a
loop around the
circumference of bit 118 to minimize the interference of bottom hole assembly
242 on the
electromagnetic field pulse, such that the plane of the current loop is
perpendicular to the axis of the
bottom hole assembly. When the current pulse propagates through the conductor
loop, it creates a
pulsed magnetic field with an axis of symmetry approximately coincident with
the axis of the bottom
hole assembly, as shown in Fig. 63. This creates a magnetic field
configuration with the peak of the
field in the direction of propagation of the electrocrushing drill, thus
providing the means to evaluate
the formation ahead of the drill, with the appropriate sensors. This
evaluation process could be
carried out during active drilling or while not drilling. Fig. 66 shows coil
990 for projecting a magnetic
field along the axis of the drill system. As shown in Fig. 67, a current loop
or coil 995 may
alternatively or additionally be built into the side of the bottom hole
assembly to create a pulsed
magnetic field whose axis of symmetry and whose maximum extent is
approximately perpendicular to
the axis of the bottom hole assembly, i.e. transverse to the axis of the drill
system. Although coils
990, 995 as shown each comprise a single turn coil, a coil comprising multiple
turns may be utilized to
match the power output of the pulsed power system to the desired magnetic
field strength, depending
on the desired magnetic field strength and the current and voltage source
capabilities of the pulsed
power system.
[00346] Another embodiment of an EM pulsed electric drill is to take
current from one or more
of the electrode sets of the EM pulsed electric drill and run the current
through one or more magnetic
loops or coils to produce a desired pulsed electromagnetic field, as
illustrated in FIG. 64. This can be
done in series, with returning the current from the loop back to the electrode
set to contribute to
drilling. It can also be done instead of drilling, with the current
circulating only through the loop. A
third embodiment is to operate it in parallel with part of the current going
through the loop and part of
it through the electrode set. Alternatively a plurality of conductor loops can
be oriented along the side
or wall of the bottom hole assembly or near the bit or near the end of the
bottom hole assembly
opposite the bit so that, by changing the phasing of the current through the
loops, the location of the
maxima of the magnetic field can be steered through the formation.
[00347] A variation of the EM pulsed electric drill is one designed for
formation evaluation and
not designed for drilling, which can be used to create a pulsed magnetic field
for formation evaluation
in the well, or can be located on the surface for formation evaluation from
the surface.
- 74 -
Date recue / Date received 2021-12-14
Electrocrushing Bits Utilizina Rod Geometries
[00348] Bits for electrocrushing drills that utilize rods as the principal
electrode geometry are
important for electrocrushing drilling of particular rock types. One such
hybrid bits comprises both
rods and curved surfaces; another comprises concentric arrays of rods. As used
throughout the
specification and claims, the term "rod shaped" means resembling a rod,
rodlike, elongated,
cylindrical, and the like. A rod shaped element may have any shape cross
section, not just circular.
[00349] Fig. 68 shows an embodiment of an electrocrushing bit comprising a
plurality of rod
shaped high voltage electrodes 1000, preferably wired in parallel, and central
ground rod electrode
1010, which are surrounded by continuous ground ring 1020. Openings 1025 in
ground ring 1020
enable drill cuttings to be flushed to the outside of the drill bit and up the
wellbore. The excavation
process proceeds from one or more of the high voltage electrodes to the
central ground electrode or
to the outer rim. The outside edge of the bit preferably structurally supports
the drill string, and so is
preferably strong enough to be capable of withstanding substantial compressive
forces. The unique
electric field distributions created by the rods substantially enhance the
electrocrushing process.
Central ground rod electrode 1010 may comprise a single rod or a plurality of
rods, in which case the
plurality of rods may be arranged in a circular configuration concentric with
high voltage electrodes
1000.
[00350] Fig. 69 shows another embodiment of a rod-based electrocrushing
drill bit comprising
a plurality of high voltage electrodes 1030 and central ground rod electrode
1040, which are
surrounded by a plurality of ground rods 1050 at the circumference of the bit.
Ground rods 1050 are
preferably concentric with high voltage electrodes 1030 and are preferably
grounded or held at a low
voltage. The use of rods at the outside circumference of the bit provides
additional control over the
electric fields in order to enhance the electrocrushing process. The spacing
between the rods
preferably enables sweeping out of the cuttings from the drilling process. In
this embodiment, the
ground rods extend directly from the bit structure. In other embodiments
ground rods 1060 can
extend out from continuous rim or rod wall 1070, as shown in Figs. 70A and
70B. In addition to
providing additional E-field and flow management, rod wall 1070 enables the
production of the same
rod-like electric fields of the embodiment shown in Fig. 69 while also
providing the structural support
capabilities of a continuous rim in order to support the drill string. As more
clearly shown in Fig. 7013,
rod wall 1070 preferably extends outwardly to the outside circumference of the
drill bit, but is
sufficiently thin so that ground rods 1060 protrude from the inner edge of the
wall towards the center
of the bit. The ground rods in both of these embodiments are preferably the
same length. As shown in
Fig. 70, rod wall 1070 preferably connects ground rods 1060 and comprises a
thickness that extends
rod wall 1070 radially outwardly as far as or beyond ground rods 1060, but not
past them radially
inwardly (i.e. toward the high voltage electrodes). Rod wall 1070 may
optionally comprise ports (not
shown) to remove the cuttings to the outside of the drill.
- 76 -
Date rogue/ Date received 2021-12-14
[00351] Fig. 71 shows another embodiment of the present invention with no
central ground
rod electrode; the bit comprises single high voltage electrode 1080 surrounded
by ground rods 1090.
The bit also comprises one or more channels 1100 running along the side of the
bit to accommodate
the flow of cuttings or debris out of the bit and up the hole. Similar
channels may be employed in any
of the embodiments herein.
[00352] Fig. 72 is a photograph of another embodiment of the present
invention comprising
current return ring 1200 which comprises a plurality of openings 1210
surrounding a single rod
shaped high voltage electrode 1215.
[00353] In any of these embodiments, the rods, continuous ground ring,
and/or rod-wall may
comprise one of many types of structural steel, including but not limited to
4140 stainless steel, high-
strength carbon steel, and super alloys that combine high toughness with high-
strength and abrasion
resistance. The cross section of any of the rods described herein can be
circular as shown, or
elliptical, airfoil shaped, or comprise any shape to enhance fluid flow out of
the center of the drill to
the periphery.
[00354] The preceding examples can be repeated with similar success by
substituting the
generically or specifically described components, mechanisms, materials,
and/or operating conditions
of this invention for those used in the preceding examples.
[00355] Although the invention has been described in detail with
particular reference to these
disclosed embodiments, other embodiments can achieve the same results.
Variations and
modifications of the present invention will be obvious to those skilled in the
art and it is intended to
cover in the appended claims all such modifications and equivalents.
- 76 -
Date recue / Date received 2021-12-14
