Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DRILLING DEVICE AND PROCESS
The contents of Provisional Application U.S. Serial No. 61/659,677
filed June 14, 2012, on which the present application is based and benefit
claimed under 35 U.S.C. 119(e), is herein incorporated by reference
Field of the Invention
[0001] This invention relates to drilling of holes in the earth, and is more
specifically related to a device and method for changing drill cutting faces
of drill
strings for use while the drill sting is in situ in the hole.
Background of the Invention
[0002] Drilling for oil and gas involves a drill bit and hundreds of lengths
of pipe. A common drill bit is cast metal or machined housing studded with
multiple protrusions. The protrusions comprise a hard surfaced material, which
may be a ceramic type material that is fortified with multiple industrial
diamonds
20. The resulting cutting discs are known in the industry as polycrystalline
diamond (PDC) cutters.
[0003] As the bit rotates it cuts through the earthen material. Pipe
sections are sequentially joined as the drilled hole becomes deeper. The
overall
length of connected pipe sections can easily be 5,000 to 40,000 feet and is
called
the drill string.
[0004] Water, chemicals and solids mixtures, called "drilling mud," are
forced through the pipe and ejected at high pressure through ports built into
the
drill bit. Drilling mud cools the bit, lubricates the cutting action, and
washes the
drilled earthen material out from the bottom of the hole, and up and around
the
exterior of the drill pipe. The mud eventually washes the material to the top
of the
hole where it is filtered and reused.
[0005] The drill bits are subject to wear, and eventually, wear out. The
rate of wear depends on the hardness and abrasion characteristics of the
drilled
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earthen material. As wear progresses, the cutting discs become dull, and less
and less effective. Changing bits requires removing the entire drill string
from the
hole to access the bit. Removal of the drill string requires pulling the top
section
of pipe up, unscrewing it, placing it aside, and repeating this sequence until
removal is complete. A 9000 foot drill string, using common pipe lengths of 30
feet, requires retraction and removal of 300 pipe sections. Once the bit is
above
ground it is removed, and a new bit is attached. The entire drill string is
then
reconstructed, one pipe section at a time, and lowered into the hole to reach
the
point where the drilling stopped. The bit replacement process can take 36
hours
or more for some holes. Drilling platforms operate on a continuous basis at a
cost of several hundred thousand dollars per day in some cases. A lost day of
drilling to replace bits once or twice a week becomes very expensive.
[0006] There is a need for a device and process that will allow a useful
bit to be placed in position for use without removing the drill string from
the hole.
Summary of the Invention
[0007] A plurality of cutting faces is attached sequentially at a distal end
of a drill string. The forward most cutting face that is distal to the top of
the hole is
exposed and used for drilling until worn to a point of inefficiency. The
forward
most or distal cutting face is then detached, exposing the next cutting face
in the
sequence. Detachment of the forward most cutting face is performed by remote
controlled actuation at the top of the drill string and/or outside the hole. A
new
cutting face is exposed without the necessity of removing the drill string.
The
detachment process is repeated as long as drilling is continued, and fresh
cutting
faces remain available for use.
Description of the Drawings
[0008] Fig. 1 demonstrates the distal end of a drill string with a plurality
of drill cutting faces in the form of cutting disks present on the mandrel.
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[0009] Fig. 2 demonstrates the drill string of Fig. 1 and associated drill
cutting faces being retracted from the bottom of the bore hole.
[0010] Fig. 3 demonstrates the most distal drill cutting face being
separated from the mandrel and discarded.
[0011] Fig. 4 demonstrates the discarded drill cutting face at the bottom
of the hole.
[0012] Figs. 5 and 6 demonstrate the discarded drill cutting face
fragmented into processable pieces.
[0013] Fig. 7 demonstrates the drill string being advanced to the bottom
of the bore hole.
[0014] Fig. 8 demonstrates continued drilling operations with the next
drill cutting face at the distal end of the drill string as drilling
operations are
continued.
[0015] Fig. 9 is a perspective view of a mandrel for a drill string with the
sequential cutting faces mounted to the mandrel.
[0016] Fig. 10 shows the mandrel of Fig. 9 with the sequential cutting
faces spaced apart from the mandrel for demonstration purposes.
[0017] Fig. 11 shows the mandrel of Fig. 9 with the sequential cutting
faces spaced apart from the mandrel for demonstration purposes, and showing
the opposite side of the cutting faces from the side shown in Fig. 10.
Detailed Description of the Preferred Embodiments
[0018] The drawing figures demonstrate a forward, or distal, end of a drill
string with the drill bit assembly comprised of a mandrel and associated
cutting
faces. The drill string in use may be of substantial length, and may be
thousands
of feet long. The drill string is formed by joining multiple sections of pipe.
The
drawing figures demonstrate only the most forward or distal section of pipe 2,
and depict only the last few feet of a hole 4 that may be thousands of feet
deep.
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[0019] Affixed to the end of the most distal pipe section, and at the most
distal end of the pipe section, is a mandrel 6. The most distal end of the
mandrel
is a plurality of drill cutting faces 8. The drill cutting faces are used to
cut away
earth, rock, and other geological material. In one embodiment, the cutting
faces
are formed as a plurality of disks having cutting material 20, such as PCD,
embedded therein. The plurality of cutting faces is present sequentially on
the
mandrel as shown in the drawing figures.
[0020] Additionally, the mandrel portion of the bit may comprise POD
cutters 22 on the sides. These cutters do not suffer the extreme wear exposure
that the multiple cutting faces of the tips experience, but the side mounted
cutters
assist with continually reaming the bore hole.
[0021] Each of the plurality of cutting faces is connected to the mandrel
and/or to an adjacent cutting face. As the cutting face wears to the point of
inefficiency at cutting and drilling the hole, the most distal cutting face is
removed
by remote controlled actuation. As demonstrated by Fig. 3, the most distal
cutting face 10 is separated from the remaining cutting faces, which causes
the
worn and discarded cutting face to fall away from the remaining cutting faces
that
remain attached to the mandrel at the distal end of the drill string. Fig. 4.
[0022] In a preferred embodiment, each of the drill cutting faces is
attached to the mandrel and/or an adjacent cutting face by an exploding
fastener.
Each disk may be connected to an adjacent cutting face and/or the mandrel by
an exploding nut or an exploding bolt, or both. The exploding fastener may be
remotely controlled to initiate the fastener explosion. Each exploding
fastener
responds to a different code or command, so that, in normal operation, the
most
distal drill cutting face is the only separated cutting face discarded by
exploding
the associated exploding fastener.
[0023] The exploding fastener may be exploded by an igniter that is
excited electrically from an internal battery in the drill mandrel. Electrical
energy
is controlled by an internal micro-processor. The internal micro-processor is
controlled by a remote surface control device using coding schemes and
security
algorithms transmitted to the internal micro-processor via a transceiver,
which
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may be present in both the mandrel and the surface controller, using RF energy
and/or ultrasonic energy.
[0024] In one embodiment, the mandrel 6 attaches to a standard drill pipe.
The mandrel accommodates several drill cutting faces each studded with
multiple
diamonds or other hardened material that acts as a material cutter. The drill
cutting faces are nested within each other and held in a stack with a bolt,
which
may be an exploding bolt.
[0025] In one embodiment, each drill cutting face has an exploding
charge embedded into it. After the worn cutting face is expelled from the
mandrel or drill string, the explosive charge is remotely actuated so that it
explodes (Fig. 5), leaving only small fragments 12. The small fragments are
flushed from the bore bottom, with the drilling mud ejected from the cutting
face
built in ports, as demonstrated by Figs. 7 and 8. The high pressure drilling
mud
is then allowed to flow and wash up the fragmented old cutting face without
the
drill string rotating for a few minutes. In this way, the discarded, worn
cutting
face does not interfere with drilling operations, and can be removed from the
bore hole.
[0026] The discs may contain internal cavities where explosives are
strategically placed. The disks may be machined or cast to possess certain
thicknesses and/or score marks to weaken the disk at strategic points to
facilitate
fragmentation. Fig 11. The cutting discs may be formed of thicker and/or
stronger materials where necessary to insure structural integrity while
cutting, but
may be formed of less material and/or weaker material at other points to
facilitate
fragmentation when discarded.
[0027] In a preferred embodiment, the plurality of drill cutting faces
attached to the mandrel will be no fewer than two sequential drill cutting
faces.
The drill cutting faces are mounted to the mandrel at the beginning of the
drilling
operation. By way of example, six or more drill cutting faces may be present
on
the distal end of the drill string. The drill cutting faces are connected by
exploding fasteners as described herein. As shown in Figs. 9, 10 and 11, three
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cutting faces 8, 10 and 14 are attached to the mandrel 6 by exploding
fasteners
16, 18.
[0028] The communications link between the surface controller and the
drill bit for remote actuation to discard the distal cutting disk is preferred
to be
wireless. Wireless technology links may include radio electromagnetic energy
that is radiated and received, or mechanical ultrasonic energy generated and
received by ultrasonic transducers. The use of wireless communications
eliminates the extra effort of threading physical wires through the drill
string,
which would be cumbersome and unreliable. Even though the drill bit may be 3
miles below the earth's surface (and the earth is an excellent RF attenuator),
the
drill string, formed of metal pipe sections, is an excellent conduit for RF,
and acts
as a long antenna. If ultrasonic technology is utilized, the string provides
an
excellent conduit for the transfer of the ultrasonic energy to the receiver
that is
associated with the drill bit at the bottom of the drill bore.
[0029] The surface controller for wireless communication and actuation
may comprise a physical container, RF transceiver or ultrasonic transceiver,
micro-processor, software and/or other appropriate means for a plurality of
digital
inputs. Embedded into the disposable cutting face may be another RF
transceiver powered by a small battery. Lithium battery technology is
preferred
for its long shelf life and low internal resistance for the high amperage
output
necessary to excite the explosive firing cap. The battery may also power an
igniter for the explosive that fragments the cutting face, and in one
embodiment,
to power a timer that delays ignition for a time after the cutting face is
separated
from the mandrel.
[0030] When a drill bit is no longer achieving the desired or expected
rate of penetration, the most distal cutting face that has been in use is
discarded
and the next most distal cutting face is exposed for use. The drill string is
retracted, usually no more than the length of one pipe section, which may be
30
feet. In the preferred embodiment, a wireless code is sent to a small receiver
embedded in the mandrel. The code may be sent by RF (radio frequency) or
ultrasonic messaging. The receiver, upon receiving the proper code, actuates
an
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electronic circuit to initiate the charge in the exploding fastener, such as
an
exploding stacking bolt. The bolt explodes, causing the distal end cutting
face to
separate from the remaining drill cutting faces. This exposes the next cutting
face
in the sequence. The next disk comprises new cutters, such as sharp PCD
material.
[0031] The drill string is then pulled upward toward the surface for
several feet to isolate the mandrel and newly exposed cutting faces from the
worn and separated cutting face. In an embodiment, separation of the worn
cutting face invokes an internal electronic timer embedded within the core of
the
cutting face. The timer counts down several seconds before initiating a second
explosion from within the worn cutting face. The explosion of the worn cutting
face core fragments the core body.
[0032] Then drill string is then lowered to the bottom of the hole. The
high pressure drilling mud then flushes the worn cutting face fragments away
from the bottom of the bore hole and up and around the pipe of the drill
string.
After the fragments are beginning to migrate upwardly and away from the bottom
of the bore hole, which generally takes only a few minutes, downward pressure
is
applied to the drill string, and the attached drill bit system. Rotation of
the drill
string resumes, which resumes the drilling process. This method allows a new
cutting face to be exposed for use without pulling the entire drill string
from the
hole. The process may be repeated as long as an unused cutting faces are
available in the sequence. The number of cutting faces that may be
sequentially
positioned or stacked for use may be to be from 2 to 6, subject to further
study
and experimentation.
[0033] The invention may be used with cone roller bit designs. Roller bits
are bits that possess a plurality of rollers, such as two or three rollers,
opposing
the other. Stacking may require additional bit structure, such as a base,
roller
support arms, bearings and rollers. Explosive material may be integrated into
the
body and associated components. Larger detonation strength is likely to be
required to sufficiently fragment the mass, and possibly a longer "flush" time
may
be required because of additional fragments.
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[0034] The mandrel may comprise an internal cavity that is accessible,
but sufficiently sealed against the environment to prevent dirt, water and
other
solids and liquids from entering the cavity. The cavity may accommodate a
variety of devices, including electronic components. A replaceable battery
pack
may be used to supply the electrical energy to power electrical components. A
micro-processor with a plurality of inputs and outputs and having support
circuitry, power conditioners, buffers, and associated integrated circuits may
function as a control or computer for the system to perform and provide
monitoring functions, communications to and from surface controllers, and to
initiate and control actions at the drill bit.
[0035] A variety and plurality of sensors may be part of the well drilling
device and may be positioned in proximity to the drilling environment may
interface with the control/computer to measure, monitor and record the
operating
environment, such as temperature, material density, drill bit pressure, and
drill
string and bit vibration. Additional sensors may include solid state
gyroscopes for
directional control and accelerometers for shock monitoring. Also, various
sensors may monitor wear gradients and patterns of the cutting faces to
facilitate
the timing of cutting face replacement. All functions, monitoring and
recording is
preferred to be communicated to the surface controllers by either RE energy of
ultrasonic energy generated and modulated by the control/computer. The
communications link is preferred to be duplex, and the surface controllers can
send instruction sets to the control/computer internal to the mandrel.
[0036] Various firing algorithms, coding and built in self tests may be
utilized to promote safety. Examples include:
1. A prominent "wear point" with a signal conductor embedded below the
wear point surface. When sufficient wear of the wear point's surface is
experienced, the exposed signal conductor wire sends a signal to the processor
that in turn relays the status to the surface control panel and invokes an
annunciator.
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2. Actuation codes for each exploding device are different.
Pseudorandom number assignments may be used to ensure that no two
explosive devices are assigned the same identifier or code.
3. Algorithmic schemes employ plural checks of each unique identifier,
and check schemes over several interrogations and iterations. Sufficient time
is
available for even thousands of checks before detonation, which may take only
a
few seconds.
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