Note: Descriptions are shown in the official language in which they were submitted.
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MUD PULSER WITH POPPET VALVE, HAVING LINEAR DISPLACEMENT
DETERMINATION MEANS
TECHNICAL FIELD
[0001] The present disclosure is directed to a pulser actuator for use in
mud pulse
telemetry, namely for use in so-called "measurement- while- drilling ("MWD")
operations.
More particularly the invention relates to a novel pulser actuator having
linear displacement
detection/determination means to determine actual linear position of a poppet
valve within said
pulser actuator.
l 0 BACKGROUND OF THE INVENTION, AND DESCRIPTION OF THE PRIOR ART
[0002] In oil and gas drilling data collected downhole from various
sensors with respect
to direction and orientation of the bit and/or geological formations
encountered during drilling
is transmitted uphole in various manners for use by the drilling operator at
surface to control
drilling.
[0003] Engaging in this practice is referred to as performing "Measurement-
While-
Drilling" (MWD). Logging data may also be transmitted uphole, in which case
engaging in this
practice is referred to as "Logging-While-Drilling" (LWD). Various types of
telemetry
technology exist to permit transmission of data collected downhole to the
surface.
[0004] One type of commercialized telemetry technology is mud pulse
telemetry. In mud
pulse telemetry, pressure pulses are created downhole by periodically
constricting the flow of the
drilling mud through a drill string by means of a pulser actuator. Such
pressure pulses then
travel back through the drilling mud and/or the formation itself, where at
surface such pressure
pulses are received and decoded to reveal valuable information about drilling
conditions
downhole. When a main valve controlled by the pulser actuator is completely
closed, mud flow
through the valve is prevented and pressure in the drilling mud increases;
when the main valve is
subsequently opened, pressure in the drilling mud decreases. Pressure pulses
can consequently
be generated in the drilling mud by repeatedly opening and closing the main
valve. One type of
main valve used in pulsers is a poppet and orifice type valve, in which a
poppet linearly
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reciprocates above a valve scat. When the poppet is pressed against the valve
scat, the orifice
and consequently the main valve are closed; the orifice and main valve are
otherwise considered
fractionally or entirely open. The pulser is typically housed within a tubular
and attached to the
bottom hole assembly (BHA) of a drill string when in use.
[0005] In some mud pulse telemetry units, a scrvo-valve having a pilot or
poppet-type
valve is used to actuate a main valve that is responsible for generating the
sizable pressure
pulses sent to the surface. The pilot/servo- valve is linearly oscillated by
an electric motor, which
poppet valve thereof is accordingly controlled to open and close at precise
times and durations
to thereby control pressure applied for similar tinies and durations to a main
valve by drilling
mud. By regulating the pressure on the main valve, the pilot valve can cause
the main valve to
open and close, at precise times and for varied duration, thereby generating
the pressure pulses to
specific intensity, duration, and sequence. In such manner data can be
transmitted uphole and
received at surface by sensors which receive such pressure pulses and decode
such pressure
pulses into useful information regarding conditions downhole during drilling.
[0006] It can be very useful to know, for a controller which controls the
servo valve
motor and thus the movement of the poppet valve to create pressure waves of
various duration
and intensity, the precise position of the pilot (servo) valve relative to the
valve seat, namely
whether the pilot valve (poppet) is in a fully open, fully closed, or some
intermediate position
therebetween. However,
frequently LCM (i.e. lost circulation material, such as fine drill
cuttings) sometimes enters the mud pulser unit and may impede or restrict to
varying degrees
the linear oscillation of the poppet, which may require the controller to
initiate a "clearing"
cycle to initiate a "back and forth" motion to the poppet valve to attempt to
clear an LCM
obstruction which otherwise prevents full open or full close positioning of
the poppet.
Knowledge of precise positioning of the poppet may then become unknown to the
controller.
[0007] One way knowledge of the precise position of the poppet can be
regained is by
driving the poppct into or away from the valve scat until the poppet is
physically restrained from
further movement, typically by abutting a mechanical "stop" which limits
further travel. When
the poppet is so restrained the controller can detect that the motor draws
increased current due to
meeting the increased resistance of the "stop", and can thereby determine the
poppet has reached
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the limit of its travel in that direction, and thereafter cease driving the
poppet in that direction.
Driving the poppet in this manner is referred to as "overdriving" the poppet.
[0008] However, it is usually very undesirable to rely on repeatedly
overdriving the
poppet , after for example a cleaning cycle, to determine its position
relative to the fully open or
fully closed position because the current spikes that overdriving produces can
relatively quickly
drain the batteries that power the motor. Maintaining battery life of a
downhole mud pulser is
an extremely important consideration in increasing the downhole time of such
pluser actuator .
Otherwise, if batteries which power the pulser- actuator are "drained" more
frequently, such
causes a drilling operator to have to more frequently 'trip out" a drill
string to replace the mud
pulser and/or batteries therein, which results in greatly-increased drilling
expense, not to mention
lost time in drilling, which adds further expense considering drilling rigs
are generally rented to
drilling companies on a per diem basis and lost time therefore results in
increased equipment
rental costs, to say nothing of the delay and lost profits caused in
prolonging the time before
revenue can be received from a well .
[0009] One example of a mud pulser/pulser actuator having a pilot valve
used to actuate
a main valve is given in US 7,564,741 to Pratt et al. In Pratt et al., the
pilot valve comprises a
poppet and a valve seat, and a stepper motor is used to linearly move the
poppet relative to the
valve seat. A controller is connected to and controls the stepper motor. A
plurality of Hall
sensors (typically three for a three-pole stepper motor) are needed, which
Hall-effect sensors are
mounted on the stator of the stepper motor ¨output from such Hall-effect
sensors allows the
controller to -count" the number of rotations the motor's rotor undergoes.
Counting the number
of rotations of the motor, which moves the poppet through known reduction
gearing, allows the
controller to determine the linear position of the poppet relative to the
valve seat. For example,
the controller may first zero the poppet by forcing it against the valve seat,
following which the
motor can open the pilot valve by lifting the poppet a certain linear distance
away from the valve
seat (i.e. by the controller directing the motor to rotate a number of
revolutions). This linear
distance may be encoded in the controller as being a function of the number of
rotations of the
motor's rotor, as determined from measurements obtained using the Hall sensors
on the motor,
instead of in more conventional units such as inches or millimeters. Once the
poppet is "zeroed",
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by overdriving the poppet it need not ever bc rc-zeroed, and thus battery life
of the mud pulser is
preserved to a degree.
[0010] The
mud pulser of Pratt is but one partial solution to the problem of continually
determining the position of the poppet valve, while avoiding frequently having
to overdrive the
poppet to determine its position with the consequent resulting degradation in
battery life.
[0011] Given
the importance of MWD and LWD to the oil and gas industry in being
best able to control drilling of wells, providing alternate mud pulser designs
is important in
providing alternate competing designs for facilitating completion in the
industry
[0012] The
foregoing background information is provided for the purpose of making
known information believed by the applicant to be of possible relevance to the
present invention.
No admission is necessarily intended, nor should be construed, that any of the
preceding
information, or the reference in the drawings to "prior art" constitutes
relevant prior art against
the present invention.
SUMMARY OF THE INVENTION
[0013] The
invention relates to a measurement-while-drilling ("MWD") servo-actuator,
such as a so called "mud pulser" for use in mud-pulse telemetry, which mud
pulser senses actual
linear position of a poppet valve therein, without counting revolutions of a
stepper motor so as
to indirectly determine such linear position of such poppet valve.
[0014] The present mud pulser design of the present invention, whose
configuration in
various embodiments is hereinafter set out, advantageously avoids having to
"overdrive" the
poppet valve and thereby waste battery life, and further avoids issues with
aforementioned prior
art designs such as contained in US 7,564,741 to Pratt et al. which indirectly
determine poppet
position by counting motor revolutions and which device requires a plurality
of hall- effect
sensors within a stepper motor in ordcr to count such stepper motor
revolutions.
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[0015] Accordingly, in a first broad embodiment of the present
invention a
measurement-while-drilling servo-actuator/pulser actuator for use in mud-pulse
telemetry is
provided, comprising:
(i) a sensor for sensing proximity of a poppet valve and providing an output
proportional to linear proximity of said poppet valve to said sensor; and
(ii) a controller for receiving said output from said sensor, and determining
poppet valve position therefrom.
[0016] The single sensor required in this invention, as opposed to
plurality of sensors
required for stepper motor pole position to effectively count motor rotations
in prior art designs,
is, in a first embodiment of the present invention, of a type which senses a
magnetic field
intensity , such sensed intensity value being proportional to the position of
the poppet valve
relative to the sensor.
[0017] In an alternative configuration, the single required sensor is
of a type which
senses the inductance of an electrical winding, the sensed inductance thereof
being proportional
to the position of the poppet valve relative to the electrical winding.
[0018] The above pulser actuator may, include a look-up table of
reference sensor
outputs corresponding to known linear positions of the poppet valve. Such look-
up table may be
used in conjunction with a sensed value received from the sensor when the
poppet valve is in an
unknown position to determine the precise position of the poppet valve when in
said unknown
position. Such determination of location may alternatively be from any one of
a number of other
cominon techniques, including but not limited to extrapolation by using a
plurality of reference
magnetic field intensities and corresponding known poppet positions, to
determine the poppet
position at said sensed value from said plurality of known sensed positions..
[0019] A particular method of determining a position of a poppet valve
in a pulser
actuator is further disclosed.
[0020] Specifically and more particularly in respect to the above
first refinement of the
present invention, such pulser actuator includes a linear position sensor
therewithin which
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continually senses the intensity of an electromagnetic or magnetic field, the
intensity of such
field being proportional to the position of the poppet relative to the sensor.
A magnetic field
source, such as preferably a permanent magnet since no electrical current or
battery power is
needed to generate such magnetic field, is used. Alternatively and less
desirably an
electromagnet may be used to create the magnetic field. The magnetic field
sensor provides an
output proportional to the intensity of the magnetic field being sensed, and
in particular
proportional to a linear distance separating the magnetic field from the
sensor, wherein one of the
magnetic field or sensor is mechanically coupled and becomes linearly
displaced upon
movement of the poppet valve, and the other remains in a fixed position within
the mud pulser.
A controller. which controls the number and direction of electrical pulses
provided to a stepper
motor, is communicatively coupled to the magnetic field sensor. The controller
compares the
intensity of the magnetic field received from the sensor to a reference of
expected measured
magnetic field intensities at various known distances of the poppet valve
between a fully open
and fully closed position, such as by comparing the sensed value of the
magnetic field intensity
with the reference values for known poppet position, and determines the
position of the poppet
valve from such comparison. In such manner a precise position of the poppet
relative to its fully
closed position and its fully open position is thereby continually known,
thereby avoiding the
need to overdrive the poppet valve from time to time to re-acquire a "fix" as
to its position and,
thereby avoiding undesirable reduction in battery life by avoiding use of
excess current and
power consumption when "overdriving" the poppet in this manner.
[0021j In the above-mentioned alternative configuration/refinement, the sensor
does not
comprise a magnetic field sensor but instead comprises a substantially
cylindrical winding of
electrically conductive wires . The poppet valve, or a material directly
coupled to said poppet
valve, is of a ferromagnetic material. The inductance of the electrically-
conductive wires
changes proportional to the proximity of said ferro-magnetic poppet valve or
said ferro-
magnetic material to said wires. The value of the electrical inductance of the
electrical wires
(cylindrical winding) is used to determine relative position of the poppet
valve relative to known
inductances at various positions of such poppet valve between a fully open
position, and a fully
closed position.
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[0022] Further mechanical detailed components of such pulser actuator
of the present
invention are set out below.
[0023] Specifically, in a first broad embodiment the measurement-while-
drilling servo-
actuator of the present invention comprises:
(i) a poppet valve, linearly moveable between an open position which permits
flow of drilling mud through a servo-valve port and a closed or substantially
closed position wherein said poppet valve obstructs said servo-valvc port to
prevent or substantially prevent flow of said drilling mud therethrough;
(ii) an electric motor having an output shaft that rotates in response to
operation
of the motor;
(iii) a rotary-to-linear motion converter, mechanically coupled at one end to
said
output shaft and at another end directly or indirectly coupled to said poppet
valve,
for linearly moving said
poppet valve back and forth between said closed
position and said open position;
(iv) a sensor for sensing proximity of said poppet valve thereto and providing
an
output proportional to proximity of said poppet valve to said sensor; and
(v) a controller for receiving said output from said sensor, and determining
poppet valve position therefrom.
[0024] In the first alternative refinement, the servo-actuator
comprises:
-a magnetic field device within said servo-actuator, which creates a magnetic
field; and
- said magnetic field device or said sensor is mechanically coupled to said
poppet valve or situated in said poppet valve, wherein
relative linear
displacement of said magnetic field device relative to said sensor occurs upon
linear movement of said poppet valve; and
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- said sensor senses intensity of said magnetic field and provides an
electrical
output proportional to proximity of said magnetic field
relative to said sensor.
[0025] In a
further embodiment the aforementioned servo-actuator comprises first and
second matingly engageable half-members,
said first half member comprising said magnetic field device and said poppet
valve; and
said second half member comprising motor and said sensor.
[0026] In
the further alternative configuration/refinement, the servo-actuator instead
of
having a magnetic field sensor comprises a sensor having a substantially
cylindrical winding of
electrically conductive wires whose inductance changes proportionally to the
proximity of
ferro-magnetic poppet valve or a ferro-magnetic material to said sensor. In
such alternative
configuration the poppet valve, or a material mechanically coupled to or
situated on said
poppet valve, is ferromagnetic so as to thereby be able to cause a change in
the inductance of
the cylindrical windings proportional to the proximity of the ferromagnetic
poppet or
ferromagnetic material thereon.
[0027] In preferred embodiments of the invention the electric motor is a
brushless DC stepper
motor, which type of electric motor is very well adapted, when receiving
electrical step pulses,
to moving the poppet valve via the rotary-to-linear converter in precise
increments.
[0028] In preferred embodiments the rotary-to-linear motion converter
comprises an internally
threaded nut member which threadably engages and receives therein an
externally- helically
threaded rotatable rod coupled to said output shaft and rotated thereby,
wherein the nut mcmbcr
is mechanically coupled to said poppet valve, and the nut member, due to
rotation of said rod
therein, becomes linearly displaced thereby linearly displacing said poppet
valve.
[0029] In a
further embodiment where the sensor is a sensor which detects intensity of a
magnetic field, the nut member of the rotary-to-linear converter possesses a
magnetic device,
and said magnetic device such as a permanent magnet is linearly displaceable
upon rotation of
the rod and the magnetic field sensor is fixedly situated in said servo-
actuator. The magnetic
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field sensor in this embodiment senses intensity of said magnetic field and
provides an electrical
output proportional to proximity of said nut member and thus poppet valve
relative to said
sensor.
[0030] In a further refinement of the invention where the sensor is
alternatively a
substantially cylindrical electrically conductive winding and which senses
changes in
inductance in the electrical winding, the nut member of the rotary ¨to-linear
converter is of a
ferromagnetic material, and the sensor senses changes in the inductance of the
electrical wires
and provides output to said controller proportional to proximity of said nut
member to said
sensor.
[0031] In another broad aspect, the pulser actuator for use with a mud
pulser comprises:
(a) a motor having an output shaft that rotates in response to operation of
the motor;
(b) a rotary-to-linear motion converter coupled to the output shaft;
(c) a servo valve comprising a poppet and a valve seat, wherein the poppet
is
coupled to the rotary-to-linear motion converter and is linearly moveable in a
reciprocating manner relative to the valve seat;
(d) a magnetic field source which generates a magnetic field, and a
magnetic field
sensor positioned within the pulser actuator, wherein one of the magnetic
field
source and sensor is coupled to or part of the poppet and the other of the
magnetic field source and sensor is fixed relative to the valve seat; and
(e) a controller communicatively coupled to the magnetic field sensor and
configured
to:
(i) measure the magnetic field using the magnetic field sensor;
(ii) compare intensity of the magnetic field to a reference of expected
measured magnetic field intensities at various distances between the
magnetic field source and sensor; and
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(iii)
determine the distance between the poppet and valve seat from the
comparing of the intensity of the magnetic field to the reference.
[0032] In
preferred embodiments, the magnetic field source is coupled to or part of the
poppet and is preferably a permanent magnet, and the magnetic field sensor is
fixed relative to a
valve scat for thc poppet valve.
[0033] In a
further embodiment of the present invention, such invention comprises a
method for determining location of a poppet valve within a pulser actuator,
the pulser actuator
comprising part of a drill string, the mcthod comprising:
(a) locating a magnetic device on said poppet valve or on a component
within said
pulser actuator that is mechanically coupled to said poppet valve, and
generating
a magnetic field;
(b) positioning a sensor at a fixed location within said pulser actuator;
(c) creating a plurality of reference magnetic field intensities for
corresponding
linear positions of said poppet valve arising from positioning said poppet
valve at
various known positions within said pulser actuator;
(d) measuring intensity of the magnetic field using said sensor at a given
unknown
position of said poppet valve relative to said sensor, to create a sensed
value;
(e) determining position of said poppet valve by comparing said sensed
value with
said reference magnetic field intensities and corresponding poppet valve
position.
[0034] In a greatly preferred embodiment the magnetic device on said poppet
valve or
on a component mechanically coupled to said poppet valve is situated co-linear
with said sensor
such that said magnetic device on said poppet valve moves in the most direct
manner toward,
and in the most direct manner away from, said sensor. In such manner, non-
linearities in
sensed magnetic field which otherwise result from movement of non-co-linarly
positioned
magnetic device and poppet valve, wherein the two do not move on paths most
directly in line
with each other, are thereby reduced. In such manner non-linearities in
changes in sensed
magnetic field can be somewhat reduced, which is advantageous if any straight-
line interpolation
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is to be used between adjacent reference field intensities for determining the
location from a
sensed magnetic field position.
[0035] In an alternative method of the present invention, such
invention comprises a
method for determining location of a poppet valve within a pulser actuator ,
said pulser actuator
comprising part of a drill string, the method comprising:
(a) providing a sensor within said pulser actuator, comprising a plurality
of
substantially cylindrically ¨wound electrically conductive wire;
(b) forming a poppet valve of ferro-magnetic material, or a ferro-magnetic
material mechanically coupled to said poppet valve so that said material is
linearly displaced upon linear displacement of said poppet valve;
(c) creating a plurality of reference inductance values as sensed by said
sensor
for various correspondingly known positions of said poppet valve;
(d) sensing, via said sensor, a sensed inductance value of said
cylindrically- wound
electrical wire for a given position of said poppet valve; and
(e) determining the location of said poppet valve by comparison of said
sensed
value with said reference values.
[0036] The above summary of various aspects and embodiments of the
invention does
not necessarily describe the entire scope of the present invention.
[0037] Other aspects, features and advantages of the invention will be
apparent to those
of ordinary skill in the art upon a proper review of the entire description of
the invention as a
whole, including the drawings and consideration of the specific embodiments of
the invention
described in the detailed description.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In the accompanying drawings, which illustrate one or more
exemplary and non-
limiting embodiments:
[0039] Fig. 1 is a cross-sectional view through one embodiment of the
pulser actuator
of the present invention having a magnetic field sensor , when said poppet
valve of the servo
valve is in the open position allowing flow of fluid through a servo-valve
port in said mud pulser
actuator;
[0040] Fig. 1A is an enlarged view of the encircled detail "A" in Fig.
1;
[0041] Fig. 2 is a cross-sectional view through the pulser actuator of
Fig. 1, when said
poppet valve of the servo valve is in the closed position preventing flow of
fluid through the
servo-valve port in said mud pulser actuator;
[0042] Fig. 2A is an enlarged view of the encircled detail "A" in Fig.
2;
[0043] Fig. 3 shows an enlarged cross-sectional view of a first half
member of the mud
pulser of the present invention, in an embodiment thereof using a magnetic
field sensor, such
first half member possessing a permanent magnet on a nut member on the rotary-
linear converter
thereof:
[0044] Fig. 4 shows an enlarged cross-sectional view of a second half
member of the
mud pulser of the present invention, in an embodiment thereof using a magnetic
field sensor,
such second half member containing such magnetic field sensor:
[0045] Fig. 5 shows an external, enlarged perspective view of the second
half member
shown in Fig. 4;
[0046] Fig. 6 shows a flowchart depicting a first broad method for
determining poppet
valve location, using a magnetic field sensor of the present invention;
[0047] Fig. 7 shows a graph of magnetic field intensity vs. distance
from the source of
the magnetic field , plotted using a series of sensed reference intensities,
each at corresponding
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known positions of said poppet valve, which data may be used as a look-up
table for a controller
to determine poppet position from a sensed magnetic field intensity.
[0048] Fig. 8 shows is a cross-sectional view through a portion of
another version of
the pulser actuator of the present invention, wherein the sensor comprising a
substantially
cylindrical electrical winding, and the nut member on the rotary-linear
converter is of a
ferromagnetic material, wherein linear displacement of said nut member and
mechanically
coupled poppet valve is sensed by changes in inductance of the electrical
winding; and
[0049] Fig. 9 shows a flowchart depicting the second alternative
method for determining
poppet valve location, using the configuration of mud pulser depicted in Fig.
8.
DETAILED DESCRIPTION OF SOME OF THE PREFERRED EMBODIMENTS OF
THE PRESENT INVENTION
[0050] Reference numbers referring to similar components are, for
consistency, referred
to by identical reference numbers throughout all of the drawings figures.
[0051] Referring now to Fig.'s 1, 1A, 2 & 2A there are shown in
sectional views a
pulser actuator 100 according to one embodiment of the present invention,
which in the
embodiment shown employs a magnetic field sensor 310 and a magnetic field
device in the form
of a permanent magnet 311, which magnet 311 may be an annular ring as shown,
or
alternatively a singular magnet positioned co-linearly with magnetic sensor
310, as best shown
in Fig. 1A.
[0052] Fig. 1 & 1A shows pulser actuator 100 and controller 190 when
the controller
has caused the pulser actuator to position the poppet valve 379 thereof in the
open position,
thereby allowing flow of fluid through a servo-valve port 381 in mud pulser
actuator 100.
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[0053] Fig. 2 & 2A show the pulser actuator 100 of Fig. 1 when the
poppet valve 379
of the servo valve (the servo valve generally shown on the right hand side of
Fig. 1, and in
detail in region 'A" of Fig. 2, namely the region depicted in Fig. 2A) having
been moved to
the closed position thereby preventing flow of fluid through the servo-valve
port 381.
[0054] The difference in open and closed positions of the servo-port 381
regulates
opening and closing of a main (downhole) valve, which thereby causes pulses in
drilling fluid
pressure supplied to the drill bit. Such pulses, whose parameters are
determined by the
controller 190, are preferably of different duration, timing between pulses,
and magnitude which
are varied in a unique sequence, as determined by the controller 190, in order
to encode valuable
information into such pressure pulses regarding sensed downhole positons. The
pressure pulses
then travel through a hydrocarbon formation to surface, where they are sensed
and decoded to
reveal the valuable information regarding downhole drilling conditions being
sent by pulser
100 via various other downhole sensors/instruments (not shown).
[0055] Pulser actuator 100 may comprise tubulars 110, 111, 117, and
119 that are
each threadably coupled together (although fewer or greater numbers of tubular
may be
employed) to form the actuator 100 as shown in Fig.'s 1 & 2. The first tubular
110 is at the top
of actuator 100 and provides actuator 100 with a male preferably threaded
connection for
coupling actuator 100 into a portion of the drill string (not shown) above the
actuator 100. The
second tubular 111, screwed into the bottom of the first tubular 110 , houses
the components
shown in Fig. 5, namely an electric motor 324 with an optional reduction
gearbox 326.
[0056] In a preferred embodiment, pulser actuator 100 may comprising a
first engageable
half member 101, as shown in Fig. 3, comprising tubulars 117 and 119inter alia
magnetic field
device in form of permanent magnet 311 and poppet valve 379, and a second half
member 102
(re. Fig. 4) matingly engageable with first half member 101, comprising
tubulars 110 and 111,
wherein the second half member 102 comprises a second sub assembly 105
comprising motor
S 324 and sensor 310, which is insertable in second half member 102. Mating
engagement of
first half member 101 with second half member 102 results in pulser actuator
100 of Fig. 1.
[0057] As may be seen from Fig. 3, to protect sliding surfaces within
half member 101,
and in particular exclude LCM from internal workings thereof, a rubber grease
boot 431 is
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provided around a portion of poppet valve 379, and 'O'ring seals 429 further
provided to assist
in excluding such material. Piston 427 may further slide on shaft 331 coupled
to poppet valve
379, to allow equalization of pressure downhole from that within the internal
workings of the
pulser actuator 100. Anti-rotation pin or collar 425 may be provided, to
isolate rotation of
rotating rod 330 from poppet 379, and a rod 329 interposed therebetween to
transmit linear
movement of internally threaded member 744 to poppet 379. A rubber coupler 401
may be
provided to connect coupler 345 and associated rotary ¨to-linear converter 700
with output shaft
210 on gearbox 326 contained in second half member 102.
[0058] As may be seen from Fig. 4., sub ¨assembly 105 containing
mandrel 361, motor
324 and gearbox 326, is adapted to be co-axially situated in half-member 102,
with a coupler 493
adapted to securably maintain sub-assembly 105 therein. A jaw coupling 404 may
further be
provided, to assist in mechanically coupling shaft 210 of gearbox 326 to
rubber coupling 401 of
the first half member 101.
Operation of Pulser Actuator and Controller
[0059] During typical operation, the pulser actuator 100 of the present
invention forms
part of a drill string (not shown) that is within a wellbore (not shown). The
first tubular 110 is
screwed to a segment of drill pipe (not shown) above the pulser actuator 100,
which segment of
drill pipe typically contains batteries or power cells and associated
electronic equipment which
decodes sensed data regarding downhole drilling conditions such as torque on
bit, angular
inclination and drill bit azimuth and the like, for supply to a controller
190. The controller 190,
typically located in drill pipe above pulser-actuator 100, via electrical
signals passing through an
electrical connection 50 to pulser actuator/servo-actuator 100, is provided
with valuable
information regarding downhole drilling conditions provided by various
downhole
sensors/instruments (not shown). Controller 190 thereafter senses position of
poppet valve 379
in the manner below explained, and initiates a series of opening and closing
of poppet valve
(whose position it has determined relative to the fully open and/or fully
closed position) to
thereby transmit the required encoded pressure pulses into the hydrocarbon
formation, to permit
such pressure pulses to be received uphole at surface.
[0060] More particularly, drilling mud that is pumped downhole to a
drill motor and
drill bit from a surface rig (not shown) enters the fourth tubular 119 of
pulser actuator 100
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CA 02879026 2016-09-07
through slots 104 in the fourth tubular 119's housing as shown in Fig. 1 & 1A,
thereby allowing
a high pressure flow to main mud valve (not shown) . This is the so-called
pulser actuator
"open" position. Drilling mud that flows through the servo valve exits the
pulser actuator 100
via an orifice 381 at the bottom end of the fourth tubular 119, where it is
then used open or close
the main mud alve as described above.
[0061]
Controller 190 thereafter actuates motor 324. Motor 324 via an (optional)
gearbox 325 and rotary-linear converter moves poppet valve 379 in the
direction of valve seat
375. When the poppet 379 is against the valve seat 375 such that no drilling
mud can pass
through servo-port 381, as shown in Fig. 2, 2A, the servo-valve is in the so-
called "closed"
position. The poppet valve 379 may thereafter be moved back, or partially back
to only thereby
partially restricted valve seat /servo-port 375.
Rotary-to-Linear Converter
[0062] In
the embodiment of the invention shown in Fig's . 1, 1A, 2, & 2A, 3, 4, & 5,
electric motor 324 provides motive force for powcring poppet valve 379 between
an open
position and a closed position. Electric motor 324 has an output shaft 210
that rotates in
response to operation of the motor 324. Electric motor 324 is typically a
brushless DC motor,
which has the advantage that it is particularly suitable for precise
electrical control by a
controller 190. Other types of electric motors, however, inay be used. Output
shaft 210 of motor
324 is mechanically coupled to a rotary-to-linear converter 700 via an
intermediary gearbox 326
containing reduction gearing, and coupling member 345. Specifically, gearbox
326 is provided
with an output shaft which is in turn coupled to, and rotates, an externally
helically threaded rod
330 of rotary-to-linear converter 700 via and coupling member 345.
Alternatively, output shaft
of motor 324 may be directly coupled to externally helically threaded rod 330
of rotary-to-lincar
converter 700 via coupling 345 without intervening gearbox 326, if electric
motor speed and
torque is acceptable without such gearbox 326.
[0063] As
best seen from Fig. 1A, 2A, Fig. 3 and Fig. 8, rotary-to-linear converter 700
comprises an internally helically threaded nut member 389, having internal
threads thereon,
which, in the embodiments shown is linearly moveable (but non-rotatable)
laterally in a back and
forth on externally helically-threaded rod 330 as a result of being situated
on an externally
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CA 02879026 2016-09-07
threaded rotatable rod member 330, the latter, as noted above, being rotated
by gearbox 326.
Roller bearings 312, mounted in bearing race 407, are provided in rotary-to-
linear converter 700
to allow rotation of helically threaded rod member 330, which is further
assisted in being able to
rotate by being mounted within bushing 405. Rotation of rod member 330 of
rotary-linear
converter 700 causes nut member 389 and intermediate mount member 744 to be
laterally
displaced, as shown in Fig. 2 & 2A in comparison to Fig. 1 and Fig. 1A, and
thus causes lateral
movement of poppet valve 379 to abut or not abut servo-port face 375 and thus
close or open,
respectively, servo-port 381.
[0064] In the embodiment shown in Fig. 1A, 2, 3, 4, & 5, at the
interface between nut
member 389 and intermediate mount member 744 a magnetic device in the form of
a permanent
magnet 311 is situated. A hall effect sensor 310 is prOvided within tubular
111, and an
electrically conductive wire 350, provided in each of internal mandrel 361 and
outer housing of
gearbox 326 (ref. Fig. 5) electrically couples sensor 310 to electrical
connection 50-electrical
connection 50 providing further electrical communication with both controller
190 (as shown in
Fig. 1) as well as a power supply in form of battery 444, as shown in Fig. 1.
Controller 190
receives power from battery 444 and ceases driving poppet valve 379 past a
closed position
when electrical signal from sensor 310 indicates, in the manner described
previously, that poppet
valve 324 has reached a closed position.
Alternative Sensor and Means for determining Poppet position
[0065] The embodiment shown in Fig. 8 depicts another alternative
configuration of the
pulser actuator 100 for determining linear displacement of the poppet valve
379 and thus
determining its position. In such alternative embodiment, instead of a magnet
being provided as
the source of a magnetic field whose position is detectead by a sensor, in
this embodiment
helical nut member 389 is comprised of a ferro-magnetic material, or possesses
a ferro-magnetic
material. A sensor comprising a cylindrical winding 366 of electrically
conductive wires or coils
is provided which encircles or partially encircles the ferro-magnetic
material, namely nut
member 389. Relative movement between the electrical winding 366 (in the
embodiment
shown being fixedly located within tubular 117) and the ferro-mangeitc
material (in the
embodiment shown in Fig. 8 being nut member 389 which is laterally moveable in
position)
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CA 02879026 2016-09-07
causes changes in the inductance of electrical winding 366 , which as a result
of such electrical
winding 366 being in electrical communication (via electrically conductive
wires 350) with
controller 190, the controller is able to determine the linear position of the
poppet 379.
[0066] In both the embodiments shown in Fig. 1, 2 and Fig. 8,
controller 190 uses
sensed values received from sensor 310 or 366 to establish poppet 379
position. Voltage
output front a hall effect sensor 310 or the inductance of an electrical
winding 366 is generally
greater the closer in proximity magnet 311 , or ferro-magnetic material of nut
member 389, is to
the sensor, and generally exhibits non-linearities in signal strength. Indeed
, as seen from Fig. 7,
the sensed magnitude in the case of magnetic field intensity increases
exponentially the closer
the magnetic field of magnet 311 approaches sensor 310. The method of using
reference values,
as hereiafter set out, greatly improves the accuracy in determining the
position of the poppet
valve, if for example a linear interpolation was used between the fully open
and fully closed
position, which would not provide a true position of the poppet valve due to
such inherent non-
linearity in magnetic field intensity, as shown in Fig. 8.
Controller and Manner of Operation thereof
[0067] In a preferred embodiment, controller 190 is further configured
to compare
output received from either of sensors 310, 366 with a plurality of reference
values and
corresponding known locations of said poppet valve 379. Controller 190 is then
able to
determine position of poppet valve 379 from comparison of a received output
from either of
sensor 311 or 366, by correlating a sensed value with a matching of said
reference values and
associated known position of poppet valve 379. To accomplish these tasks,
controller 190 may
be provided with a microprocessor, microcontroller, programmable logic
controller, field
programmable gate array, or an application-specific integrated circuit, to
store reference values
on computer readable media, and to compare same with sensed values as sensed
by either of
sensors 310 or 366. Examples of computer readable media are non-transitory and
semiconductor
-based media suitable for use in controller 190 are flash mcdia, random access
memory, and
read- only memory or EPROM chips, the latter offering the possibility of
providing each
controller 190 of each pulser actuator with uniquely calibrated measured
reference values for
each pulser actuator 100 of the present invention.
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CA 02879026 2016-09-07
[0068] While
in the depicted embodiments a single controller 190 (ref. Fig. 1) is used to
perform the method of the present invention for determining poppet position
and to control the
motor 324, in alternative embodiments these tasks may be divided between two
or more
controllers 190.
Methods of working the Pulser actuator/servo valve of the present invention to
determine poppet
location
[0069] Fig.
6 shows one einbodiment of a method for determining position of poppet
valve 379, using a magnetic device 311 and magnetic field sensor 310.
[0070] In
block 702 a magnetic field in pulser actuator 100 is generated, and the
magnetic field is sensed and measured via sensor 310 when poppet valve and
associated nut
member 389 of rotary-linear converter 700 positions the poppet valve 379 in
the closed position
abutting valve face 375.
[0071]
Thereafter, in block 704 a magnetic field in pulser actuator 100 is generated
and
the magnetic field is sensed and measured via sensor 310 when poppet valve and
associated nut
member 389 of rotary-linear converter 700 positions the poppct valve 379 in
the open position..
[0072] In
block 706, magnetic field is generated, sensed and measured via sensor 310
when poppet valve and associated nut member 389 of rotary-linear converter 700
positions the
poppet valve 379 in various intermediate positions, and with the values sensed
in block 702, 704
creating a reference table ("look-up" table) of sensed magnetic field
intensity values at known
positions of poppet 379. The order of operations in blocks 702 , 704, and 706
can be
interchanged.
[0073]
Thereafter, in block 707, an intensity of the magnetic field is measured for a
given
unkown position of the poppet valve 379.
[0074] Block
710 indicates the final step to the method, wherein the look-up table
residing in controller 190 is accessed, to determine position of poppet valve
379 relative to the
pulser actuator 100's fully open or fully closed position.
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[0075] Fig.
9 shows another embodiment of a method for determining position of
poppet valve 379, using a ferromagnetic material located on nut member 389,
and an electrical
winding 366.
[0076] In
such alternative method, block/step 902 sets out the first step of providing a
sensor 366 comprising a cylindrically-wound electrically conductive wire.
Block 904 sets out
the second step of providing a ferro-magnetic material , mechanically coupled
to poppet valve
379 which moves within or in close proximity to the electrical winding 366.
Block/step 906
comprises creating a reference of inductance values and corresponding poppet
valve 379
position, as measured by electrical windings comprising sensor 366, for
various positions of
poppet valve 370 between fully open and fully closed position.
[0077]
Subsequent block/step 908 comprises measuring, via sensor 366, a sensed
inductance value of the cylindrically-wound electrical wire for a given
position of poppet valve
379.
[0078]
Finally, block/step 910 comprises determining ( at a later time when poppet
valve 379 position is initially unknown) the location of the poppet valve 379
by comparison of
the sensed inductance value at such (unknown) location with the reference
values, typically
contained in a look-up table, and selecting a match.
[0079] It is
contemplated that any part of any aspect or embodiment discussed in this
specification can be implemented or combined with any part of any other aspect
or embodiment
discussed in this specification.
[0080]
Directional terms such as "top," "bottom," "upwards," "downwards,"
"vertically,"
and "laterally" used in the above description are for the purpose of providing
relative reference
only, and are not intended to suggest any limitations on how any article is to
be positioned during
use, or to be 'mounted in an assembly or relative to an environment.
[0081] Use of examples in the specification, including examples of terms,
is for
illustrative purposes only and is not intended to limit the scope and meaning
of the embodiments
of the invention set out and described in the disclosure. In the
specification, the word
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CA 02879026 2016-09-07
-comprising" is used as an open-ended term, substantially equivalent to the
phrase "including,
but not limited to," and the word "comprises" has a corresponding meaning.
[0082] The scope of the claims should not be limited by the preferred
embodiments set
forth in the foregoing examples, but should be given the broadest
interpretation consistent with
the description as a whole, and the claims are not to be limited to the
preferred or exemplified
embodiments of the invention.
CALLAW\ 2551415\1
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