1. Field of the Invention
The present disclosure relates generally to down-hole measurements related to oil and
gas exploration and drilling operations. More particularly, embodiments of the disclosure
relate to systems and methods for communicating data related the down-hole measurements
from below a mud motor to destinations above the mud motor.
2. Background
Wellbores are often drilled through a geologic formation for hydrocarbon exploration
and recovery operations. Measurements can be made in the wellbores related to various
properties of the geologic formations, e.g., hardness, porosity, etc., and also to the properties
of the wellbores themselves such as direction or inclination. Often, these measurements are
made while the wellbores are being drilled. Systems for making these measurements during
a drilling operation can be described as logging-while-drilling (LWD) or measurement-whiledrilling
(MWD) systems, and generally include various sensors carried by a bottom hole
assembly (BHA) of a drill string. These measurements can be useful in steering a drilling
apparatus, e.g., to maintain a predetermined path of a wellbore, and/or these measurements
may be evaluated once the wellbore is complete for planning future operations.
At least some of the sensors of an LWD or MWD system may be disposed as near a
down-hole end of the BHA as possible to provide measurements representative the conditions
in which a drill bit is operating. Data provided by the sensors can be telemetered up-hole to a
surface location or to other portions of the drill string by a telemetry tool located in the BHA.
The telemetry tool may communicate with a variety of technologies including, e.g., mud
pulse, electromagnetic and acoustic technologies. In some instances, a mud motor may be
included in a BHA to drive the drill bit, and communication across the mud motor may be
required between the sensors and the telemetry tool. A mud motor generally operates by
turning a shaft in response to the passage of high pressure drilling fluid therethrough. Due in
part to the rotational nature of a mud motor, transmission of information from the sensors
disposed below the mud motor to a telemetry unit above the mud motor can be challenging.
In some systems, a direct wired connection is passed through the mud motor to couple the
sensors to the telemetry unit. The wires can be susceptible to erosion by the drilling fluid,
and thus, the reliability of these systems can be limited. Other systems, such as "short-hop"
electromagnetic systems, are used to communicate data across a mud motor. These systems
may be adversely affected by electromagnetic properties of the geologic formation or by
operation of the mud motor or other components of the BHA. Systems for transmitting data
across a mud motor (in both up-hole and down-hole directions) remain lacking in the
hydrocarbon drilling arts.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure is described in detail hereinafter on the basis of embodiments
represented in the accompanying figures, in which:
FIG. 1 is a cross-sectional schematic side-view of a drilling system including a BHA
having a down-hole mud motor and a communication module for transmitting data across the
mud motor in accordance with one or more exemplary embodiments of the disclosure;
FIG. 2 is a schematic view of the BHA of FIG. 1 illustrating communication pathways
defined within the BHA;
FIG. 3 is schematic block diagram of the communication module of FIG. 1 illustrating
a mechanical braking system disposed between a turbine and a generator of the
communication module;
FIG. 4 is a cross-sectional schematic side-view of the communication module of
FIGS. 1 and 3; and
FIG. 5 is a flowchart illustrating operational procedures employing the down-hole
communication modules of FIGS. 3 and 4.
DETAILED DESCRIPTION
The disclosure may repeat reference numerals and/or letters in the various examples
or Figures. This repetition is for the purpose of simplicity and clarity and does not in itself
dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as beneath, below, lower, above, upper, up-hole, downhole,
upstream, downstream, and the like, may be used herein for ease of description to
describe one element or feature's relationship to another element(s) or features) as
illustrated, the upward direction being toward the top of the corresponding figure and the
downward direction being toward the bottom of the corresponding figure, the up-hole
direction being toward the surface of the wellbore, the down-hole direction being toward the
toe of the wellbore. Unless otherwise stated, the spatially relative terms are intended to
encompass different orientations of the apparatus in use or operation in addition to the
orientation depicted in the Figures. For example, if an apparatus in the Figures is turned
over, elements described as being '¾elow" or '¾eneath" other elements or features would
then be oriented "above" the other elements or features. Thus, the exemplary term '¾elow"
can encompass both an orientation of above and below. The apparatus may be otherwise
oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors
used herein may likewise be interpreted accordingly.
Moreover even though a Figure may depict an apparatus in a portion of a wellbore
having a specific orientation, unless indicated otherwise, it should be understood by those
skilled in the art that the apparatus according to the present disclosure may be equally well
suited for use in wellbore portions having other orientations including vertical, slanted,
horizontal, curved, etc. Likewise, unless otherwise noted, even though a Figure may depict
an onshore or terrestrial operation, it should be understood by those skilled in the art that the
apparatus according to the present disclosure is equally well suited for use in offshore
operations. Further, unless otherwise noted, even though a Figure may depict a wellbore that
is partially cased, it should be understood by those skilled in the art that the apparatus
according to the present disclosure may be equally well suited for use in fully open-hole
wellbores.
1. Description of Exemplary Embodiments
Referring to FIG. 1, a directional drilling system 10 is illustrated that includes a
down-hole communication module 100, in accordance with one or more embodiments of the
present disclosure. Although directional drilling system 10 is illustrated in the context of a
terrestrial drilling operation, it will be appreciated by those skilled in the art that aspects of
the disclosure may also be practiced in connection with offshore platforms and or other types
of hydrocarbon exploration and recovery systems as well.
Directional drilling system 10 is partially disposed within a directional wellbore 12
traversing a geologic formation "G." The directional wellbore 12 extends from a surface
location "S" along a curved longitudinal axis Xi. In some exemplary embodiments, the
longitudinal axis Xi includes a vertical section 12a, a build section 12b and a tangent section
12c. The tangent section 12c is the deepest section of the wellbore 12, and generally exhibits
lower build rates (changes in the inclination of the wellbore 12) than the build section 12b. In
some exemplary embodiments (not shown), the tangent section 12c is generally horizontal.
Additionally, in one or more other exemplary embodiments, the wellbore 12 includes a wide
variety of vertical, directional, deviated, slanted and/or horizontal portions therein, and may
extend along any trajectory through the geologic formation "G."
A rotary drill bit 14 is provided at a down-hole location in the wellbore 12 (illustrated
in the tangent section 12c) for cutting into the geologic formation "G." When rotated, the
drill bit 14 operates to break up and generally disintegrate the geological formation "G." At
the surface location "S" a drilling rig 22 is provided to facilitate rotation of the drill bit 14 and
drilling of the wellbore 12. The drilling rig 22 includes a turntable 28 that generally rotates
the drill string 18 and the drill bit 14 together about the longitudinal axis X \ . The turntable
28 is selectively driven by an engine 30, chain drive system or other or other apparatus.
Rotation of the drill string 18 and the drill bit 14 together may generally be referred to as
drilling in a "rotating mode," which maintains the directional heading of the rotary drill bit 14
and serves to produce a straight section of the wellbore 12, e.g., vertical section 12a and
tangent section 12c.
In contrast, a "sliding mode" may be employed to change the direction of the rotary
drill bit 14 and thereby produce a curved section of the wellbore 12, e.g., build section 12b.
To operate in sliding mode, the turn table 28 may be locked such that the drill string 18 does
not rotate about the longitudinal axis Xi, and the rotary drill bit 14 may be rotated with
respect to the drill string 18. To facilitate rotation of the rotary drill bit 14 with respect to the
drill string 18, a bottom hole assembly or BHA 32 is provided in the drill string 18 at a downhole
location in the wellbore 12.
In the illustrated embodiments, the BHA 32 includes a mud motor 34 that generates
torque in response to the circulation of a drilling fluid, such as mud 36, therethrough. The
mud 36 can be pumped down-hole by mud pump 38 through an interior of the drill string 18.
The mud 36 passes through the BHA 32 including the mud motor 34, which extracts energy
from the mud 36 to turn the rotary drill bit 14. As the mud 36 passes through the BHA 32,
the mud 36 may also lubricate bearings (not explicitly shown) defined therein before being
expelled through nozzles (not explicitly shown) defined in the rotary drill bit 14. The mud 36
lubricates the rotary drill bit 14 and flushes geologic cuttings from the path of the rotary drill
bit 14. The mud 36 is then returned through an annulus 40 defined between the drill string 18
and the geologic formation "G." The geologic cuttings and other debris are carried by the
mud 36 to the surface location "S" where the cuttings and debris can be removed from the
mud stream.
In accordance with some exemplary embodiments of the disclosure, the BHA 32
includes drilling tool 40 disposed down-hole of the mud motor 34. The drilling tool 40 may
include components for operating the rotary drill bit 14 such as bearing assemblies (not
shown) or steering mechanisms (not shown) to facilitate the directional drilling of the
wellbore 12. The drilling tool 40 may carry a feedback device 42 thereon for measuring a
parameter of the down-hole environment at a location near the rotary drill bit 14. In some
exemplary embodiments, the feedback device 42 may include accelerometers, inclinometers,
thermometers or other types of sensors for measuring characteristics of the wellbore 12.
Also, in some exemplary embodiments, the feedback device 42 may include radiation
detectors, acoustic detectors, electromagnetic detectors or other devices for measuring
characteristics of the geologic formation "G" near the rotary drill bit 14. In other exemplary
embodiments, the feedback device 42 may measure an operational characteristic of the BHA
32 such as a rotational speed of the rotary drill bit 14. In still other exemplary embodiments,
the particular parameter measured by the feedback device 42 may not be related to a drilling
operation, and therefore, the exemplary embodiments of the feedback device 42 should not be
considered limiting.
The BHA 32 may also include a data collection tool 44, such as an MWD tool or a
LWD tool, disposed up-hole of the mud-motor 34. The data collection tool 44 is operable to
measure, process, and/or store information therein. The data collection tool 44 may include
devices (not explicitly shown) for measuring a weight on the rotary drill bit 14, for measuring
a resistive torque applied to the BHA 32 by the geologic formation "G," for measuring
vibrational energy and\or for measuring any other parameters associated with MWD or LWD
tools as recognized by those skilled in the art.
The data collection tool 44 is operatively coupled to a telemetry tool 46, which is also
disposed up-hole of the mud motor 34. In exemplary embodiments, the telemetry tool 46 can
include and employ any type of telemetry system or any combination of telemetry systems,
such as electromagnetic, acoustic and\or wired drill pipe telemetry systems for two-way
communication with the surface location "S" or with other portions of the drill string 18. The
telemetry tool 46 may transmit data collected from the data collection tool 44 and/or feedback
device 42 in an up-hole direction, and may also receive instructions or data transmitted in a
down-hole direction from the surface location "S," for example. In the exemplary
embodiments illustrated FIG. 1, the telemetry tool 46 comprises a mud pulse telemetry
system that is operable generate disturbances in a column of mud 36 in the wellbore 12 that
can be detected by an up-hole receiver 50 disposed at the surface location "S." The up-hole
receiver 50 is operable to detect and measure pressure changes in mud 36, and is illustrated as
being in fluid communication with mud 36 in the annulus 40. However, as one skilled in the
art will appreciate, the up-hole receiver 50 may additionally or alternatively be fiuidly
coupled to mud 36 within the drill string 18. The up-hole receiver 50 is communicatively
coupled to a processing unit 52 that is operable to receive, interpret and analyze signals
detected by the up-hole receiver 50.
The down-hole communication module 100 is provided for communicating across the
mud motor 34. As described in greater detail below, in some exemplary embodiments, the
communication module 100 may be operable to receive data from the feedback device 42,
and then to transmit the data to the telemetry tool 46 on an opposite side of the mud motor 34.
The telemetry tool 46 may receive the transmission from the communication module 100, and
then, in turn, transmit the information up-hole to the surface location "S."
Referring to FIG. 2, a communications network within the BHA 32 is illustrated. A
first sub bus 60 extends along the drilling tool 40 and provides a communicative pathway for
data provided by the feedback device 42 to reach the communication module 100. A second
sub bus 62 extends along the data collection tool 44 and the telemetry tool 46, and provides a
communicative pathway for data collected by the data collection tool 62 to reach the
telemetry tool 46. The communication module 100 provides a communicative pathway 64
that bridges the first sub bus 60 and second sub bus 62. Communication may thus be
established along the entire BHA 32 through the first sub bus 60, second sub bus 64 and
communicative pathway 64. Communication into and out of the BHA 46 may be established
with the telemetry tool 46.
Referring now to FIGS. 3 and 4, the communication module 100 includes a braking
system 102 operatively coupled between a turbine 104 and a generator 106. The braking
system 102 includes a braking component 110 and a controller 112 that is operable to provide
instructions to the braking component 110 as described in greater detail below.
In some exemplary embodiments, the turbine 104 can be a positive-displacement
pump, sometimes referred to as a Moineau-type pump. The turbine 104 includes a stator 116,
which is mounted in a stationary manner with respect to an outer housing 118. A rotor 120 is
rotationally supported within the stator 116 and includes a turbine shaft 124. The stator 116
and the rotor 120 are shaped such that movement of the mud 36 (FIG. 1) through a central
flow passage 126 induces rotation of the rotor 120 with respect to the stator 116. The rotor
120 extracts hydraulic energy from the circulation of the mud 36 (FIG. 1) through the turbine
104, and converts the hydraulic energy into mechanical rotational movement of the turbine
shaft 124. The turbine shaft 124 can be operatively coupled to a generator shaft 128 through
the braking component 110 such that the generator shaft 128 receives the rotational motion
from the turbine shaft 124. Rotation of the generator shaft 128 produces an electric voltage
that can be used to power down-hole electronics such as feedback device 42 and controller
112.
The braking system 102 is selectively operable limit the rotational speed of the
turbine shaft 124 and generator shaft 128. By changing the rotational speed of the turbine
shaft 124, local pressure variations will be produced in the mud 36 (FIG. 1), which can be
detected and/or decoded by the telemetry tool 46 (FIG. 2). In some exemplary embodiments,
the braking component of the 110 can include a mechanical brake that is operable to generate
frictional forces that produce a counter-torque to retard the rotational motion in the turbine
shaft 124. In other exemplary embodiments, the braking component 110 includes a
hysteresis brake. A hysteresis brake generally includes internal magnets (not shown) that are
responsive to an input current or a control current from the controller 112 to vary an output
torque. The output torque can be applied to the counter the rotational motion of the turbine
shaft 124. Since there is no frictional contact between the magnets of a hysteresis brake, a
hysteresis brake is generally durable and can provide consistent torque without producing
large quantities of heat, which can be difficult to dissipate in a down-hole environment.
In some exemplary embodiments, the controller 112 of the braking system 102 can
include a computer having a processor 112a and a computer readable medium 112b operably
coupled thereto. The computer readable medium 112b can include a nonvolatile or nontransitory
memory with data and instructions that are accessible to the processor 112a and
executable thereby. In one or more embodiments, the computer readable medium 112b is
pre-programmed with a set of instructions for encoding data received from the feedback
device 42 into a sequence of pressure pulses. The processor 112a can execute the instructions
to appropriately provide the input current to the hysteresis brake of braking component 110 to
thereby slow the turbine shaft 124 and produce the sequence of pressure pulses in the mud 36
(FIG. 1).
In the exemplary embodiments illustrated in FIGS. 3 and 4, the generator 106 is
arranged to provide electrical power to the controller 112 and feedback device 42. The
electrical output of the generator 106 may be relatively small since the hysteresis brake of the
braking system 102 requires a relatively small amount of power to produce the necessary
counter-torque to slow the turbine 104. In other embodiments, electrical power can be
provided by a battery or other down-hole power sources as recognized in the art. In some
exemplary embodiments, the drilling tool 40 may include an internal turbine and generator
(not shown) that provides electrical power to the feedback device 42.
2. Example Implementation
Referring now to FIG. 5, and with reference to FIGS. 1 through 4, exemplary
embodiments of an operational procedure 200 are described that employ the communication
module 100 described above. Initially at step 202, the BHA 32 is deployed into the wellborc
12, and drilling mud 36 is circulated through the turbine 104 and mud motor 34 (step 204).
Circulation of the mud 36 through the mud motor 34 induces rotational motion in the turbine
shaft 124 and the mud motor 34, which can hinder communication through the mud motor 34
with conventional mechanisms. At step 206, a parameter of the wellborc 12, geologic
formation "G" or the BHA 32 can be detected by the feedback device 42. Since the feedback
device 42 is disposed down-hole of the mud motor 34, communication of data provided by
the feedback device 42 may be transmitted across the mud motor 34 with the communication
module 100.
The controller 112 receives data from the feedback device 42 and encodes the data as
a series of pressure pulses (step 208). Next, at step 210, the controller 112 can provide
instructions to the braking component 110 to provide a counter-torque to the turbine shaft 124
in an appropriate pattern to slow the turbine shaft 124 in a manner that produces the sequence
of pressure pulses in the mud 36. The pressure pulses travel up the wellbore 12 across the
mud motor 34 and can be detected by a detector disposed up-hole of the mud motor 34 (step
212). In some exemplary embodiments, the pressure pulses can be detected by the telemetry
tool 46, which can decode the pressure pulses (step 214) and transmit signals representative
of the data provided by the feedback device 42 to the surface location "S." In some other
exemplary embodiments, the pressure pulses can be detected directly by the up-hole receiver
50, which is disposed at the surface location "S." The pressure pulses can then de decoded
by the processing unit 52.
In some exemplary embodiments, at step 216 the decoded pressure pulses can be
employed to modify drilling of the wellbore 12, e.g., to alter a directional heading of the
rotary drill bit 14. hi other embodiments, the decoded pressure pulses may be stored and
accumulated to plan future exploration or drilling operations.
In some exemplary embodiments, the communication module 100 may be employed
when an independent communication system (not shown) experiences a failure or when
communication by conventional means becomes unavailable. Additionally, in some
embodiments, the communication module 100 can be deployed in the wellbore 12 in alternate
locations, e.g., on drill string 18 above the a mud motor 34, or on another other work string
(not shown) that does not include a mud motor 34.
3. Aspects of the Disclosure
In one aspect, the disclosure is directed to a down-hole communication module. The
down-hole communication module includes a turbine responsive to the circulation of drilling
fluid therethrough to generate rotational motion in a turbine shaft thereof, and also includes a
braking system selectively operable to transmit a counter-torque from the braking system to
the turbine shaft to retard the rotational motion in the turbine shaft. The braking system
includes a braking component coupled to the turbine shaft and a controller operable to
provide instructions to the braking component to provide the counter torque the turbine shaft
in a predetermined pattern.
In some exemplary embodiments, the braking component includes a hysteresis brake,
and in some embodiments, the down-hole communication module further includes an
electrical generator operably coupled to the turbine shaft to receive rotational motion from
the turbine shaft and to produce electrical power from the rotational motion. In one or more
exemplary embodiments, the controller is operatively coupled to the electrical generator to
receive electrical power therefrom.
In one or more exemplary embodiments, the down-hole communication module
further includes a feedback device operatively coupled to the controller, and the controller
includes instructions stored thereon to encode data provided by the feedback device as a
series of pressure pulses and to provide the instructions to the baking component based on
encoded data. The feedback device may be operable to measure at least parameter of at least
one of a wellbore in which the feedback device is disposed, a geologic formation in which the
feedback device is disposed, and an operational characteristic of a bottom hole assembly in
which the feedback device is disposed. In some exemplary embodiments, the braking
component comprises a mechanical braking component operable to produce frictional forces
therein to produce the counter torque in the turbine shaft.
In another aspect, the disclosure is directed to a bottom hole assembly that includes a
mud motor responsive to the circulation of drilling fluid there through to induce rotational
motion in a rotary drill bit. The bottom hole assembly also includes a feedback device
disposed below the mud motor that is operative to measure a parameter of a down-hole
environment in the vicinity of the rotary drill bit, and a turbine disposed below the mud motor
that is responsive to the circulation of the drilling fluid therethrough to generate rotational
motion in a turbine shaft thereof. The bottom hole assembly further includes a braking
system selectively operable to transmit a counter-torque from the braking system to the
turbine shaft to retard the rotational motion in the turbine shaft in a pattern representative of
the parameter measurable by the feedback device.
In one or more exemplary embodiments, the braking system comprises a hysteresis
brake, and in some exemplary embodiments, the bottom hole assembly further includes a
telemetry tool disposed above the mud motor. The telemetry tool may be operable to receive
and decode pressure pulses generated by the braking system. In some exemplary
embodiments, the telemetry tool is communicatively coupled to a data acquisition tool
disposed above the mud motor, and the data acquisition tool includes at least one of an MWD
tool and a LWD tool.
In another aspect, the disclosure is directed to a method of communicating in a
wellbore including (a) circulating a drilling fluid through a turbine disposed in the wellbore to
generate rotational motion in a turbine shaft of the turbine, (b) transmitting a counter-torque
to the turbine shaft in a predetermined pattern from a braking system coupled to the turbine
shaft to thereby generate pressure pulses in the drilling fluid, and (c) detecting the pressure
pulses with a receiver in fluid communication with the drilling fluid.
In some exemplary embodiments, the braking system includes a hysteresis brake, and
transmitting the counter torque to the turbine shaft includes applying a control current to the
hysteresis brake in a predetermined pattern. In one or more exemplary embodiments, the
method further includes operating a mud motor disposed between the turbine and the receiver
while transmitting the counter torque to the turbine shaft.
In one or more exemplary embodiments, the method further includes measuring a
down-hole parameter with a feedback device communicatively coupled to the braking
system, and transmitting the counter-torque to the turbine shaft includes transmitting the
counter torque in a turbine shaft in a pattern representative of the parameter detected. In
some exemplary embodiments, the method further includes adjusting a parameter of a drilling
operation responsive to receiving a signal representative of the parameter detected.
Moreover, any of the methods described herein may be embodied within a system
including electronic processing circuitry to implement any of the methods, or a in a
computer-program product including instructions which, when executed by at least one
processor, causes the processor to perform any of the methods described herein.
The Abstract of the disclosure is solely for providing the United States Patent and
Trademark Office and the public at large with a way by which to determine quickly from a
cursory reading the nature and gist of technical disclosure, and it represents solely one or
more embodiments.
While various embodiments have been illustrated in detail, the disclosure is not
limited to the embodiments shown. Modifications and adaptations of the above embodiments
may occur to those skilled in the art. Such modifications and adaptations are in the spirit and
scope of the disclosure.

CLAIMS
WHAT IS CLAIMED IS:
1. A down-hole communication module, comprising:
a turbine responsive to the circulation of drilling fluid therethrough to generate
rotational motion in a turbine shaft thereof; and
a braking system selectively operable to transmit a counter-torque from the braking
system to the turbine shaft to retard the rotational motion in the turbine shaft, the braking
system comprising:
a braking component coupled to the turbine shaft; and
a controller operable to provide instructions to the braking component to
provide the counter torque the turbine shaft in a predetermined pattern.
2. The down-hole communication module of claim 1, wherein the braking component
comprises a hysteresis brake
3. The down-hole communication module of claim 2, further comprising an electrical
generator operably coupled to the turbine shaft to receive rotational motion from the turbine
shaft and to produce electrical power from the rotational motion.
4. The down-hole communication module of claim 3, wherein the controller is
operatively coupled to the electrical generator to receive electrical power therefrom.
5. The down-hole communication module of claim 1, further comprising a feedback
device operatively coupled to the controller, wherein the controller includes instructions
stored thereon to encode data provided by the feedback device as a series of pressure pulses
and to provide the instructions to the baking component based on encoded data.
6. The down-hole communication module of claim 5, wherein the feedback device is
operable to measure at least parameter of at least one of a wellbore in which the feedback
device is disposed, a geologic formation in which the feedback device is disposed, and an
operational characteristic of a bottom hole assembly in which the feedback device is
disposed.
7. The down-hole communication module of claim 1, wherein the braking component
comprises a mechanical braking component operable to produce frictional forces therein to
produce the counter torque in the turbine shaft.
8. A bottom hole assembly comprising:
a mud motor responsive to the circulation of drilling fluid there through to induce
rotational motion in a rotary drill bit;
a feedback device disposed below the mud motor, the feedback operative to measure a
parameter of a down-hole environment in the vicinity of the rotary drill bit;
a turbine disposed below the mud motor, the turbine responsive to the circulation of
the drilling fluid therethrough to generate rotational motion in a turbine shaft thereof; and
a braking system selectively operable to transmit a counter-torque from the braking
system to the turbine shaft to retard the rotational motion in the turbine shaft in a pattern
representative of the parameter measurable by the feedback device.
9. The bottom hole assembly of claim 8, wherein the braking system comprises a
hysteresis brake.
10. The bottom hole assembly of claim 8, further comprising a telemetry tool disposed
above the mud motor, wherein the telemetry tool is operable to receive and decode pressure
pulses generated by the braking system.
11. The bottom hole assembly of claim 10, wherein the telemetry tool is communicatively
coupled to a data acquisition tool disposed above the mud motor, and wherein the data
acquisition tool comprises at least one of an MWD tool and a LWD tool.
12. A method of communicating in a wellbore, the method comprising:
circulating a drilling fluid through a turbine disposed in the wellbore to generate
rotational motion in a turbine shaft of the turbine;
transmitting a counter-torque to the turbine shaft in a predetermined pattern from a
braking system coupled to the turbine shaft to thereby generate pressure pulses in the drilling
fluid; and
detecting the pressure pulses with a receiver in fluid communication with the drilling
fluid.
13. The method of claim 12, wherein the braking system comprises a hysteresis brake,
and wherein transmitting the counter torque to the turbine shaft comprises applying a control
current to the hysteresis brake in a predetermined pattern.
14. The method of claim 12, further comprising operating a mud motor disposed between
the turbine and the receiver while transmitting the counter torque to the turbine shaft.
15. The method of claim 12, further comprising measuring a down-hole parameter with a
feedback device communicatively coupled to the braking system, and wherein transmitting
the counter-torque to the turbine shaft comprises transmitting the counter torque in a turbine
shaft in a pattern representative of the parameter detected.
16. The method of claim 15, further comprising adjusting a parameter of a drilling
operation responsive to receiving a signal representative of the parameter detected.