U.S. patent application number 10/375920 was filed with the patent office on 2003-11-20 for apparatus for transferring electrical energy between rotating and non-rotating members of downhole tools.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Krueger, Volker.
Application Number | 20030213620 10/375920 |
Document ID | / |
Family ID | 22571666 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030213620 |
Kind Code |
A1 |
Krueger, Volker |
November 20, 2003 |
Apparatus for transferring electrical energy between rotating and
non-rotating members of downhole tools
Abstract
In general, the present invention provides a contactless
apparatus for power and data transfer over a gap between rotating
and non-rotating members of downhole oilfield tools. The gap
usually contains a fluid, such as drilling fluid, or oil for
operating hydraulic devices in the downhole tool. The downhole tool
in one embodiment is a drilling assembly wherein a drive shaft is
rotated by a downhole motor to rotate the drill bit attached to the
bottom end of the drive shaft. A substantially non-rotating sleeve
around the drive shaft includes at least one electrically-operated
device. An electric power and data transfer device transfers
electric power and data between the rotating and non-rotating
members. An electronic control circuit associated with the rotating
member controls the transfer of power and data from the rotating
member to the non-rotating member. An electrical control circuit
carried by the non-rotating member controls the transfer of data
from sensors and devices carried by the non-rotating member to the
rotating member.
Inventors: |
Krueger, Volker; (Celle,
DE) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Assignee: |
Baker Hughes Incorporated
3900 Essex, Suite 1200
Houston
TX
77046
|
Family ID: |
22571666 |
Appl. No.: |
10/375920 |
Filed: |
February 27, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10375920 |
Feb 27, 2003 |
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09687680 |
Oct 13, 2000 |
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6540032 |
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60159234 |
Oct 13, 1999 |
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Current U.S.
Class: |
175/40 |
Current CPC
Class: |
E21B 47/12 20130101;
E21B 17/028 20130101; E21B 41/0085 20130101 |
Class at
Publication: |
175/40 |
International
Class: |
E21C 025/00; E21B
047/00 |
Claims
What is claimed is:
1. A drilling assembly for use in drilling of a wellbore,
comprising: (a) a rotating member; (b) a non-rotating sleeve placed
around the rotating member with a gap there between; and (c) a
inductive coupling device associated with the rotating member and
the non-rotating sleeve for transferring electric power between the
rotating member and the non-rotating sleeve.
2. The drilling assembly according to claim 1, wherein the
inductive coupling device includes a transmitter and a
receiver.
3. The drilling assembly according to claim 1, wherein the gap is
filled by a fluid.
4. The drilling assembly according to claim 3, wherein said fluid
is selected from a group consisting of (i) drilling fluid, (ii) oil
sealed between said rotating member and said non-rotating sleeve,
(iii) a conductive fluid, and (iv) a non-conductive fluid.
5. The drilling assembly according to claim 2, wherein the
transmitter is carried by the rotating member and the receiver is
carried by the non-rotating sleeve.
6. The drilling assembly according to claim 2 further comprising a
first control circuit carried by said rotating member, said first
control circuit supplying electric power to said transmitter, for
transferring said electric power to said non-rotating sleeve.
7. The drilling assembly according to claim 1 further comprising an
electrically-operated device on the non-rotating sleeve for
performing an operation downhole.
8. The drilling assembly according to claim 7 further comprising a
second control circuit carried by the non-rotating sleeve for
transferring electric power to said electrically-operated
device.
9. The drilling assembly according to claim 7, wherein the
electrically operated device is one of (i) electrically-operated
pump; (ii) a control valve; and (iii) a downhole sensor.
10. The drilling assembly according to claim 1, wherein the
inductive coupling device transfers information between the
rotating member and the non-rotating sleeve.
11. The drilling assembly according to claim 10, wherein the data
is transferred by one of (i) frequency modulation, (ii) amplitude
modulation, and (iii) discrete signals.
12. The drilling assembly according to claim 7 further comprising a
secondary control circuit associated with the non-rotating sleeve
for controlling the operation of said electrically-operated
device.
13. The drilling assembly according to claim 1, wherein said
rotating member is a drill shaft rotatably disposed in the
non-rotating sleeve.
14. The drilling assembly according to claim 1, wherein the
inductive coupling device is disposed uphole of a mud motor in the
drilling assembly and the electric power is transferred from the
non-rotating sleeve to the rotating member.
15. The drilling assembly according to claim 14, wherein the
rotating member is rotated by the mud motor.
16. The drilling assembly according to claim 14, wherein said mud
motor is operatively coupled to a drill bit to rotate said drill
bit during drilling of the wellbore and wherein said drill bit
includes at least one (1) electrically-operated device that
utilizes electric power transferred to said rotating member.
17. The drilling assembly according claim 14 further comprising an
electrical control circuit.
18. The drilling assembly according to claim 2, wherein said
transmitter is disposed in the non-rotating sleeve and the receiver
is carried by the rotating member.
19. The drilling assembly according to claim 18, wherein the
rotating member is a drill shaft adapted to be coupled to a drill
bit.
20. The drilling assembly according to claim 18 further comprising
at least one (1) sensor associated with said drill bit, said sensor
receiving electric power from said receiver.
21. A drilling assembly for drilling a wellbore comprising: (a) a
mud motor having (i) a power section containing a rotor disposed in
a stator, said rotor rotating in said stator upon the passage of
fluid under pressure through the mud motor; and (ii) a bearing
assembly having a drive shaft disposed in a non-rotating housing
with a gap therebetween, said driveshaft operatively coupled to and
rotated by said rotor, and said drive shaft adapted to accommodate
a drill bit at an end thereof; (b) an inductive coupling device in
said bearing assembly for transferring electric power from said
non-rotating housing to said rotating drive shaft during drilling
of the wellbore.
22. The drilling assembly according to claim 21, wherein said
inductive coupling device receives electric power from a source
uphole of said mud motor.
23. The drilling assembly according to claim 21 further comprising
at least one (1) sensor associated with said rotating drill shaft,
said sensor receiving electric power transferred to said rotating
drill shaft.
24. The drilling assembly according to claim 22, wherein said
inductive coupling device includes a transmitter in said housing
and a receiver carried by said drill shaft.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application is related to U.S. Provisional Application
Serial No. 60/159,234 filed in the United States Patent and
Trademark Office on Oct. 13, 1999 priority from which is claimed
and the specification of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to oilfield downhole tools
and more particularly to drilling assemblies utilized for drilling
wellbores in which electrical power and data are transferred
between rotating and a non-rotating sections of the drilling
assembly.
[0004] 2. Description of the Related Art
[0005] To obtain hydrocarbons such as oil and gas, boreholes or
wellbores are drilled by rotating a drill bit attached to the
bottom of a drilling assembly (also referred to herein as a "Bottom
Hole Assembly" or "BHA"). The drilling assembly is attached to the
bottom of a tubing, which is usually either a jointed rigid pipe or
a relatively flexible spoolable tubing commonly referred to in the
art as the "coiled tubing." The string comprising the tubing and
the drilling assembly is usually referred to as the "drill string."
When jointed pipe is utilized as the tubing, the drill bit is
rotated by rotating the jointed pipe from the surface and/or by a
mud motor contained in the drilling assembly. In the case of a
coiled tubing, the drill bit is rotated by the mud motor. During
drilling, a drilling fluid (also referred to as the "mud") is
supplied under pressure into the tubing. The drilling fluid passes
through the drilling assembly and then discharges at the drill bit
bottom. The drilling fluid provides lubrication to the drill bit
and carries to the surface rock pieces disintegrated by the drill
bit in drilling the wellbore. The mud motor is rotated by the
drilling fluid passing through the drilling assembly. A drive shaft
connected to the motor and the drill bit rotates the drill bit.
[0006] A substantial proportion of the current drilling activity
involves drilling of deviated and horizontal wellbores to more
fully exploit the hydrocarbon reservoirs. Such boreholes can have
relatively complex well profiles. To drill such complex boreholes,
drilling assemblies are utilized which include a plurality of
independently operable force application members to apply force on
the wellbore wall during drilling of the wellbore to maintain the
drill bit along a prescribed path and to alter the drilling
direction. Such force application members may be disposed, on the
outer periphery of the drilling assembly body or on a non-rotating
sleeve disposed around the rotating drive shaft. These force
application members are moved radially to apply force on the
wellbore in order to guide the drill bit and/or to change the
drilling direction outward by electrical devices or
electro-hydraulic devices. In such drilling assemblies, there
exists a gap between the rotating and the non-rotating sections. To
reduce the overall size of the drilling assembly and to provide
more power to the ribs, it is desirable to locate the devices (such
as motor and pump) required to operate the force application
members in the non-rotating section. It is also desirable to locate
electronic circuits and certain sensors in the non-rotating
section. Thus, power must be transferred between the rotating
section and the non-rotating section to operate
electrically-operated devices and the sensors in the non-rotating
section. Data also must be transferred between the rotating and the
non-rotating sections of such a drilling assembly. Sealed slip
rings are often utilized for transferring power and data. The seals
often break causing tool failures downhole.
[0007] In drilling assemblies which do not include a non-rotating
sleeve as described above, it is desirable to transfer power and
data between the rotating drill shaft of a drilling motor and the
stationary housing surrounding the drill shaft. The power
transferred to the rotating shaft may be utilized to operate
sensors in the rotating shaft and/or drill bit. Power and data
transfer between rotating and non-rotating section having a gap
therebetween can also be useful in other downhole tool
configurations.
[0008] The present invention provides contactless inductive
coupling to transfer power and data between rotating and
non-rotating sections of downhole oilfield tools, including the
drilling assemblies containing rotating and non-rotating
members.
SUMMARY OF THE INVENTION
[0009] In general, the present invention provides apparatus and
method for power and data transfer over a gap between rotating and
non-rotating members of downhole oilfield tools. The gap may
contain a non-conductive fluid, such as drilling fluid or oil for
operating hydraulic devices in the downhole tool. The downhole
tool, in one embodiment, is a drilling assembly wherein a drive
shaft is rotated by a downhole motor to rotate the drill bit
attached to the bottom end of the drive shaft. A substantially
non-rotating sleeve around the drive shaft includes a plurality of
independently-operated force application members, wherein each such
member is adapted to be moved radially between a retracted position
and an extended position. The force application members are
operated to exert the force required to maintain and/or alter the
drilling direction. In a preferred system, a common or separate
electrically-operated hydraulic units provide energy (power) to the
force application members. An inductive coupling transfers device
transfers electrical power and data between the rotating and
non-rotating members. An electronic control circuit or unit
associated with the rotating member controls the transfer of power
and data between the rotating member and the non-rotating member.
An electrical control circuit or unit carried by the non-rotating
member controls power to the devices in the non-rotating member and
also controls the transfer of data from sensors and devices carried
by the non-rotating member to the rotating member.
[0010] In an alternative embodiment of the invention, an inductive
coupling device transfers power from the substantially non-rotating
housing of a drilling motor to the rotating drill shaft. The
electrical power transferred to the rotating drill shaft is
utilized to operate one or more sensors in the drill bit and/or the
bearing assembly. A control circuit near the drill bit controls
transfer of data from the sensors in the rotating member to the
non-rotating housing.
[0011] The inductive coupling may also be provided in a separate
module above the mud motor to transfer power from a non-rotating
section to the rotating member of the mud motor and the drill bit.
The power transferred may be utilized to operate devices and
sensors in the rotating sections of the drilling assembly, such as
the drill shaft and the drill bit. Data is transferred from devices
and sensors in the rotating section to the non-rotating section via
the same or a separate inductive coupling. Data in the various
embodiments is transferred by frequency modulation, amplitude
modulation or by discrete signals.
[0012] Examples of the more important features of the invention
thus have been summarized rather broadly in order that the detailed
description thereof that follows may be better-understood, and in
order that the contributions to the art may be appreciated. There
are, of course, additional features of the invention that will be
described hereinafter and which will form the subject of the claims
appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For detailed understanding of the present invention,
references should be made to the following detailed description of
the preferred embodiment, taken in conjunction with the
accompanying drawings, in which like elements have been given like
numerals and wherein:
[0014] FIG. 1 is an isometric view of a section of a drilling
assembly showing the relative position of a rotating drive shaft
(the "rotating member") and a non-rotating sleeve (the
"non-rotating member") and an electrical power and data transfer
device for transferring power and data between the rotating and
non-rotating members across a gap according to one embodiment of
the present invention.
[0015] FIG. 2 is a line diagram of a section of a drilling assembly
showing the electrical power and data transfer device and the
electrical control circuits for transferring power and data between
the rotating and non-rotating sections of the drilling assembly
according to one embodiment of the present invention.
[0016] FIGS. 3A-3D are schematic functional diagrams showing
several embodiments relating to the power and data transfer device
shown in FIGS. 1-2 and for operating devices in a non-rotating
section utilizing the power and data transferred from the rotating
to the non-rotating sections and for operating devices in a
rotating section utilizing power and data transferred from a
non-rotating to the rotating sections.
[0017] FIG. 4 is a schematic diagram of a portion of a drilling
assembly, wherein an inductive coupling is shown disposed in at two
alternative locations for transferring power and data between
rotating and non-rotating members.
[0018] FIGS. 5A-5B are cross-section diagrams of two possible
configurations for the inductive coupling of a tool according to
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIG. 1 is an isometric view of a section or portion 100 of a
drilling assembly showing the relative position of a rotating
hollow drive shaft 112 (rotating member) and a non-rotating sleeve
120 (non-rotating member) with a gap 113 therebetween and an
electric power and data transfer device 135 for transferring power
and data between the rotating drive shaft and the nonrotating
sleeve over the gap 113, according to one embodiment of the present
invention. The gap 113 may or may not be filled with a fluid. The
fluid, if used, may be conductive or non-conductive.
[0020] Section 100 forms the lowermost part of the drilling
assembly in one embodiment. The drive shaft 112 has a lower drill
bit section 114 and an upper mud motor connection section 116. A
reduced diameter portion of the hollow shaft 112 connects the
sections 114 and 116. The drive shaft 110 has a through bore 118
which forms the passageway for drilling fluid 121 supplied under
pressure to the drilling assembly from a surface location. The
upper connection section 116 is coupled to the power section of a
drilling motor or mud motor (not shown) via a flexible shaft (not
shown). A rotor in the drilling motor rotates the flexible shaft,
which in turn rotates the drive shaft 110. The lower section 114
houses a drill bit (not shown) and rotates as the drive shaft 110
rotates. A substantially non-rotating sleeve 120 is disposed around
the drive shaft 110 between the upper connection section 116 and
the drill bit section 114. During drilling, the sleeve 120 may not
be completely stationary, but rotate at a very low rotational
speed. Typically, the drill shaft rotates between 100 to 600
revolutions per minute (r.p.m.) while the sleeve 120 may rotate at
less than 2 r.p.m. Thus, the sleeve 120 is substantially
non-rotating with respect to the drive shaft 110 and is, therefore,
referred to herein as the substantially non-rotating or
non-rotating member or section. The sleeve 120 includes at least
one device 130 that requires electric power. In the configuration
of FIG. 1, the device 130 operates one or more force application
members, such as member 132.
[0021] The electric power transfer device 135 includes a
transmitter section 142 attached to the outside periphery of the
rotating drive shaft 112 and a receiver section 144 attached to the
inside of the non-rotating sleeve 120. In the assembled downhole
tool, the transmitter section 142 and the receiver section 144 are
across from each other with an air gap between the two sections.
The outer dimensions of the transmitter section 142 are smaller
than the inner dimension of the receiver section 144 so that the
sleeve 120 with the receiver section 144 attached thereto can slide
over the transmitter section 142. An electronic control circuit 125
(also referred to herein as the "primary electronics") in the
rotating member 110 provides the desired electric power to the
transmitter 142 and also controls the operation of the transmitter
142. The primary electronics 125 also provides the data and control
signals to the transmitter section 142, which transfers the
electric power and data to the receiver 144. A secondary electronic
control circuit (also referred to herein as the "secondary
electronics") is carried by the non-rotating sleeve 120. The
secondary electronics 134 receives electric energy from the
receiver 144, controls the operation of the electrically-operated
device 130 in the non-rotating member 120, receives measurement
signals from sensors in the non-rotating section 120, and generates
signals which are transferred to the primary electronics via the
inductive coupling 135. The transfer of electric power and data
between the rotating and non-rotating members are described below
with reference to FIGS. 2-4.
[0022] FIG. 2 is a line diagram of a bearing assembly 200 section
of a drilling assembly which shows, among other things, the
relative placement of the various elements shown in FIG. 1. The
bearing assembly 200 has a drive shaft 201 which is attached at its
upper end 202 to a coupling 204, which in turn is attached to a
flexible rod that is rotated by the mud motor in the drilling
assembly. A non-rotating sleeve 210 is placed around a section of
the drive shaft 211. Bearings 206 and 208 provide radial and axial
support to the drive shaft 211 during drilling of the wellbore. The
non-rotating sleeve 210 houses a plurality of expandable force
application members, such as members 220a-220b (ribs). The rib 220a
resides in a cavity 224a in the sleeve 210. The cavity 224a also
includes sealed electro-hydraulic components for radially expanding
the rib 220a. The electro-hydraulic components may include a motor
that drives a pump, which supplies fluid under pressure to a piston
226a that moves the rib 220a radially outward. These components are
described below in more detail in reference to FIGS. 3A-3D.
[0023] An inductive coupling device 230 transfers electric power
between the rotating and non-rotating members. The device 230
includes a transmitter section 232 carried by the rotating member
110 and a receiver section 234 carried by the non-rotating sleeve
210. The device 230 preferably is an inductive device, in which
both the transmitter and receiver include suitable coils. Primary
control electronics 236 is preferably placed in the upper coupling
section 204. Other sections of the rotating member may also be
utilized for housing part or all of the primary electronics 236.
Secondary electronics 238 is preferably placed adjacent to the
receiver 234. Conductors and communication links 242 placed in the
rotating member 201 transfer power and signals between the primary
electronics 236 and the transmitter 232. Power in downhole tools
such as shown in FIG. 2 is typically generated by a turbine rotated
by the drilling fluid supplied under pressure to the drilling
assembly. Power may also be supplied from the surface via
electrical lines in the tubing or by batteries in the downhole
tool.
[0024] FIG. 3A is a functional diagram of a drilling assembly 300
that depicts the method for power and data transfer between the
rotating and non-rotating sections of the drilling assembly.
Drilling assemblies also referred to as bottom hole assemblies or
BHA's used for drilling wellbores and for providing various
formation evaluation measurements and measurements-while-drilling
measurements are well known in the art and, thus, their detailed
layout or functions are not described herein. The description given
below is primarily in the context of transferring electric power
and data between a rotating and non-rotating members.
[0025] Still referring to the FIG. 3A, the drilling assembly 300 is
coupled at its top end or uphole end 302 to a tubing 310 via a
coupling device 304. The tubing 310, which is usually a jointed
pipe or a coiled tubing, along with the drilling assembly 300 is
conveyed from a surface rig into the wellbore being drilled. The
drilling assembly 300 includes a mud motor power section 320 that
has a rotor 322 inside a stator 324. Drilling fluid 301 supplied
under pressure to the tubing 310 passes through the mud motor power
section 320, which rotates the rotor 322. The rotor 322 drives a
flexible coupling shaft 326, which in turn rotates the drive shaft
328. A variety of measurement-while-drilling ("MWD") and/or
logging-while-drilling sensors ("LWD"), generally referenced herein
by numeral 340, carried by the drilling assembly 300 provide
measurements for various parameters, including borehole parameters,
formation evaluation parameters, and drilling assembly health
parameters. These sensors may be placed in a separate section or
module, such as a section 341, or distributed in one or more
sections of the drilling assembly 300. Usually, some of the sensors
are placed in the housing 342 of the drilling assembly 300.
[0026] Electric power is usually generated by a turbine-driven
alternator 344. The turbine is driven by the drilling fluid 301.
Electric power also may be supplied from the surface via
appropriate conductors or from batteries in the drilling assembly
300. In the exemplary system shown in FIG. 3A, the drive shaft 328
is the rotating member and the sleeve 360 is the non-rotating
member. The preferred power and data transfer device 370 between
the rotating and non-rotating members is an inductive transformer,
which includes a transmitter section 372 carried by the rotating
member 328 and a receiver section 374 placed in the non-rotating
sleeve 360 across from the transmitter 372. The transmitter 372 and
receiver 374 respectively contain coils 376 and 378. Power to the
coils 376 is supplied by the primary electrical control circuit
380. The primary electronics 380 generates a suitable A.C. voltage
and frequency to be supplied to the coils 376. The A.C. voltage
supplied to the coils 376 is preferably at a high frequency e.g.
above 500 Hz. The primary electronics also preferably generates a
suitable D.C. voltage, which is then used for not-shown circuits on
the rotating member 328. The rotation of the drill shaft 328
induces current into the receiver section 374, which delivers A.C.
voltage as the output. The secondary control circuit or the
secondary electronics 382 in the non-rotating member 360 converts
the A.C. voltage from the receiver 372 to the D.C. voltage. D.C.
voltage is then utilized to operate various electronic components
in the secondary electronics and any electrically-operated devices.
Drilling fluid 301 usually fills the gap 311 between the rotating
and non-rotating members 328 and 360.
[0027] The electric power and the data/signals from a location
uphole of the drilling motor power section 320 may be transferred
to a location below or downhole of the mud motor power section in a
manner similar to as described above in reference to the device
370. In the drilling assembly 300 configuration electric power and
data/signals from sections 344 and 340 may be transferred to the
rotating members 328 via an inductive coupling device 330a, which
includes a transmitter section 330a that may be placed at a
suitable location in the non-rotating section 324 (stator) of the
drilling motor 320 and a receiver section 330b that may be placed
in the rotating section 322 (the rotor). The electric power and
data/signals are provided to the transmitter via suitable
conductors or links 331a while power and data/signals are
transferred between the receiver 330b and the primary electronics
380 and other devices in the rotating members via communication
links 331b. Alternatively, the electric power and data/signal
transfer device may be located toward the lower end of the power
section, such as shown by the location of the device 332. The
device 332 includes a transmitter section 332a and a receiver
section 332b. Communication links 333a respectively transfers
electric power and data/signals between power section 344 and
sensor section 340 on one side and the transmitter 332a while
communication links 333b transfer power and data/signals between
receiver 332b and devices or circuits, such as circuit 380, in the
rotating sections.
[0028] Still referring to FIG. 3A and as noted above, a motor 350
operated by the secondary electronics 382 drives a pump 364, which
supplies a working fluid, such as oil, from a source 365 to a
piston 366. The piston 366 moves its associated rib 368 radially
outward from the non-rotating member 360 to exert force on the
wellbore. The pump speed is controlled or modulated to control the
force applied by the rib on the borehole wall. Alternatively, a
fluid flow control valve 367 in the hydraulic line 369 to the
piston may be utilized to control the supply of fluid to the piston
and thereby the force applied by the rib 368. The secondary
electronics 362 controls the operation of the valve 369. A
plurality of spaced apart ribs (usually three) are carried by the
non-rotating member 360, each rib being independently operated by a
common or separate secondary electronics.
[0029] The secondary electronics 382 receives signals from sensors
379 carried by the non-rotating member 360. At least one of the
sensors 379 provides measurements indicative of the force applied
by the rib 368. Each rib has a corresponding sensor. The secondary
electronics 382 conditions the sensor signals and may compute
values of the corresponding parameters and supplies signals
indicative of such parameters to the receiver 372, which transfers
such signals to the transmitter 372. A separate transmitter and
receiver may be utilized for transferring data between rotating and
non-rotating sections. Frequency and/or amplitude modulating
techniques and discrete signal transmitting techniques, known in
the art, may be utilized to transfer information between the
transmitter and receiver or vice versa. The information from the
primary electronics may include command signals for controlling the
operation of the devices in the non-rotating sleeve.
[0030] In the alternative embodiment, the primary electronics and
the transmitter are placed in the non-rotating section while the
secondary electronics and receiver are located in the rotating
section of the downhole tool, thereby transferring electric power
from the non-rotating member to the rotating member. These
embodiments are described below in more detail with reference to
FIG. 4.
[0031] Thus, in one aspect of the present invention, electric power
and data are transferred between a rotating drill shaft and a
non-rotating sleeve of a drilling assembly via an inductive
coupling. The transferred power is utilized to operate electrical
devices and sensors carried by the non-rotating sleeve. The role of
the transmitter and receiver may be reversed.
[0032] FIG. 3B is a partial functional line diagram of an
alternative configuration of a drilling assembly 30 showing the use
of the electric power and data/signal transfer device of the
present invention. The drilling assembly 30 is shown to include an
upper section 32 that may be composed of more than one serially
coupled sections or modules. The upper section 32 includes a power
section or unit that provides electrical power from a source
thereof, MWD/LWD sensors and a two-way telemetry unit. The electric
power may be supplied from the surface or generated within the
section 32 as described above. The upper section is coupled to a
lower section 34 that includes a rotating member 36 which rotates a
drill bit 35. A non-rotating member or sleeve 38 is disposed around
the rotating member 36.
[0033] The drilling assembly 30 is coupled to a drill pipe 31 that
is rotated from the surface. The drill pipe 31 rotates the upper
section 32 of the drilling assembly 30 and the rotating member 36.
The non-rotating member 38 remains substantially stationary with
respect to the rotating member 36. Line 37a indicates the transfer
of electric power from the upper section 32 to the non-rotating
section 38 via the transfer device 37 while line 37b indicates the
two-way communication of data/signals between the rotating member
36 and the non-rotating section 38.
[0034] FIG. 3C shows a functional line diagram of yet another
configuration of a drilling assembly 40 which includes the section
32 and 34 of FIG. 3B and a drilling motor uphole of the section 32.
In this configuration, a rotor 44 of a drilling motor 42 rotates
the section 32 and the rotating member 36 attached to the drill bit
35. Tubing 45 may be a drill pipe or a coiled tubing. If drill pipe
is used as the tubing 45, it may be rotated from the surface. The
rotation of the drill pipe would be superimposed on the drilling
motor rotation to increase the rotation speed of the bit 35. The
electric power and data/signals are transferred between the
non-rotating section 38 and the rotating section 36 via device 37
as described above in reference to FIG. 3B.
[0035] FIG. 3D shows a partial functional line diagram of yet
another configuration of a modular drilling assembly 50 utilizing
the power and data/signal transfer device of the present invention.
The drilling assembly 50 includes a lower section 54, a drilling
motor section 52, a power section or module 56 between the drilling
motor 52 and the lower section 54 and a sensor/telemetry section 58
uphole of the drilling motor 52. In this configuration, a common
electric power module 56 may be used to supply electric power to
the lower section 54 and the sensor/telemetry section 58, which is
above the mud motor. In this configuration, the drilling motor
rotates both the power module 56 and a rotating member 66.
Communication link 67a indicate transfer of electric power from the
power module 56 to the non-rotating member 68 via an inductive
coupling device 67 while links 67b indicate two-way data/signal
transfer between the rotating member 66 and the non-rotating member
68. Power and data between the power section 56 and the
sensor/telemetry section 58 may be transferred via an inductive
coupling 70 which includes a transmitter 70a in the rotor 51 and a
receiver 70b in the stationary section 53 (stator section). The
power and data transfer between the stator 53 and the sensor
telemetry section may be done via communication links 73. The power
and data transfer device 70 may be placed at any other suitable
location, such as near the upper end, as shown by the dashed-line
device 77. A tubing 79 is coupled to the top end of the section 58.
A drill pipe or a coiled tubing may be used as the tubing 79. If a
drill pipe is used as the tubing 79, it may be rotated from the
surface. In such a case, the drill pipe rotation is superimposed on
the drilling motor rotation as described above with reference to
FIG. 3C.
[0036] FIG. 4 is a schematic diagram of a portion 400 of an
exemplary drilling assembly which show two alternative arrangements
for the power and data transfer device. FIG. 4 shows a drilling
motor section 415 that includes a rotor 416 disposed in a stator
418. The rotor 416 is coupled to a flexible shaft 422 at a coupling
424. A drill shaft 430 is connected to the lower end 420 of the
flexible shaft 422. The drill shaft 430 is disposed in a bearing
assembly with a gap 436 therebetween. Drilling fluid 401 supplied
under pressure from the surface passes through the power section
410 of the motor 400 and rotates the rotor 416. The rotor rotates
the flexible shaft 422, which in turn rotates the drill shaft 430.
A drill bit (not shown) housed at the bottom end 438 of the drill
shaft 430 rotates as the drill shaft rotates. Bearings 442 and 494
provide radial and axial stability to the drill shaft 430. The
upper end 450 of the motor power section 410 is coupled to MWD
sensors via suitable connectors. A common or continuous housing 445
may be utilized for the mud motor section 415.
[0037] In one embodiment, power and data are transferred between
the bearing assembly housing 461 and the rotating drive shaft 430
by an inductive coupling device 470. The transmitter 471 is placed
on the stationary housing 461 while the receiver 472 is placed on
the rotating drive shaft 430. One or more power and data
communication links 480 are run from a suitable location above the
mud motor 410 to the transmitter 471. Electric power may be
supplied to the power and communication links 480 from a suitable
power source in the drilling assembly 400 or from the surface. The
communication links 480, may be coupled to a primary control
electronics (not shown) and the MWD devices. A variety of sensors,
such as pressure sensor S.sub.1, temperature sensors S.sub.2,
vibration sensors S.sub.3 etc. are placed in the drill bit.
[0038] The secondary control electronics 482 converts the A.C.
voltage from the receiver to D.C. voltage and supplies it to the
various electronic components in the circuit 482 and to the sensors
S.sub.1-S.sub.3. The control electronics 482 conditions the sensor
signals and transmits them to the data transmission section of the
device 470, which transmits such signals to the transmitter 371.
These signals are then utilized by a primary electronics in the
drilling assembly 400. Thus, in the embodiment described above, an
inductive coupling device transfers electric power from a
non-rotating section of the bearing assembly to a rotating member.
The inductive coupling device also transfers signals between these
rotating and non-rotating members. The electric power transferred
to the rotating member is utilized to operate sensors and devices
in the rotating member. The inductive devices also establishes a
two-way data communication link between the rotating and
non-rotating members.
[0039] In an alternative embodiment, a separate subassembly or
module 490 containing an inductive device 491 may be disposed above
or uphole of the mud motor 415. The module 490 includes a member
492, rotatably disposed in a non-rotating housing 493. The member
492 is rotated by the mud motor 410. The transmitter 496 is
disposed on the non-rotating housing 493 while the receiver 497 is
attached to the rotating member 492. Power and signals are provided
to the transmitter 496 via conductors 494 while the received power
is transferred to the rotating sections via conductors 495. The
conductors 495 may be run through the rotor, flexible shaft and the
drill shaft. The power supplied to the rotating sections may be
utilized to operate any device or sensor in the rotating sections
as described above. Thus, in this embodiment, electric power is
transferred to the rotating members of the drilling assembly by a
separate module or unit above the mud motor.
[0040] FIGS. 5A-5B are cross-section diagrams of two possible
configurations of an inductive coupling for use in embodiments of
the present invention such as those described above and shown in
FIGS. 1-4. In FIG. 5A, a portion 500 of a drilling assembly
according to the present invention includes a rotating member 502
and a non-rotating member 504. Elements of the invention not shown
in FIG. 5A are substantially identical to elements described above
and shown in FIGS. 1-4.
[0041] A rotating member 502 is coupled to the drilling assembly
500. A transmitter 506 is coupled to the rotating member 502. The
transmitter 506 includes transmitter windings 510 of insulated
wires. The transmitter 506 includes at least a portion 522
comprising a soft ferro-magnetic material such as soft iron or
Ferrite used to concentrate a magnetic field to be described
later.
[0042] A non-rotating member 504 is coaxially disposed about the
rotating member 502. A receiver 509 is coupled to the non-rotating
member 504. The receiver 509 includes receiver windings 508 of
insulated wires. The receiver 509 includes at least a portion 524
comprising a soft ferro-magnetic material such as soft iron or
Ferrite used to concentrate a magnetic field through the receiver
windings 508.
[0043] The transmitter windings 510 and receiver windings 508 are
separated from each other by a gap 520. The gap 520 may be filled
or evacuated. If filled, the gap may be filled with a fluid of gas
or liquid, and the fluid may be either conducting or
non-conducting.
[0044] Electrical current provided by an electronic control circuit
(see ref. 125 of FIG. 1) flows through the transmitter windings
510, to generate an electromagnetic field 512. The field 512
traverses the gap 520 and encompasses the receiver windings 508. A
current is generated in the receiver windings 508 whenever the
field 512 is a changing field. The field 512 is effectively a
changing field if the current in the transmitter windings 510 is an
AC current.
[0045] The current induced in the receiver windings 508 may be used
to provide power, data or both to various electrical components
carried by the non-rotating member 504. Specific electrical
components are not shown in FIG. 5A, although examples of
electrical components are described above and shown in FIGS. 1-4.
One or more points 514, 516 and 518 on the receiver windings 508
are used for connecting circuits to the receiver 509. Those versed
in the art will recognize that a particular point 514 selected on
the receiver winding 508 will establish a particular voltage
referenced to a predetermined ground (or neutral) point which is
another point 518 along the receiver winding 508.
[0046] In an alternative embodiment (not shown), the receiver 509
comprises a plurality of receiver winding sections electrically and
physically separated from each other. Each receiver winding may be
used to receive power and/or data signals from the transmitter 506.
Each receiver winding may then conduct the power and/or data
signals to an independent electrical component in the non-rotating
sleeve 504.
[0047] FIG. 5B shows a partial cross-section of a drilling assembly
500 according to the present invention with an alternative
configuration of an inductive coupling. Elements of the invention
not shown in FIG. 5B are substantially identical to elements
described above and shown in FIGS. 1-4.
[0048] The configuration shown in FIG. 5B includes a transmitter
544 coupled to a rotating member 540 of the drilling assembly 500.
A plurality of transmitter elements (shoes) 552 are coupled to the
transmitter such that the shoes 552 rotate with the rotating member
540. Each transmitter shoe 552 comprises a transmitter winding 546
that rotates with the rotating member 540. The transmitter 544
includes at least a portion 564 comprising a soft ferro-magnetic
material such as soft iron or Ferrite used to concentrate a
magnetic field through the transmitter windings 546. In a preferred
embodiment, each transmitter shoe structure is included in the
portion 564.
[0049] A substantially non-rotating member 542 is disposed about
the rotating member 540. A receiver 545 is coupled to the
non-rotating member 542. A plurality of receiver elements (shoes)
550 are coupled to the receiver 545, and each receiver shoe 550
includes a receiver winding 548. The receiver 545 includes at least
a portion 562 comprising a soft ferro-magnetic material such as
Soft iron or Ferrite used to concentrate a magnetic field through
the receiver windings 548. In a preferred embodiment, each shoe
structure is included in the portion 562.
[0050] A gap 560 separates the receiver 545 from the transmitter
544. The gap 560 may be filled or evacuated. If filled, the gap may
be filled with a fluid of gas or liquid either conducting or
non-conducting. The gap 560 is preferably filled with a
substantially non-conducting fluid.
[0051] As described above and shown in FIG. 5A, a plurality of
not-shown electrical components may be operated using power and
data signals taken from the receiver 545. A different component may
be connected to the receiver 545 at any of a number of points 554,
556 and 558. Each connection point is preferably a winding 548 of a
particular receiver shoe 550.
[0052] The foregoing description is directed to particular
embodiments of the present invention for the purpose of
illustration and explanation. It will be apparent, however, to one
skilled in the art that many modifications and changes to the
embodiment set forth above are possible without departing from the
scope and the spirit of the invention. It is intended that the
following claims be interpreted to embrace all such modifications
and changes.
* * * * *