U.S. patent application number 09/758065 was filed with the patent office on 2001-11-22 for steerable modular drilling assembly.
Invention is credited to Krueger, Volker, Kruspe, Thomas, Ragnitz, Detlef, Rehbock, Hans, Witte, Johannes.
Application Number | 20010042643 09/758065 |
Document ID | / |
Family ID | 22641517 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042643 |
Kind Code |
A1 |
Krueger, Volker ; et
al. |
November 22, 2001 |
Steerable modular drilling assembly
Abstract
In general, the present invention provides a modular drilling
assembly having a module for contactless power and data transfer
over a nonconductive gap between rotating and non-rotating members
of a steering module. The gap usually contains 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 modular drilling assembly wherein a drive shaft is rotated by
a downhill motor to rotate a 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. The
drilling assembly is modular in that it includes at least one
steering module at the bottom end of the drilling assembly that has
at least one steering device module that provides power to the
force application member. A power and data communication uphole of
the steering module provides power to the steering module and data
communication between the drilling assembly and the surface.
Inventors: |
Krueger, Volker; (Celle,
DE) ; Rehbock, Hans; (Wienhausen, DE) ;
Kruspe, Thomas; (Wienhausen, DE) ; Witte,
Johannes; (Braunschweig, DE) ; Ragnitz, Detlef;
(Hornoldendorf, DE) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Family ID: |
22641517 |
Appl. No.: |
09/758065 |
Filed: |
January 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60175758 |
Jan 12, 2000 |
|
|
|
Current U.S.
Class: |
175/73 ;
175/325.3; 175/61 |
Current CPC
Class: |
E21B 7/062 20130101;
E21B 47/13 20200501; E21B 17/028 20130101; E21B 17/1014 20130101;
E21B 41/0085 20130101; E21B 7/068 20130101 |
Class at
Publication: |
175/73 ; 175/61;
175/325.3 |
International
Class: |
E21B 007/08 |
Claims
What is claimed is:
1. A modular drilling assembly for drilling a wellbore, comprising:
a steering module at a bottom end of said drilling assembly, said
steering module including a substantially non-rotating member
outside a rotating member, said non-rotating member including at
least one steering device having a pluggable power unit that
provides power to a force application member to cause said force
application member to extend radially outward from said drilling
assembly to exert pressure on the wellbore; a drill bit carried by
said steering module for drilling said wellbore.
2. The modular drilling assembly of claim 1 further comprising an
electrical power generation module uphole of said steering module
for providing electrical power to said steering module.
3. The modular drilling assembly of claim 1, wherein said pluggable
power unit includes a motor, a pump and hydraulic fluid for
supplying said hydraulic fluid under pressure to operate said force
application member.
4. The modular drilling assembly of claim 1, wherein said steering
module further includes an inductive coupling device for
transferring power between said non-rotating and rotating
members.
5. The modular drilling assembly of claim 1 further comprising at
least one module containing at least one sensor for providing
measurements for determining a parameter of interest relating to
the drilling of the wellbore.
6. The modular drilling assembly of claim 5, wherein said at least
one sensor is selected from a group consisting of (i) an
inclination sensor; (ii) a formation evaluation sensor; and (iii) a
sensor for determining a physical condition of said drilling
assembly.
7. The modular drilling assembly of claim 1 further comprising a
module uphole of said steering module that is selected from a group
consisting of (i) a module containing at least one sensor for
determining drilling direction of the wellbore; (ii) a module
containing a battery; (iii) a module containing memory to store
data downhole; (iv) a module containing at least a resistivity
sensor and a gamma ray sensor; (v) a module containing at least one
logging-while-drilling sensor; and (vi) a module containing a mud
motor for rotating said drill bit.
8. The modular drilling assembly according to claim 1, wherein said
pluggable power unit electrically plugs into a secondary electronic
circuit carried by said non-rotating member.
9. The modular drilling assembly according to claim 8, wherein said
power unit is disposed in a recess in said non-rotating member.
10. A modular drilling assembly comprising a steering module having
a substantially non-rotating member operatively coupled to a
rotating member, a plurality of interchangeable modules coupled to
a drill string, wherein each of the plurality of interchangeable
module and the steering module include at least one coupling for
intrechangably coupling to one or more other modules of the
plurality of interchangeable modules, and a drill bit coupled to a
distal end of the drilling assembly.
11. The modular drilling assembly of claim 10, wherein the at least
one coupling is a plug coupling.
12. The modular drilling assembly of claim 10, wherein the
plurality of interchangeable modules includes at least one of a
directional module, a power module, a communications module, a
sensor module, and a control module.
13. The modular drilling assembly of claim 10, wherein the steering
module includes an inductive coupling device for transferring power
between the non-rotating and rotating members.
14. The modular drilling assembly of claim 10, wherein at least one
of the plurality of interchangeable modules is located uphole of
the steering module and is selected from a group consisting of (i)
a module containing a battery, (ii) a module containing memory to
store data downhole; (iii) a module containing a resistivity sensor
and a gamma ray sensor; (iv) a module containing at least one
logging-while-drilling sensor; and (v) a module containing a mud
motor for rotating the drill bit.
15. The modular drilling assembly of claim 12, wherein the power
module is disposed in a recess in the non-rotating member.
16. A modular steering assembly for use in a drilling assembly, the
modular steering assembly comprising a steering module coupled to
the drilling assembly, the steering module having a substantially
non-rotating member operatively coupled to a rotating member; one
or more modules interchangeably coupled to the steering module; and
a dill bit coupled to the steering module.
17. The modular steering assembly of claim 16 further comprising
one or more force application modules interchangeably coupled to
the steering module and adapted to selectively extend in a
generally radial direction from the steering module to contact a
wellbore wall.
18. The modular steering assembly of claim 16, wherein the one or
more modules includes a sensor module having a sensor for measuring
at least one parameter of interest.
19. The modular drilling assembly of claim 18 wherein the sensor is
selected from a group consisting of (i) an inclination sensor; (ii)
a formation evaluation sensor; and (iii) a sensor for determining a
physical condition of the drilling assembly.
20. The modular drilling assembly of claim 16 further comprising a
control module for controlling the steering module, the control
module being selectively locatable along the drilling assembly.
21. The modular steering assembly of claim 17 further comprising a
power module that provides power to the force application
module.
22. A steerable drilling assembly, comprising: a drill string
comprising a drill bit coupled to a distal end of the drill string,
and a plurality of interchangeable modules disposed at several
locations along the drill string, the plurality of interchangeable
modules further comprising; a steering module having a
substantially non-rotating sleeve operatively coupled to a rotating
sleeve, the steering module being disposed at a first location on
the drill string; a directional module at a second location on the
drill string for determining drilling direction; and a power module
at a third location on the drill string for providing power to the
steering module, wherein each module in the plurality of
interchangeable module includes at least one connector adapted to
allow each module in the plurality of interchangeable modules to be
relocated to any of the several locations.
23. The steerable drilling assembly of claim 22, wherein the
plurality of interchangeable modules further comprises at least one
of: a communications module at a fourth location on the drill
string for transferring power and data between modules of the
plurality of modules; a sensor module at a fifth location on the
drill string for sending at lease a physical characteristic of the
steerable drilling assembly; and a control module at a sixth
location on the drill string for controlling the steering module.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application takes priority from U.S. Provisional Patent
Application Ser. No. 60/175,758, filed Jan. 12, 2000, assigned to
the assignee of this application, and which is hereby incorporated
herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to oilfield downhole tools
and more particularly to modular drilling assemblies utilized for
drilling wellbores in which electrical power and data are
transferred between rotating and 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 "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 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 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 sections 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 nonconductive 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 the preferred system, a common or separate
electrically-operated hydraulic unit provide energy (power) to the
force application members. An inductive coupling transfer 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 non-rotating housing 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 preferably transferred by frequency modulation.
[0012] The drilling assembly is modular, in that relatively easily
connectable modules make up the drilling assembly. The modular
drilling assembly includes at least a steering module that carries
the drill bit and includes a non-rotating sleeve that includes a
plurality of pluggable steering device modules. A power and data
communication module uphole of the steering module provides power
to the steering module and two-way data communication between the
steering module and the remaining drilling assembly. A subassembly
containing multipropagation sensitivity sensors and gamma ray
sensors is disposed uphole of the steering module. This subassembly
may include a memory module and a vibration module. A directional
module containing sensors for determining the drilling assembly
direction is preferably disposed uphole of the resistivity and
gamma sensor subassembly. Modular subassemblies make up portions of
the steering assembly. The primary electronics, secondary
electronics inductive coupling transformers of the steering module
are also individual pluggable modules.
[0013] 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
[0014] 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:
[0015] 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 non-conductive gap according to one
embodiment of the present invention.
[0016] 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.
[0017] FIGS. 3A and 3B show a schematic functional block diagram
relating to the power and data transfer device shown in FIGS. 1-2
and for operating a device in the non-rotating section utilizing
the power transferred from the rotating to the non-rotating
sections.
[0018] FIG. 4 is a schematic diagram of a portion of a drilling
assembly, wherein an inductive coupling is shown disposed in two
alternative locations for transferring power and data between
rotating and non-rotating members.
[0019] FIG. 5 is a modular drilling assembly according to one
embodiment of the present invention.
[0020] FIG. 6 is an isometric view showing the relative placement
of certain major components' of the steering module and the
bidirectional power and data communication modules shown in FIG.
5.
[0021] FIG. 7 shows a first alternative modular arrangement for the
drilling assembly of the present invention.
[0022] FIG. 8 is a second alternative modular arrangement for the
drilling assembly of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIG. 1 is an isometric view of a section or portion 100 of a
drilling assembly showing the relative position of a rotating drive
shaft 110 (rotating member) and a non-rotating sleeve 120
(non-rotating member) with a non-conductive gap therebetween and an
electric power and data transfer device 135 for transferring power
and data between the rotating drive shaft and the non-rotating
sleeve over a non-conductive gap 113, according to one embodiment
of the present invention.
[0024] Section 100 forms the lowermost part of the drilling
assembly. The drive shaft 110 has a lower drill bit section 114 and
an upper mud motor connection section 116. A reduced diameter
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 rotates at a very
low rotational speed relative to the rotation of the drive shaft
110. 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.
[0025] 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
separated by 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
of the data transfer device 135. The transfer of electric power and
data between the rotating and non-rotating members are described
below with reference to FIGS. 2 through 3B.
[0026] 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 211 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 and 3B.
[0027] An inductive coupling data transfer 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 211 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. A secondary electronics module 238 is preferably
placed adjacent to the receiver 234. Conductors and communication
links 242 placed in the rotating member 211 transfer power and data
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.
[0028] FIGS. 3A and 3B show a block 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 or BHA's used for drilling
wellbores and for providing various measurements-while-drilling
measurements are well known in the art and, therefore, 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 rotating and non-rotating
members.
[0029] Still referring to FIGS. 3A and 3B, 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 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") 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 parameters, and drilling assembly health parameters.
These sensors may be placed in a separate section, such as a
section 341, or disposed 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.
[0030] Electric power is usually generated by a turbine 344 driven
by the drilling fluid 301. Electric power also may be supplied from
the surface via appropriate conductors. In the exemplary system
shown in FIG. 3, 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 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 opposite
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 turbine
344 generates a.c. voltage. The primary electronics 380 conditions
a.c. voltage and supplies it to the coils 376. 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 d.c.
voltage. The. 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.
[0031] Still referring to FIGS. 3A and 3B 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 wall. The pump speed is controlled or modulated to
control the force applied by the rib on the wellbore 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.
[0032] 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 section 374, 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 modulating
techniques, known in the art, may be utilized to transfer signals
between the transmitter and receiver or vice versa. The signals
from the primary electronics may include command signals for
controlling the operation of the devices in the non-rotating
sleeve.
[0033] In an 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.
[0034] 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.
[0035] FIG. 4 is a schematic diagram of a portion 400 of a drilling
assembly which shows 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 a 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 444 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.
[0036] 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.
[0037] 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 471.
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.
[0038] 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.
[0039] The drilling assemblies described above preferably are
modular, in that relatively easily connectable modules makeup the
drilling assembly. Modular construction is preferred for ease of
manufacturing, repairing of the drilling assembly and
interchangeability of modules in the field. FIG. 5 shows a modular
drilling assembly 500 according to one embodiment of the present
invention. The lowermost module 510 preferably is a steering module
510 having a drill bit 501 at its bottom end. The steering module
510 performs the same functions as assembly 200 shown in FIG. 2.
The steering module 510 includes a non-rotating sleeve 511 which
carries a plurality of modular steering devices 512 and modular
ribs 515 which are described in more detail in reference to FIG. 6.
The steering module 510 preferably includes the inductive coupling
power and data transfer devices described above with respect to
FIGS. 1-3B. The steering module 510 also preferably includes
sensors and electronics 514 (near bit inclination devices) for
determining the inclination of the drilling assembly 500. The near
bit inclination devices 514 may include three (3) axis
accelerometers, gyroscopic devices and signal processing circuitry
as generally known in the art. A gamma ray device 516 on the
non-rotating sleeve 511 provides information about changes in the
formation as the drilling progresses from one type of a formation
to another.
[0040] A bidirectional power and data communication module ("BPCM")
module 520 uphole of the steering module 510 provides power to the
steering unit 510 and two-way data communication between the
drilling assembly 500 and surface devices. The power in the BPCM is
preferably generated by a mud-driven alternator 522. The data
signals are preferably generated by a mud pulser 524. The
mud-driven power generation units (mud pulsers) are known in the
art thus not described in greater detail. The BPCM preferably is
separate module that can be attached to the upper end 513 of the
steering module 510 via a suitable connector mechanism 518.
Although, FIG. 5 shows BPCM attached to the upper end of the
steering module, it however, may be placed at any other suitable
location in the drilling assembly 500. A number of additional
modules also are provided to make up the entire drilling assembly.
The steering module 510 and BPCM 520 include certain additional
modular features, which are described next in reference to FIG. 6
prior to describing the additional modules of the drilling assembly
500.
[0041] FIG. 6 is an isometric view 600 showing in greater detail
certain modular and other features within the steering module 510
(610 in FIG. 6) and BPCM 520 (640 in FIG. 6) shown in FIG. 5. The
non-rotating sleeve 601 includes a plurality of steering devices
613, each containing a rib 611 and a plugable self-contained
hydraulic power unit or module 612. The hydraulic power module 612
plugs into the secondary electronics 616 disposed inside the
non-rotating sleeve 601 via a connector 614a coupled to the
hydraulic power module 612 and a mating connector 614b coupled to
the secondary electronics 616. Each hydraulic power unit 612
preferably is sealed and includes a motor, a pump and hydraulic
fluid to drive a piston, which moves an associated rib 611 radially
outward. A separate recess, such as recess 617, is provided in the
non-rotating sleeve for accommodating each hydraulic power unit 612
and its associated rib 611. At least one sensor 615 (such as a
pressure sensor) provides signals to the secondary electronics 616
corresponding to or representative of the force applied by its
associated rib 611 to the wellbore. Other sensors, such as
dispacement measuring sensors, may also be utilized to determine
the amount of force applied by each rib 611 on the wellbore. The
secondary or outer part 618 of the inductive coupling is
electrically coupled to the secondary electronics 616 via a
plugable pin connector 619 associated with the secondary
electronics 616. Thus, the steering module 610 described thus far
includes a non-rotating sleeve 601 which has a plurality of
plugable, self-contained steering rib hydraulic power units 612
(one for each rib), a plugable secondary electronics 616 (attached
to the inside of the non-rotating sleeve) and plugable outer coils
618 of the inductive coupling which are attached to the inside of
the non-rotating sleeve 601.
[0042] An upper drive shaft 622 runs through the non-rotating
sleeve 601 and is coupled to a lower drive shaft 624, which drives
the drill bit 602. The primary electronics 625 is coupled to the
outside of the upper drive shaft 622. Primary coils or inner part
632 of the inductive coupling is plugably connected to the primary
electronics 625. Thus, in one embodiment, the steering module 610
includes (i) a non-rotating sleeve with a plurality of
self-contained and sealed plugable hydraulic power units, one for
each rib, (ii) a primary electronics module that plugs into a
primary inductive coupling coil module; and (iii) a secondary
electronics module that is plugably connected to the secondary
inductive coupling coils and each of the hydraulic power units.
[0043] Still referring to FIG. 6, the BPCM 640 disposed uphole or
above steering unit 610, contains an electric power generation unit
641 that includes a turbine 642 which is driven by the drilling
fluid (mud) 648 supplied under pressure from the surface. The
turbine 642 rotates an alternator 643 which supplies electrical
power to the steering unit 610 via a double pin adapter 650. A ring
connector 644 on the adapter 650 and a ring connector 648 on the
upper drive shaft 622 transfer power and data between the power
generation unit 641 and the primary electronics 625. In an
alternative embodiment, the ring connector 644 may be built into
the BPCM, thereby eliminating the adapter 650. A pulser in the BPCM
generates telemetry signals (pressure pulses) corresponding to data
to be transmitted to the surface in accordance with signals from
the primary electronics 625 and other circuitry contained in the
drilling assembly 600. As noted above, the mud-driven power
generation units and pulsers are known. In the present invention
the electrical power generation unit and/or the pulser is a module
that can be connected to the steering module 610 and/or which can
be placed at other suitable locations in the drilling assembly
600.
[0044] Referring back to FIG. 5, a stabilizer module 530 having one
or more stabilizing elements 531 is disposed above the BPCM 520 to
provide lateral subility to the lower part of the drilling assembly
500. In an alternative embodiment, the stabilizing elements 531 may
be integrated into or disposed outside of the BPCM 520 as shown by
dotted lines 531 a.
[0045] A measurement-while-drilling module or "MWD module" 550,
preferably containing a resistivity and a gamma sensor, is
removably attached uphole or above the BPCM 520. A directional
module 560 containing sensors, such as magnetometers, to provide
measurements for determining the drilling direction is preferably
placed uphole of the MWD module 550. A logging-while-drilling
("LWD") module 565, containing formation evaluation sensors such as
resistivity, acoustic and nuclear sensors is preferably disposed
proximate to the upper end of the drilling assembly 500. An
alternator/downlink module 551 which detects telemetered data from
the surface for use by the drilling assembly 500 may be placed at
any suitable location. A memory module 552 is suitably disposed in
the MWD module 550. A battery pack module 556 to store and provide
back-up electric power may be placed at any suitable location in
the drilling assembly 500. Additional modules are provided
depending upon the specific drilling requirements. For example, a
module 554 containing sensors that provide parameters about the
downhole physical conditions, such as vibrations, whirl, slick
slip, friction, etc., may be suitably placed in the drilling
assembly.
[0046] Thus, in one modular embodiment, the drilling assembly
includes a lowermost steering module 510 that includes a plurality
of modular steering devices 512 and a power and data communication
module 520 uphole of the steering module 510. Near bit inclination
sensors are included in the steering module 510. The drilling
assembly includes an MWD module that contains a resistivity sensor
and a gamma sensor and an LWD module that includes at least one
formation evaluation sensor for providing information about the
formation penetrated by the drill bit. A directional module,
containing one or more magnetometers, may be placed at a suitable
location in the drilling assembly to provide information about the
direction of the wellbore drilled or penetrated by the drill
bit.
[0047] FIG. 7 shows an alternative configuration for the modular
drilling assembly 800 of the present invention. The lowermost
section (above the drill bit 801) is the modular steering unit 810
as described above. The drilling assembly 800 includes a modular
BPCM 812, a measurement-while-drilling ("MWD") module 814, a
formation evaluation or FE module 816 and a physical parameter
measuring sensor module 818 for measuring physical parameters. Each
of the modules 812, 814, 816 and 818 is interchangeable. For
example, the BPCM 812 may be connected above the MWD module 814 or
above the FE module 816. Similarly, the FE module 816 may be placed
below the MWD module 814, if desired, although usually MWD module
814 is placed closer to the drill bit since it includes directional
sensors. Each of the modules 812, 814, 816 and 818 includes
appropriate electrical and data communication connectors at each of
their respective ends so that electrical power and data can be
transferred between adjacent modules.
[0048] FIG. 8 shows yet another configuration 850 of a drilling
assembly according to an embodiment of the present invention. The
drilling assembly 850 includes a modular mud motor section 856
uphole of a steering module 852. The mud motor module or unit 856
includes an electrical connector (not shown) at its each end with
one or more conductors (not shown) running through the entire
length of the mud motor module 856. The conductors in the mud motor
enable transfer of power and data between the two ends of the motor
module 856, thereby allowing power and data transfer between
modules uphole and downhole of the mud motor module 856. The mud
motor module 856 is placed above the steering module 852 and below
FE modules 858 but may be placed at any other place above the
steering module 852. The particular modular configuration chosen
depends upon the operational requirements.
[0049] 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.
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