U.S. patent application number 14/765714 was filed with the patent office on 2015-12-31 for downhole tool with radial array of conformable sensors for downhole detection and imaging.
The applicant listed for this patent is HALLIBURTON ENERGY SERVICES, INC.. Invention is credited to Burkay Donderici.
Application Number | 20150378046 14/765714 |
Document ID | / |
Family ID | 52779096 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150378046 |
Kind Code |
A1 |
Donderici; Burkay |
December 31, 2015 |
DOWNHOLE TOOL WITH RADIAL ARRAY OF CONFORMABLE SENSORS FOR DOWNHOLE
DETECTION AND IMAGING
Abstract
According to aspects of the present disclosure, an example
downhole tool may include tool body, a first pad radially
extendable from the tool body, and a radial array of conformable
sensors coupled to the first pad. At least one conformable sensor
of the radial array of conformable sensors may include a first
flexible material. A transmitter may be coupled to one of the tool
body and the first flexible material, and a receiver may be coupled
to one of the tool body and the first flexible material. At least
one of the transmitter and the receiver may be coupled to the first
flexible material.
Inventors: |
Donderici; Burkay; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HALLIBURTON ENERGY SERVICES, INC. |
Houston |
TX |
US |
|
|
Family ID: |
52779096 |
Appl. No.: |
14/765714 |
Filed: |
October 1, 2014 |
PCT Filed: |
October 1, 2014 |
PCT NO: |
PCT/US2014/058572 |
371 Date: |
August 4, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61886255 |
Oct 3, 2013 |
|
|
|
Current U.S.
Class: |
324/339 |
Current CPC
Class: |
G01V 3/38 20130101; E21B
47/002 20200501; G01V 11/005 20130101; E21B 47/007 20200501; G01V
3/28 20130101 |
International
Class: |
G01V 3/28 20060101
G01V003/28; E21B 47/00 20060101 E21B047/00 |
Claims
1. A downhole tool, comprising a tool body; a first pad radially
extendable from the tool body; a radial array of conformable
sensors coupled to the first pad, wherein at least one conformable
sensor of the radial array of conformable sensors comprises a first
flexible material; a transmitter coupled to one of the tool body
and the first flexible material; and a receiver coupled to one of
the tool body and the first flexible material; wherein at least one
of the transmitter and the receiver is coupled to the first
flexible material.
2. The downhole tool of claim 1, wherein both the transmitter and
the receiver are coupled to the first flexible material; and the
receiver comprises at least two windings with different
orientations.
3. The downhole tool of claim 1, further comprising a second pad
extendable from the tool body; and an azimuthal array of
conformable sensors coupled to the second pad.
4. The downhole tool of one of claims 3, wherein the second pad is
coupled to the first pad.
5. The downhole tool of claim 3, wherein the azimuthal array of
conformable sensors comprises a second conformable sensor that
includes a second flexible material; a second transmitter coupled
to the second flexible material; and a second receiver coupled to
the second flexible material.
6. The downhole tool of claim 1, further comprising a control unit
comprising a processor and a memory device coupled to the
processor, the memory device containing a set of instructions that,
when executed by the processor, cause the processor to: select a
first combination of conformable sensors to generate a current
response measurement with a first depth of investigation; and
select a second combination of conformable sensors to generate a
current response measurement with a second depth of
investigation.
7. The downhole tool of claim 6, wherein the first combination of
sensors comprises at least one of two conformable sensors of the
azimuthal array of sensors, two conformable sensors of the radial
array of sensors; and one conformable sensor of the azimuthal array
of conformable sensors and one conformable sensor of the radial
array of conformable sensors.
8. The downhole tool of claim 6, wherein the first depth of
investigation is larger than the second depth of investigation.
9. The downhole tool of claim 8, wherein the set of instructions
further causes the processor to determine a parameter of a downhole
element remote from radial array of conformable sensors and the
azimuthal array of conformable sensors based, at least in part, on
at least one of the current response measurement with the first
depth of investigation and the current response measurement with
the second depth of investigation.
10. A method for downhole surveying or measuring, comprising
positioning a downhole tool with a radial array of conformable
sensors at least partially within a borehole in a subterranean
formation; generating a first measurement with a first depth of
investigation using a first combination of conformable sensors in
the radial array of conformable sensors; and generating a second
measurement with a second depth of investigation using a second
combination of sensors in the radial array of conformable
sensors.
11. The method of claim 10, wherein the radial array of conformable
sensors is coupled to a first pad extendable from the downhole
tool.
12. The method of one of claims 11, wherein positioning the
downhole tool with the radial array of conformable sensors at least
partially within the borehole comprises positioning the downhole
tool with the radial array of conformable sensors and an azimuthal
array of conformable sensors within the borehole.
13. The method of claim 13, wherein the azimuthal array of
conformable sensors is coupled to a second pad coupled to the first
pad.
14. The method of claim 13, further comprising generating a third
measurement with a third depth of investigation using a third
combination of conformable sensors in the radial and azimuthal
arrays of conformable sensors.
15. The method of claim 10, wherein the first and second
measurements correspond to current responses of at least one
downhole element within the borehole to an electromagnetic signal
generated by the conformable sensors.
16. The method of claim 15, further comprising determining a
parameter for a downhole element based, at least in part, on at
least one of the first and second measurements.
17. The method of claim 16, further comprising generating a first
visualization of the downhole element based, at least in part, on
the determined parameter.
18. The method of claim 17, wherein downhole element comprises one
of a casing, a cement layer outside of the casing, a wall of the
borehole, and the subterranean formation.
19. The method of claim 18, wherein the casing comprises a casing
remote from the radial and azimuthal arrays of conformable
sensors.
20. The method of claim 16, further comprising determining a
parameter for another downhole element based, at least in part, on
at least one of the first and second measurements wherein the
downhole element comprises a casing and the other downhole element
comprises another casing concentric with and outside of the casing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. provisional
No. 61/886,255, filed Oct. 3, 2013 and titled "DOWNHOLE TOOL WITH
RADIAL ARRAY OF CONFORMABLE SENSORS FOR CASING DETECTION AND
IMAGING," which is incorporated herein by reference in its entirety
for all purposes.
BACKGROUND
[0002] The present disclosure relates generally to downhole
drilling operations and, more particularly, to a downhole tool with
a radial array of conformable sensors for casing detection and
imaging. Hydrocarbons, such as oil and gas, are commonly obtained
from subterranean formations that may be located onshore or
offshore. The development of subterranean operations and the
processes involved in removing hydrocarbons from a subterranean
formation are complex. Typically, subterranean operations involve a
number of different steps such as, for example, drilling a wellbore
at a desired well site, treating the wellbore to optimize
production of hydrocarbons, and performing the necessary steps to
produce and process the hydrocarbons from the subterranean
formation. In certain operations, measurements within the wellbore
may be generated, including measurements of a casing within the
wellbore. Typically, those measurements are limited with respect to
their granularity, and small features within the wellbore may not
be identifiable through the measurements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] A more complete understanding of the present embodiments and
advantages thereof may be acquired by referring to the following
description taken in conjunction with the accompanying drawings, in
which like reference numbers indicate like features.
[0004] FIG. 1 is a diagram that shows two example downhole tools
with conformable sensors on different type of pads, according to
aspects of the present disclosure.
[0005] FIG. 2 is a diagram of example antenna windings for a
conformable sensor, according to aspects of the present
disclosure.
[0006] FIG. 3 is a diagram of an example downhole tool within a
multiple casing environment, according to aspects of the present
disclosure.
[0007] FIG. 4 is a diagram of an example control system for a
downhole tool with a radial array of sensors, according to aspects
of the present disclosure.
[0008] FIG. 5 is a block diagram of an example inversion algorithm
for measurements from a cased environment, according to aspects of
the present disclosure.
[0009] FIG. 6 is a diagram of an example production environment
with multiple, concentric casings.
[0010] FIG. 7 is a diagram showing an illustrative logging while
drilling environment, according to aspects of the present
disclosure.
[0011] FIG. 8 is a diagram showing an illustrative wireline logging
environment, according to aspects of the present disclosure.
[0012] While embodiments of this disclosure have been depicted and
described and are defined by reference to exemplary embodiments of
the disclosure, such references do not imply a limitation on the
disclosure, and no such limitation is to be inferred. The subject
matter disclosed is capable of considerable modification,
alteration, and equivalents in form and function, as will occur to
those skilled in the pertinent art and having the benefit of this
disclosure. The depicted and described embodiments of this
disclosure are examples only, and not exhaustive of the scope of
the disclosure.
DETAILED DESCRIPTION
[0013] The present disclosure relates generally to downhole
drilling operations and, more particularly, to a radial array of
conformable sensors for casing detection and imaging.
[0014] For purposes of this disclosure, an information handling
system may include any instrumentality or aggregate of
instrumentalities operable to compute, classify, process, transmit,
receive, retrieve, originate, switch, store, display, manifest,
detect, record, reproduce, handle, or utilize any form of
information, intelligence, or data for business, scientific,
control, or other purposes. For example, an information handling
system may be a personal computer, a network storage device, or any
other suitable device and may vary in size, shape, performance,
functionality, and price. The information handling system may
include random access memory (RAM), one or more processing
resources such as a central processing unit (CPU) or hardware or
software control logic, ROM, and/or other types of nonvolatile
memory. Additional components of the information handling system
may include one or more disk drives, one or more network ports for
communication with external devices as well as various input and
output (I/O) devices, such as a keyboard, a mouse, and a video
display. The information handling system may also include one or
more buses operable to transmit communications between the various
hardware components. It may also include one or more interface
units capable of transmitting one or more signals to a controller,
actuator, or like device.
[0015] For the purposes of this disclosure, computer-readable media
may include any instrumentality or aggregation of instrumentalities
that may retain data and/or instructions for a period of time.
Computer-readable media may include, for example, without
limitation, storage media such as a direct access storage device
(e.g., a hard disk drive or floppy disk drive), a sequential access
storage device (e.g., a tape disk drive), compact disk, CD-ROM,
DVD, RAM, ROM, electrically erasable programmable read-only memory
(EEPROM), and/or flash memory; as well as communications media such
wires, optical fibers, microwaves, radio waves, and other
electromagnetic and/or optical carriers; and/or any combination of
the foregoing.
[0016] Illustrative embodiments of the present disclosure are
described in detail herein. In the interest of clarity, not all
features of an actual implementation may be described in this
specification. It will of course be appreciated that in the
development of any such actual embodiment, numerous
implementation-specific decisions are made to achieve the specific
implementation goals, which will vary from one implementation to
another. Moreover, it will be appreciated that such a development
effort might be complex and time-consuming, but would nevertheless
be a routine undertaking for those of ordinary skill in the art
having the benefit of the present disclosure.
[0017] To facilitate a better understanding of the present
disclosure, the following examples of certain embodiments are
given. In no way should the following examples be read to limit, or
define, the scope of the disclosure. Embodiments of the present
disclosure may be applicable to horizontal, vertical, deviated, or
otherwise nonlinear wellbores in any type of subterranean
formation. Embodiments may be applicable to injection wells as well
as production wells, including hydrocarbon wells. Embodiments may
be implemented using a tool that is made suitable for testing,
retrieval and sampling along sections of the formation. Embodiments
may be implemented with tools that, for example, may be conveyed
through a flow passage in tubular string or using a wireline,
slickline, coiled tubing, downhole robot or the like.
[0018] The terms "couple" or "couples" as used herein are intended
to mean either an indirect or a direct connection. Thus, if a first
device couples to a second device, that connection may be through a
direct connection or through an indirect mechanical or electrical
connection via other devices and connections. Similarly, the term
"communicatively coupled" as used herein is intended to mean either
a direct or an indirect communication connection. Such connection
may be a wired or wireless connection such as, for example,
Ethernet or LAN. Such wired and wireless connections are well known
to those of ordinary skill in the art and will therefore not be
discussed in detail herein. Thus, if a first device communicatively
couples to a second device, that connection may be through a direct
connection, or through an indirect communication connection via
other devices and connections.
[0019] Modern petroleum drilling and production operations demand
information relating to parameters and conditions downhole. Several
methods exist for downhole information collection, including
logging-while-drilling ("LWD") and measurement-while-drilling
("MWD"). In LWD, data is typically collected during the drilling
process, thereby avoiding any need to remove the drilling assembly
to insert a wireline logging tool. LWD consequently allows the
driller to make accurate real-time modifications or corrections to
optimize performance while minimizing down time. MWD is the term
for measuring conditions downhole concerning the movement and
location of the drilling assembly while the drilling continues. LWD
concentrates more on formation parameter measurement. While
distinctions between MWD and LWD may exist, the terms MWD and LWD
often are used interchangeably. For the purposes of this
disclosure, the term LWD will be used with the understanding that
this term encompasses both the collection of formation parameters
and the collection of information relating to the movement and
position of the drilling assembly.
[0020] Hydrocarbons may be trapped in porous rock formations
thousands of feet below the surface. Recovering the hydrocarbons
typically requires drilling a borehole into the porous rock
formation so that the hydrocarbons may be pumped to the surface.
Metal pipes, referred to as casings, may be secured within the
borehole as part of the hydrocarbon recovery operation. FIG. 6 is a
diagram of an example production environment and illustrates
casings 1002, 1004, and 1006 disposed within a borehole 1008 in a
rock formation 1010. The casings 1002-1006 may be concentric or
nearly concentric and secured within the borehole 1008 and each
other through cement layers 1012, 1014, and 1016. The center casing
102 may comprise a production casing where hydrocarbon from the
formation strata 1018 is received at the surface (not shown).
[0021] The casings 1002-1006 may serve numerous purposes within a
production and drilling environment, including preventing the
borehole 1008 from collapsing after it is drilled and while it is
being drilling, protecting a water table in the formation 1010 from
contamination, and maintaining pressure within the borehole 1008.
Accordingly, damage to the integrity of the casings 1002-1006 is
problematic. Common damage to the casings includes crack and
corrosion, which can be an indication of a defective cement bond
between a casing and the borehole wall.
[0022] According to aspects of the present disclosure, a tool with
a radial array of sensors may be positioned downhole proximate to
survey, detect, and/or inspect the casings or other downhole
elements, such as a borehole. In certain embodiments, the sensors
may comprise flexible, conformable sensors. As used herein,
conformable sensors may comprise planar sensors that are printed or
disposed on a flexible material that can conform to the shape of a
surface with which it is in contact, and that provide for a high
resolution, azimuthally sensitive measurement of a target. As will
be described below, utilizing a radial array of conformable sensors
provides for high-resolution measurements corresponding to a first
casing closest to the downhole tool as well as a large depth on
investigation to generate measurements corresponding to other,
concentric casings outside of the first casing. Although the
measurements will be primarily described below with respect to
casings, similar measurements may be taken of a borehole or
formation without a casing.
[0023] FIG. 1 is a diagram that shows two example downhole tools
100 and 150 with conformable sensors, according to aspects of the
present disclosure. Both are shown disposed in concentric pipes 102
and 104, such as in a cased environment. In certain embodiments,
the downhole tools 100 and 150 may comprise wireline survey or
measurement tools that can be introduced into an open hole
(non-cased) environment, a cased environment, or within the bore of
a drill string in a conventional drilling assembly. In certain
embodiments, the downhole tools 100 and 150 may be included in a
LWD/MWD segment of a bottom hole assembly (BHA) in a conventional
drilling assembly. The tools 100 and 150 may be physically and/or
communicably coupled to a control unit (not shown) at the surface
through a wireline or slickline, or any other conveyance, or
through a downhole telemetry systems, such as a mud pulse telemetry
system. The tool 100 may also comprise a control unit that is
communicably coupled to the conformable sensors of the tools. As
used herein, a control unit may include an information handling
system or any other device that contains at least one processor
communicably coupled to a non-transitory computer readable memory
device containing a set of instructions that when executed by the
processor, cause it to perform certain actions. Example processors
include microprocessors, microcontrollers, digital signal
processors (DSP), application specific integrated circuits (ASIC),
or any other digital or analog circuitry configured to interpret
and/or execute program instructions and/or process data.
[0024] The tools 100 and 150 may comprise respective tool bodies
118 and 168, and at least one conformable sensor coupled to the
respective tool bodies. For example, conformable sensor 112 is
coupled to the tool body 118, and conformable sensor 162 is coupled
to tool body 168. The conformable sensor 112 that is one of an
azimuthal array 110 of conformable sensors disposed on a pad 106
that is coupled to and extendable from a tool body 118 of the tool
100 through spring mechanisms or motorized arms 108. When extended,
the pad 106 and the conformable sensor 112 may contact the pipe
102, but may also be used to contact a borehole wall in other
applications. The elasticity of the pad 106 and tension in the arm
108 may be designed in such a way that the pad 106 will
substantially deform to the shape of the pipe 102, increasing the
resolution of the resulting measurements. Other pads similar to pad
106 may be arranged on different sides of the tool 100 to
mechanically balance the tool 100 within the pipe 102. In other
embodiments, expandable arms may be used opposite the pad 106 to
mechanically balance the tool 100. In certain embodiments, the
array 110 of conformable sensors may be arranged on the pad 106 to
perform sensing at different azimuthal positions with respect to
the tool body 118. In embodiments where multiple pads are used,
each pad may include an array of conformable sensors to perform
sensing at different azimuthal positions, and the pads may be
arranged with respect to the tool body 118 such that there is full
360 degree coverage around the tool 100, where one pad covers one
set of angles, and other stations cover other sets, providing full
coverage.
[0025] In contrast to the downhole tool 100, the conformable sensor
162 is one of a radial array 160 of conformable sensors disposed on
an pad 156 that is coupled to and extendable from a tool body 168
of the tool 150 through spring mechanisms or motorized arms 158.
When extended, an outer edge of the pad 156 may come near to or
contact the pipe 102. Other pads similar to pad 156 may be arranged
on different sides of the tool 150. In certain embodiments, the
radial array 160 of conformable sensors may collect measurements at
different radial orientations with respect to the tool body 168. In
embodiments where multiple pads are used, the pads may be
azimuthally spaced around the tool body 168 such that measurements
at the different radial orientations are made to cover a full 360
degrees the tool body 168, where one pad covers one set of angles,
and other pads cover other sets, providing full coverage.
[0026] The conformable sensors 112 and 162 may include portions
that function as transmitters that generate electromagnetic (EM)
fields in a target, such as pipe 102, and portions that function as
receivers that receive and measure the current responses of the
target to the generated EM fields. In certain embodiments, in
addition to the conformable sensors 112 and 112, the downhole tools
100 and 150 may comprise separate transmitters 114 or receivers 116
mounted on the tool body 118. These additional transmitters 114 or
receivers 116 may be inductive-type antennas, realized with coils,
solenoids or rotating or moving magnets. In certain embodiments, EM
fields may be generated and the corresponding current responses
measured with any combination of the transmitter 114, the receiver
112, and the transmitters and receivers within the conformable
sensors 112 and 162. As will be described in detail below, the
measured current responses may be processed to identify physical
and electrical parameters of the target and the parameters may be
visualized to identify features of the target. Notably, when the
transmitter is farther away from the receiver, the depth of
investigation increases but the measurement resolution decreases.
Utilizing combinations of the transmitters and receivers in the
conformable sensors of the radial array 160, therefore, provide
flexibility to increase the depth of investigation used to measure
the pipes 102 and 104 while still maintaining an acceptable level
of resolution.
[0027] In use, the downhole tool 100 may generate high-resolution
measurements of the pipe 102 by placing the pad 106 in contact with
the pipe 102 and transmitting a time-varying EM signal from a
transmitter of the conformable sensor 112. The signal may generate
eddy currents in the pipe 102. The eddy currents may generate
secondary currents that contain information about the parameters of
the pipe 102, and the secondary currents may be measured at one or
more receivers of the conformable sensor 112. In contrast, the
downhole tool 150 may generate lower-resolution, higher depth of
investigation measurements of the pipes 102 and 104 by transmitting
a time-varying EM signal from transmitter 114 and measuring the
current response of the pipe 104 at one or more receivers of the
radial array 160.
[0028] FIG. 2 is a diagram of example antenna configuration for a
conformable sensor, according to aspects of the present disclosure.
The configuration shown may comprise a single conformable sensor
and may be formed by circuit printing or other deposition methods
on a flexible surface (not shown). As can be seen, the windings
include an outer transmitter T1 and an array of receivers R1-RN. In
certain embodiments, each of the receivers R1-RN may comprise one
or more antenna windings to measure signals in at least two
different directions. Although one example configuration for a
conformable sensor is shown in FIG. 2, other configurations are
possible. For example, the size, number, and relative orientations
of the transmitter T1 and receivers R1-RN may be altered, and the
functionality of the receivers and transmitters can be
switched.
[0029] Ports of the transmitter T1 and receivers R1-RN may be
electrically connected to transmitter and receiver boards (not
shown) that cause the transmitter T1 to generate EM signals and
cause the receivers R1-RN to measure the responses to the generated
EM signals. In certain embodiments, the transmitter T1 may generate
a signal, and each of the receivers R1-RN may separately measure a
response to the signal. Accordingly, the number and size of the
receivers may determine the granularity and resolution of an image
resulting from the receiver measurements. In certain embodiments,
the combinations of transmitters and receivers used to generate EM
signals and measure current responses may be varied dynamically by
a control unit coupled to the transmitter and receiver boards.
[0030] FIG. 3 is a diagram of an example downhole tool 300,
according to aspects of the present disclosure. The downhole tool
300 is shown positioned within casings or pipes 350 and 352 in a
downhole environment. The pipes 350 and 352 may be separated by a
cement layer 354. In certain embodiments, additional pipes (not
shown) may be located outside of pipe 352. The downhole tool 300
comprises a conformable sensor 304 that is one sensor of a radial
array of sensors 302, and a conformable sensor 308 that is one
sensor of an azimuthal array of sensors 306. The radial array 302
and azimuthal array 306 may be positioned on flexible pads 310 and
312, respectively. The pad 310 may be coupled to and extendable
from a tool body 314 of the downhole tool 300 through an extendable
arm 316. When extended, the pad 310 may form a generally planar
surface forming a tangent from a surface of the tool body 314.
[0031] In certain embodiment, the pad 312 may be coupled to the pad
310, such as through a hinge mechanism (not shown). When the pad
310 is extended by the arm 316, the pad 312 may contact the pipe
350, substantially conforming to the shape of the pipe 350.
Notably, when the pad 312 is in contact within the pipe 350, the
conformable sensor 308 may also contact the pipe 350, and may
provide a high-resolution, azimuthally sensitive measurements of
the pipe 350 using a transmitter and receiver co-located on the
conformable sensor 308.
[0032] FIG. 3 further illustrates measurement ranges accomplished
using different combinations of transmitters and receivers from
conformable sensors of the radial and azimuthal arrays. The depth
of investigation increases and the measurement resolution decreases
as the transmitter moves further away from the receiver. Within a
single conformable sensor 340, for example, the distance between
the transmitter and receiver is negligible or non-existent because
the receiver may be located within the transmitter winding, leading
to a high-resolution localized measurement of the pipe 350. In
contrast, when transmitters and receivers from different
conformable sensors are used, the depth of investigation may
increase. Circle 380 illustrates the depth of investigation when
measurements are taken using transmitter T1 from a conformable
sensor 382 located in an azimuthal array and a receiver R1 of a
conformable sensor 384 located in a radial array. Similarly circle
390 illustrates the depth of investigation when measurements are
taken using transmitter T2 from a conformable sensor 392 located in
radial array and a receiver R2 of a conformable sensor 394 located
in an azimuthal array. As can be seen, the transmitter T2 is
further from the receiver R2 than the transmitter T1 is to receiver
R1, leading to a larger range of measurement 390 for the
transmitter T2 and the receiver R2. Notably, the range 390 covers a
portion of the pipe 352, resulting in a response from the pipe 352
being measured by the receiver R2. Any combination of conformable
sensors may be used.
[0033] In certain embodiments, a downhole tool with a radial array
of conformable sensors may comprise a control system to control
when and how the EM signals are transmitted and the responses are
measured. FIG. 4 is a diagram of an example control system 400 for
a downhole tool with a conformable sensor, according to aspects of
the present disclosure. The system 400 comprises a control unit 402
that may function as the primary controller for the tool and may be
communicably coupled to transmitters 1-N through transmitter
electronics 404, to receivers 1-M through receiver electronics 406,
and to mechanical, electrical or hydraulic elements 430 coupled to
and configured to extend pads to which the transmitters 1-N and
receivers 1-M coupled. The transmitters 1-N and receivers 1-M may
comprise elements of conformable sensors located in a radial array
of a conformable sensors, or conformable sensors located in radial
and azimuthal arrays of conformable sensors. The transmitter
electronics 404 and receiver electronics 406 may comprise circuit
boards to which some or all of the transmitters 1-N and receivers
1-M are coupled.
[0034] The control unit 402 may trigger the transmitter electronics
404 to generate a time-varying EM signal through one or more of the
transmitters 1-N. The time-varying EM signal may be a sinusoidal
signal, its phase and amplitude set at a desired value. As is
described above, the EM signals generated through the transmitters
1-N may generate eddy currents in a pipe that is in immediate
contact with the conformable sensors, as well as pipes that are
located away from the conformable sensors, provided a transmitter
and receiver combination with a sufficient depth of investigation
is used. The eddy currents may generate secondary currents that
contain information about pipes. The secondary currents generated
may be measured at the receivers 1-M. In the case of a frequency
domain operation, the measurements from the receivers 1-M may be
represented as voltage or current numbers in complex domain with
real and imaginary parts, in phasor domain as amplitude and phase,
or any other domain that can be obtained by analytical mapping from
any of these domains. In the case of a time domain operation, the
measurements from the receivers 1-M may be represented as
magnitudes as a function of time which can be positive or negative.
Results from time and frequency domain can be transferred from one
to another by using Fourier transform or inverse Fourier
transform.
[0035] The control unit 402 may receive the measurements from the
receivers 1-N through the receiver electronics 406 and may transmit
the measurements to the data acquisition unit 408. For a specific
transmitter excitation, measurements from multiple receivers can be
generated and received at the same time. Similarly, multiple
transmitters 1-N can be excited at the same time and they can be
time, frequency or jointly multiplexed for latter demultiplexing
operation at the receivers. Upon reception at the data acquisition
unit 408, the measurements may be digitized, stored in a data
buffer 410, preprocessed at data processing unit 412, and sent to
the surface 414 through a communication unit 416, which may
comprise a downhole telemetry system.
[0036] In certain embodiments, the control unit 402 may select the
combinations of the transmitters and receivers to use to make
measurements based, at least in part, on the corresponding depth of
investigation for the transmitters and receivers. The control unit
402 may comprise a set of instructions and may generate control
signals to the transmitter and receiver electronics based, at least
in part, on the instructions. For example, the control center 402
may issue control signals to the transmitter and receivers to take
different types of measurements within certain time periods.
Example types of measurements include measurements with low-depth
of investigations, medium depth of investigation, and high depth of
investigation.
[0037] In certain embodiments, the resulting measurements may be
aggregated and processed to determine for one or more casings or
pipes in a downhole environment. In certain embodiments, processing
the measurements may comprise processing the measurements using a
control unit located either within the downhole tool or the surface
above the downhole tool. When processed at the surface, the
measurements may be communicated to the surface in real time, such
as through a wireline, or stored in a downhole tool and later
processed when the tool is retrieved to the surface. The
measurements may be processed with an inversion algorithm stored as
a set of instructions in a memory device of the control unit and
executable by a processor of the control unit to perform data
calculations and manipulations necessary for the inversion
algorithm. The inversion algorithm may be specific to the
environment in which the downhole tool is used and may be designed
to calculate downhole parameters unique to the environment.
[0038] FIG. 5 is a block diagram on an example inversion algorithm
for a downhole environment with one or more casings or pipes,
according to aspects of the present disclosure. Although the
inversion algorithm in FIG. 5 is directed to determining parameters
of a downhole pipe, a similar inversion algorithm may be used to
determine parameters of a borehole. An input signal 501 may
comprise measurements from the receivers of conformable sensors
arranged in a radial array on the downhole tool. In certain
embodiments, the input signals may be divided into time components
and may be identified by the receiver which made the measurement
and the transmitter that generated the eddy current/secondary
current measured by the receiver. The measurements may also be
identified by the pipe to which they correspond, when measurements
on multiple pipes in a downhole environment are taken.
[0039] The inversion algorithm may comprise a pre-processing block
502, which may receive the input signals 501. The pre-processing
block 502 may process the input signals to compensate for downhole
conditions or to convert the input signals to a form usable within
an inversion block 503. For example, the pre-processing block 502
may process the measurements to calibrate for temperature effects,
convert between frequency to time domain, convert between
complex-value to phase and amplitudes, and/or to remove noise by
filtering in azimuth or depth.
[0040] The inversion algorithm further may comprise an inversion
block 503, which may receive and process the signals from the
pre-processing block 502 to determine parameters for one or more of
the pipes or casings in the downhole environment. In certain
embodiments, the inversion block 503 may receive a model 504 of a
downhole environment with one or more pipes. The inversion block
503 may implement a cost function to determine pipe parameters that
produce the minimum mismatch between the model 504 and the input
signals 501, examples of which are described below. The cost
function may be defined, for example, by utilizing least squares
minimization through L.sub.2 norm.
[0041] In certain embodiments, a library 505 of pipe responses to
different signals can be used instead of or in addition to the
model 504. For example, the library 505 may be used if the
parameter dimensions of the pipe responses are low in number and
also small in range, so that an accurate library can be calculated.
If library 505 is used, a multi-dimensional interpolation can be
used to obtain the pipe parameters closest to the measurements
reflected in the input signal 501.
[0042] In certain embodiments, the inversion block 503 may further
account for the flex and radius of any azimuthal arrays of
conformable sensors used in the downhole tool, as well as pad flex
characteristics, tool face, and arm orientation of any radial
arrays of conformable sensors used in the downhole tool. The
inversion block 503 may use the tool information when processing
using the model 504 or library 505 to determine the exact positions
of the sensors by utilizing geometrical calculations that involve
pad flexing characteristics and also tool face angle and arm
orientation.
[0043] The inversion block 503 may output one of more pipe
parameters determined using the cost function. The parameters may
comprise physical parameters, such as the stand-off distances
between the sensors and the pipes and the thicknesses of the pipes,
as well as electrical parameters of the pipes, such as
conductivity, permeability, and permittivity. Visualizations can be
generated based, at least in part, on the determined pipe
parameters and used to identify features of the pipes, such as
cracks or corrosion. Notably, because of the resolution of the
conformable sensors, the resulting visualizations may have
high-resolution and azimuthal sensitivity, indicating very small
changes in the pipe parameters that correspond to very small
features (on the order of 0.1 inches) on the pipe in direct contact
with the conformable sensor.
[0044] In a multi-pipe environment, where measurements are made on
more than one pipe, the resulting measurements may be indexed to
identify the corresponding pipe. Notably, the resolution of the
measurements and resulting images for each pipe decreases the
further the pipe is away from the conformable sensor, due to the
increasing stand-off of between the pipe and the transmitters and
receivers of the conformable sensors. However, the use of radial
arrays of sensors may improve and increase the data points for the
outer pipes, providing better estimates for the pipe
parameters.
[0045] In certain embodiments, the downhole tool may make
measurements as it is lowered to different depths within the pipe,
collecting more data points. In certain embodiments, pipe
parameters may be determined for each of the data points and
combined to form a log of the pipe, providing an image of the
entire pipe, rather than one axial portion. Alternatively, discrete
azimuthal measurements from each depth can be combined to obtain an
image of the pipe. In addition to the pipe parameters, certain
environmental parameters, such as temperature, pipe stresses,
eccentricity of the tool in the borehole or pipe can be
obtained.
[0046] FIG. 7 is a diagram of a subterranean drilling system 80
incorporating a downhole tool 26 with conformable sensors arranged
in a radial array, according to aspects of the present disclosure.
The drilling system 80 comprises a drilling platform 2 positioned
at the surface 82. In the embodiment shown, the surface 82
comprises the top of a formation 84 containing one or more rock
strata or layers 18a-c, and the drilling platform 2 may be in
contact with the surface 82. In other embodiments, such as in an
off-shore drilling operation, the surface 82 may be separated from
the drilling platform 2 by a volume of water.
[0047] The drilling system 80 comprises a derrick 4 supported by
the drilling platform 2 and having a traveling block 6 for raising
and lowering a drill string 8. A kelly 10 may support the drill
string 8 as it is lowered through a rotary table 12. A drill bit 14
may be coupled to the drill string 8 and driven by a downhole motor
and/or rotation of the drill string 8 by the rotary table 12. As
bit 14 rotates, it creates a borehole 16 that passes through one or
more rock strata or layers 18. A pump 20 may circulate drilling
fluid through a feed pipe 22 to kelly 10, downhole through the
interior of drill string 8, through orifices in drill bit 14, back
to the surface via the annulus around drill string 8, and into a
retention pit 24. The drilling fluid transports cuttings from the
borehole 16 into the pit 24 and aids in maintaining integrity or
the borehole 16.
[0048] The drilling system 80 may comprise a bottom hole assembly
(BHA) coupled to the drill string 8 near the drill bit 14. The BHA
may comprise various downhole measurement tools and sensors and LWD
and MWD elements, including the downhole tool 26 with a radial
array of conformable sensors extending from the tool 26. As the bit
extends the borehole 16 through the formations 18, the tool 26 may
collect measurements relating to borehole 16 and formation the
resistivity of the formation 84. In certain embodiments, the
orientation and position of the tool 26 may be tracked using, for
example, an azimuthal orientation indicator, which may include
magnetometers, inclinometers, and/or accelerometers, though other
sensor types such as gyroscopes may be used in some
embodiments.
[0049] The tools and sensors of the BHA including the tool 26 may
be communicably coupled to a telemetry element 28. The telemetry
element 28 may transfer measurements from tool 26 to a surface
receiver 30 and/or to receive commands from the surface receiver
30. The telemetry element 28 may comprise a mud pulse telemetry
system, and acoustic telemetry system, a wired communications
system, a wireless communications system, or any other type of
communications system that would be appreciated by one of ordinary
skill in the art in view of this disclosure. In certain
embodiments, some or all of the measurements taken at the tool 26
may also be stored within the tool 26 or the telemetry element 28
for later retrieval at the surface 82.
[0050] In certain embodiments, the drilling system 80 may comprise
a surface control unit 32 positioned at the surface 102. The
surface control unit 32 may be communicably coupled to the surface
receiver 30 and may receive measurements from the tool 26 and/or
transmit commands to the tool 26 though the surface receiver 30.
The surface control unit 32 may also receive measurements from the
tool 26 when the tool 26 is retrieved at the surface 102. As is
described above, the surface control unit 32 may process some or
all of the measurements from the tool 26 to determine certain
parameters of downhole elements, including the borehole 16 and
formation 84, and may also generate visualizations of the borehole
16 and formation 84 based, at least in part, on the determined
parameters through which features of the downhole elements, such as
cracks and fractures, may be identified.
[0051] At various times during the drilling process, the drill
string 8 may be removed from the borehole 16 as shown in FIG. 8.
Once the drill string 8 has been removed, measurement/logging
operations can be conducted using a wireline tool 34, i.e., an
instrument that is suspended into the borehole 16 by a cable 15
having conductors for transporting power to the tool and telemetry
from the tool body to the surface 102. The wireline tool 34 may
comprise a downhole tool 36 having a radial array of conformable
sensors, similar to the tool 26 described above. The tool 36 may be
communicatively coupled to the cable 15. A logging facility 44
(shown in FIG. 8 as a truck, although it may be any other
structure) may collect measurements from the tool 36, and may
include computing facilities (including, e.g., a control
unit/information handling system) for controlling, processing,
storing, and/or visualizing the measurements gathered by the tool
36. The computing facilities may be communicatively coupled to the
tool 36 by way of the cable 15. In certain embodiments, the control
unit 32 may serve as the computing facilities of the logging
facility 44.
[0052] According to aspects of the present disclosure, an example
downhole tool may include tool body, a first pad radially
extendable from the tool body, and a radial array of conformable
sensors coupled to the first pad. At least one conformable sensor
of the radial array of conformable sensors may include a first
flexible material. A transmitter may be coupled to one of the tool
body and the first flexible material, and a receiver may be coupled
to one of the tool body and the first flexible material. At least
one of the transmitter and the receiver may be coupled to the first
flexible material. The transmitter and the receiver may be directly
or indirectly coupled to the tool body by being coupled to the
first pad or the first flexible material.
[0053] In certain embodiments, the receiver may comprise at least
two windings with different orientations. In certain embodiments,
the tool may further include a second pad extendable from the tool
body and an azimuthal array of conformable sensors coupled to the
second pad. The second pad may be coupled to the first pad. In any
of the embodiments described in this paragraph, the azimuthal array
of conformable sensors may comprise a second conformable sensor
that includes a second flexible material, a second transmitter
coupled to the second flexible material, and a second receiver
coupled to the second flexible material.
[0054] In any of the embodiments of the preceding two paragraphs,
the downhole tool further may comprise a control unit comprising a
processor and a memory device coupled to the processor, the memory
device containing a set of instructions that, when executed by the
processor, cause the processor to select a first combination of
conformable sensors to generate a current response measurement with
a first depth of investigation; and select a second combination of
conformable sensors to generate a current response measurement with
a second depth of investigation. In certain embodiments, the first
combination of sensors may comprise at least one of two conformable
sensors of the azimuthal array of sensors, two conformable sensors
of the radial array of sensors; and one conformable sensor of the
azimuthal array of conformable sensors and one conformable sensor
of the radial array of conformable sensors. In certain embodiments,
the first depth of investigation may be larger than the second
depth of investigation. In certain embodiments, the set of
instructions further may cause the processor to determine a
parameter of a downhole element remote from radial array of
conformable sensors and the azimuthal array of conformable sensors
based, at least in part, on at least one of the current response
measurement with the first depth of investigation and the current
response measurement with the second depth of investigation.
[0055] According to aspects of the present disclosure, an example
method for downhole surveying or measuring may include positioning
a downhole tool with a radial array of conformable sensors within a
borehole in a subterranean formation; generating a first
measurement with a first depth of investigation using a first
combination of conformable sensors in the radial array of
conformable sensors; and generating a second measurement with a
second depth of investigation using a second combination of sensors
in the radial array of conformable sensors. In certain embodiments,
the radial array of conformable sensors is coupled to a first pad
extendable from the downhole tool. In certain embodiments,
positioning the downhole tool with the radial array of conformable
sensors within the borehole comprises positioning the downhole tool
with the radial array of conformable sensors and an azimuthal array
of conformable sensors within the borehole. In certain embodiments,
the azimuthal array of conformable sensors is coupled to a second
pad coupled to the first pad. In certain embodiments, the method
further includes generating a third measurement with a third depth
of investigation using a third combination of conformable sensors
in the radial and azimuthal arrays of conformable sensors.
[0056] In any embodiment described in the preceding paragraph, the
first and second measurements may correspond to current responses
of at least one downhole element within the borehole to an
electromagnetic signal generated by the conformable sensors. In
certain embodiments, the method may further comprise determining a
parameter for a downhole element based, at least in part, on at
least one of the first and second measurements. In certain
embodiments, the method may further comprise generating a first
visualization of the downhole element based, at least in part, on
the determined parameter. In certain embodiments, the downhole
element may comprise one of a casing, a cement layer outside of the
casing, a wall of the borehole, and the subterranean formation. In
certain embodiments, the casing may comprise a casing remote from
the radial and azimuthal arrays of conformable sensors. In certain
embodiments, the method may further comprise determining a
parameter for another downhole element based, at least in part, on
at least one of the first and second measurements wherein the
downhole element comprises a casing and the other downhole element
comprises an other casing concentric with and outside of the
casing.
[0057] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered or modified
and all such variations are considered within the scope and spirit
of the present invention. Also, the terms in the claims have their
plain, ordinary meaning unless otherwise explicitly and clearly
defined by the patentee. The indefinite articles "a" or "an," as
used in the claims, are each defined herein to mean one or more
than one of the element that it introduces.
* * * * *