U.S. patent application number 14/211633 was filed with the patent office on 2014-09-18 for borehole instrument for borehole profiling and imaging.
This patent application is currently assigned to DGI Geoscience Inc.. The applicant listed for this patent is DGI Geoscience Inc.. Invention is credited to Vladimir Chpakovski, Sergey Gavrilov, Vincent John Gerrie, Nebojsa Jovanovic, Cameron Serles, John Stevenson, Ilya Voronov.
Application Number | 20140278111 14/211633 |
Document ID | / |
Family ID | 51531632 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140278111 |
Kind Code |
A1 |
Gerrie; Vincent John ; et
al. |
September 18, 2014 |
BOREHOLE INSTRUMENT FOR BOREHOLE PROFILING AND IMAGING
Abstract
A borehole instrument includes a housing sized and shaped to fit
inside a borehole, at least one image sensor disposed within the
housing and configured to capture images of an inside wall of the
borehole, at least one illumination light source disposed within
the housing and configured to illuminate the inside wall of the
borehole, a laser light source disposed within the housing and
configured to emit laser light towards the inside wall of the
borehole, a data processing subsystem coupled to the image sensor
and configured to receive image data from the image sensor, the
image data representative of images of the inside wall of the
borehole. The data processing subsystem is further configured to
capture borehole profile data from images containing laser light
reflected from the inside wall of the borehole.
Inventors: |
Gerrie; Vincent John;
(Toronto, CA) ; Chpakovski; Vladimir;
(Mississauga, CA) ; Gavrilov; Sergey; (Vaughan,
CA) ; Voronov; Ilya; (Mississauga, CA) ;
Stevenson; John; (Oakville, CA) ; Serles;
Cameron; (Oakville, CA) ; Jovanovic; Nebojsa;
(Burlington, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DGI Geoscience Inc. |
Toronto |
|
CA |
|
|
Assignee: |
DGI Geoscience Inc.
Toronto
CA
|
Family ID: |
51531632 |
Appl. No.: |
14/211633 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61782767 |
Mar 14, 2013 |
|
|
|
Current U.S.
Class: |
702/8 |
Current CPC
Class: |
E21B 47/002
20200501 |
Class at
Publication: |
702/8 |
International
Class: |
E21B 47/00 20060101
E21B047/00 |
Claims
1. A borehole instrument comprising: a housing sized and shaped to
fit inside a borehole; at least one image sensor disposed within
the housing and configured to capture images of an inside wall of
the borehole; at least one illumination light source disposed
within the housing and configured to illuminate the inside wall of
the borehole; a laser light source disposed within the housing and
configured to emit laser light towards the inside wall of the
borehole; and a data processing subsystem coupled to the image
sensor and configured to receive image data from the image sensor,
the image data representative of images of the inside wall of the
borehole, the data processing subsystem further configured to
capture borehole profile data from images containing laser light
reflected from the inside wall of the borehole.
2. The borehole instrument of claim 1, further comprising capturing
optics positioned to direct image light reflected from the inside
wall onto the image sensor and positioned to direct laser light
reflected from the inside wall onto the image sensor.
3. The borehole instrument of claim 2, wherein the capturing optics
comprises an aspheric imaging mirror.
4. The borehole instrument of claim 1, wherein the data processing
subsystem comprises a communications interface configured to
transmit the image data, the borehole profile data, or both the
image data and the borehole profile data to a computer.
5. The borehole instrument of claim 4, wherein the computer is an
on-board disposed inside the housing.
6. The borehole instrument of claim 5, wherein the computer is
configured to transmit data to an up-hole computer.
7. The borehole instrument of claim 1, wherein the data processing
subsystem comprises a data processor configured to perform image
processing on the image data, the borehole profile data, or both
the borehole image data and the profile data.
8. The borehole instrument of claim 7, wherein the image processing
is pre-processing and the data processing subsystem further
comprises a communications interface configured to transmit
pre-processed data to a computer.
9. The borehole instrument of claim 1, further comprising
laser-shaping optics configured to shaped emitted laser light into
a sheet.
10. The borehole instrument of claim 9, wherein the sheet is
frustoconical in shape and is at an angle of between about 10
degree and about 30 degrees with respect to a field of view of the
image sensor.
11. The borehole instrument of claim 1, wherein the data processing
subsystem is configured to modulate the laser light source and the
illumination light source to capture images containing laser light
reflected from the inside wall of the borehole more often than
capturing images of the inside wall containing laser light.
12. The borehole instrument of claim 1, further comprising a
cylindrical window positioned to allow emission of illumination
light and laser light and to allow capture of images by the image
sensor.
13. The borehole instrument of claim 1, further comprising an
inertial measurement unit connected to the data processing
subsystem.
14. A borehole instrument comprising: a housing sized and shaped to
fit inside a borehole; a window; an image sensor disposed within
the housing and configured to capture images of an inside wall of
the borehole through the window; at least one illumination light
source disposed within the housing and configured to direct
illumination light through the window to the inside wall of the
borehole; a laser light source disposed within the housing and
configured to emit laser light; laser-shaping optics configured to
shaped emitted laser light into a sheet directed through the window
to the inside wall of the borehole; capturing optics positioned to
direct image light reflected from the inside wall onto the image
sensor and positioned to direct laser light reflected from the
inside wall onto the image sensor; a data processing subsystem
coupled to the image sensor and configured to receive image data
from the image sensor, the image data representative of images of
the inside wall of the borehole, the data processing subsystem
further configured to capture borehole profile data from images
containing laser light reflected from the inside wall of the
borehole; and a computer connected to the data processing
subsystem, wherein the data processing subsystem is configured to
transmit the image data, the borehole profile data, or both the
image data and the borehole profile data to the computer.
15. The borehole instrument of claim 14, wherein the data
processing subsystem is configured to modulate the laser light
source and the illumination light source to capture images
containing laser light reflected from the inside wall of the
borehole more often than capturing images of the inside wall
containing laser light.
16. The borehole instrument of claim 14, wherein the computer is
configured to transmit data to an up-hole computer.
17. The borehole instrument of claim 14, wherein the data
processing subsystem is configured to perform pre-processing on the
image data, the borehole profile data, or both the borehole image
data and the profile data.
18. The borehole instrument of claim 14, wherein the sheet of laser
light is frustoconical in shape and is at an angle of between about
10 degree and about 30 degrees with respect to a field of view of
the image sensor.
19. A method for capturing data from a borehole, the method
comprising: illuminating an inside wall of the borehole; emitting
laser light onto the inside wall of the borehole; capturing images
of the inside wall of the borehole to obtain captured images that
are represented by image data; processing the image data to extract
borehole profile data from laser light present in the captured
images; and performing the illuminating, the emitting of laser
light, and the capturing of images during a single pass of the
borehole.
20. The method of claim 19, further comprising using the captured
images and the borehole profile data to generate a 3D
representation of the borehole.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional patent
application 61/782,767, filed Mar. 14, 2013, and to US
non-provisional patent application Ser. No. 13/826,214, filed Mar.
14, 2013, both of which are incorporated herein by reference.
FIELD
[0002] The present invention relates to borehole instruments.
BACKGROUND
[0003] Existing borehole instruments are limited in the sense that
limited amounts of data can be captured during a single pass of the
instrument within the borehole. Further, such instruments may only
be able to capture data at low rates, which constrains the speed of
travel of the instrument within the borehole and increases the time
required to capture the data.
[0004] When an instrument spends much time within the borehole, it
cannot be serving other boreholes. Thus, the efficiency of
geoscience and engineering projects, such as exploration,
geotechnical, hydrogeology, civil engineering, mining, oil and gas,
and pipe inspection projects, is reduced in waiting for instruments
to serve all boreholes. Project cost and complexity can increase
due to an increase in the amount of instruments needed. In
addition, as the time within a borehole increases, the risk of an
instrument becoming physically stuck within the borehole also
increases, and a stuck instrument may have to be abandoned.
[0005] Another problem arises in analyzing different sets of data
captured by different kinds of borehole instruments. Different sets
of data must typically be aligned with each other by highly skilled
people. For instance, visual analysis is performed to adjust
different datasets so that they coincide at all depths. The files
containing the datasets are then typically merged. This can lead to
errors and additional time before data is ready for geoscience and
engineering analysis.
[0006] Furthermore, because running different instruments in the
same borehole adds time to a project, datasets considered
nice-to-have but not essential to a project are often missing
because time saving was paramount and an optional instrument was
not run.
[0007] Thus, state-of-the-art borehole instruments may cause
geoscience and engineering projects to be carried out with poor
efficiency, and further may result in gaps in geological
knowledge.
SUMMARY
[0008] According to one aspect of the present invention, a borehole
instrument includes a housing sized and shaped to fit inside a
borehole, at least one image sensor disposed within the housing and
configured to capture images of an inside wall of the borehole, at
least one illumination light source disposed within the housing and
configured to illuminate the inside wall of the borehole, at least
one laser light source disposed within the housing and configured
to emit laser light towards the inside wall of the borehole, a data
processing subsystem coupled to the image sensor(s) and configured
to receive image data from the image sensor(s), the image data
representative of images of the inside wall of the borehole. The
data processing subsystem is further configured to capture borehole
profile data from images containing laser light reflected from the
inside wall of the borehole.
[0009] According to another aspect of the present invention, a
borehole instrument includes a housing sized and shaped to fit
inside a borehole, a window, at least one image sensor disposed
within the housing and configured to capture images of an inside
wall of the borehole through the window, at least one illumination
light source disposed within the housing and configured to direct
illumination light through the window to the inside wall of the
borehole, at least one laser light source disposed within the
housing and configured to emit laser light, laser-shaping optics
configured to shaped emitted laser light into a sheet directed
through the window to the inside wall of the borehole, capturing
optics positioned to direct image light reflected from the inside
wall onto the image sensor(s) and positioned to direct laser light
reflected from the inside wall onto the image sensor(s), a data
processing subsystem coupled to the image sensor(s) and configured
to receive image data from the image sensor(s), and a computer
connected to the data processing subsystem. The image data is
representative of images of the inside wall of the borehole. The
data processing subsystem is further configured to capture borehole
profile data from images containing laser light reflected from the
inside wall of the borehole and to transmit the image data, the
borehole profile data, or both the image data and the borehole
profile data to the computer.
[0010] According to another aspect of the present invention, a
method for capturing data from a borehole includes illuminating an
inside wall of the borehole, emitting laser light onto the inside
wall of the borehole, and capturing images of the inside wall of
the borehole. The captured images are represented by image data.
The method further includes processing the image data to extract
borehole profile data from laser light present in the captured
images, and performing the illuminating, the emitting of laser
light, and the capturing of images during a single pass of the
borehole.
BRIEF DESCRIPTION OF THE FIGURES
[0011] FIG. 1 is a schematic diagram of borehole analysis using a
borehole instrument according to an example of the present
invention.
[0012] FIG. 2 is a schematic diagram of the borehole
instrument.
[0013] FIG. 3 is a functional block diagram of the borehole
instrument.
[0014] FIG. 4 is a functional block diagram of a borehole
instrument according to another example.
[0015] FIG. 5 is a schematic diagram of example optical elements of
a borehole instrument.
[0016] FIG. 6 is a block diagram of an example of a processing
subsystem.
[0017] FIGS. 7a-d are schematic diagrams of example topologies for
power and communications with the borehole instrument.
[0018] FIG. 8 is a schematic diagram of power and communications
through a winch.
[0019] FIG. 9 is a graph illustrating a calibration table.
DETAILED DESCRIPTION
[0020] The present invention relates to an in-situ borehole
instrument configured to capture several different datasets from a
borehole in as few passes as possible and as fast as possible, and
at higher resolution. In some examples and under certain dataset
requirements and borehole conditions, only a single pass of the
borehole instrument is needed. Because different datasets can be
captured during the same pass, the need to align different datasets
at a later time is reduced or eliminated. Many of the problems
discussed above are solved or have their detrimental effects
reduced.
[0021] The present description adopts the context of geological
analysis in the field of mining and mineral exploration. However,
the borehole instruments, methods, and other techniques described
herein may find other uses and solve problems in other fields, such
as pipe inspection, hydrogeology, oil and gas exploration,
engineering, and scientific study.
[0022] FIG. 1 shows a borehole instrument 10 being used to collect
data from a borehole 12 drilled into a rock formation 14. The
instrument 10 may be known as a borehole televiewer. The borehole
12 may be open or cased. The borehole instrument 10 is connected to
the surface by a cable 16 that runs from the borehole instrument 10
to outside the borehole 12, through a rigging apparatus 18, and to
a vehicle 20.
[0023] The cable 16 physically carries the weight of borehole
instrument 10, as well as its own weight, as the borehole
instrument 10 is raised and lowered within the borehole 12. To
assist in this, the rigging apparatus 18 may include a pulley
supported by one or more support arms, which may extend from the
vehicle 20 or may be braced against the ground. At the vehicle 20,
the cable 16 can be wrapped around a drum or winch that is driven
to spool the cable 16 in and out.
[0024] The cable 16 can also connect the borehole instrument 10 to
the vehicle 20 for the purposes of signal communications. The cable
16 may therefore include one or more wire conductors, which may be
situated within a weight-carrying braided steel sheath. The vehicle
20 can include data acquisition hardware, such as a computer 22 or
other device that is connected to the wire conductors inside the
cable 16.
[0025] The vehicle 20 can be a truck, van, or similar. In other
examples, a non-vehicular winch is provided mounted to a portable
frame, which can be configured to be air-dropped to remote
regions.
[0026] A depth transducer 24, such an optically encoded wheel in
frictional contact with the cable 16, is connected to the up-hole
computer 22 to measure the depth of the borehole instrument 10 in
the borehole 12 (i.e., with respect to the surface of the ground or
some other reference datum). Depth data 30 can therefore be
collected based on the spooling and unspooling of the cable 16. The
depth data 30 can be compensated for cable stretch and other
factors so that an accurate depth of the borehole instrument 10 can
be recorded. The depth data 30 can be recorded in any increment
(e.g., 1 mm, 1 cm, 2 cm, etc.). The depth transducer may be capable
of determining depth with a higher degree of precision. For
illustrative purposes, it is assumed that N samples of depth data
30 are taken for a particular borehole, so that depths D(1), D(2) .
. . D(N) are measured and stored at the computer 22.
[0027] The borehole instrument 10 is configured to capture image
data 32 of images of the inside wall of the borehole 12. In this
example, images I(1), I(3) . . . I(N-2), I(N) are captured at
regular depths D(1), D(3) . . . D(N-2), D(N) and transmitted to
outside the borehole 12 via the cable 16 to be stored in the
computer 22. The images captured have a height (e.g., 2-4 cm), so
that images need not be captured at each depth increment and so
that sufficient overlap exists to splice images together. For
example, image I(1) is captured at depth D(1), image I(3) is
captured at depth D(3), and the height of the captured images means
that no image need be captured at depth D(2) and that images I(1)
and I(3) have sufficient overlap to provide an image at depth D(2)
and to permit splicing of images I(1) and I(3) to produce a
continuous image of a segment of the borehole 12.
[0028] The borehole instrument 10 is also configured to measure the
profile of the inside wall of the borehole 12 to capture profile
data 34. Borehole profiles define the interior dimensions of the
borehole and can include a series of radial measurements, a series
of diametrical measurements, a series of deviations (+/-) from
nominal diameter or radius, or the like. In this example, borehole
profiles P(1), P(2) . . . P(N) are measured at regular depths D(1),
D(2) . . . D(N) and transmitted to outside the borehole 12 via the
cable 16 to be stored in the computer 22.
[0029] The borehole instrument 10 is also configured to measure its
direction or orientation within the borehole 12 to capture
orientation data 36. Direction data may be measured and stored with
respect to a reference datum, such as magnetic north. In this
example, instrument orientations S(1), S(2) . . . S(N) are measured
at regular depths D(1), D(2) . . . D(N) and transmitted to outside
the borehole 12 via the cable 16 to be stored in the computer 22.
The orientation data 36 can be used to laterally shift captured
images and profile measurements to compensate for any rotation of
the borehole instrument 10 within the borehole 12.
[0030] The borehole instrument 10 performs image capture, profile
measurement, and orientation measurement during the same pass of
the borehole 12. Captured image data 32 and profile data 34 are
thus both measured directly in association with the same depth and
orientation measurements. This means that images and profile
measurements are depth-aligned and of the same orientation without
the need for post processing, which has until now included
substantial human effort.
[0031] FIG. 2 shows the borehole instrument 10 in greater detail.
The borehole instrument 10 includes a housing 42 sized and shaped
to fit inside the borehole 12 with clearance. In this example, the
housing 42 includes a hollow metal cylindrical tube having closed
ends. A transparent or semi-transparent window 44 is provided in
the housing 42 and is positioned to allow light emitted from inside
the housing 42 to illuminate the inside wall of the borehole 12. In
this example, the window 44 includes a hollow transparent cylinder
made of glass or similar material. The window 44 can be made of
abrasion-resistant material and can have an outside diameter
smaller than the outside diameter of the housing 42 to reduce wear
induced by the borehole 12.
[0032] The borehole instrument 10 may further include one or more
centralizers 45 attached to the outside of the housing 42. The
centralizers 45 serve to keep the borehole instrument 10 centered
in the borehole 12. When one centralizer 45 is used, it may be
located above or below the window 44. When two or more centralizers
45 are used, there may be centralizers 45 located above and below
the window 44.
[0033] In some examples, the housing 42 and centralizers 45 are
sized to accommodate boreholes between 75 mm and 300 mm in
diameter. For example, the housing 42 and centralizers 45 are
dimensioned to accommodate a borehole of 75 mm diameter when the
centralizers 45 are near their most-compressed state, and the same
housing 42 and centralizers 45 are further dimensioned to
accommodate a borehole of 300 mm diameter when the centralizers 45
are near their most-expanded state. The same borehole instrument 10
can thus be used in a range of different borehole sizes.
[0034] The housing 42 is sized and shaped to accommodate borehole
conditions, such as pressure of up to 200 bar (2900 PSI) and
temperatures of up to 50 degrees Celsius. In other examples, the
housing 42 can be configured to withstand other temperatures and
pressures.
[0035] The borehole instrument 10 further includes an optical
imager 52, a borehole profiler 54, an inertial measurement unit
(IMU) 58, and a data processing subsystem 56 disposed within the
interior 46 of the housing 42. The optical imager 52, borehole
profiler 54, and IMU 58 are each electrically connected to the data
processing subsystem 56, which is connected to the computer 22 via
one or more conductive transmission lines 62, which form part of
the cable 16.
[0036] The cable 16 further includes an electrically insulative
inner sheath 64 that electrically isolates the conductive
transmission lines 62 from an outer braided cable sheath 66, which
can be made of steel braid and provides tensile strength to the
cable 16.
[0037] Light and other signals emitted from and captured by one or
more of the optical imager 52 and the borehole profiler 54 pass
through the window 44. Data captured about the borehole 12 using
the optical imager 52, borehole profiler 54, and IMU 58 are
collected by the data processing subsystem 56 synchronously, so
that image data 32, profile data 34, and orientation data 36 are
inherently depth aligned at capture. Power can be provided to the
components 52-58 along one or more of the lines 62, and the outer
sheath 66 may be used to provide grounding.
[0038] The data processing subsystem 56 can be configured to
process captured image, profile, and other sensor data, pre-process
such data, communicate such data to an on-board computer (e.g.,
ref. 160 in FIGS. 7a-d) or to the up-hole computer 22, store such
data, or any combination of these tasks. Raw captured data that is
pre-processed, fully processed, or communicated to a computer can
be stored at the data processing subsystem 56 for redundancy or can
be deleted. When data is stored down-hole, such as in the data
processing subsystem 56 or an on-board computer, the data
processing subsystem 56 can be configured to send snapshots to the
up-hole computer 22 to show the operator that tool is working
properly.
[0039] FIG. 3 shows a functional block diagram of the borehole
instrument 10.
[0040] The optical imager 52 includes one or more illumination
light sources 72 positioned to illuminate an inside wall 82 of the
borehole 12 via the window 44. The optical imager 52 further
includes one or more image sensors 74 aligned with the window 44
and positioned to capture images of the inside wall 82 of the
borehole 12. The optical imager 52 may further include a processor,
memory, and other hardware to perform image capture. Imaging light
emitted and reflected by the optical imager 52 is shown as dashed
lines.
[0041] The illumination light source 72 can include one or more
light-emitting diodes (LEDs), incandescent bulbs, other kinds of
light-emitting devices, or a combination of such. When the light
source 72 includes multiple discreet elements, these can be
positioned to cast a substantially even field of light into the
borehole. The light source 72 can include optics, such as one or
more diffusers, mirrors, lenses, or a combination of such to assist
in generating the light field. In other examples, the light source
72 includes a down-hole end of an optical fiber (or bundle of such)
that runs the length of the cable 16, with the light emitting
element being located at an up-hole end of the optical fiber (or
bundle). Using an optical fiber may help reduce heat generation and
accumulation inside the borehole profiler 54 and thus may prolong
its operating life and extend its operating widow of borehole
conditions (e.g., greater borehole temperatures can be tolerated if
the profiler 54 is configured to generate less heat itself).
[0042] The borehole profiler 54 is configured to emit a signal
towards the inside wall 82 of the borehole 12 to measure the
profile of the inside of the borehole 12. In this example, the
borehole profiler 54 includes a laser light source 76 aligned with
the window 44. Laser light emitted by the laser light source 76 and
reflected from the wall 82 is shown in dotted line. The laser light
source 76 is aligned so that laser light reflected by the inside
wall 82 of the borehole 12 is incident upon the image sensor 74 of
the optical imager 52, which captures profile measurement signals
of the inside wall 82 of the borehole 12 in the form of images of
reflected laser light. One advantage of using the laser light
source 76 is that profiles can be measured in wet, dry, or
partially dry boreholes.
[0043] The laser light source 76 can include a laser-generating
device, such as an 11 mW device having a wavelength of 660 nm,
installed within the housing 42.
[0044] In other examples, the laser light source 76 includes a
down-hole end of an optical fiber (or bundle of such) that runs the
length of the cable 16, with the laser-generating device being
located at an up-hole end of the optical fiber (or bundle). This
may help reduce heat generation and accumulation inside the
borehole profiler 54.
[0045] The image sensor 74 may be a high-speed and high-resolution
charge-coupled device (CCD) or CMOS image sensor, or similar. In
this example, the illumination light source 72 and image sensor 74
are configured to capture full-color images in, for instance, the
RBG color-space. A set of optics may be provided to direct and
focus both the light of images to be captured and laser light from
the profiler 54 into the image sensor 74. The image sensor 74 may
include optical elements (e.g., a lens or the like) or may omit
such optical elements.
[0046] The illumination light source 72, image sensor 74, and laser
light source 76 are configured to capture data for the full 360
degrees of the inside of borehole 12.
[0047] In this example, the same image sensor 74 is used to capture
image data 32 and profile data 34. Using a single, shared image
sensor can advantageously reduce the weight, size, and cost of the
borehole instrument 10. Further, this may also reduce the
complexity of the data processing subsystem 56, in that the data
processing subsystem 56 may only be required to transmit one format
of data, i.e., data captured by the image sensor 74.
[0048] The IMU 58 may include a magnetometer with tilt-meters, a
gyroscope, accelerometers, or similar device configured to generate
orientation signals with reference to magnetic north or to the
high-side of the borehole in angled holes. In some examples, the
IMU 58 includes a 6-axis gyroscope/accelerometer chip from
STMicroelectronics, a tilt sensor from Murata Manufacturing Co.
Ltd., and a compass from STMicroelectronics.
[0049] As shown, the data processing subsystem 56 is electrically
coupled to the optical imager 52, the borehole profiler 54, and the
IMU 58 to receive images, profile measurement signals, and
orientation signals from the optical imager 52, which carries the
shared image sensor 74. The data processing subsystem 56 may
communicate power level settings for the illumination light source
72 and the laser light source 76, and may further communicate
capture signals indicative of when to capture images and profile
measurements. Capture signals may include depth data 30, which is
then encoded with the image data 32, profile data 34, and
orientation data 36 before such is sent up-hole along the lines 62
to the computer 22.
[0050] The data processing subsystem 56 may use any suitable
protocol for transmitting the captured data 32-36 along the lines
62, and such protocol may depend on the length of the cable 16, the
speed of the borehole instrument, and the amount of data 32-36 to
be captured, among other factors. In this example, the protocol is
configured to transmit image data for 360-degree full-color images
with 0.5 mm resolution and profile data also at 0.5 mm resolution
at speeds of 6 m/min of the instrument 10 within the borehole 12
under normal operating conditions. The protocol may employ data
compression and error correction.
[0051] FIG. 4 shows a functional block diagram of a borehole
instrument 90 according to another example, in which two image
sensors are used. The instrument 90 is similar to the instrument 10
and for clarity, and only differences will be described in detail.
For other features and aspects of the instrument 90, the
description of the instrument 10 can be referenced, with like
reference numerals identifying like elements.
[0052] The borehole instrument 90 includes a borehole profiler 94
similar to the borehole profiler 54. The borehole profiler 94
includes an image sensor 96 positioned to capture laser light
emitted by the laser light source 76 and reflected from the inside
wall 82 of the borehole 12. The image sensor 96 thus measures the
borehole profile, while the different image sensor 74 of the
optical imager 52 can be dedicated to capturing images of the
borehole wall 82.
[0053] The image sensor 96 may be a high-speed and high-resolution
CCD or CMOS image sensor, or similar. In this example, the image
sensor 96 is configured to capture light of the wavelength band of
the laser light source 76.
[0054] The image sensors 74, 96 may be of the same or different
types. The image sensors 74 and 96 may have different sets of
optics.
[0055] In further examples, additional sensors can be provided to
the borehole instrument 10, such as a temperature sensor, a water
sensor (for detecting leaks into the housing), a current/voltage
sensor (to detect electrical faults), and similar.
[0056] With reference to FIGS. 3 and 4, in other examples, the
borehole profiler 54 is an acoustic device that includes a rotating
transducer that transmits an acoustic pulse into the borehole 12
and measures the returning amplitude and travel time of the pulse
reflected from the borehole wall 82. Profile data 34 is thus
captured by the rotating transducer. This example is suitable for
use in wet boreholes and when moving parts can be tolerated.
[0057] In view of the above, it should be apparent that the present
invention allows data capture to be performed faster. For example,
up until now a 1000 meter borehole may have required as much as 800
minutes of scanning time (i.e., 400 minutes each for a profile pass
and a separate imaging pass). With the present invention, a single
pass of 400 minutes captures depth-aligned and mutually oriented
profile data and image data, resulting in substantial time saved.
Moreover, increased data capture speed allows for faster movement
in the borehole, such that total capture time may be reduced to
less than 200 minutes.
[0058] Further, there can be a reduction in the amount of manual
work and potential for error in manually aligning profile data and
image data. This may also further save time.
[0059] In addition, image and profile data can be acquired with
higher resolution than currently available. For example, existing
acoustic profile technology is limited by a 2 mm acoustic beam
diameter, which means that the typical highest resolution possible
is a 2 mm.times.2 mm pixel size or a maximum annular resolution of
288 measurements per 360 degrees. A 2 mm pixel size is usually not
adequate to measure roughness in situ. When using the laser light
source as discussed herein, pixel size can be as small as 0.5
mm.times.0.5 mm, which can result in an annular resolution of
approximately 1000 measurements per 360 degrees.
[0060] FIG. 5 shows an example of optical elements an example
borehole instrument in accordance with the techniques discussed
herein.
[0061] The borehole instrument includes the laser light source 76,
which is selected to emit laser light of about 635-680 nm. A
multimode fiber 100 connected the laser light source 76 to a laser
output head 102, which is located at a suitable location inside the
housing 42. As apparent from this example, the laser light source
76 can be located within the housing 42 or at another location,
such as up-hole with the fiber 100 extending the length of the
cable 16 (FIG. 2).
[0062] A camera board 104 having the image sensor 74 is fixed
inside the housing 42. A pinhole objective lens 106 or other
optical element can be positioned ahead of the image sensor 74. The
image sensor 74 is used to capture both borehole images and profile
measurements, as discussed above with respect to FIG. 3.
[0063] The borehole instrument further includes the illumination
light source 72, which in this example includes a plurality of
white LEDs 108 and reflectors 110 arranged to cast illumination
light out of the housing and through the window 44. In this
example, 50-100 LEDs are used and are operated in pulse mode with
3-5 times over-current (using pulse mode).
[0064] The window 44 in this example is in the shape of a hollow
cylinder and is made of fused silica. In other examples, flat panes
of material can be arranged in a polygonal shape, such as an
octagon or the like. In this example, the fused silica cylindrical
window 44 under 200 bar pressure requires a 6.5 mm thickness for
the window 44. Hence, when the outside diameter of the housing is
selected to be 45 mm to accommodate 75 mm diameter boreholes, then
the housing's inside diameter for fitting of the internal
components is 32 mm.
[0065] The borehole instrument further includes capturing optics
for directing light entering the window 44 towards the image sensor
74. In this example, the capturing optics is an imaging mirror 112.
The imaging mirror 112 is aspheric in shape and is positioned to
face the pinhole objective lens 106 so as to concentrate light
incoming through the window 44 onto the pinhole objective lens 106
for capture by the image sensor 74. In other examples, a lens, such
as a wide-angle or fisheye lens is used as the capturing optics
instead of the imaging mirror. In still other examples, multiple
mirrors, multiple lenses, or combinations of one or more mirrors
and one or more lenses can be used as the capturing optics.
[0066] In other examples, multiple image sensors 74 are positioned
to directly face the window 44 and arranged in a circular pattern
to capture 360 degrees of the borehole wall 82 with overlap for
image combining. In such examples, capturing optics may not be
required.
[0067] The borehole instrument further includes laser-shaping
optics 114 positioned in the path of the laser and configured to
shape the laser for projection onto the borehole wall 82. The
laser-shaping optics 114 can include reflectors, lenses, beam
expanders, and the like. In this example, the laser-shaping optics
114 are configured to shape the laser into a frustoconical sheet
116 of laser light (dashed line) that projects onto the borehole
wall 82 as a ring, which is captured by the image sensor 73 for the
borehole profile measurement.
[0068] The laser-shaping optics 114 can be configured to direct the
laser light towards the 82 at an angle A with respect to the
general or average direction 118 of incoming light from the field
of view (dotted lines) for capture by the image sensor 74. The
angle A affects the sensitivity of the borehole profile
measurement, and can be selected to provide a desired sensitively
without being overly sensitive so as to cause the laser ring to
leave the field of view of the image sensor 74. Examples of
suitable angles and ranges of angles for angle A include 10-30
degrees, 10-20 degrees, and about 15 degrees.
[0069] In other examples, The laser-shaping optics 114 can be
configured to cast patterns different from a single ring, such as
two or more rings at different positions and/or different angles A
or a grid or mesh pattern.
[0070] The image sensor 74 can be a CMOSIS CMV2000 image sensor
having a 1088.times.2048 pixel resolution with a color Bayer
pattern, and operable at 340 full frames/sec. The resolution at a
working distance of 90 mm is about 56 um/pixel and the resolution
at a working distance of 250 mm is about 158 um/pixel. The
resolution at a working distance of 250 mm with angle A of 15
degrees is about 500 um/pixel. When the borehole instrument is
moved at a rate of about 6 m/min, the image sensor capture rate
allows for a 28.5 mm high image of a wall of a 75 mm borehole with
about 50% overlap between images and at least 40 profile
measurement captures per borehole image captured. The resolution
allows for at least a 0.5 mm horizontal (circumferential)
resolution for a 300 mm borehole. The exposure time can be set to
about 2.86 msec for a vertical resolution better than about 0.5 mm
at 6 m/min instrument speed.
[0071] FIG. 6 shows a block diagram of an example of the processing
subsystem 56.
[0072] The processing subsystem 56 is connected to the image sensor
74, the IMU 58, and a computer, such as the up-hole computer 22 or
a computer onboard the borehole instrument.
[0073] The processing subsystem 56 includes a laser controller 130
coupled to or forming part of the laser light source 76 and an
illumination controller 132 coupled to or forming part of the
illumination light source 72. The processing subsystem 56 further
includes a microcontroller 134, a data acquisition controller 136,
a data processor 138, a communications interface 140, and two
buffers 142, 144.
[0074] The laser controller 130 is connected to the data
acquisition controller 136 and is configured to drive and modulate
the laser light source 76 according to commands from the data
acquisition controller 136. That is, when the data acquisition
controller 136 is to capture a profile measurement, the data
acquisition controller 136 can control the laser controller 130 to
turn on the laser light source 76. Conversely, when the data
acquisition controller 136 is to capture an image of the borehole
without the laser ring, then the data acquisition controller 136
can control the laser controller 130 to turn off the laser light
source 76.
[0075] The illumination controller 130 is connected to the data
acquisition controller 136 and is configured to drive and modulate
the illumination light source 72 according to commands from the
data acquisition controller 136. When the data acquisition
controller 136 is to capture an image of the borehole wall, the
data acquisition controller 136 can control the illumination
controller 130 to turn on the illumination light source 72.
Conversely, when the data acquisition controller 136 is to capture
a laser profile measurement, then the data acquisition controller
136 can control the illumination controller 130 to turn off the
illumination light source 72.
[0076] The microcontroller 134 communicates with the computer via
the communications interface 140. Such communications may be routed
through an intermediate interface 146 that is coupled between the
data processor 138 and the communications interface 140. The
microcontroller 134 is connected to data acquisition controller 136
and data processor 138 and controls such based on commands received
via the communications interface 140. The microcontroller 134 is
also connected to the IMU 58 and receives data from the IMU 58 and
forwards such to the data acquisition controller 136. The
microcontroller 134 can be programmed to control the overall
operations of the processing subsystem 56, such as changing the
amounts/ratios of images and profile measurements captured, the
intensity and timing of illumination and laser light, and image
sensor 74 operating parameters such as gain. In this example, the
microcontroller 134 is an ARM Cortex M4 microcontroller or similar
device.
[0077] The data acquisition controller 136 controls image capture
from the image sensor 74 and receives borehole wall images and
laser profile images. The data acquisition controller 136 can be
configured with capture rates and other capture parameters. The
data acquisition controller 136 can provide clock signal for the
image sensor 74 and read in real-time pixel values (e.g., 16 pixels
in parallel). The data acquisition controller 136 is selectably
connected to the buffers 142, 144 and sends read pixel data to the
selected buffer 142, 144. The data acquisition controller 136 can
also provide control signals to the illumination controller 132 and
the laser controller 130.
[0078] The data processor 138 is selectably connected to the
buffers 142, 144 and receives pixel data from the selected buffer
142, 144.
[0079] The data processor 138 can be configured to perform various
amounts of processing. In one example, the data processor 138
performs all borehole image processing and borehole profile
measurement, as well as directional data processing, and sends
resulting data to the communications interface 140, via the
intermediate interface 146, for storage in the borehole instrument
and/or communication to the up-hole computer 22.
[0080] In another example, the data processor 138 performs
pre-processing on some or all of the captured borehole image data,
borehole profile measurements, and captured directional data. The
data processor 138 then sends pre-processed data to the
communications interface 140, via the intermediate interface 146,
for storage in the borehole instrument, further processing by an
onboard computer, and/or communication to the up-hole computer
22.
[0081] If data is stored in memory in the borehole instrument, it
can be retrieved when the borehole instrument is removed from the
borehole.
[0082] In the current example, the data processor 138 performs
pre-processing by finding laser pixels in images that contain the
laser ring and determining a center-of-gravity of the laser ring.
This compensates for any lateral movement of instrument in the
borehole and any changes in profile of the borehole, which is
useful when processing the borehole wall images. In another
example, the pre-processing by data processor 138 is limited to
finding and isolating laser pixels in images that contain the laser
ring for later center-of-gravity determination by a computer.
[0083] The data processor 138 can further be configured to compress
borehole images, including those with or without laser rings,
before sending such to the communications interface 140. Such
compression can be lossless (e.g., PNG) or lossy (e.g., JPEG,
MPEG).
[0084] The data processor 138 can further be configured to align
captured borehole images with the relevant profile measurements and
with position/yaw/pitch/tilt/direction data from the IMU 58, as
well as data from any additional sensors. The data processor 138
can further timestamp captured data before sending such to
communications interface 140.
[0085] The buffers 142, 144 are switched so as to allow the data
acquisition controller 136 to fill one buffer while the data
processor reads the other. In this example, the buffers 142, 144
include dual-port SRAM configured in dual-buffer fashion.
[0086] The communications interface 140 is configured to provide
two-way communications between the processing subsystem 56 and a
computer, such as the up-hole computer 22 or a computer on board
the instrument. The communications interface 140 can include a
high-speed USB interface, an Ethernet interface, or the like.
[0087] In this example, the data acquisition controller 136, data
processor 138, and intermediate interface 146 are provided on a
field-programmable gate array (FPGA) 150, such as the Spartan-6
FPGA from Xilinx, Inc. A co-processor, such as the STM32F407 MCU
from STMicroelectronics, may also be provided to support the FPGA
and increase efficiency.
[0088] FIGS. 7a-d show example topologies for power and
communications with the borehole instrument.
[0089] In FIG. 7a, the up-hole computer 22 communicates with a
computer 160 on board the borehole instrument. The on-board
computer 160 is connected to the processing subsystem 56, which
directly controls data acquisition. The on-board computer 160
receives raw or pre-processed data from the processing subsystem 56
and further processes it for communication to the up-hole computer
22, which can be supplied with memory sufficient for long-term
storage or captured and processed data. The communications link 162
between the computers 22, 160 is selected for suitable performance
over expected operational depths of the borehole instrument, such
as hundreds of meters. In one example, the communications link 162
is an Ethernet link. Power-over-Ethernet (PoE) may also be used to
supply power to the on-board computer, the processing subsystem 56,
and other components of the borehole instrument. The shorter
communications link 164 between the on-board computer 160 and the
processing subsystem 56 can be selected to be a USB link or
similar.
[0090] In FIG. 7b, the up-hole computer 22 communicates directly
with the processing subsystem 56. The up-hole computer 22 receives
raw or pre-processed data from the processing subsystem 56 and
further processes it for long-term storage in suitable memory, or
simply stores raw or pre-processed data for off-site processing.
The communications link 162 between the computer 22 and the
processing subsystem 56 can be an Ethernet link or similar, and
accordingly the processing subsystem 56 can be provided with an
Ethernet interface. Power-over-Ethernet may also be used to supply
power to the processing subsystem 56 and other components of the
borehole instrument.
[0091] In FIG. 7c, the up-hole computer 22 is omitted and only a
power source 166 is provided at the up-hole end. The on-board
computer 160 receives raw or pre-processed data from the processing
subsystem 56 and further processes it for long-term storage in
suitable memory, or simply stores raw or pre-processed data for
off-site processing. Power lines 168 are provided between the power
source 166 and the on-board computer 160, the processing subsystem
56, and other components of the borehole instrument. The
communications link 164 between the on-board computer 160 and the
processing subsystem 56 can be selected to be a USB link or
similar.
[0092] In FIG. 7d, the computers 22, 160 are omitted and only a
power source 166 is provided at the up-hole end. The processing
subsystem 56 has sufficient memory for long-term storage of raw or
pre-processed data. Power lines 168 are provided between the power
source 166 and the processing subsystem 56 and other components of
the borehole instrument.
[0093] Computers suitable for use as the computers 22, 160 include
computers having an ARM Cortex A8 AM335x processor from Texas
Instruments running Linux, high speed USB2 ports, DDR3 memory
interface for 16-bit 256 MB memory, Ethernet 1000-baseT ports, and
a Micro-SD card interface. Each computer 22, 160 may further
include a VDSL-2 modem, such as the MT2301 chipset available from
Metanoia Communications Inc. of Taiwan that allows compact
Ethernet-to-Ethernet connection over twisted pair.
[0094] With reference to FIG. 7a, in one example, the on-board
computer 160 is configured to obtain image and profile data from
the data processor 138 (FIG. 6) via the communications interface
140, store such data in DDR memory, compress borehole wall images
(to lossless PNG, lossless/lossy JPEG, etc.), run a client side of
a network, send frames upstream to the up-hole computer 22 (which
operates as a server) through the Ethernet link 162 using the
VDSL-2 modem, and receive and decode commands from the up-hole
computer 22 and send such to the microcontroller 134 of the
processing subsystem 56.
[0095] The up-hole computer 22 is configured to receive data
through the Ethernet link 162 using the VDSL-2 modem, decompress
received images, unwrap borehole wall images into the cylindrical
shape of the borehole, build the 3D representation of the borehole
surface using 3D triangulation data and OpenGL, stitch borehole
images together using data from the IMU 58 and/or data from the
depth transducer 24 and/or graphical image stitching techniques,
and display and store the assembled 3D representation of the
borehole.
[0096] FIG. 8 shows an example of how power and communications can
be transmitted across a winch 180 between the up-hole computer 22
and the borehole instrument, with reference to the example topology
of FIG. 7a.
[0097] One or more power lines 182 from the up-hole computer 22 (or
a separate power source) are routed through the slip rings 184 of
the winch 180. A wireless link 186, such as a WIFI link, is
provided between the up-hole computer 22 and a wireless device 188,
such as a modem or router, that is wire-connected to the top of the
cable and mounted to the rotating part of the winch 180. This can
avoid electrical noise from the slip rings 184 from entering the
communications link.
[0098] With reference to FIG. 9, borehole wall images can be
processed by triangulation using pre-calculated 3D conversion
tables. A calibration process can be performed to construct these
tables before the instrument is deployed. Conversion tables can be
stored and applied in any of the processing subsystem 56 and the
computers 22, 160.
[0099] Round-shaped borehole images result from the optical
arrangement shown in FIG. 5. In other optical arrangements,
different shaped images may result and these may also require
calibration tables. Conversion tables allow such images to be
unwrapped and represented as rectangular (unrolled cylindrical)
images or cylindrical 3D images. FIG. 9 shows the logic behind
example conversion tables for round-shaped images. The R-axis
represents the radius of the round-shaped image in pixels, the
.PHI.-axis represents the angle in increments. Output for
triangulation (D) shows a distance coordinate, i.e., a radius
distance to the surface of the wall. The output for unwrapping (H)
shows a vertical coordinate of the pixel in the unwrapped
image.
[0100] While the foregoing provides certain non-limiting example
embodiments, it should be understood that combinations, subsets,
and variations of the foregoing are contemplated. The monopoly
sought is defined by the claims.
* * * * *