US20140260590A1

US20140260590A1 - Borehole profiling and imaging

Info

Publication number: US20140260590A1
Application number: US13/826,214
Authority: US
Inventors: Vincent John Gerrie
Original assignee: DGI Geoscience Inc
Current assignee: DGI Geoscience Inc
Priority date: 2013-03-14
Filing date: 2013-03-14
Publication date: 2014-09-18
Also published as: CA2845910A1

Abstract

A borehole instrument includes an image sensor for capturing images of an inside wall of a borehole. A borehole profile may also be measured by, for example, a laser. The same image sensor may be used for image capture and profile measurement. Different image sensors may be used for image capture and profile measurement. Image capture and profile measurement may be performed with reference to the same depth measurement, so that images and profiles are depth-aligned at capture. Orientation of the instrument within the borehole may also be measured to compensate for rotation of the instrument. A communications subsystem can transmit image data, profile data, and orientation data to a computer located outside the borehole for storage and analysis.

Description

FIELD

The present invention relates to borehole instruments.

BACKGROUND

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.
When an instrument spends much time within the borehole, it cannot be serving other boreholes. Thus, the efficiency of an exploration project 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.
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 geological analysis.
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.
Thus, state-of-the-art borehole instruments may cause exploration projects to be carried out with poor efficiency, and further may result in gaps in geological knowledge.

SUMMARY

According to one aspect of the present invention, a borehole instrument includes a housing sized and shaped to fit inside a borehole and an optical imager disposed within the housing. The optical imager has an image sensor configured to capture images of an inside wall of the borehole. The borehole instrument further includes a borehole profiler disposed within the housing and configured to emit a signal towards the inside wall of the borehole to measure a profile of the inside of the borehole. The borehole instrument further includes a communications subsystem coupled to the optical imager and to the borehole profiler. The communications subsystem is configured to receive image data from the optical imager and to receive profile data from one of the optical imager and the borehole profiler. The communications subsystem is further configured to transmit the image data and the profile data along at least one transmission line to outside of the borehole.
The borehole profiler can include a laser.
The image sensor can be further configured to capture profile measurements as laser light reflected by the inside wall of the borehole. The communications subsystem can be further configured to receive profile data from the optical imager.
The optical imager can include a light source positioned to illuminate the inside wall of the borehole.
The housing can include a window aligned with the image sensor, the light source, and the laser.
The borehole profiler can further include another image sensor configured to capture profile measurements as laser light reflected by the inside wall of the borehole. The communications subsystem can be further configured to receive profile data from the borehole profiler.
The instrument can further include a direction sensor configured to determine an orientation of the borehole instrument within the borehole. The direction sensor can be coupled to the communications subsystem. The communications subsystem can further be configured to receive orientation data from the direction sensor and transmit the orientation data along the transmission line to the outside of the borehole.
According to another aspect of the present invention, a method of capturing data from a borehole includes capturing images of an inside wall of the borehole, measuring profiles of the inside of the borehole, transmitting captured image data and captured profile data to a computer outside the borehole, and performing the capturing, measuring, and transmitting during a same pass through the borehole.
The capturing and measuring can be performed based on a same depth measurement of the same pass within the borehole to generate depth-aligned datasets of image data and profile data.
The method can further include capturing orientations of a sensor within the borehole during the same pass.
The method can further include measuring the profiles using a laser.
The capturing and measuring can be performed using a same image sensor.
The capturing and measuring can be performed using different image sensors.
According to another aspect of the present invention, a borehole instrument includes a housing sized and shaped to fit inside a borehole. The housing has a window. The instrument further includes a light source disposed within the housing and aligned with the window. The light source is configured to illuminate an inside wall of the borehole. The instrument further includes a laser disposed within the housing and aligned with the window. The laser is configured to emit laser light towards the inside wall of the borehole. The instrument further includes an image sensor disposed within the housing and aligned with the window. The image sensor is configured to capture light of the light source reflected by the inside wall of the borehole to capture images of the inside wall of the borehole. The image sensor is further configured to capture laser light reflected by the inside wall of the borehole to measure the profile of the borehole. The instrument further includes a communications subsystem coupled to the image sensor. The communications subsystem is configured to receive image data and profile data from the image sensor. The communications subsystem is further configured to transmit the image data and the profile data along at least one transmission line to a computer outside the borehole.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of borehole analysis using a borehole instrument according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of the borehole instrument.

FIG. 3 is a functional block diagram of the borehole instrument.

FIG. 4 is a functional block diagram of a borehole instrument according to another embodiment.

DETAILED DESCRIPTION

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 embodiments 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.
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, oil and gas exploration and scientific study.
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.
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.
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.
The vehicle 20 can be a truck, van, or similar. In other embodiments, a non-vehicular winch is provided mounted to a portable frame, which can be configured to be air-dropped to remote regions.
A depth transducer 24, such an optically encoded wheel in frictional contact with the cable 16, is connected to the 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.
The borehole instrument 10 is configured to capture image data 32 of images of the inside wall of the borehole 12. In this embodiment, 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.
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 embodiment, 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.
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 embodiment, 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.
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.
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 embodiment, 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 embodiment, 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.
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.
The borehole instrument 10 further includes an optical imager 52, a borehole profiler 54, a direction sensor 58, and a communications subsystem 56 disposed within the interior 46 of the housing 42. The optical imager 52, borehole profiler 54, and direction sensor 58 are each electrically connected to the communications subsystem 56, which is connected to the computer 22 via one or more conductive transmission lines 62, which form part of the cable 16.
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.
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 direction sensor 58 are collected by the communications 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.
FIG. 3 shows a functional block diagram of the borehole instrument 10.
The optical imager 52 includes a light source 72 positioned to illuminate an inside wall 82 of the borehole 12 via the window 44. The optical imager 52 further includes an image sensor 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.
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 embodiment, the borehole profiler 54 includes a laser 76 aligned with the window 44. Laser light emitted by the laser 76 and reflected from the wall 82 is shown in dotted line. The laser 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 76 is that profiles can be measured in wet, dry, or partially dry boreholes.
The image sensor 74 may be a high-speed and high-resolution charge-coupled device (CCD) or CMOS image sensor, or similar. In this embodiment, the 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 light source 72, image sensor 74, and laser 76 are configured to capture data for the full 360 degrees of the inside of borehole 12.
In this embodiment, the same image sensor 74 is used to capture image data 32 and profile data 34. Using a single image sensor can advantageously reduce the weight, size, and cost of the borehole instrument 10. Further, this may also reduce the complexity of the communications subsystem 56, in that the communications subsystem 56 may only be required to transmit one format of data, i.e., data captured by the image sensor 74.
The direction sensor 58 may be a magnetometer with tilt-meters, a gyroscope, an inertial sensor, or similar device configured to generate orientation signals with reference to magnetic north or to the high side of the borehole in angled holes.
As shown, the communications subsystem 56 is electrically coupled to the optical imager 52, the borehole profiler 54, and the direction sensor 58 to receive images, profile measurement signals, and orientation signals from the optical imager 54, which carries the shared image sensor 74. The communications subsystem 56 may communicate power level settings for the light source 72 and the laser 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.
The communications 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 embodiment, 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.
FIG. 4 shows a functional block diagram of a borehole instrument 90 according to another embodiment, 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.
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 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 82 can be dedicated to capturing images of the borehole wall 82.
The image sensor 96 may be a high-speed and high-resolution CCD or CMOS image sensor, or similar. In this embodiment, the image sensor 96 is configured to capture light of the wavelength band of the laser 76.
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.
With reference to FIGS. 3 and 4, in other embodiments, 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 embodiment is suitable for use in wet boreholes and when moving parts can be tolerated.
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.
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.
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×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 as discussed herein, pixel size can be as small as 0.5 mm×0.5 mm, which can result in an annular resolution of approximately 1000 measurements per 360 degrees.
In addition, it is advantageous that use of the laser for profile measurements allows such measurements to be taken in wet, dry, and partially dry boreholes.
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.

Claims

What is claimed is:

1. A borehole instrument comprising:

a housing sized and shaped to fit inside a borehole;

an optical imager disposed within the housing, the optical imager having an image sensor configured to capture images of an inside wall of the borehole;

a borehole profiler disposed within the housing and configured to emit a signal towards the inside wall of the borehole to measure a profile of the inside of the borehole; and

a communications subsystem coupled to the optical imager and to the borehole profiler, the communications subsystem configured to receive image data from the optical imager and to receive profile data from one of the optical imager and the borehole profiler, the communications subsystem further configured to transmit the image data and the profile data along at least one transmission line to outside of the borehole.

2. The instrument of claim 1, wherein the borehole profiler comprises a laser.

3. The instrument of claim 2, wherein the image sensor is further configured to capture profile measurements as laser light reflected by the inside wall of the borehole, and the communications subsystem is configured to receive profile data from the optical imager.

4. The instrument of claim 2, wherein the optical imager comprises a light source positioned to illuminate the inside wall of the borehole.

5. The instrument of claim 4, wherein the housing comprises a window aligned with the image sensor, the light source, and the laser.

6. The instrument of claim 1, wherein the borehole profiler further comprises another image sensor configured to capture profile measurements as laser light reflected by the inside wall of the borehole, and the communications subsystem is configured to receive profile data from the borehole profiler.

7. The instrument of claim 1, further comprising a direction sensor configured to determine an orientation of the borehole instrument within the borehole, the direction sensor coupled to the communications subsystem, and the communications subsystem further configured to receive orientation data from the direction sensor and transmit the orientation data along the transmission line to the outside of the borehole.

8. A method of capturing data from a borehole, the method comprising:

capturing images of an inside wall of the borehole;

measuring profiles of the inside of the borehole;

transmitting captured image data and captured profile data to a computer outside the borehole; and

performing the capturing, measuring, and transmitting during a same pass through the borehole.

9. The method of claim 8, wherein the capturing and measuring are performed based on a same depth measurement of the same pass within the borehole to generate depth-aligned datasets of image data and profile data.

10. The method of claim 8, further comprising capturing orientations of a sensor within the borehole during the same pass.

11. The method of claim 8, further comprising measuring the profiles using a laser.

12. The method of claim 11, wherein the capturing and measuring are performed using a same image sensor.

13. The method of claim 11, wherein the capturing and measuring are performed using different image sensors.

14. A borehole instrument comprising:

a housing sized and shaped to fit inside a borehole, the housing having a window;

a light source disposed within the housing and aligned with the window, the light source configured to illuminate an inside wall of the borehole;

a laser disposed within the housing and aligned with the window, the laser configured to emit laser light towards the inside wall of the borehole;

an image sensor disposed within the housing and aligned with the window, the image sensor configured to capture light of the light source reflected by the inside wall of the borehole to capture images of the inside wall of the borehole, the image sensor further configured to capture laser light reflected by the inside wall of the borehole to measure the profile of the borehole; and

a communications subsystem coupled to the image sensor, the communications subsystem configured to receive image data and profile data from the image sensor, the communications subsystem further configured to transmit the image data and the profile data along at least one transmission line to a computer outside the borehole.

15. The instrument of claim 14, further comprising a direction sensor configured to determine an orientation of the borehole instrument within the borehole, the direction sensor coupled to the communications subsystem, and the communications subsystem further configured to receive orientation data from the direction sensor and transmit the orientation data along the transmission line to the computer outside of the borehole.