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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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

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 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.

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.

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 geoscience and engineering 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, 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.

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.

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

FIG. 1 is a schematic diagram of borehole analysis using a borehole instrument according to an example 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 example.

FIG. 5 is a schematic diagram of example optical elements of a borehole instrument.

FIG. 6 is a block diagram of an example of a processing subsystem.

FIGS. 7a-d are schematic diagrams of example topologies for power and communications with the borehole instrument.

FIG. 8 is a schematic diagram of power and communications through a winch.

FIG. 9 is a graph illustrating a calibration table.

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 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.

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.

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 examples, 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 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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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 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.

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.

FIG. 3 shows a functional block diagram of the borehole instrument 10.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 light source 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.

FIG. 5 shows an example of optical elements an example borehole instrument in accordance with the techniques discussed herein.

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).

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.

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).

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.

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.

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.

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.

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.

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.

The image sensor 74 can be a CMOSIS CMV2000 image sensor having a 1088×2048 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.

FIG. 6 shows a block diagram of an example of the processing subsystem 56.

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.

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.

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.

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.

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.

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.

The data processor 138 is selectably connected to the buffers 142, 144 and receives pixel data from the selected buffer 142, 144.

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.

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.

If data is stored in memory in the borehole instrument, it can be retrieved when the borehole instrument is removed from the borehole.

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.

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).

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.

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.

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.

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.

FIGS. 7a-d show example topologies for power and communications with the borehole instrument.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 Φ-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.

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

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.