Patent Publication Number: US-2023135710-A1

Title: System and method for orienting geological core samples

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to geological core samples, and, more particularly, to a system and method for automatically orienting geological core samples. 
     BACKGROUND OF THE DISCLOSURE 
     During geologic exploration such as in the oil and gas industry, core samples are obtained from wells. Such core samples can be indexed, examined, and divided into separate core samples. During such examination and division, the orientation of adjacent core samples can be lost. Absolute core orientation is the process of determining the original orientation angle of a rock core in reference to a reference core or to a standard orientation, such as geographic north. The orientation process can be done during coring using mechanical techniques, or by examining the core using core-based techniques. Such orientation processes can be subjective in matching features of core cross-sections, and can be prone to error. 
     SUMMARY OF THE DISCLOSURE 
     According to an embodiment consistent with the present disclosure, a system and method automatically orient geological core samples. 
     In an embodiment, the system for orienting a core sample comprises a camera, a core analyzer module, and a core sample rotation apparatus. The camera is configured to capture a reference image of a cross-section of a reference core sample from a well, and to capture a sample image of a cross-section of the to-be-oriented core sample from the well. The core analyzer module comprises code executable in a hardware processor to process the sample image to substantially match the reference image, and to determine an orientation angle of the match. The core sample rotation apparatus is configured to orient the to-be-oriented core sample by the orientation angle. 
     The system further comprises a memory, and the core analyzer module processes the sample image by flipping the sample image within the memory about a diametric axis to obtain a flipped sample image. The core analyzer module processes the sample image by incrementally rotating the flipped sample image within the memory until the code executing in the hardware processor identifies the flipped sample image as substantially matching the reference image. The core analyzer module is configured by code to measure a mis-fit metric of the rotated flipped sample image relative to the reference image. The sample image substantially matches the reference image when the mis-fit metric is less than a predetermined threshold. Alternatively, the sample image substantially matches the reference image when the mis-fit metric is minimized. The orientation angle corresponds to the minimized mis-fit metric. 
     In another embodiment, a core analyzer comprises an input device and a hardware processor. The input device is configured to receive a reference image of a cross-section of a reference core sample from a well and a sample image of a cross-section of a to-be-oriented core sample from the well. The hardware processor has code therein which configures the hardware processor to process the sample image to substantially match the reference image, to determine an orientation angle of the match, and to control rotation of the to-be-oriented core sample in a core sample rotation apparatus by the orientation angle. 
     The core analyzer further comprises a memory, and the hardware processor flips the sample image within the memory about a diametric axis to obtain a flipped sample image. The hardware processor is further configured by the code therein to incrementally rotate the flipped sample image within the memory until the flipped sample image substantially matches the reference image. The hardware processor is further configured by the code therein to measure a mis-fit metric of the rotated flipped sample image relative to the reference image. The sample image substantially matches the reference image when the mis-fit metric is less than a predetermined threshold. Alternatively, the sample image substantially matches the reference image when the mis-fit metric is minimized. The orientation angle corresponds to the minimized mis-fit metric. 
     In a further embodiment, a method for orienting a core sample from a well comprises receiving, from a camera, a reference image of a cross-section of a reference core sample from the well, and then receiving, from the camera, a sample image of a cross-section of a to-be-oriented core sample from the well. The method then processes the sample image using a hardware processor with code executing therein to substantially match the reference image, and the method determines an orientation angle of the match, and controls rotation of the to-be-oriented core sample in a core sample rotation apparatus by the orientation angle. The processing includes flipping the sample image about a diametric axis within a memory which is in communication with the hardware processor to obtain a flipped sample image. The processing includes incrementally rotating the flipped sample image within the memory until the flipped sample image substantially matches the reference image. The processing includes measuring a mis-fit metric of the rotated flipped sample image relative to the reference image. The sample image substantially matches the reference image when the mis-fit metric is minimized. The orientation angle corresponds to the minimized mis-fit metric. 
     Any combinations of the various embodiments and implementations disclosed herein can be used in a further embodiment, consistent with the disclosure. These and other aspects and features can be appreciated from the following description of certain embodiments presented herein in accordance with the disclosure and the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic of a system, according to an embodiment. 
         FIG.  2    illustrates two core samples. 
         FIG.  3    illustrates a camera image of a core sample. 
         FIG.  4    illustrates an image of the core sample of  FIG.  3   . 
         FIG.  5    illustrates a flipped image of the core sample of  FIG.  3   . 
         FIG.  6    illustrates an oriented flipped image of the core sample of  FIG.  3   . 
         FIG.  6 A  illustrates a selection of pixels from a processed image of a core sample. 
         FIG.  7    illustrates a graph of a mis-fit metric plotted with reference to an orientation angle. 
         FIG.  8    is a flowchart of a method of operation of the system. 
     
    
    
     It is noted that the drawings are illustrative and are not necessarily to scale. 
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE DISCLOSURE 
     Example embodiments consistent with the teachings included in the present disclosure are directed to a system  10  and method  100  for automatically orienting geological core samples. 
     As shown in  FIG.  1   , the system  10  includes a core analyzer module  12 , a camera  14  with a field of view (FoV)  16  directed to a cross-section  18  of a core sample  20 , and a core sample rotation apparatus  22 . The camera  14  captures any features of the exposed two-dimensional core surface at the cross-section  18 . The core analyzer module  12  includes a hardware processor  24 , a memory  26 , an input device  28 , and an output device  30 . The hardware processor  24  can be a microprocessor. The input device  28  can be a communication interface configured to receive images from the camera  14 . Alternatively, the input device  28  can be a keyboard, mouse, or other known input devices accessible by a user. The output device  30  can be a display configured to display an image, such as the images provided by the camera  14 , as well as images modified by the processor  24 , as described below. The core sample rotation apparatus  22  can receive a to-be-oriented core sample  20 . The core sample rotation apparatus  22  can then rotate the core sample  20  by any angle, such as an orientation angle as described below. The core sample rotation apparatus  22  can be the apparatus described in U.S. Patent Publication No. US 2021/0063325 A1, which is incorporated herein by reference. 
     Referring to  FIG.  2   , the input device  28  is configured to receive a reference image of a cross-section  42  of a reference core sample  40  from a well and a sample image of the cross-section  18  of the to-be-oriented core sample  20  from the well. The images or live-feed of the cross-sections  18 ,  42  are the axial top or bottom of the respective core samples  20 ,  40  captured by the camera  14 . As described in greater detail below, the hardware processor  24  has code therein which configures the hardware processor  24  to process the sample image to substantially match the reference image, to determine an orientation angle of the match, and to control rotation of the to-be-oriented core sample  20  in the core sample rotation apparatus  22  by the orientation angle. 
     Referring again to  FIG.  2   , the core sample  20  and the reference core sample  40  can have a common longitudinal axis  44 . Alternatively, the reference core sample  40  has the longitudinal axis  44 , while the core sample  20  has an axis  46  of rotation. The axes  44 ,  46  can be aligned. During rotation of the core sample  20  by the core sample rotation apparatus  22 , the core sample  20  rotates about the axis  46  along the rotation path  48 . The core sample  20  can be rotated to at any angle  50 . 
     Referring to  FIG.  3   , the hardware processor  24  obtains an image  60  from the camera  14  having a sub-image  62  showing the cross-section  18  of the core sample  20 . The hardware processor  24  processes the image  60  and sub-image  62  in the memory  26  to remove background pixels, and to only consider the axial cross-sections  18 ,  42  of the two cores  20 ,  40  as circles. Referring to  FIG.  4   , the sub-image  62  is processed in the memory  26  by the hardware processor  24 . The sub-image  62  is then modified in the memory  26  by the hardware processor  24  to include an annular indexing by, for example, single degrees of arc, configured as an annular protractor. The sub-image  62  and the indexing form a processed image  70  in the memory  26 . The processed image  70  can have a diametric axis  72  extending through the 0° and 180° marks. 
     Referring to  FIG.  5   , the hardware processor  24  flips the processed image in the memory  26  about the diametric axis  72  to obtain a flipped sample image  74  stored in the memory  26 . The flipping is performed to generally orient the features of the sample image  60  from the cross-section  18  with the reference image of the cross-section  42 , since the cross-section  18  is substantially a mirror version the reference cross-section  42 . Referring to  FIG.  6   , the hardware processor  24  is further configured by the code therein to incrementally rotate the flipped sample image in the memory  26  to form a rotated image  76  until the flipped sample image substantially matches the reference image when a matching angle  78  is attained. As shown in  FIG.  6 A , a selected section of the rotated and flipped core image  76  is enlarged to show the individual pixels  80 ,  82 , and each square-shaped pixel has different information assigned to it, such as RGB values, intensity, etc. 
     The hardware processor  24  is further configured by the code therein to measure a mis-fit metric of the rotated flipped sample image relative to the reference image. The mis-fit metric can be an inverse of a correlation metric since a correlation metric measures agreement or matching while a mis-fit metric measures a degree of non-matching. The mis-fit metric can be calculated by any known method, such as a Pearson correlation coefficient, a cosine similarity, an absolute mean difference, an absolute cumulative difference, etc. As shown in  FIG.  7   , the mis-fit metric versus the orientation angle of rotation of the flipped sample can be displayed as a graph output by the output device  30 . The sample image substantially matches the reference image when the mis-fit metric is less than a predetermined threshold. For example, the predetermined threshold can be 0.1. Using the input device  28 , a user can enter a customized threshold. Alternatively, the sample image substantially matches the reference image when the mis-fit metric is minimized, such as at point  92  on the graph shown in  FIG.  7    corresponding to, for example, an orientation angle of about 230°. The orientation angle for the to-be-rotated core  20  corresponds to the minimized mis-fit metric. The orientation angle refers to the adjustment magnitude of the angle of one core around its main axis needed to fit another core. The core sample rotation apparatus  22  is configured to orient the to-be-oriented core sample  20 , inserted into the core sample rotation apparatus  22 , by the orientation angle. Once the hardware processor  24  determines the orientation angle, the hardware processor  24  sends a control signal to the core sample rotation apparatus  22  to rotate the inserted core sample  20  to the orientation angle. The reorientation process described herein does not align external features to the two cores  20 ,  40 . Instead, the reorientation process determines the relative orientation of two cores, at a time, to each other. In addition, the absolute orientation of the reference core  40  does not have to be known. If, however, the absolute orientation of the reference core  40  in space is known, then the system  10  can be used to reorient the unoriented core  20  to the reference core  40 , and hence to extrapolate the absolute orientation information to the unoriented core  20 . 
     As shown in  FIG.  8   , the method  100  for orienting a core sample from a well comprises obtaining, from the camera  14 , the reference image of the cross-section  42  of the reference core sample  40  from the well in step  102 . The images, once obtained, are maintained in a memory which is communication with the hardware processor. The method  100  includes the step of receiving, from the camera  14 , the sample image of the cross-section  18  of the to-be-oriented core sample  20  from the well in step  104 . This sample image is also maintained in the memory. The method  100  then flips the core sample image about the diametric axis  72  in step  106 , incrementally rotates the flipped sample image in step  108 , and measures a mis-fit metric of the rotated flipped sample image relative to the reference image in step  110 . The flip and measurement of the mis-fit metric are done by manipulating the image data included in the memory under control of the hardware processor which is executing code that configures the processor for these two purposes. The method  100  then inserts the to-be-oriented core sample  20  into the core sample rotation apparatus  22  in step  112 , and the inserted core sample is rotated in step  114  to an angle which minimizes the mis-fit metric to substantially match the orientation of the inserted core sample to the fixed reference core sample. 
     Portions of the methods described herein can be performed by software or firmware in machine readable form on a tangible (e.g., non-transitory) storage medium. For example, the software or firmware can be in the form of a computer program including computer program code adapted to cause the system to perform various actions described herein when the program is run on a computer or suitable hardware device, and where the computer program can be embodied on a computer readable medium. Examples of tangible storage media include computer storage devices having computer-readable media such as disks, thumb drives, flash memory, and the like, and do not include propagated signals. Propagated signals can be present in a tangible storage media. The software can be suitable for execution on a parallel processor or a serial processor such that various actions described herein can be carried out in any suitable order, or simultaneously. 
     It is to be further understood that like or similar numerals in the drawings represent like or similar elements through the several figures, and that not all components or steps described and illustrated with reference to the figures are required for all embodiments or arrangements. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “contains”, “containing”, “includes”, “including,” “comprises”, and/or “comprising,” and variations thereof, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Terms of orientation are used herein merely for purposes of convention and referencing and are not to be construed as limiting. However, it is recognized these terms could be used with reference to an operator or user. Accordingly, no limitations are implied or to be inferred. In addition, the use of ordinal numbers (e.g., first, second, third) is for distinction and not counting. For example, the use of “third” does not imply there is a corresponding “first” or “second.” Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     While the disclosure has described several exemplary embodiments, it will be understood by those skilled in the art that various changes can be made, and equivalents can be substituted for elements thereof, without departing from the spirit and scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation, or material to embodiments of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, or to the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 
     The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes can be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the invention encompassed by the present disclosure, which is defined by the set of recitations in the following claims and by structures and functions or steps which are equivalent to these recitations.