Weak plane coring method and system based on CT scanning

Abstract

The invention discloses a weak plane coring method and system based on CT scanning. The method comprises the following steps: obtaining a three-dimensional structure diagram of an original rock core sample; performing weak surface identification on the original rock core sample according to the three-dimensional structure diagram to obtain a weak structural surface and characteristics of the original rock core sample; and marking the coring position, shape and size on the weak structural plane, and coring the original core sample. The weak structural plane of the rock sample can be accurately judged, the coring requirement of an experiment is met, and the sampling precision is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas reservoir evaluation, and in particular to a weak surface coring method and system based on CT scanning. Background Art

[0002] The main purpose of reservoir coring is to obtain various characteristic parameters of oil and gas reservoirs as comprehensively and accurately as possible through experimental analysis of core samples. The current core sample analysis projects generally include: conventional physical property testing, particle size analysis, whole rock mineral composition analysis, conventional mercury injection, constant rate mercury injection, nuclear magnetic resonance, CT scanning, relative permeability testing and rock electrical experiments and other indoor experimental projects. The results obtained from these experiments directly affect the key work content of oil and gas reservoir exploration and development, such as geological research, well logging interpretation and oil and gas reservoir engineering calculation.

[0003] As the problem of wellbore instability in strata containing weak planes such as shale and coal rock has attracted more and more attention, the method of treating rock elasticity, strength and other properties as isotropic is facing more and more challenges due to the existence of weak structural planes such as bedding planes, cleats, and microcracks. Anisotropy must be considered in the prediction of ground stress and collapse pressure in strata containing weak planes. Conventional coring methods are relatively simple, usually only specifying the sampling density of the core.

[0004] In actual operation, due to the drillability of samples and the requirements of experimental design, core sampling is often a simple random sampling based on human judgment, without fully considering the control of experimental errors and the randomization of experimental unit processing, and the determination of the number of samples is usually based on field experience. This causes human errors in core experimental data and affects the accuracy and representativeness of experimental data.

[0005] Therefore, a method is needed to obtain the microstructural characteristics of the rock interior through CT scanning coring, reasonably arrange the number, position and length of coring samples, and effectively improve the sampling accuracy. Summary of the invention

[0006] The purpose of the present invention is to provide a weak surface coring method and system based on CT scanning, which can accurately determine the weak structural surface of rock samples, perform coring to meet experimental needs, and effectively improve sampling accuracy.

[0007] To achieve the above object, the present invention provides a weak surface coring method based on CT scanning, comprising:

[0008] Obtain a three-dimensional structural map of the original core sample;

[0009] Identify the weak surface of the original core sample according to the three-dimensional structure diagram to obtain the weak structural surface of the original core sample and its characteristics;

[0010] The coring position and shape and size are marked on the weak structural surface, and the original core sample is cored.

[0011] Furthermore, the three-dimensional structure diagram of the original core sample is obtained, including:

[0012] Perform three-dimensional scanning on the original core sample to obtain scanning data;

[0013] The scanned data is subjected to image processing and three-dimensional reconstruction to obtain a three-dimensional structural diagram of the original core sample.

[0014] Furthermore, the original core sample is subjected to three-dimensional scanning to obtain scanning data, including:

[0015] Using a micro-CT device to perform an omnidirectional scan on the original core sample to obtain a CT scan image of the original core sample;

[0016] Wherein, the original core sample is a full-diameter core and meets a predetermined diameter and a predetermined height.

[0017] Further, weak surface identification is performed on the original core sample according to the three-dimensional structure diagram to obtain the weak structural surface and characteristics of the original core sample, including:

[0018] Using graphic analysis software to identify weak surfaces in the three-dimensional structure diagram, and identifying the position and shape of the weak structural surface of the original core sample;

[0019] Wherein, the weak structural planes include: rock bedding planes, cleat planes and microcracks.

[0020] Further, marking the coring position and shape size on the weak structural surface, coring the original core sample, including:

[0021] The coring position and shape and size are marked on the weak structural surface, and after the original core sample is fixed on the core drilling equipment, the drill bit position and coring parameters are adjusted to perform drilling to obtain the core column of the original core sample.

[0022] Based on the same inventive concept, the present invention also provides a weak surface coring system based on CT scanning, including:

[0023] An acquisition unit, used to obtain a three-dimensional structure map of the original core sample;

[0024] An identification unit, used for identifying weak surfaces of the original core sample according to the three-dimensional structure diagram, and obtaining weak structural surfaces and characteristics of the original core sample;

[0025] The coring unit marks the coring position and shape and size on the weak structural surface and coring the original core sample.

[0026] Furthermore, the acquisition unit includes a scanning subunit and a reconstruction subunit.

[0027] The scanning subunit is used to perform three-dimensional scanning on the original core sample to obtain scanning data;

[0028] The reconstruction subunit is used to perform image processing and three-dimensional reconstruction on the scan data to obtain a three-dimensional structural diagram of the original core sample.

[0029] Further, the scanning subunit is specifically used to perform an all-round scan of the original core sample using a micro-CT device to obtain a CT scan image of the original core sample; wherein the original core sample is a full-diameter core and meets a predetermined diameter and a predetermined height;

[0030] The identification unit is specifically used to identify weak surfaces of the three-dimensional structure diagram using graphic analysis software, and identify the position and shape of the weak structural surface of the original core sample; wherein the weak structural surface includes: rock bedding planes, cleat planes and microcracks.

[0031] Based on the same inventive concept, an embodiment of the present invention also provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the aforementioned weak surface coring method based on CT scanning is implemented.

[0032] Based on the same inventive concept, an embodiment of the present invention further provides a computer storage medium, in which computer executable instructions are stored. When the computer executable instructions are executed, the aforementioned weak surface coring method based on CT scanning is implemented.

[0033] The technical effects and advantages of the present invention: The present invention can accurately determine the weak surface structure of the original rock sample through micro-CT scanning technology identification, so as to accurately select the weak surface coring position, size and angle of the core sample according to the requirements of different core experiments, which can accurately meet the experimental needs and effectively improve the sampling accuracy. In addition, the present invention has visualization, simple and efficient operation, and can greatly control the number and accuracy of coring, meet the test and evaluation requirements of the weak surface structure of the core, and has great economic benefits.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a flow chart of a weak surface coring method based on CT scanning according to an embodiment of the present invention;

[0037] Figure 2 This is a structural schematic diagram of a weak surface coring system based on CT scanning according to an embodiment of the present invention;

[0038] Figure 3 The figure is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to solve the shortcomings of the existing technology, such as Figure 1 As shown, the present invention discloses a weak surface coring method based on CT scanning, comprising:

[0041] Step S1, obtaining a three-dimensional structure diagram of the original core sample.

[0042] Step S2: identifying weak surfaces of the original core sample according to the three-dimensional structure diagram to obtain the weak structural surfaces and characteristics of the original core sample.

[0043] Step S3: mark the coring position and shape and size on the weak structural surface, and coring the original core sample.

[0044] In some specific embodiments, step S1, obtaining a three-dimensional structure diagram of an original core sample, comprises:

[0045] Step S101, performing three-dimensional scanning on the original core sample to obtain scanning data;

[0046] Step S102: perform image processing and three-dimensional reconstruction on the scanned data to obtain a three-dimensional structure diagram of the original core sample.

[0047] In some specific embodiments, step S101, three-dimensional scanning of the original core sample to obtain scanning data is specifically:

[0048] The original core sample is scanned in all directions using a micro-CT device with scanning imaging function to obtain a CT scanning image of the original core sample;

[0049] Among them, the spatial resolution of the micro-CT device used in the present invention is 0.5 μm, it has an image acquisition function, and is equipped with three-dimensional reconstruction software;

[0050] The original core sample is a full-diameter core and meets a predetermined diameter (eg, diameter ≤ 10 cm) and a predetermined height (eg, height ≤ 20 cm).

[0051] In some specific embodiments, step S102, image processing and three-dimensional reconstruction are performed on the scanned data to obtain a three-dimensional structure diagram of the original core sample; specifically:

[0052] The image reconstruction software VoxelStudio Recon provided by the micro-CT device is used to perform three-dimensional reconstruction on the CT scan image of the original core sample to obtain a three-dimensional reconstructed model of the original core sample; then, based on the three-dimensional reconstructed model of the original core sample, a three-dimensional structural diagram of the original core sample is obtained.

[0053] In some specific embodiments, step S2, identifying weak surfaces of the original core sample according to the three-dimensional structure diagram to obtain weak structural surfaces and characteristics of the original core sample, includes:

[0054] Based on the three-dimensional structure diagram of the original core sample, the image analysis software is used to identify the weak surface of the original core sample, and the weak structural surface of the original core sample and its position and morphology are identified.

[0055] Among them, weak structural planes include: rock bedding planes, cleat planes and directional microcracks, etc. The graphic analysis software can be any one of Avizo, Dragonfly and VG.

[0056] In some specific embodiments, step S3, marking the coring position and shape size on the weak structural surface, and coring the original core sample, comprises:

[0057] According to the weak structural surface characteristics of the original core sample and the experimental needs, the coring position, shape, size and direction are marked on the weak structural surface with a marker pen, and the original core sample is fixed on the clamp of the core drilling equipment using the matching clamp of the drilling equipment. Then the drill bit position and coring parameters are adjusted for drilling, and the start switch is pressed to coring, and finally the core column of the original core sample is obtained.

[0058] Among them, the core drilling equipment must meet the requirements that the drill bit is made of diamond material +, the drill bit diameter is Φ25mm, the coring length is ≥20cm, and it must be equipped with core cutting and fine grinding functions.

[0059] Based on the same inventive concept, Figure 2 As shown, the present invention also provides a weak surface coring system based on CT scanning, comprising:

[0060] An acquisition unit, used to obtain a three-dimensional structure map of the original core sample;

[0061] An identification unit, used for identifying weak surfaces of the original core sample according to the three-dimensional structure diagram, and obtaining the weak structural surface and characteristics of the original core sample;

[0062] The coring unit marks the coring position and shape and size on the weak structural surface and coring the original core sample.

[0063] In some specific embodiments, the acquisition unit includes a scanning subunit and a reconstruction subunit.

[0064] A scanning subunit is used to perform three-dimensional scanning on the original core sample to obtain scanning data;

[0065] The reconstruction subunit is used to perform image processing and three-dimensional reconstruction on the scanned data to obtain a three-dimensional structural diagram of the original core sample.

[0066] In some specific embodiments, the scanning subunit is specifically used to perform an all-round scan of the original core sample using a micro-CT device to obtain a CT scan image of the original core sample; wherein the original core sample is a full-diameter core and meets a predetermined diameter and a predetermined height.

[0067] The identification unit is specifically used to identify weak surfaces of the three-dimensional structure diagram using graphic analysis software, and identify the position and shape of the weak structural surface of the original core sample; wherein the weak structural surface includes: rock bedding surface, cleat surface and microcracks.

[0068] Regarding the system in the above embodiment, the specific manner in which each unit module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0069] Based on the same inventive concept, an embodiment of the present invention further provides an electronic device, whose structure is as follows: Figure 3 As shown, it includes: a memory and a processor, wherein the processor is used to read and execute a computer program stored in the memory to implement the aforementioned weak surface coring method based on CT scanning.

[0070] Based on the same inventive concept, an embodiment of the present invention further provides a computer storage medium, in which computer executable instructions are stored. When the computer executable instructions are executed, the aforementioned weak surface coring method based on CT scanning is implemented.

[0071] Embodiment 1:

[0072] Select core sample 1# and perform the following steps to coring:

[0073] Step 1: Use micro-CT equipment to perform three-dimensional scanning on the original core sample 1#. After obtaining the scanning data, image processing and three-dimensional reconstruction are performed on the scanning data to obtain a true and accurate three-dimensional structure diagram of the original rock sample.

[0074] Step 2: Based on the microstructure of the three-dimensional structural diagram, find out the weak structural surfaces such as rock bedding planes, cleats, and microcracks, and mark the core sampling position and shape and size on the weak structural surfaces.

[0075] Step 3: Finally, fix the core sample 1# on the core drilling equipment, adjust the coring parameters, and perform coring to obtain the core column.

[0076] The present invention can accurately determine the weak surface structure of the original rock sample through micro-CT scanning technology identification, so as to accurately select the weak surface coring position, size and angle of the core sample according to the requirements of different core experiments, accurately meet the experimental needs, and effectively improve the sampling accuracy. In addition, the present invention has visualization, simple operation, high efficiency, and can greatly control the number and accuracy of coring, meet the test and evaluation requirements of the weak surface structure of the core, and have great economic benefits.

[0077] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A weak surface coring method based on CT scanning, characterized in that: include: Obtain a three-dimensional structural map of the original core sample; Identify the weak surface of the original core sample according to the three-dimensional structure diagram to obtain the weak structural surface of the original core sample and its characteristics; The coring position and shape and size are marked on the weak structural surface, and the original core sample is cored.

2. A weak surface coring method based on CT scanning according to claim 1, characterized in that: The method of obtaining a three-dimensional structure diagram of the original core sample comprises: Perform three-dimensional scanning on the original core sample to obtain scanning data; The scanned data is subjected to image processing and three-dimensional reconstruction to obtain a three-dimensional structural diagram of the original core sample.

3. A weak surface coring method based on CT scanning according to claim 1, characterized in that: Perform 3D scanning on the original core sample to obtain scanning data, including: Using a micro-CT device to perform an omnidirectional scan on the original core sample to obtain a CT scan image of the original core sample; Wherein, the original core sample is a full-diameter core and meets a predetermined diameter and a predetermined height.

4. A weak surface coring method based on CT scanning according to claim 2, characterized in that: The weak surface of the original core sample is identified according to the three-dimensional structure diagram to obtain the weak structural surface of the original core sample and its characteristics, including: Using graphic analysis software to identify weak surfaces in the three-dimensional structure diagram, and identifying the position and shape of the weak structural surface of the original core sample; Wherein, the weak structural planes include: rock bedding planes, cleat planes and microcracks.

5. The weak surface coring method based on CT scanning according to claim 1, characterized in that: Marking the coring position and shape and size on the weak structural surface, coring the original core sample, including: The coring position and shape and size are marked on the weak structural surface, and after the original core sample is fixed on the core drilling equipment, the drill bit position and coring parameters are adjusted to perform drilling to obtain the core column of the original core sample.

6. A weak surface coring system based on CT scanning, characterized in that: include: An acquisition unit, used to obtain a three-dimensional structure map of the original core sample; An identification unit, used for identifying weak surfaces of the original core sample according to the three-dimensional structure diagram, and obtaining weak structural surfaces and characteristics of the original core sample; The coring unit marks the coring position and shape and size on the weak structural surface and coring the original core sample.

7. A weak surface coring system based on CT scanning according to claim 6, characterized in that: The acquisition unit includes a scanning subunit and a reconstruction subunit, The scanning subunit is used to perform three-dimensional scanning on the original core sample to obtain scanning data; The reconstruction subunit is used to perform image processing and three-dimensional reconstruction on the scan data to obtain a three-dimensional structural diagram of the original core sample.

8. The weak surface coring system based on CT scanning according to claim 7, characterized in that: The scanning subunit is specifically used to perform an all-round scan of the original core sample using a micro-CT device to obtain a CT scan image of the original core sample; wherein the original core sample is a full-diameter core and meets a predetermined diameter and a predetermined height; The identification unit is specifically used to identify weak surfaces of the three-dimensional structure diagram using graphic analysis software, and identify the position and shape of the weak structural surface of the original core sample; wherein the weak structural surface includes: rock bedding planes, cleat planes and microcracks.

9. An electronic device, characterized in that: include: Memory, processor; The processor is used to read and execute the computer program stored in the memory to implement the weak surface coring method based on CT scanning as described in any one of claims 1-5.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are executed, the weak-surface coring method based on CT scanning described in any one of claims 1 to 5 is implemented.

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