Sample preparation method and heterogeneity research method of fine-grained heterogeneous sedimentary rock samples

Abstract

The application discloses a sample preparation method and a heterogeneity research method for a fine-grained heterogeneous sedimentary rock sample. The sample preparation method comprises the following steps: determining a reference surface direction according to the extension direction of the bedding plane of the fine-grained heterogeneous sedimentary rock sample, cutting and flattening the top surface and the bottom surface of the sample along the direction parallel to the reference surface direction, cutting the side surface of the sample along the direction perpendicular to the reference surface, so that the shapes of the cross sections of the sample parallel to the reference surface are consistent; cutting the sample into a first rock sample and a second rock sample along the direction perpendicular to the reference surface; obtaining an XRF scanning map of the cutting surface of the second rock sample, obtaining a sequence of segmentation lines arranged in an up-down order according to the data difference in the scanning map, and the segmentation lines being consistent with the direction of the bedding plane at the corresponding positions; and cutting the first rock sample according to the sequence of segmentation lines in sequence to obtain a plurality of rock samples. The rock samples prepared by the method are full in types, good in heterogeneity representation, and the rock samples are homogeneous bodies.

Description

Technical Field

[0001] This invention relates to the fields of petroleum geology and rock sample preparation technology, specifically to a method for preparing fine-grained heterogeneous sedimentary rock samples and a method for studying heterogeneity. Background Technology

[0002] Currently, the domestic geological industry typically has two requirements for core sampling and preparation: 1) samples with similar properties to facilitate parallel testing; and 2) samples with significant differences in properties, encompassing all types to facilitate comparative testing. Fine-grained sedimentary rocks exhibit strong heterogeneity; therefore, when the primary purpose is to study heterogeneity, the preparation of fine-grained sedimentary rock samples needs to include significant differences in properties and encompass all types. Currently, there are few conventional techniques for rock sample selection and preparation, and these are insufficient to meet the resolution requirements of fine-grained sedimentary rocks with grains smaller than 0.0625 mm (more than 50%), especially in highly heterogeneous fine-grained sedimentary rocks where sample property variations are typically at the millimeter-micrometer level. To precisely study the heterogeneity of fine-grained sedimentary rocks, there is an urgent need to develop more refined sample preparation methods. Summary of the Invention

[0003] In order to at least partially solve the above-mentioned technical problems existing in the prior art, the inventors made this invention, which provides a method for preparing fine-grained heterogeneous sedimentary rock samples and a method for studying heterogeneity through specific embodiments. The prepared rock samples are of a complete range of types, have good heterogeneity representativeness, and are homogeneous.

[0004] In a first aspect, embodiments of the present invention provide a method for preparing a fine-grained heterogeneous sedimentary rock sample, comprising:

[0005] The reference plane direction is determined based on the extension direction of the bedding plane of the fine-grained heterogeneous sedimentary rock sample. The top and bottom surfaces of the sample are cut flat along the direction parallel to the reference plane, and the side surface of the sample is cut along the direction perpendicular to the reference plane, so that the cross-sectional shape of the sample parallel to the reference plane is consistent.

[0006] The sample is cut into a first rock sample and a second rock sample along a direction perpendicular to the reference plane;

[0007] Obtain XRF scan images of the cut surfaces of the second rock sample, and obtain a sequence of dividing lines arranged in vertical order based on the data differences in the scan images. The dividing lines are aligned with the bedding planes at the corresponding positions.

[0008] The first rock sample was cut sequentially according to the dividing line sequence to obtain multiple rock samples.

[0009] In some embodiments, determining the reference plane direction based on the bedding plane extension direction of the fine-grained heterogeneous sedimentary rock sample includes:

[0010] The orientation of bedding planes in fine-grained heterogeneous sedimentary rock samples was statistically analyzed, and the orientation with the most abundant bedding planes was determined as the reference plane orientation; or,

[0011] Based on the bedding plane orientations of each layer of fine-grained heterogeneous sedimentary rock sample, the reference plane orientation is obtained through cluster analysis.

[0012] In some embodiments, the volume ratio of the first rock sample to the second rock sample is greater than 10;

[0013] The width of the cut surface of the second rock sample is 1 to 5 cm.

[0014] In some embodiments, the XRF scan image is a content distribution map of multiple set elements, and obtaining a sequence of dividing lines arranged in vertical order based on the data differences in the scan images includes:

[0015] For each XRF scan image, points where the content change rate of the corresponding element is higher than a set threshold are identified to obtain a scatter set. Through scatter clustering analysis, multiple possible dividing lines are obtained from the scatter set, and the two endpoints of each possible dividing line are on the two opposite sides of the cutting surface of the second rock sample.

[0016] By using the line clustering analysis method, the possible segmentation lines obtained from each XRF scan are clustered to obtain a sequence of segmentation lines arranged in vertical order.

[0017] In some embodiments, it also includes:

[0018] Determine whether the distance between two adjacent dividing lines is less than a set distance threshold;

[0019] If so, delete one of the dividing lines, or merge two adjacent dividing lines whose distance is less than a set distance threshold according to the merging rules of cluster analysis to obtain a new dividing line.

[0020] In some embodiments, the set distance threshold satisfies the following requirements:

[0021] With the set distance threshold as the thickness, the volume of the rock sample with the cross-section of the first rock sample as the cross-section is not less than the set volume threshold.

[0022] In some embodiments, the set distance threshold is 0.2 mm.

[0023] In some embodiments, the first rock sample is sequentially cut according to the dividing line sequence to obtain multiple rock samples, including:

[0024] Determine at least one cutting direction perpendicular to the reference plane according to the research needs, and complete the vertical cutting of the first rock sample according to each cutting direction;

[0025] Wrap the first rock sample after cutting with a set material, and then cut the wrapped first rock sample in sequence according to the dividing line sequence to obtain multiple rock samples.

[0026] In some embodiments, after obtaining multiple rock samples, the method further includes:

[0027] The rock samples obtained from the cutting process are then further cut according to the principle of maximizing volume, so that the top and bottom surfaces of the rock samples are parallel.

[0028] Secondly, embodiments of the present invention provide a method for studying the heterogeneity of fine-grained heterogeneous sedimentary rock samples, comprising:

[0029] The fine-grained heterogeneous sedimentary rock samples were cut and prepared using the method described above to obtain multiple rock samples;

[0030] Heterogeneity studies were conducted based on multiple rock samples obtained.

[0031] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0032] (1) The sample preparation method for fine-grained heterogeneous sedimentary rock samples provided in this embodiment of the invention involves cutting the sample into a first rock sample and a second rock sample along a direction perpendicular to the reference plane; obtaining an XRF scan image of the cut surface of the second rock sample; and obtaining a sequence of dividing lines arranged in vertical order based on the data differences in the scan image; and then cutting the first rock sample sequentially according to the dividing line sequence to obtain multiple rock samples. This continuous slice preparation method for the microscopic heterogeneity of fine-grained sedimentary rocks improves work efficiency and reduces sample loss rate; the dividing lines are aligned with the bedding planes at the corresponding positions, resulting in a complete range of rock sample types, good heterogeneity representativeness, and homogeneous rock samples, providing a basis for rapid and high-resolution sample property determination.

[0033] (2) The sample preparation method of fine-grained heterogeneous sedimentary rock sample provided in the embodiment of the present invention cuts the sample into a first rock sample and a second rock sample along the direction perpendicular to the reference plane; the second rock sample is not cut, but is used as a reference rock sample. Since it has the same vertical cutting surface as the first rock sample, the second rock sample can provide a physical reference for the analysis of the longitudinal heterogeneity distribution characteristics of the first rock sample at any time during the cutting process of the first rock sample.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0036] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0037] Figure 1 This is a flowchart of the sample preparation method for fine-grained heterogeneous sedimentary rock samples in Embodiment 1 of the present invention;

[0038] Figure 2 This is an example diagram illustrating the sample preparation process of a fine-grained heterogeneous sedimentary rock sample in Embodiment 2 of the present invention;

[0039] Figure 3 This is an example cross-sectional view of a sample in Embodiment 2 of the present invention;

[0040] Figure 4 This is an example image of an XRF scan from Embodiment 2 of the present invention. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] In the description of this invention, it should be noted that the terms "comprising", "including", "having", "containing", etc., are all open-ended terms, meaning that they include but are not limited to.

[0045] This invention aims to address the challenge of preparing representative samples for the experimental analysis of fine-grained sedimentary rocks with strong microscopic heterogeneity. This invention provides a method for preparing fine-grained heterogeneous sedimentary rock samples and a method for studying heterogeneity. The method produces rock samples with a wide variety of types, good heterogeneity representativeness, and homogeneous composition.

[0046] Example 1

[0047] Embodiment 1 of the present invention provides a method for preparing fine-grained heterogeneous sedimentary rock samples, referring to... Figure 1 As shown, it includes the following steps:

[0048] Step S11: Determine the reference plane direction based on the extension direction of the bedding plane of the fine-grained heterogeneous sedimentary rock sample. Cut the top and bottom surfaces of the sample flat along the direction parallel to the reference plane, and cut the side surfaces of the sample along the direction perpendicular to the reference plane, so that the cross-sectional shape of the sample parallel to the reference plane is consistent.

[0049] Rock samples are typically cored sections, with their top and bottom surfaces being two end faces perpendicular to the axis of the cored section.

[0050] Typically, the research direction for heterogeneity is perpendicular to the dominant bedding plane. In this case, the reference plane direction can be determined by either of the following two methods:

[0051] (1) Statistically analyze the bedding plane direction of fine-grained heterogeneous sedimentary rock samples and determine the direction with the most bedding plane development as the reference plane direction.

[0052] (2) Based on the orientation of each bedding plane of the fine-grained heterogeneous sedimentary rock sample, the orientation of the reference plane is obtained by cluster analysis.

[0053] For example, the final determined reference plane direction is the direction with the smallest sum of differences from each reference plane. The difference from each reference plane is determined separately, and the direction with the smallest sum of differences is determined as the reference plane direction.

[0054] Optionally, the research direction of heterogeneity may not be perpendicular to the direction of the dominant bedding plane. In this case, the direction perpendicular to the research direction of heterogeneity is directly taken as the reference plane direction.

[0055] Taking the reference plane direction as P and the direction perpendicular to the reference plane as V as an example, the side of the sample is cut along the direction perpendicular to the reference plane so that the cross-sectional shape of the sample parallel to the reference plane is consistent. This can be achieved by taking the shape of the sample's minimum cross-sectional area polygon parallel to P or any shape smaller than the minimum cross-sectional area polygon as the boundary, denoted as Z, and cutting the sample polygon Z along the vector V so that the cross-sectional area of ​​the sample along the direction of the vector P is equal.

[0056] Step S12: Cut the sample into a first rock sample and a second rock sample along a direction perpendicular to the reference plane.

[0057] Grind the cut surface to make it level, with a height difference not exceeding 1mm.

[0058] The first rock sample serves as the scanning and reference sample, while the second rock sample serves as the sample to be cut. Therefore, the volume of the first rock sample does not need to be too large. Preferably, the volume ratio of the first rock sample to the second rock sample is greater than 10.

[0059] Step S13: Obtain the XRF scan image of the cut surface of the second rock sample, and obtain the sequence of dividing lines arranged in vertical order based on the data differences in the scan image.

[0060] The second rock sample was placed in a Micro-XRF (micro-area X-ray fluorescence spectrometer) instrument, and the profile was adjusted to a horizontal state. The profile was scanned using Micro-XRF to generate XRF scan images (data). The XRF scan images are multiple content distribution maps of set elements.

[0061] The conditions for XRF scanning along vector V can be: a resolution of 5 micrometers, a scan width W = 1–2 cm (correspondingly, the cut surface width of the second rock sample should be 1–5 cm), and a scan length H, where H is the length of the sample within the range where heterogeneity studies are required, preferably 1 cm–30 cm, and not exceeding the maximum of HMax or the upper limit of the sample chamber of the XRF scanner. HMax is the maximum height of the rock sample, which is the vertical distance between the top and bottom surfaces of the sample.

[0062] In some embodiments, obtaining the segmentation line sequence may include,

[0063] For each XRF scan image, points where the content change rate of the corresponding element is higher than a set threshold are identified, resulting in a scatter set. Using scatter clustering analysis, multiple possible dividing lines are obtained from the scatter set. The two endpoints of each possible dividing line are located on the two opposite sides of the cutting surface of the second rock sample. Using line clustering analysis, the possible dividing lines obtained from each XRF scan image are clustered to obtain a sequence of dividing lines arranged in vertical order.

[0064] The dividing line determined by the above method is formed by the aggregation of points whose corresponding element content change rate is higher than a set threshold, and the dividing line is consistent with the direction of the bedding plane at the corresponding position. Specifically, each dividing line is located on a bedding plane and is the line where the bedding plane and the cutting plane intersect.

[0065] Fine-grained sedimentary rocks are those whose grain size meets the grain size requirements for sedimentary rocks classified by grain size. In other words, fine-grained sedimentary rocks refer to sedimentary rocks with a grain size smaller than a set grain size threshold.

[0066] The fine-grained heterogeneous sedimentary rocks studied in this application's embodiments are defined specifically as fine-grained sedimentary rocks, which are defined in geological sedimentology as sedimentary rocks with grains smaller than 0.0625 mm (more than 50%).

[0067] Due to the need for high precision in studying the heterogeneity of fine-grained sedimentary rocks, it is usually necessary to prepare rock samples with a thickness of not less than 0.2 mm.

[0068] Therefore, after obtaining the segmentation line sequence through the image method, it can also include determining whether the distance between two adjacent segmentation lines is less than a set distance threshold; if so, deleting one of the segmentation lines, or merging two adjacent segmentation lines with a distance less than the set distance threshold according to the merging rule of the similarity principle of cluster analysis, to obtain a new segmentation line.

[0069] The aforementioned distance threshold is typically set to 0.2 mm.

[0070] For example, TOC monitoring requires grinding rock samples into powder, thus the prepared rock samples need to meet certain volume requirements to ensure that the size meets the research needs. Therefore, in some embodiments, a distance threshold is set to meet the following requirements:

[0071] With a set distance threshold as the thickness, the volume of the rock sample with the cross-section of the first rock sample as the cross-section is not less than the set volume threshold.

[0072] Step S14: Cut the first rock sample sequentially according to the dividing line sequence to obtain multiple rock samples.

[0073] A diamond wire cutter can be used to cut the first rock sample according to the sequence of dividing lines.

[0074] Furthermore, since the dividing lines are aligned with the bedding planes at the corresponding locations, but not necessarily parallel to the reference plane, and the dividing lines are not necessarily parallel to each other, after the first rock sample is cut according to the dividing line sequence, the rock sample obtained from the cutting can be further cut according to the principle of maximizing volume, so that the top and bottom surfaces of the rock sample are parallel.

[0075] In the same vertical direction, multiple rock samples can be cut according to research needs. Therefore, in some embodiments, it may include determining at least one cutting direction perpendicular to the reference plane according to research needs, completing the vertical cutting of the first rock sample according to each cutting direction; wrapping the cut first rock sample with a set material (industrial wax can be used for wrapping), and cutting the wrapped first rock sample in sequence according to the dividing line sequence to obtain multiple rock samples.

[0076] Furthermore, the rock samples obtained from the cutting process can be further cut according to the principle of maximizing volume, so that the top and bottom surfaces of the rock samples are parallel.

[0077] The sample preparation method for fine-grained heterogeneous sedimentary rock samples provided in Embodiment 1 of this invention involves cutting the sample into a first rock sample and a second rock sample along a direction perpendicular to a reference plane; obtaining XRF scan images of the cut surfaces of the second rock sample; and obtaining a sequence of dividing lines arranged vertically based on the data differences in the scan images; and then cutting the first rock sample sequentially according to the dividing line sequence to obtain multiple rock samples. This continuous slice preparation method, designed for the microscopic heterogeneity of fine-grained sedimentary rocks, improves work efficiency and reduces sample loss. The dividing lines align with the direction of the corresponding bedding planes, resulting in a comprehensive range of rock sample types, good heterogeneity representativeness, and homogeneous rock samples, providing a foundation for rapid and high-resolution sample property determination.

[0078] The sample preparation method for fine-grained heterogeneous sedimentary rock samples provided in Embodiment 1 of the present invention involves cutting the sample into a first rock sample and a second rock sample along a direction perpendicular to the reference plane. The second rock sample is not cut but serves as a reference rock sample. Since it has the same vertical cut surface as the first rock sample, the second rock sample can provide a physical reference for the analysis of the longitudinal heterogeneity distribution characteristics of the first rock sample during the cutting process of the first rock sample.

[0079] Example 2

[0080] Embodiment 2 of the present invention provides a specific implementation flow of a method for preparing fine-grained heterogeneous sedimentary rock samples, referring to... Figure 2 The diagram illustrates the implementation process, which may include the following steps:

[0081] (1) The dominant bedding plane that accounts for more than 75% of the bedding planes in the sample deposition structure is taken as the reference plane and set as P.

[0082] (2) Parallel to the reference plane P, cut and flatten both ends of the sample, and set the vertical vector from the top surface to the bottom surface as V.

[0083] (3) Take the boundary of the minimum cross-sectional area polygon of the sample parallel to the reference plane P as the boundary, let it be Z, and cut the sample polygon Z along the vector V so that the cross-sectional area of ​​the sample along the direction of the vector P is equal.

[0084] (4) Cut the sample into two parts along vector V, and denote them as A and A' respectively. The volume ratio of A to A' is greater than 10. Grind the cut section in A' to make it horizontal and the height difference does not exceed 1mm.

[0085] Preferably, the cross-sectional width of A' is between 1cm and 5cm. If it is too wide, the XRF scanning speed is slow, and if it is too narrow, the amount of information is small.

[0086] (5) Place sample A' into the Micro-XRF (micro-area X-ray fluorescence spectrometer) instrument and adjust the profile to a horizontal state; use Micro-XRF to scan the profile and generate images and data.

[0087] Preferably, the conditions for XRF scanning of the cross-section of sample A' along vector V are: a resolution of 5 micrometers, a scan width W = 2 cm, and a scan length H of 20 cm.

[0088] See Figure 3 The image shown is an example cross-sectional view of the sample; see also... Figure 4 The image shown is an example of the obtained XRF scan image. From left to right, it shows the content distribution of Al, Fe, K, S and Si elements.

[0089] Figure 4 The marks 1-10 in the diagram indicate the locations of 10 defined dividing lines. (By...) Figure 4 As can be seen from the content variation diagram of each element, the development direction of the bedding planes of the rock sample is basically parallel to the reference plane. Therefore, Example 2 is used as an example to illustrate that the determined dividing lines are all parallel to the reference plane direction.

[0090] (6) Use the areas with large differences in the images or obvious changes in the data as dividing lines, and record the samples as D1, D2, ..., Dn to complete the first-level sampling.

[0091] (7) Calculate the distance between adjacent dividing lines in the first-level sampling. If the distance is less than 0.2 mm, merge them. The merging rule is based on the similarity principle of cluster analysis. Complete the second-level sampling. The sampling labels are S1, S2, S3, ..., Sn.

[0092] (8) Based on the secondary sampling mark results, sample A is cut and separated. Using a diamond wire cutter, sample A is cut parallel to the reference plane P.

[0093] Preferably, before cutting sample A, sample A is first cut into several parts along vector V (the number and position are determined according to the research needs), and then wrapped with industrial wax before cutting, so that each small slice is in the same position.

[0094] Preferably, before cutting sample A, the volume of the prepared sample needs to be estimated based on the area and thickness of the secondary sample to meet the sample quantity requirements for subsequent testing. If a test item requires a large amount of sample, it needs to be merged again to ensure the sample quantity.

[0095] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0096] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0097] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term “comprising” as used in the specification or claims is interpreted in a manner similar to the term “including,” as it is understood when used as a conjunction in the claims. Additionally, the use of any term “or” in the specification of the claims is intended to mean “non-exclusive or.” The terms “first” and “second” are used for descriptive purposes and should not be construed as indicating or implying relative importance.

Claims

1. A method of sample preparation of a fine-grained, heterogeneous sedimentary rock sample, characterized in that, The method comprises the following steps: determining a reference surface direction according to the extension direction of the bedding surface of a fine-grained and heterogeneous sedimentary rock sample, cutting the top surface and the bottom surface of the sample along a direction parallel to the reference surface direction, and cutting the side surface of the sample along a direction perpendicular to the reference surface direction, so that the shape of the cross section of the sample parallel to the reference surface is consistent; cutting the sample along a direction perpendicular to the reference surface into a first rock sample and a second rock sample; obtaining XRF scan maps of the cutting surface of the second rock sample, wherein the XRF scan maps are a plurality of element content distribution maps; for each XRF scan map, identifying points with a content variation rate of a corresponding element higher than a set threshold value to obtain a scatter point set, and obtaining a plurality of possible division lines from the scatter point set by a scatter point clustering analysis method, wherein the two end points of each possible division line are located on the two opposite edges of the cutting surface of the second rock sample; performing clustering analysis on the possible division lines obtained according to each XRF scan map by a line clustering analysis method to obtain a division line sequence arranged in an up-down order, wherein the division line is consistent with the direction of the bedding surface at the corresponding position; cutting the first rock sample according to the division line sequence to obtain a plurality of rock samples.

2. The method of claim 1, wherein, The method for determining the reference surface direction according to the extension direction of the bedding surface of the fine-grained and heterogeneous sedimentary rock sample comprises the following steps: counting the directions of the bedding surfaces of the fine-grained and heterogeneous sedimentary rock sample, and determining the direction with the most developed bedding surface as the reference surface direction; or obtaining the reference surface direction by a clustering analysis method based on the directions of the bedding surfaces of the fine-grained and heterogeneous sedimentary rock sample.

3. The method of claim 1, wherein, The volume ratio of the first rock sample to the second rock sample is greater than 10. The width of the cutting surface of the second rock sample is 1-5 cm.

4. The method of claim 1, wherein, The method further comprises the following steps: determining whether the distance between two adjacent division lines is less than a set distance threshold value; if yes, deleting one of the two division lines, or merging the two adjacent division lines with a distance less than the set distance threshold value according to the merging rule of the clustering analysis to obtain a new division line.

5. The method of claim 4, wherein, The set distance threshold value satisfies the following requirement: the volume of a rock sample with a cross section of the cross section of the first rock sample and a thickness of the set distance threshold value is not less than a set volume threshold value.

6. The method of claim 4, wherein, The set distance threshold value is 0.2 mm.

7. The method of claim 1, wherein, The method for cutting the first rock sample according to the division line sequence to obtain a plurality of rock samples comprises the following steps: determining at least one cutting direction perpendicular to the reference surface direction according to research needs, and performing vertical cutting of the first rock sample according to each cutting direction; wrapping the cut first rock sample with a set material, and cutting the wrapped first rock sample according to the division line sequence to obtain a plurality of rock samples.

8. The method according to any one of claims 1 to 7, characterized in that After obtaining the plurality of rock samples, the method further comprises the following steps: re-cutting the rock samples obtained by cutting according to the principle of maximum volume to make the top and bottom surfaces of the rock samples parallel.

9. A method of investigating the heterogeneity of a fine-grained, heterogeneous sedimentary rock sample, characterized in that, The method comprises the following steps: cutting a fine-grained and heterogeneous sedimentary rock sample according to the method of any one of claims 1-8 to obtain a plurality of rock samples; performing heterogeneity research based on the obtained plurality of rock samples.

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