Method and device for analyzing clay swelling in sandstone-type uranium deposits

Abstract

The application discloses a kind of sandstone type uranium mine clay expansion analysis method and equipment.The application is scanned by X-ray micro-CT and AVIZO software respectively to determine the three-dimensional CT model of core sample before and after being treated by working medium continuous seepage, and based on the obtained three-dimensional CT model, the change of core sample pore structure is determined, the characteristics of sandstone micro-pore throat structure and pore throat connectivity are analyzed, so as to finely describe the swelling performance of clay minerals at different spatial positions and the change of pore structure in high clay area, and the dissolution and pore change of uranium minerals wrapped by clay minerals when contacting with working medium can also be observed, which provides guidance for leaching process, and further solves the problems that the local swelling effect of clay minerals in different regions of core sample under the action of working medium cannot be finely described, and the swelling rate determined by powder mineral sample has limited guidance for in-situ leaching process in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of in-situ leaching of uranium deposits, and particularly relates to a method and device for analyzing clay swelling in sandstone-type uranium deposits. BACKGROUND

[0002] The X-ray CT scanning technology and stereoscopic microscopy technology are used to identify the mineral types of the sandstone core samples before and after the treatment of the working medium. The spatial distribution of the clay minerals is determined by the brightness value and the gray value (the brightness range is selected as -5300-1700 in the AVITO software) in the three-dimensional CT model. The clay mineral region is divided and the volume thereof is counted by selecting the region and performing the noise reduction processing on the gray image, so that the volume change of the clay minerals in different working media is determined, and the clay swelling rate is calculated.

[0003] Currently, the common evaluation method for the clay swelling is to determine the linear swelling rate of the sample. The determination method is to press the crushed clay sample into a circular core column in a sample chamber, then inject the working medium into the core column and measure the height of the rising clay surface at intervals until the height no longer changes. The linear swelling rate of the sample is calculated according to the length change of the sample before and after the action of the working medium. The evaluation method of the linear swelling rate can only evaluate the action of the clay and the working medium from the macroscopic perspective, and cannot observe the action effect of the clay and the working fluid at different spatial positions from the microscopic scale. The determination of the linear swelling rate refers to the coal industry standard MT-171-1987 "Method for Determining Rock Swelling Rate". The specific determination method is as follows:

[0004] The swelling rate of the sample is determined by using the swelling instrument. The columnar sample is loaded in the columnar swelling instrument water box with the specification of DN50mm*20mm. The dial gauge is installed on the swelling instrument. The working medium is added into the swelling instrument water box in three or four times in the test, until the dial gauge reading remains unchanged. At this time, the instantaneous swelling rate of the core sample is calculated.

[0005] The calculation formula of the swelling rate is: V=(H1-H0) / H*100% (1)

[0006] Wherein, V-linear swelling rate, H-original height of the test piece, H1-dial gauge reading after the swelling of the test piece, H0-dial gauge reading before the swelling of the test piece.

[0007] The linear swelling rate can only measure the clay swelling rate from the macroscopic core scale, and cannot finely describe the local description of the clay minerals in different regions of the core sample under the action of the working medium. In the in-situ leaching field, since the ore body has not been artificially mined and subsequently crushed, the swelling rate determined by using the powder sample has limited guiding effect on the in-situ leaching process. SUMMARY

[0008] To address the aforementioned problems in the existing technology, this invention provides an analytical method and equipment for analyzing clay swelling in sandstone-type uranium deposits.

[0009] To achieve the above objectives, the present invention provides the following solution:

[0010] An analytical method for clay swelling in sandstone-type uranium deposits includes:

[0011] Core samples were prepared based on sandstone uranium ore cored in the field.

[0012] The core sample was subjected to X-ray micro-area CT scanning and AVIZO software processing to obtain the first three-dimensional CT model;

[0013] The core sample was soaked in a working medium saturation process until it reached saturation; the core sample reaching saturation means that the liquid permeability of the core sample is constant.

[0014] The core sample that has reached saturation was subjected to X-ray micro-area CT scanning and AVIZO software processing to obtain a second three-dimensional CT model;

[0015] The CT difference is determined based on the first 3D CT model and the second 3D CT model;

[0016] The changes in the pore structure of the core sample are determined based on the CT difference. At the same time, CT imaging technology is used to analyze the characteristics of the micropore throat structure and pore throat connectivity of sandstone based on the first three-dimensional CT model and the second three-dimensional CT model.

[0017] Preferably, the step of performing X-ray micro-area CT scanning and AVIZO software processing on the core sample to obtain the first three-dimensional CT model specifically includes:

[0018] The core sample was subjected to X-ray micro-area CT scanning to obtain the first CT scan image;

[0019] Based on the first CT scan image, first two-dimensional CT scan images at different layers are obtained;

[0020] The first three-dimensional CT model is obtained by processing the first CT scan image and the first two-dimensional CT scan image using AVIZO software.

[0021] Preferably, the step of performing X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model specifically includes:

[0022] The core sample that has reached saturation was subjected to X-ray micro-area CT scanning to obtain a second CT scan image;

[0023] Based on the second CT scan image, second two-dimensional CT scan images at different slice levels are obtained;

[0024] The second 3D CT model was obtained by processing the second CT scan image and the second 2D CT scan image using AVIZO software.

[0025] Preferably, after performing X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model, the method further includes:

[0026] The clay volume expansion rate of the core sample is determined based on the volume percentage of clay minerals in the first two-dimensional CT scan and the volume percentage of clay minerals in the second two-dimensional CT scan.

[0027] Preferably, the working medium permeation saturation process is a CO2+O2 leaching process.

[0028] Preferably, the process of obtaining a 3D CT model using AVIZO software is as follows:

[0029] Import the CT scan image and the 2D CT scan image into AVIZO software to obtain 2D slice images of different locations of the core sample;

[0030] Threshold segmentation of clay minerals reveals the distribution of clay in core CT and micro-area CT in different CT slices of the core;

[0031] The intersection of clay structures in core CT and micro-area CT is extracted to determine the final three-dimensional CT model of core clay.

[0032] Preferably, CT imaging technology is used to analyze the characteristics of sandstone micropore throat structure and pore throat connectivity based on the first three-dimensional CT model and the second three-dimensional CT model. Specifically, this includes: performing threshold segmentation on the first three-dimensional CT model and the second three-dimensional CT model to extract pores, using a pore connectivity analysis algorithm to determine connected pores, segmenting the connected pores, and generating a pore mesh model.

[0033] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0034] The present invention provides an analytical method for clay swelling in sandstone-type uranium deposits. This method uses X-ray micro-area CT scanning and AVIZO software to determine the three-dimensional CT models of core samples before and after continuous seepage treatment with a working medium. Based on these three-dimensional CT models, the method determines the changes in the pore structure of the core samples, analyzes the microscopic pore-throat structure and pore-throat connectivity characteristics of the sandstone, and can precisely describe the swelling performance of clay minerals in different spatial locations and the changes in pore structure in high-clay areas. It can also observe the dissolution and pore changes of uranium minerals encased in clay minerals when in contact with the working medium, providing guidance for the leaching process. This addresses the problems of existing technologies, such as the inability to precisely describe the local swelling effect of clay minerals in different regions of the core sample under the action of the working medium, and the limited guidance of the swelling rate measured using powdered mineral samples for the in-situ leaching process.

[0035] Corresponding to the above-described analytical method for clay swelling in sandstone-type uranium deposits, this invention also provides an analytical apparatus for clay swelling in sandstone-type uranium deposits, the apparatus comprising:

[0036] A sample preparation module is used to prepare core samples; the core samples are prepared based on sandstone uranium ore obtained from in-situ core sampling.

[0037] The first model construction module is used to perform X-ray micro-area CT scanning and AVIZO software processing on the core sample to obtain the first three-dimensional CT model.

[0038] The sample working medium seepage treatment module is used to soak the core sample using a working medium seepage saturation process until the core sample reaches saturation; the core sample reaching saturation means that the liquid permeability of the core sample is constant.

[0039] The second model construction module is used to perform X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model.

[0040] The CT difference determination module is used to determine the CT difference based on the first three-dimensional CT model and the second three-dimensional CT model.

[0041] The feature analysis module is used to determine the changes in the pore structure of the core sample based on the CT difference. At the same time, CT imaging technology is used to analyze the characteristics of the micropore throat structure and pore throat connectivity of sandstone based on the first three-dimensional CT model and the second three-dimensional CT model.

[0042] Since the technical effects achieved by the equipment provided by this invention are the same as those achieved by the above-mentioned analytical method for clay swelling in sandstone-type uranium ore, they will not be described again here. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart of the analytical method for clay swelling in sandstone-type uranium deposits provided by the present invention;

[0045] Figure 2 This is a schematic diagram of a plunger-shaped core CT sample provided in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of an industrial CT clay model provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of a micro-area CT clay model provided in an embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the final core clay model formed by the intersection of industrial CT and micro-area CT models provided in an embodiment of the present invention.

[0049] Figure 6 Flowchart for establishing a three-dimensional CT model of core clay provided in this embodiment of the invention;

[0050] Figure 7 This is a schematic diagram of a three-dimensional clay CT scan model obtained by processing with AVITO software according to an embodiment of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The purpose of this invention is to provide an analytical method and equipment for clay swelling in sandstone-type uranium deposits. This method can precisely describe the swelling properties of clay minerals in different spatial locations and the changes in pore structure in high-clay areas. It can also observe the dissolution and pore changes of uranium minerals encased in clay minerals when in contact with the working medium, thereby providing guidance for the leaching process. This addresses the problems of existing technologies, such as the inability to provide precise descriptions of the local swelling of clay minerals in different regions of core samples under the action of the working medium, and the limited guidance of the swelling rate measured using powdered mineral samples for the in-situ leaching process.

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] like Figure 1 As shown, the analytical method for clay swelling in sandstone-type uranium deposits provided by this invention includes:

[0055] Step 100: Core Sample Preparation. Core samples are prepared from sandstone uranium ore obtained from in-situ core sampling. Based on core logging results and geophysical well interpretation, cylindrical core samples are prepared from sandstone uranium ore with high clay content. Specific core sample preparation requirements are shown in enterprise standard Q / CNNC JB14-2014. The specific preparation process is as follows: 1) Use a core drill and grinding machine to cut the core into cylindrical shapes. 2) Prepare small cylindrical samples with a diameter of 2.5cm or 3.8cm, with a minimum length-to-diameter ratio of 1. 3) For horizontal permeability samples, small cylindrical samples should be drilled parallel to the formation. For vertical permeability samples, they should be drilled perpendicular to the formation bedding plane. The core column should be immediately placed on a core rack marked with horizontal and vertical markings, both ends should be cut flat as required, and the sample should be returned to its original position. 4) Core samples should be dried to constant weight, and the drying time should exceed 4 hours before use. The prepared core samples are shown below. Figure 2 As shown.

[0056] Step 101: The core sample is subjected to X-ray micro-area CT scanning and processed using AVIZO software to obtain the first 3D CT model. For example, the selected CT scanner is a Zeiss Xradia 410 Versa micro-CT scanner. The micro-CT system irradiates the core sample with X-rays. The intensity of the X-rays changes after passing through the material of the core sample. The detector then converts the intensity signal into an image signal, thereby determining the spatial distribution of clay minerals and the pore structure of the core sample. The grayscale value of the image is related to density, thus obtaining 2D CT scan images of different layers. The CT scan images and the 2D micro-area CT scan images are then processed using AVIZO software to obtain the 3D CT model. For example, ... Figure 6 As shown, the AVIZO software processes the data as follows:

[0057] First, CT data was imported into AVIZO software to obtain two-dimensional slice images of different locations in the core sample. Then, clay minerals were segmented using a threshold (with a brightness range of -5233 to 1444) to obtain the distribution of clay in different CT slices of the core in both core CT and micro-area CT. Finally, the intersection of the clay structure from the CT core and micro-area CT was extracted to determine the final three-dimensional CT model of the core clay. After the model was built, AVIZO displayed the percentage of clay volume in the total core volume. Specific modeling results are shown below. Figures 3-5As shown. The resulting 3D CT model is as follows. Figure 7 As shown.

[0058] Step 102: The core sample is treated using a working medium seepage saturation process until it reaches saturation. Saturation of the core sample means that the liquid permeability of the core sample is constant. In this invention, the processing flow for the working medium seepage saturation process using CO2+O2 leaching is as follows: First, CO2 and O2 are reconstituted in an intermediate container to form an alkaline leaching solution with a bicarbonate concentration of 1-3 g / L and a dissolved oxygen content of 200-600 mg / L. Then, an expansion rate test is performed on the sandstone sample using a liquid permeability meter. During the test, the liquid permeability of the core sample is monitored in real time. Once the liquid permeability no longer changes, the core sample is considered to have reached saturation.

[0059] Step 103: Perform X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model. The specific modeling process in this step is consistent with that in Step 101, and simultaneously obtains the percentage content of clay minerals in the overall core after working medium treatment. Specifically, AVIZO software determines the change in the volume fraction of clay minerals in the CT scan after contact with different working media by comparing the changes in the volume occupied by the ball-and-stick model before and after working medium treatment. Based on this volume change, the clay volume expansion rate under the working medium condition is calculated, and the specific calculation formula is shown in Equation 2.

[0060] α=(cps1-cps2) / cps2*100%(2)

[0061] cps1 represents the volume percentage of clay minerals in the CT model (i.e., the first three-dimensional CT model) of the core sample before the experiment, cps-2 represents the volume percentage of clay minerals in the CT model (i.e., the second three-dimensional CT model) of the core sample after the working medium treatment, and α represents the clay volume expansion rate.

[0062] Step 104: Determine the CT difference based on the first 3D CT model and the second 3D CT model.

[0063] Step 105: Determine the changes in pore structure of the core sample based on the CT difference. Simultaneously, use CT imaging technology to analyze the characteristics of the sandstone's micropore-throat structure and pore-throat connectivity based on the first and second 3D CT models. That is, compare the CT scan models of the core sample before and after the leaching agent treatment, and determine the changes in pore structure based on the magnitude of the CT difference. Simultaneously, use CT imaging technology to analyze the characteristics of the low-permeability sandstone's micropore-throat structure and pore-throat connectivity based on the 3D reconstruction of the core before and after the reaction. The specific operation process is as follows: Threshold segmentation is performed on the 3D reconstructed core to extract pores; connected pores are determined using a pore connectivity analysis algorithm; connected pores are segmented to generate a pore mesh model.

[0064] Based on the above description, in terms of evaluating expansion performance, compared with the traditional linear expansion rate evaluation method, this invention targets sandstone uranium ore core samples with high clay content. This invention introduces X-ray micro-area CT scanning technology into the clay expansion evaluation system, providing a refined characterization of clay expansion at different spatial locations at the microscale. Simultaneously, it allows for direct measurement of the original core sample without crushing. Compared to traditional powdered samples, this invention can, on the one hand, precisely describe the expansion performance of clay minerals in different spatial locations and the changes in pore structure in high-clay areas. On the other hand, it can observe the dissolution and pore changes of uranium minerals encapsulated by clay minerals when in contact with the working medium, thus providing guidance for the leaching process, especially for in-situ leaching. This method, through micro-area CT scanning results before and after the experiment, can obtain the volume occupied by clay expansion after treatment with different working media, calculate the clay expansion rate in different regions, and, combined with the bonding form of uranium minerals and clay minerals in the ore, observe the changes in pore connectivity before and after the action of the leaching agent, providing guidance for optimizing the leaching process.

[0065] The following specific embodiment illustrates the advantages of the analytical method for clay swelling in sandstone-type uranium ore provided by the present invention.

[0066] Low permeability is a common problem in many uranium deposits in the Ordos Basin. Process mineralogical analysis results show that the overall content of clay minerals in the samples is relatively high (15-25%), and the clay minerals are mainly expansive montmorillonite (accounting for 75% of the total clay). During in-situ leaching, the leaching agent reacts with the carbonate minerals in the ore layer, and the released calcium and magnesium ions interact with expansive clay minerals such as montmorillonite. The ion exchange reaction with the montmorillonite interlayer causes the clay to expand, which in turn leads to a reduction in pore structure and a decrease in permeability.

[0067] In this region, a sandstone uranium ore sample with high clay content contains 20-25% clay and 60-80% montmorillonite. Formation water was used to conduct a clay swelling experiment. Before the experiment, a uranium ore core sample with high clay content was selected and processed to obtain a cylindrical core sample with a diameter of 2.5 cm and a length of 5 cm. Micro-area CT scanning was performed on this core sample, and clay minerals were labeled in the CT image according to grayscale and brightness ranges, resulting in a three-dimensional CT model of the lithological sample before the experiment.

[0068] The liquid permeability of the lithological samples was determined using a liquid permeability meter. The working medium used in the experiment was an alkaline leaching agent prepared with CO2+O2 (the concentration of bicarbonate in the leaching agent was 2-2.2 g / L, and the dissolved oxygen content was controlled at 400-600 mg / L). The seepage rate was 5 ml / min. The changes in liquid permeability were monitored during the experiment. After the liquid permeability stabilized, the core samples were removed.

[0069] Saturated core samples were structurally scanned using X-ray three-dimensional CT to obtain a micro-area CT scan model after working medium treatment. The volume count points of clay minerals in the CT scan images before and after working medium treatment were measured using data processing software, and the swelling rate of clay minerals under the action of groundwater was obtained according to formula (2).

[0070] In addition, corresponding to the above-mentioned analytical method for clay swelling in sandstone-type uranium ore, the present invention also provides an analytical device for clay swelling in sandstone-type uranium ore, which includes: a sample preparation module, a first model construction module, a sample working medium percolation treatment module, a second model construction module, a CT difference determination module, and a condition feature analysis module.

[0071] The sample preparation module is used to prepare core samples. The core samples are prepared based on sandstone uranium ore obtained from in-situ core sampling.

[0072] The first model construction module is used to perform X-ray micro-area CT scanning on the core sample and process it with AVIZO software to obtain the first three-dimensional CT model.

[0073] The sample working medium permeation treatment module is used to soak core samples using a working medium permeation saturation process until the core samples reach saturation. Core sample saturation means that the liquid permeability of the core sample is constant.

[0074] The second model building module is used to perform X-ray micro-area CT scanning and AVIZO software processing on saturated core samples to obtain a second three-dimensional CT model.

[0075] The CT difference determination module is used to determine the CT difference based on the first 3D CT model and the second 3D CT model.

[0076] The feature analysis module is used to determine the changes in the pore structure of the core sample based on the CT difference. At the same time, CT imaging technology is used to analyze the characteristics of the micropore throat structure and pore throat connectivity of sandstone based on the first three-dimensional CT model and the second three-dimensional CT model.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0078] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An analytical method for clay swelling in sandstone-type uranium deposits, characterized in that, include: Preparation of core samples; The core samples were prepared based on sandstone uranium ore cored in the field. The core sample was subjected to X-ray micro-area CT scanning and AVIZO software processing to obtain the first three-dimensional CT model; The core samples were soaked in a working medium saturation process until they reached saturation. Saturation of the core sample means that the liquid permeability of the core sample is constant. The working medium saturation process is a CO2+O2 leaching process. The process is as follows: First, CO2 and O2 are reconstituted in an intermediate container to form an alkaline leaching solution with a bicarbonate concentration of 1-3 g / L and a dissolved oxygen content of 200-600 mg / L. Then, the sandstone samples are subjected to an expansion rate test using a liquid permeability meter. The liquid permeability of the core samples is monitored in real time during the test. The core sample is considered to have reached saturation when the liquid permeability no longer changes. The core sample that has reached saturation was subjected to X-ray micro-area CT scanning and AVIZO software processing to obtain a second three-dimensional CT model; The CT difference is determined based on the first 3D CT model and the second 3D CT model; The changes in the pore structure of the core sample are determined based on the CT difference. At the same time, CT imaging technology is used to analyze the characteristics of the micropore throat structure and pore throat connectivity of sandstone based on the first three-dimensional CT model and the second three-dimensional CT model. The process of obtaining a 3D CT model using AVIZO software is as follows: Import the CT scan image and the 2D CT scan image into AVIZO software to obtain 2D slice images of different locations of the core sample; Threshold segmentation of clay minerals reveals the distribution of clay in core CT and micro-area CT in different CT slices of the core; The intersection of clay structures in core CT and micro-area CT is extracted to determine the final three-dimensional CT model of core clay.

2. The analytical method for clay swelling in sandstone-type uranium deposits according to claim 1, characterized in that, The process of performing X-ray micro-area CT scanning and AVIZO software processing on the core sample to obtain the first three-dimensional CT model specifically includes: The core sample was subjected to X-ray micro-area CT scanning to obtain the first CT scan image; Based on the first CT scan image, first two-dimensional CT scan images at different layers are obtained; The first three-dimensional CT model is obtained by processing the first CT scan image and the first two-dimensional CT scan image using AVIZO software.

3. The analytical method for clay swelling in sandstone-type uranium deposits according to claim 2, characterized in that, The process of performing X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model specifically includes: The core sample that has reached saturation was subjected to X-ray micro-area CT scanning to obtain a second CT scan image; Based on the second CT scan image, second two-dimensional CT scan images at different slice levels are obtained; The second 3D CT model was obtained by processing the second CT scan image and the second 2D CT scan image using AVIZO software.

4. The analytical method for clay swelling in sandstone-type uranium deposits according to claim 3, characterized in that, After obtaining a second three-dimensional CT model by performing X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample, the process also includes: The clay volume expansion rate of the core sample is determined based on the volume percentage of clay minerals in the first two-dimensional CT scan and the volume percentage of clay minerals in the second two-dimensional CT scan.

5. The analytical method for clay swelling in sandstone-type uranium deposits according to claim 1, characterized in that, Using CT imaging technology, the microscopic pore throat structure and pore throat connectivity characteristics of sandstone are analyzed based on the first three-dimensional CT model and the second three-dimensional CT model. Specifically, this includes: thresholding the first three-dimensional CT model and the second three-dimensional CT model to extract pores, using a pore connectivity analysis algorithm to determine connected pores, segmenting the connected pores, and generating a pore mesh model.

6. An analytical apparatus for analyzing clay swelling in sandstone-type uranium deposits, characterized in that, The analytical apparatus for analyzing clay swelling in sandstone-type uranium deposits is used to implement the analytical method for clay swelling in sandstone-type uranium deposits as described in any one of claims 1-5; the apparatus includes: A sample preparation module is used to prepare core samples; the core samples are prepared based on sandstone uranium ore obtained from in-situ core sampling. The first model construction module is used to perform X-ray micro-area CT scanning and AVIZO software processing on the core sample to obtain the first three-dimensional CT model. The sample working medium seepage treatment module is used to treat core samples using a working medium seepage saturation process until the core sample reaches saturation; the core sample reaching saturation means that the liquid permeability of the core sample is constant. The second model construction module is used to perform X-ray micro-area CT scanning and AVIZO software processing on the saturated core sample to obtain a second three-dimensional CT model. The CT difference determination module is used to determine the CT difference based on the first three-dimensional CT model and the second three-dimensional CT model. The feature analysis module is used to determine the changes in the pore structure of the core sample based on the CT difference. At the same time, CT imaging technology is used to analyze the characteristics of the micropore throat structure and pore throat connectivity of sandstone based on the first three-dimensional CT model and the second three-dimensional CT model.

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