Methods, apparatus, equipment, and media for determining CO2 breakthrough pressure in mudstone caprock.

Abstract

The application discloses a method and device for determining CO2 breakthrough pressure of mudstone cap rock, equipment and medium. The method comprises the following steps: scanning and reconstructing the mudstone sample according to the peak pore diameter of the macropore and / or micropore of the clay in the mudstone sample, determining the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel; extracting the three-dimensional pore network and the basic geometric information of the pore throat according to the reconstructed pore structure for the macropore or micropore determined as the main control seepage channel; and determining the CO2 breakthrough pressure of the mudstone cap rock by two-phase quasi-static displacement simulation according to the three-dimensional pore network and the basic geometric information of the pore throat. The technical scheme can quickly and effectively determine the CO2 breakthrough pressure of the mudstone cap rock.

Description

Technical Field

[0001] This application relates to the field of digital rock physics technology, and in particular to a method, apparatus, equipment and medium for determining the CO2 breakthrough pressure of mudstone caprock. Background Technology

[0002] CO2 geological sequestration refers to the process of capturing and continuously injecting large amounts of CO2 generated by human activities into geological storage bodies (such as oil fields, natural gas reservoirs, saline formations, or unminable coal seams). To ensure the feasibility and safety of CO2 geological sequestration, the sealing performance assessment of mudstone caprocks is crucial. The sealing performance assessment indicators for mudstone caprocks include the water-rock reaction of saturated CO2-water, the mechanical fatigue damage of the caprock under cyclic injection, and the caprock capillary force breakthrough pressure. Among these, the caprock capillary force breakthrough pressure directly determines the reservoir pressure control during CO2 injection and the maximum plume height for CO2 geological sequestration in the reservoir.

[0003] Currently, laboratory methods for measuring CO2 breakthrough pressure in mudstone caprock typically rely on in-situ simulations based on pressure balance techniques at the inlet and outlet of test cores. However, this method is time-consuming, costly, and lacks repeatability. Additionally, high-pressure mercury intrusion porosimetry (HIP) has been used to indirectly estimate CO2 breakthrough pressure in mudstone caprock, but this method suffers from significant uncertainty and lacks theoretical support.

[0004] Therefore, how to provide a technical solution that can quickly and effectively determine the CO2 breakthrough pressure of mudstone caprock is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, and medium for determining the CO2 breakthrough pressure of mudstone caprock, which can quickly and effectively determine the CO2 breakthrough pressure of mudstone caprock.

[0006] According to one aspect of this application, a method for determining the CO2 breakthrough pressure of a mudstone caprock is provided, the method comprising:

[0007] Based on the peak pore size of clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the main control seepage channels of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channels.

[0008] For macropores or micropores that are identified as the main control seepage channels, three-dimensional pore networks and basic geometric information of pore throats are extracted based on the reconstructed pore structure.

[0009] Based on the three-dimensional pore network and the basic geometric information of the pore throat, a two-phase quasi-static displacement simulation was performed to determine the CO2 breakthrough pressure of the mudstone caprock.

[0010] According to another aspect of this application, a device for determining the CO2 breakthrough pressure of a mudstone caprock is provided, the device comprising:

[0011] The main control seepage channel determination module is used to scan and reconstruct the mudstone sample based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, and determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel.

[0012] The pore network extraction module is used to extract the three-dimensional pore network and basic geometric information of the pore throat based on the reconstructed pore structure for macropores or micropores that are identified as the main control seepage channels.

[0013] The CO2 breakthrough pressure determination module is used to perform two-phase quasi-static displacement simulation based on the three-dimensional pore network and the basic geometric information of the pore throat to determine the CO2 breakthrough pressure of the mudstone caprock.

[0014] According to another aspect of this application, a device for determining the CO2 breakthrough pressure of a mudstone caprock is provided, the device comprising:

[0015] At least one processor; and

[0016] A memory communicatively connected to the at least one processor; wherein,

[0017] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the method for determining the CO2 breakthrough pressure of mudstone caprock according to any embodiment of this application.

[0018] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the method for determining the CO2 breakthrough pressure of mudstone caprock as described in any embodiment of this application.

[0019] The technical solution provided in this application involves scanning and reconstructing mudstone samples based on the peak pore size of clay macropores and / or micropores to determine the dominant seepage channels and the corresponding reconstructed pore structures. For the macropores or micropores identified as dominant seepage channels, a three-dimensional pore network and basic geometric information of the pore throats are extracted based on the reconstructed pore structures. Based on the three-dimensional pore network and basic geometric information of the pore throats, a two-phase quasi-static displacement simulation is performed to determine the CO2 breakthrough pressure of the mudstone caprock. This technical solution can quickly and effectively determine the CO2 breakthrough pressure of the mudstone caprock.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating a method for determining the CO2 breakthrough pressure in a mudstone caprock according to Embodiment 1 of the present invention;

[0023] Figure 2 A flowchart illustrating a method for determining the CO2 breakthrough pressure of a mudstone caprock according to Embodiment 2 of the present invention;

[0024] Figure 3 A flowchart illustrating a method for determining the CO2 breakthrough pressure of a mudstone caprock according to Embodiment 2 of the present invention;

[0025] Figure 4 This is a schematic diagram of a low-resolution SEM scan provided in Embodiment 2 of the present invention;

[0026] Figure 5 This is a schematic diagram of a high-resolution SEM scan provided in Embodiment 2 of the present invention;

[0027] Figure 6 This is an aperture distribution diagram provided in Embodiment 2 of the present invention;

[0028] Figure 7 This is a schematic diagram of a large-pore reconstructed pore structure provided in Embodiment 2 of the present invention;

[0029] Figure 8 This is a schematic diagram of a FIB-SEM scan provided in Embodiment 2 of the present invention;

[0030] Figure 9 This is a three-dimensional digital core image provided in Embodiment 2 of the present invention;

[0031] Figure 10 This is a schematic diagram of a three-dimensional pore network provided in Embodiment 2 of the present invention;

[0032] Figure 11 This is a pore diameter distribution diagram provided in Embodiment 2 of the present invention;

[0033] Figure 12This is a modified pore diameter distribution diagram provided in Embodiment 2 of the present invention;

[0034] Figure 13 This is a schematic diagram of a three-dimensional pore network during supercritical CO2 breakthrough in a non-wetting phase, provided in Embodiment 2 of the present invention.

[0035] Figure 14 This is a schematic diagram of CO2 breakthrough pressure during a displacement process provided in Embodiment 2 of the present invention;

[0036] Figure 15 This is a schematic diagram of a device for determining the CO2 breakthrough pressure of a mudstone caprock, according to Embodiment 3 of this application.

[0037] Figure 16 This is a schematic diagram of the device used to implement a method for determining the CO2 breakthrough pressure of a mudstone caprock according to an embodiment of this application. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0039] It should be noted that the terms "first," "second," "candidate," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] Example 1

[0041] Figure 1 This is a flowchart illustrating a method for determining the CO2 breakthrough pressure of a mudstone caprock according to Embodiment 1 of the present invention. This embodiment is applicable to determining the CO2 breakthrough pressure of a mudstone caprock. The method can be executed by a device for determining the CO2 breakthrough pressure of a mudstone caprock. This device can be implemented in hardware and / or software and can be configured in a device with data processing capabilities. Figure 1 As shown, the method includes:

[0042] S110. Based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel.

[0043] Mudstone samples can be obtained from the mudstone caprock through methods such as drilling. The main control seepage channels are those with high permeability and strong conductivity within the mudstone caprock.

[0044] It is understandable that mudstone caprocks are composed of inorganic minerals, organic matter, and water, forming a complex system. Inorganic minerals include clay, carbonates, quartz, and feldspar, and the structural characteristics of clay, to a certain extent, determine the capillary sealing capacity of the mudstone caprock. The pores between inorganic mineral particles are typically micron-sized macropores, while the clay matrix is ​​rich in nano-sized micropores. These different pore structures determine the dominant seepage channels of the mudstone caprock, which in turn determine the capillary sealing capacity of the caprock.

[0045] Specifically, the peak pore size of clay macropores and / or micropores in mudstone samples can be determined through the following process: the mudstone sample is cut into thin slices of 8*8*3 size and the surface is polished with argon ions; the polished mudstone sample is subjected to low-temperature nitrogen adsorption and high-pressure mercury intrusion experiments to obtain the full-size pore size distribution of clay pores, and then the peak pore size of clay macropores and / or micropores can be determined.

[0046] It should be noted that when performing SEM scanning on polished mudstone samples, low-resolution SEM images can be used to determine the spatial distribution of macropores and clay minerals rich in micropores, followed by high-resolution SEM images to determine the shape, size, and distribution characteristics of the clay mineral micropores. Furthermore, after obtaining the peak pore size of the clay macropores and / or micropores, the pore distribution characteristics of the clay obtained from the SEM scan can be compared with the peak pore size to determine if the observation results are consistent. If they are inconsistent, a new mudstone sample should be obtained.

[0047] In this embodiment of the invention, an appropriate CT scan resolution can be selected based on the peak pore size of macropores and / or micropores in the mudstone sample. The mudstone sample is then subjected to CT scan to obtain CT scan images. The CT scan images are then subjected to filtering and noise reduction, threshold segmentation, and three-dimensional reconstruction processing in sequence to obtain the reconstructed pore structure of macropores and / or micropores. The main control flow channel of the mudstone sample is then determined based on the reconstructed pore structure of macropores and / or micropores.

[0048] S120. For the macropores or micropores that are determined to be the main control seepage channels, extract the three-dimensional pore network and basic geometric information of the pore throat based on the reconstructed pore structure.

[0049] The three-dimensional pore network can be abstracted from the reconstructed pore structure into a network model composed of pores and throats. The basic geometric information of the pore throats may include the incircle diameter, circumcircle diameter, volume, cross-sectional shape factor, and connectivity.

[0050] In this embodiment of the invention, pore network extraction algorithms such as the watershed algorithm, the central axis algorithm, the watershed-central axis algorithm, the maximum sphere filling algorithm, and the central axis surface algorithm can be used to extract the three-dimensional pore network and basic geometric information of the pore throat from the reconstructed pore structure of the large or micro pores that are determined to be the main control seepage channels.

[0051] In this embodiment of the invention, the representativeness of the reconstructed pore structure obtained after scanning and reconstruction in step S110 can be determined by comparing the basic geometric information of the pore throat with the peak pore diameter of the large or micro pores that are determined to be the main control flow channel.

[0052] S130. Based on the three-dimensional pore network and the basic geometric information of the pore throat, perform a two-phase quasi-static displacement simulation to determine the CO2 breakthrough pressure of the mudstone caprock.

[0053] The two-phase quasi-static displacement simulation can be described as the process of displacement between the wetting and non-wetting phases under a certain pressure. In this embodiment of the invention, the three-dimensional pore network can be a quasi-static pore model. The quasi-static model is a pore network model that does not consider viscosity and is entirely controlled by capillary forces, while the dynamic model is a pore network model that considers both viscosity and capillary forces. Therefore, this embodiment of the invention can perform two-phase quasi-static displacement simulation based on the three-dimensional pore network and the basic geometric information of the pore throat, which can improve the accuracy of determining the CO2 breakthrough pressure of the mudstone caprock.

[0054] It should be noted that two-phase quasi-static displacement simulations can also be performed using models such as Lattice Boltzmann Method (LBM), Volume of Fluid (VOF), and Pore Morphology (PM).

[0055] As an optional but non-limiting implementation, based on the three-dimensional pore network and the basic geometric information of the pore throat, a two-phase quasi-static displacement simulation is performed to determine the CO2 breakthrough pressure of the mudstone caprock, including but not limited to the following steps A1-A2:

[0056] Step A1: Based on the three-dimensional pore network and the basic geometric information of the pore throat, construct a supercritical CO2-salt water two-phase quasi-static displacement model.

[0057] It is understandable that CO2 exists in four phases under different temperatures and pressures: gas, liquid, solid, and supercritical. Among them, CO2 reaches the supercritical state when the temperature is above 31.1℃ and the pressure is above 7.38MPa.

[0058] As an optional but non-limiting implementation, a supercritical CO2-brittle water two-phase quasi-static displacement model is constructed based on the three-dimensional pore network and the basic geometric information of the pore throat, including but not limited to the following steps B1-B2:

[0059] Step B1: Correct the pore radius in the basic geometric information of the pore throat according to the effective stress of the mudstone sample to obtain the pore correction radius.

[0060] The effective stress can be the contact stress between particles in the mudstone sample, which can be determined based on the burial depth of the caprock in the mudstone sample.

[0061] In this embodiment of the invention, the pore correction radius can be determined according to the following formula:

[0062]

[0063] Where r is the pore correction radius, r0 is the pore radius, p1 is the effective stress measured when the pore is completely closed, and σ eff The effective stress, σ, is measured in situ from the mudstone sample. eff0 denoted as the effective stress measured during imaging scanning of the mudstone sample, and m as the roughness coefficient of the pore surface.

[0064] Of course, the present invention does not limit the method of determining the pore correction radius, and it can also be determined according to other empirical correction formulas.

[0065] Step B2: Based on the three-dimensional pore network, the basic geometric information of the pore throat, the pore correction radius, the preset empirical parameters, and the clay mineral composition in the mudstone sample, construct a supercritical CO2-saltwater two-phase quasi-static displacement model.

[0066] The clay mineral composition can be determined using XRD (Diffraction of X-rays) whole-rock and clay mineral analysis experiments. Preset empirical parameters can include, for example, displacement contact angle and surface tension.

[0067] In this embodiment of the invention, the three-dimensional pore network, basic geometric information of pore throats, pore correction radius, preset empirical parameters, and clay mineral composition in mudstone samples can be used as boundary conditions to set the supercritical CO2-saltwater two-phase quasi-static displacement model, and then the supercritical CO2-saltwater two-phase quasi-static displacement model can be constructed based on each boundary condition.

[0068] Specifically, the process of determining the boundary conditions is as follows: First, isolated pore throat units in the three-dimensional pore network are removed, and inlet and outlet pore throat units are added along the flow direction; second, the surface tension is set according to the fluid properties of the simulated two phases, and the displacement contact angle is randomly assigned to each pore throat unit according to the clay mineral composition in the mudstone sample; finally, the squeezing pressure of the pore throat is calculated according to the MS-P theory.

[0069] The beneficial effect of the above technical solution is that it refines the pore network construction process of the main control seepage channel of the caprock and improves the accuracy of the supercritical CO2-saltwater two-phase quasi-static displacement model.

[0070] Step A2: Perform a two-phase quasi-static displacement simulation on the supercritical CO2-saltwater two-phase quasi-static displacement model to determine the CO2 breakthrough pressure of the mudstone caprock.

[0071] Specifically, the intrusion-percolation model algorithm can be used to simulate the two-phase quasi-static displacement of the supercritical CO2-brine two-phase quasi-static displacement model. That is, an intrusion pressure is applied at the inlet pore throat unit of the supercritical CO2-brine two-phase quasi-static displacement model, and the pressure at which the non-wetting supercritical CO2 breaks through to the outlet pore throat unit of the supercritical CO2-brine two-phase quasi-static displacement model is taken as the CO2 breakthrough pressure of the mudstone caprock.

[0072] The beneficial effect of the above technical solution is that by constructing a supercritical CO2-saltwater two-phase quasi-static displacement model to realize two-phase quasi-static displacement simulation, it is beneficial to quickly and effectively determine the CO2 breakthrough pressure of the mudstone caprock.

[0073] This invention provides a method for determining the CO2 breakthrough pressure of mudstone caprock. The method involves scanning and reconstructing the mudstone sample based on the peak pore size of the clay macropores and / or micropores to identify the dominant seepage channels and the corresponding reconstructed pore structures. For the macropores or micropores identified as the dominant seepage channels, a three-dimensional pore network and basic geometric information of the pore throats are extracted based on the reconstructed pore structures. Based on the three-dimensional pore network and basic geometric information of the pore throats, a two-phase quasi-static displacement simulation is performed to determine the CO2 breakthrough pressure of the mudstone caprock. This technical solution overcomes the disadvantages of long laboratory measurement times, high costs, and poor repeatability of CO2 breakthrough pressure. By combining conventional experimental methods, image analysis techniques, and pore-scale numerical simulation methods, it can quickly and effectively determine the CO2 breakthrough pressure of mudstone caprock, laying the foundation for research on multi-scale seepage mechanics mechanisms.

[0074] Example 2

[0075] Figure 2This is a flowchart illustrating a method for determining the CO2 breakthrough pressure of a mudstone caprock according to Embodiment 2 of the present invention. This embodiment is an optimization based on the above embodiment. Figure 2 As shown, the method in this embodiment specifically includes the following steps:

[0076] S210. Based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the reconstructed pore structure of the macropores and / or micropores.

[0077] Specifically, the reconstructed pore structure of macropores and / or micropores can be obtained by CT scanning electron microscopy and then reconstructed.

[0078] As an optional but non-limiting implementation, the mudstone sample is scanned and reconstructed based on the peak pore size of the clay macropores and / or micropores in the mudstone sample to determine the reconstructed pore structure of the macropores and / or micropores, including but not limited to the following steps C11-C22:

[0079] Step C11: Determine the first scanning resolution corresponding to the peak pore size of the clay macropores in the mudstone sample.

[0080] The first scanning resolution can be the resolution at which the clay macropores in the mudstone sample can be clearly identified during scanning. In this embodiment of the invention, a suitable first scanning resolution is determined based on the peak pore size of the clay macropores in the mudstone sample to ensure the scanning accuracy and precision of the clay macropores in the mudstone sample.

[0081] Specifically, the first scan resolution can be one-tenth to one-third of the peak aperture of the macropore. For example, if the peak aperture of the macropore is 7 micrometers, then the first scan resolution can be 1 micrometer.

[0082] Step C12: Based on the first scanning resolution, scan and reconstruct the mudstone sample to determine the reconstructed pore structure of the macropores.

[0083] Specifically, the mudstone sample is scanned according to the first scanning resolution to obtain a scanned image of the clay macropores in the mudstone sample. The scanned image can then be filtered for noise reduction, thresholded for segmentation, and reconstructed in three dimensions to obtain a reconstructed image of the macropores. The reconstructed pore structure of the macropores is then determined based on the reconstructed image.

[0084] And / or, step C21, determine the second scanning resolution corresponding to the peak pore size of the clay micropores in the mudstone sample.

[0085] The second scanning resolution is the resolution at which clay micropores in the mudstone sample can be clearly identified during scanning. In this embodiment of the invention, a suitable second scanning resolution is determined based on the peak pore size of the clay micropores in the mudstone sample to ensure the scanning accuracy and precision of the clay micropores in the mudstone sample.

[0086] Specifically, the second scanning resolution can be one-tenth to one-third of the peak pore size of the micropore. For example, if the peak pore size of the micropore is 30 nanometers, then the second scanning resolution can be 10 nanometers.

[0087] Step C22: Scan and reconstruct the mudstone sample according to the second scanning resolution to determine the reconstructed pore structure of the micropores.

[0088] Specifically, the mudstone sample is scanned according to the second scanning resolution to obtain a scanned image of clay micropores in the mudstone sample. The scanned image can be filtered and denoised, thresholded and segmented, and three-dimensionally reconstructed in sequence to obtain a reconstructed image of the micropores. The reconstructed pore structure of the micropores is determined based on the reconstructed image.

[0089] It should be noted that, in the embodiments of the present invention, scanning reconstruction can be performed on both macropores and micropores simultaneously, or only on macropores, or only on micropores. The embodiments of the present invention do not limit this.

[0090] S220. Based on the reconstructed pore structure of the macropores and / or micropores, determine the candidate connectivity results of the macropores and / or micropores.

[0091] Among them, connectivity results can be parameters characterizing the fluid flow capacity between pores. For example, connectivity results can be the pore-throat coordination number, that is, the number of throats connecting each pore; or, for another example, connectivity results can be the pore-throat average diameter ratio, that is, the ratio of the average diameter of the pore to the average diameter of the throat, reflecting the size difference between the pore and the throat.

[0092] For example, based on the reconstructed pore structure of macropores and / or micropores, the average throat coordination number of a predetermined number of pores in the reconstructed pore structure of macropores and / or micropores can be determined, and the average throat coordination number can be used as a candidate connectivity result for macropores and / or micropores. As another example, based on the reconstructed pore structure of macropores and / or micropores, the average throat diameter ratio of a predetermined number of pores in the reconstructed pore structure of macropores and / or micropores can be determined, and the average throat diameter ratio can be used as a candidate connectivity result for macropores and / or micropores.

[0093] S230. Based on the candidate connectivity results of the macropores and / or micropores, determine the main control flow channel of the mudstone sample and the reconstructed pore structure corresponding to the main control flow channel.

[0094] Specifically, the better the candidate connectivity result, the higher the permeability and the stronger the conductivity of the pores corresponding to that connectivity. When the candidate connectivity result meets certain conditions, the pores corresponding to that candidate connectivity result can be determined as the main control flow channels of the mudstone sample.

[0095] As an optional but non-limiting implementation, determining the main control flow channel of the mudstone sample based on the candidate connectivity results of the macropores and / or micropores includes: if the candidate connectivity results of the macropores meet a preset connectivity condition, then the main control flow channel of the mudstone sample is determined to be a macropore; or, if the candidate connectivity results of the micropores meet a preset connectivity condition, then the main control flow channel of the mudstone sample is determined to be a micropore; or, if both the candidate connectivity results of the macropores and the candidate connectivity results of the micropores meet the preset connectivity condition, then the main control flow channel of the mudstone sample is determined to be a macropore.

[0096] Specifically, if step S210 only scans and reconstructs the mudstone sample based on the peak pore size of the clay macropores in the mudstone sample, then when the candidate connectivity results of the macropores meet the preset connectivity conditions, it can be determined that the main control flow channel of the mudstone sample is a macropore. When the candidate connectivity results of the macropores do not meet the preset connectivity conditions, it can be determined that the main control flow channel of the mudstone sample is not a macropore and is not necessarily a micropore, and further analysis of the micropores is required.

[0097] Alternatively, if step S210 only scans and reconstructs the mudstone sample based on the peak pore size of clay micropores in the mudstone sample, then when the candidate connectivity results of the micropores meet the preset connectivity conditions, it can be determined that the main control flow channel of the mudstone sample is a micropore; when the candidate connectivity results of the micropores do not meet the preset connectivity conditions, it can be determined that the main control flow channel of the mudstone sample is not a micropore and is not necessarily a macropore, and further analysis of the macropores is required.

[0098] Alternatively, if in step S210 the mudstone sample is scanned and reconstructed based on the peak pore size of macropores and clay micropores in the mudstone sample, respectively, and candidate connectivity results of macropores and micropores are obtained, then when both candidate connectivity results of macropores and micropores meet the preset connectivity conditions, the main control flow channel of the mudstone sample can be determined to be macropores; when neither candidate connectivity results of macropores nor candidate connectivity results of micropores meet the preset connectivity conditions, the mudstone sample can be re-acquired.

[0099] As an optional but non-limiting implementation, the mudstone sample is scanned and reconstructed based on the peak pore size of clay macropores and / or micropores in the mudstone sample to determine the reconstructed pore structure corresponding to the main control flow channel. This includes: if scanning and reconstructing the mudstone sample based on the peak pore size of clay macropores in the mudstone sample determines that the main control flow channel of the mudstone sample is not a macropore, then scanning and reconstructing the mudstone sample based on the peak pore size of clay micropores in the mudstone sample yields the reconstructed pore structure of the micropores; if scanning and reconstructing the mudstone sample based on the peak pore size of clay micropores in the mudstone sample determines that the main control flow channel of the mudstone sample is not a micropore, then scanning and reconstructing the mudstone sample based on the peak pore size of clay macropores in the mudstone sample yields the reconstructed pore structure of the macropores.

[0100] Specifically, reconstructing the pore structure of clay macropores in mudstone samples only determines whether macropores are the primary control seepage channels, not whether micropores are. Similarly, reconstructing the pore structure of clay micropores in mudstone samples only determines whether micropores are the primary control seepage channels, not whether macropores are. Therefore, when the primary control seepage channel cannot be determined solely based on the reconstructed pore structure of macropores or micropores, it is necessary to scan and reconstruct another type of pore to obtain its reconstructed pore structure, and then analyze whether this other type of pore is the primary control seepage channel.

[0101] S240. For the macropores or micropores that are determined to be the main control seepage channels, extract the three-dimensional pore network and basic geometric information of the pore throat based on the reconstructed pore structure.

[0102] S250. Based on the three-dimensional pore network and the basic geometric information of the pore throat, perform a two-phase quasi-static displacement simulation to determine the CO2 breakthrough pressure of the mudstone caprock.

[0103] This invention provides a method for determining the CO2 breakthrough pressure of a mudstone caprock. The method involves scanning and reconstructing the mudstone sample based on the peak pore size of the clay macropores and / or micropores to determine the reconstructed pore structure of the macropores and / or micropores; determining candidate connectivity results for the macropores and / or micropores based on the reconstructed pore structure; identifying the main control flow channels and corresponding reconstructed pore structures based on the candidate connectivity results; extracting three-dimensional pore network and basic pore throat geometry information for the macropores or micropores identified as the main control flow channels based on the reconstructed pore structure; and performing a two-phase quasi-static displacement simulation based on the three-dimensional pore network and basic pore throat geometry information to determine the CO2 breakthrough pressure of the mudstone caprock. This technical solution combines multiple pore structure characterization techniques, such as XRD, mercury porosimetry, SEM, and micro / nano CT scanning, to define the main control flow channels for CO2 breakthrough in the multi-scale pore structure of mudstone, thereby improving the accuracy of determining the CO2 breakthrough pressure of mudstone caprock.

[0104] Taking a marine mudstone caprock with a burial depth of 1671m as an example, the process of determining the CO2 breakthrough pressure of this mudstone caprock is explained. Figure 3 This is a schematic diagram of a marine mudstone caprock core sample provided in Embodiment 2 of the present invention. Specifically, the process of determining the CO2 breakthrough pressure of the mudstone caprock includes the following steps:

[0105] The first step was to cut a portion of the core sample and grind it into 1mm particles for XRD whole-rock and clay mineral analysis. The results showed that the clay content in the mudstone was 16.5%, and the main clay components were illite-montmorillonite mixed layer and illite, both of which are strong water minerals.

[0106] The second step involves cutting a portion of the sample from the core sample and wire-cutting it into 8×8×3mm mudstone samples. The surface of the mudstone samples is then subjected to argon ion polishing, and the treated mudstone samples are then scanned using SEM.

[0107] Specifically, firstly, the processed mudstone sample was scanned using SEM at a resolution of 300 micrometers to obtain a low-resolution scan image. Figure 4 This is a schematic diagram of a low-resolution SEM scan provided in Embodiment 2 of the present invention, as shown below. Figure 4 As shown, clay minerals are mainly found filling the spaces between rock particles, with scattered micron-sized pores. Next, the processed mudstone sample was scanned using SEM at a resolution of 10 micrometers, yielding a high-resolution image. Figure 5 This is a schematic diagram of a high-resolution SEM scan provided in Embodiment 2 of the present invention, as shown below. Figure 5 As shown, it can be observed that the clay mineral is rich in nanopores, with the pore size mainly concentrated between tens and hundreds of nanometers.

[0108] The third step involves obtaining a full-size pore distribution map of the mudstone sample based on low-temperature nitrogen adsorption and high-pressure mercury intrusion experiments.

[0109] Figure 6 An aperture distribution diagram provided in Embodiment 2 of the present invention, such as Figure 6 As shown, the pore size distribution of the mudstone sample exhibits a distinct bimodal phenomenon, with the peak pore sizes of macropores and micropores being 7 micrometers and 30 nanometers, respectively.

[0110] The fourth step is to determine the first scanning resolution corresponding to the peak pore size of the clay macropores in the mudstone sample as 1 micrometer based on the peak pore size. The mudstone sample is then subjected to CT scanning at a resolution of 1 micrometer. The obtained CT scan image is then processed sequentially with filtering for coarse noise reduction, threshold segmentation, and three-dimensional reconstruction to obtain the reconstructed pore structure of the macropores.

[0111] Figure 7 This is a schematic diagram of a macroporous reconstructed pore structure provided in Embodiment 2 of the present invention, as shown below. Figure 7 As shown, there are no connected channels, and the connectivity of the macropores is poor. Therefore, the macropores are not the main control flow channels in the mudstone caprock.

[0112] Step 5: Based on the peak pore size of clay micropores in the mudstone sample, determine the second scanning resolution corresponding to the peak pore size as 9 nanometers. Perform FIB-SEM (Focused Ion Beam-Scanning Electron Microscope) scanning on the mudstone sample at a resolution of 9 nanometers, and process the obtained scan images to obtain the reconstructed pore structure of the micropores.

[0113] First, it can be based on Figure 5 A representative target scanning area is selected from the high-resolution scan image obtained by scanning, and FIB-SEM scanning is performed on the target scanning area to obtain a schematic diagram of FIB-SEM scanning. Figure 8 This is a schematic diagram of a FIB-SEM scan provided in Embodiment 2 of the present invention, as shown below. Figure 8 As shown in Figure 8, the dimensions are 2670 x 2179 pixels, resulting in a total of 1072 images.

[0114] Secondly, image calibration is performed on the FIB-SEM scan to eliminate errors caused by image drift during the scanning process.

[0115] Secondly, to reduce computational load and remove large rock particles, the calibrated image was cropped to a subdomain of 1524×453×490 pixels (i.e., 13.2×4.1×4.4μm). 3 First, filter the extracted area to eliminate the "curtain" noise.

[0116] Secondly, threshold segmentation is performed on the filtered and eliminated image to extract the pore structure and obtain a three-dimensional digital core image. Figure 9 A three-dimensional digital core image is provided in Embodiment 2 of the present invention, such as Figure 9 As shown, micropores have good connectivity, but due to the complexity of their structure, it is difficult to quantitatively describe their pore size distribution.

[0117] Finally, the SNOW algorithm was used to extract the equivalent three-dimensional pore network and basic geometric information of the pore throat of the pore structure. Figure 10 This is a schematic diagram of a three-dimensional pore network provided in Embodiment 2 of the present invention. Figure 11 This is a pore diameter distribution diagram provided in Embodiment 2 of the present invention, as shown below. Figure 11 As shown, with Figure 6 The distribution of micropores in the obtained pore size distribution map is basically consistent, which proves that the scanning area is representative.

[0118] Step 6: Based on the extracted three-dimensional pore network, conduct a two-phase quasi-static displacement simulation to determine the breakthrough pressure of CO2 in the mudstone caprock.

[0119] First, the effective stress is determined based on the burial depth of the mudstone cap layer, and the pore diameter in the three-dimensional pore network is corrected using the geostress correction formula; Figure 12 This is a modified pore diameter distribution diagram provided in Embodiment 2 of the present invention, as shown below. Figure 12 As shown, the corrected pore diameter is mainly concentrated between 5-30 nm, compared to Figure 11 The pore diameter before the correction was significantly reduced.

[0120] Secondly, isolated pore units in the modified pore network are removed, and inlet and outlet pore units are added along the flow direction.

[0121] Secondly, the two phases were simulated as carbon dioxide and brine, with a surface tension of 48.3 mN / m. The main mineral components of the main control seepage channel region were illite and illite-montmorillonite mixed layers, and each pore throat unit was randomly assigned a displacement contact angle between 0° and 30°.

[0122] Finally, the intrusion pressure of the pore throat was calculated using the MS-P theory, and the displacement of the two phases in the pore network was numerically simulated using the intrusion-percolation model algorithm. The pressure when the supercritical CO2 of the non-wetting phase breaks through to the outlet end of the pore network was taken as the CO2 breakthrough pressure of the mudstone caprock. Figure 13 This is a schematic diagram of a three-dimensional pore network during supercritical CO2 breakthrough in a non-wetting phase, provided in Embodiment 2 of the present invention. In this diagram, black represents pores that have been broken through by CO2, and white represents pores occupied by brine. Figure 14 This is a schematic diagram of the CO2 breakthrough pressure during the displacement process provided in Embodiment 2 of the present invention, combined with... Figure 13 and Figure 14 The CO2 breakthrough pressure of the mudstone caprock can be determined to be 9.4 MPa.

[0123] Example 3

[0124] Figure 15 This is a schematic diagram of a device for determining the CO2 breakthrough pressure of a mudstone caprock, provided in Embodiment 3 of this application. Figure 15 As shown, the device includes:

[0125] The main control seepage channel determination module 310 is used to scan and reconstruct the mudstone sample based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, and determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel.

[0126] The pore network extraction module 320 is used to extract the three-dimensional pore network and basic geometric information of the pore throat based on the reconstructed pore structure for macropores or micropores that are determined to be the main control seepage channels.

[0127] The CO2 breakthrough pressure determination module 330 is used to perform two-phase quasi-static displacement simulation based on the three-dimensional pore network and the basic geometric information of the pore throat to determine the CO2 breakthrough pressure of the mudstone caprock.

[0128] This invention provides a device for determining the CO2 breakthrough pressure of mudstone caprock. The device scans and reconstructs mudstone samples based on the peak pore size of clay macropores and / or micropores, identifying the dominant seepage channels and the corresponding reconstructed pore structures. For the macropores or micropores identified as dominant seepage channels, a three-dimensional pore network and basic geometric information of the pore throats are extracted based on the reconstructed pore structures. Based on the three-dimensional pore network and basic geometric information of the pore throats, a two-phase quasi-static displacement simulation is performed to determine the CO2 breakthrough pressure of the mudstone caprock. This technical solution overcomes the disadvantages of long laboratory measurement times, high costs, and poor repeatability of CO2 breakthrough pressure. By combining conventional experimental methods, image analysis techniques, and pore-scale numerical simulation methods, it can quickly and effectively determine the CO2 breakthrough pressure of mudstone caprock, laying the foundation for research on multi-scale seepage mechanics mechanisms.

[0129] Furthermore, the main control seepage channel determination module 310 includes:

[0130] The first reconstructed pore structure determination unit is used to scan and reconstruct the mudstone sample based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, and determine the reconstructed pore structure of the macropores and / or micropores.

[0131] A connectivity result determination unit is used to determine candidate connectivity results of the macropores and / or micropores based on the reconstructed pore structure of the macropores and / or micropores.

[0132] The main control seepage channel determination unit is used to determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel based on the candidate connectivity results of the macropores and / or micropores.

[0133] Furthermore, the first reconstructed pore structure determination unit includes:

[0134] The first scanning resolution determination subunit is used to determine the first scanning resolution corresponding to the peak pore size of the clay macropores in the mudstone sample.

[0135] A macropore reconstruction pore structure determination subunit is used to scan and reconstruct the mudstone sample according to the first scanning resolution to determine the reconstructed pore structure of the macropores; and / or,

[0136] The second scanning resolution determination subunit is used to determine the second scanning resolution corresponding to the peak pore size of clay micropores in the mudstone sample.

[0137] The micropore reconstruction pore structure determination subunit is used to scan and reconstruct the mudstone sample according to the second scanning resolution to determine the reconstructed pore structure of the micropores.

[0138] Furthermore, the main control seepage channel determination unit includes:

[0139] The first main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a macropore if the candidate connectivity result of the macropore meets a preset connectivity condition; or,

[0140] The second main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a micropore if the candidate connectivity results of the micropores meet a preset connectivity condition; or,

[0141] The third main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a macropore if both the candidate connectivity results of the macropores and the candidate connectivity results of the micropores meet the preset connectivity conditions.

[0142] Furthermore, the main control seepage channel determination unit includes:

[0143] The second reconstructed pore structure determination subunit is used to scan and reconstruct the mudstone sample based on the peak pore size of clay macropores in the mudstone sample and determine that the main control seepage channel of the mudstone sample is not a macropore, and then scan and reconstruct the mudstone sample based on the peak pore size of clay micropores in the mudstone sample to obtain the reconstructed pore structure of the micropores.

[0144] The third reconstructed pore structure determination subunit is used to scan and reconstruct the mudstone sample based on the peak pore size of clay micropores in the mudstone sample, and determine that the main control flow channel of the mudstone sample is not a micropore. Then, it scans and reconstructs the mudstone sample based on the peak pore size of clay macropores in the mudstone sample to obtain the reconstructed pore structure of the macropores.

[0145] Furthermore, the CO2 breakthrough pressure determination module 330 includes:

[0146] The displacement model construction unit is used to construct a supercritical CO2-salt water two-phase quasi-static displacement model based on the three-dimensional pore network and the basic geometric information of the pore throat.

[0147] The displacement simulation unit is used to perform two-phase quasi-static displacement simulation on the supercritical CO2-saltwater two-phase quasi-static displacement model to determine the CO2 breakthrough pressure of the mudstone caprock.

[0148] Furthermore, the displacement model building blocks include:

[0149] The pore correction radius determination subunit is used to correct the pore radius in the basic geometry of the pore throat based on the effective stress of the mudstone sample, so as to obtain the pore correction radius.

[0150] The displacement model construction subunit is used to construct a supercritical CO2-saltwater two-phase quasi-static displacement model based on the three-dimensional pore network, the basic geometric information of the pore throat, the pore correction radius, the preset empirical parameters, and the clay mineral composition in the mudstone sample.

[0151] The device for determining the CO2 breakthrough pressure of mudstone caprock provided in this application embodiment can execute the method for determining the CO2 breakthrough pressure of mudstone caprock provided in any embodiment of this application, and has the corresponding functional modules and beneficial effects of the method.

[0152] Example 4

[0153] Figure 16 A schematic diagram of the structure of a device 10 that can be used to implement embodiments of this application is shown. The device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the application described and / or claimed herein.

[0154] like Figure 16As shown, device 10 includes at least one processor 11 and a memory, such as read-only memory (ROM) 12, random access memory (RAM) 13, etc., communicatively connected to at least one processor 11. The memory stores computer programs executable by at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 may also store various programs and data required for the operation of device 10. The processor 11, ROM 12, and RAM 13 are interconnected via bus 14. Input / output (I / O) interface 15 is also connected to bus 14.

[0155] Multiple components in device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of monitors, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0156] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as methods for determining CO2 breakthrough pressure in mudstone caprock.

[0157] In some embodiments, the method for determining the CO2 breakthrough pressure of the mudstone caprock can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the method for determining the CO2 breakthrough pressure of the mudstone caprock described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the method for determining the CO2 breakthrough pressure of the mudstone caprock by any other suitable means (e.g., by means of firmware).

[0158] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0159] Computer programs used to implement the methods of this application may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0160] In the context of this application, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0161] To provide interaction with a user, the systems and techniques described herein can be implemented on a device having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or haptic feedback); and input from the user can be received in any form (including sound input, voice input, or haptic input).

[0162] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0163] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0164] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0165] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for determining the CO2 breakthrough pressure of a mudstone caprock, characterized in that, The method includes: Based on the peak pore size of clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the main control seepage channels of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channels. For macropores or micropores that are identified as the main control seepage channels, three-dimensional pore networks and basic geometric information of pore throats are extracted based on the reconstructed pore structure. Based on the three-dimensional pore network and the basic geometric information of the pore throat, a two-phase quasi-static displacement simulation was performed to determine the CO2 breakthrough pressure of the mudstone caprock. Specifically, based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the main control flow channels and the reconstructed pore structure corresponding to the main control flow channels, including: Based on the peak pore size of clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the reconstructed pore structure of the macropores and / or micropores. Based on the reconstructed pore structure of the macropores and / or micropores, determine the candidate connectivity results of the macropores and / or micropores; Based on the candidate connectivity results of the macropores and / or micropores, the main control flow channels of the mudstone sample and the reconstructed pore structure corresponding to the main control flow channels are determined. Specifically, based on the candidate connectivity results of the macropores and / or micropores, the main controlling seepage channels of the mudstone sample are determined, including: If the candidate connectivity results of the macropores meet the preset connectivity conditions, then the main control flow channel of the mudstone sample is determined to be a macropore. Alternatively, if the candidate connectivity results of the micropores meet the preset connectivity conditions, then the main control flow channel of the mudstone sample is determined to be a micropore. Alternatively, if both the candidate connectivity results of the macropores and the candidate connectivity results of the micropores satisfy the preset connectivity conditions, then the main control flow channel of the mudstone sample is determined to be a macropore.

2. The method according to claim 1, characterized in that, Based on the peak pore size of clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the reconstructed pore structure of the macropores and / or micropores, including: Based on the peak pore size of the clay macropores in the mudstone sample, determine the first scanning resolution corresponding to the peak pore size; Based on the first scanning resolution, the mudstone sample is scanned and reconstructed to determine the reconstructed pore structure of the macropores; and / or, Based on the peak pore size of clay micropores in the mudstone sample, determine the second scanning resolution corresponding to the peak pore size of the micropores; The mudstone sample is scanned and reconstructed according to the second scanning resolution to determine the reconstructed pore structure of the micropores.

3. The method according to claim 1, characterized in that, Based on the peak pore size of clay macropores and / or micropores in the mudstone sample, the mudstone sample is scanned and reconstructed to determine the reconstructed pore structure corresponding to the main control seepage channel, including: If the mudstone sample is scanned and reconstructed based on the peak pore size of the clay macropores in the mudstone sample, and it is determined that the main control flow channel of the mudstone sample is not a macropore, then the mudstone sample is scanned and reconstructed based on the peak pore size of the clay micropores in the mudstone sample to obtain the reconstructed pore structure of the micropores. If the mudstone sample is scanned and reconstructed based on the peak pore size of clay micropores in the mudstone sample, and it is determined that the main control flow channel of the mudstone sample is not a micropore, then the mudstone sample is scanned and reconstructed based on the peak pore size of clay macropores in the mudstone sample to obtain the reconstructed pore structure of the macropores.

4. The method according to claim 1, characterized in that, Based on the three-dimensional pore network and the basic geometric information of the pore throat, a two-phase quasi-static displacement simulation is performed to determine the CO2 breakthrough pressure of the mudstone caprock, including: Based on the three-dimensional pore network and the basic geometric information of the pore throat, a quasi-static displacement model of supercritical CO2-salt water phase is constructed. Two-phase quasi-static displacement simulation was performed on the supercritical CO2-saltwater two-phase quasi-static displacement model to determine the CO2 breakthrough pressure of the mudstone caprock.

5. The method according to claim 4, characterized in that, Based on the three-dimensional pore network and the basic geometric information of the pore throat, a supercritical CO2-brine two-phase quasi-static displacement model is constructed, including: Based on the effective stress of the mudstone sample, the pore radius in the basic geometric information of the pore throat is corrected to obtain the pore correction radius; Based on the three-dimensional pore network, the basic geometric information of the pore throat, the pore correction radius, the preset empirical parameters, and the clay mineral composition in the mudstone sample, a supercritical CO2-saltwater two-phase quasi-static displacement model is constructed.

6. A device for determining the CO2 breakthrough pressure of a mudstone caprock, characterized in that, The device includes: The main control seepage channel determination module is used to scan and reconstruct the mudstone sample based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, and determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel. The pore network extraction module is used to extract the three-dimensional pore network and basic geometric information of the pore throat based on the reconstructed pore structure for macropores or micropores that are determined to be the main control seepage channels. The CO2 breakthrough pressure determination module is used to perform two-phase quasi-static displacement simulation based on the three-dimensional pore network and the basic geometric information of the pore throat to determine the CO2 breakthrough pressure of the mudstone caprock. The main control seepage channel determination module includes: The first reconstructed pore structure determination unit is used to scan and reconstruct the mudstone sample based on the peak pore size of the clay macropores and / or micropores in the mudstone sample, and determine the reconstructed pore structure of the macropores and / or micropores. A connectivity result determination unit is used to determine candidate connectivity results of the macropores and / or micropores based on the reconstructed pore structure of the macropores and / or micropores. The main control seepage channel determination unit is used to determine the main control seepage channel of the mudstone sample and the reconstructed pore structure corresponding to the main control seepage channel based on the candidate connectivity results of the macropores and / or micropores. The main control seepage channel determination unit includes: The first main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a macropore if the candidate connectivity result of the macropore meets the preset connectivity condition. The second main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a micropore if the candidate connectivity result of the micropore meets the preset connectivity condition. The third main control seepage channel determination subunit is used to determine the main control seepage channel of the mudstone sample as a macropore if both the candidate connectivity results of the macropores and the candidate connectivity results of the micropores meet the preset connectivity conditions.

7. An electronic device, characterized in that, The device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, which enables the at least one processor to perform the method for determining the CO2 breakthrough pressure of the mudstone caprock as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the method for determining the CO2 breakthrough pressure of the mudstone caprock as described in any one of claims 1-5.

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