A method and system for calculating effective permeability considering entering pressure

Abstract

The application discloses a kind of effective permeability calculation method and system considering entering pressure, comprising: obtaining the binary image of rock-soil material;Based on binary image, the pore size distribution characteristics of rock-soil material pore are obtained;Based on pore size distribution characteristics, obtain the inherent permeability of rock-soil material;Through the relationship between porosity and tortuosity, the change of tortuosity affecting inherent permeability is estimated, and the inherent permeability meeting the preset requirement is obtained;According to the relationship between fluid pressure and rock-soil material pore diameter, the minimum diameter allowed to pass under the preset fluid pressure is determined;According to the inherent permeability meeting the preset requirement and the minimum diameter allowed to pass under the preset fluid pressure, the effective permeability under the preset fluid pressure is obtained.The application considers the relationship between capillary pore diameter and pressure, improves the accurate description of fluid seepage behavior, realizes the accurate prediction of effective permeability under different pressure gradients, realizes the understanding and prediction ability for underground fluid transport characteristics.

Description

Technical Field

[0001] This invention can be applied to fields such as groundwater resource assessment, geotechnical engineering design, and oil extraction, and specifically relates to a method and system for calculating effective permeability considering ingress pressure. Background Technology

[0002] In fields such as deep hazardous waste storage and oil extraction, fluid flow has significant engineering implications. For example, accurately describing the seepage behavior of groundwater is crucial, and in the petroleum industry, understanding the seepage characteristics of oil in pores is essential for optimizing reservoir engineering and improving production efficiency.

[0003] Traditionally, permeability calculations typically assume a homogeneous flow medium, allowing the permeability to be obtained by calculating the overall pore size distribution. However, in reality, when capillary pore sizes are small, fluid entry is difficult and depends on fluid pressure, a phenomenon often overlooked. Therefore, to more accurately describe seepage characteristics, the influence of capillary pore size must be fully considered. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes an effective permeability calculation method and system that considers ingress pressure. By taking into account the relationship between capillary pore size and pressure, it improves the accuracy of describing fluid seepage behavior, enables the prediction of effective permeability under different pressure gradients, improves accuracy, and enhances the ability to understand and predict the transport characteristics of underground fluids.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method for calculating effective permeability considering ingress pressure includes the following steps:

[0007] Obtain a binarized image of the soil and rock material;

[0008] Based on the binarized image, the pore size distribution characteristics of the soil and rock materials are obtained;

[0009] Based on the aforementioned pore size distribution characteristics, the inherent permeability of the rock and soil materials is obtained;

[0010] By analyzing the relationship between porosity and tortuosity, the change in tortuosity that affects the inherent permeability can be predicted, thereby obtaining the inherent permeability that meets the preset requirements.

[0011] Based on the relationship between fluid pressure and pore size of soil and rock materials, determine the minimum allowable pore size under the preset fluid pressure;

[0012] The effective permeability at the preset fluid pressure is obtained based on the inherent permeability that meets the preset requirements and the minimum pore size allowed to pass through under the preset fluid pressure.

[0013] Preferably, the method for obtaining the pore size distribution characteristics of soil and rock materials based on the binarized image includes:

[0014] Obtain images of specific areas of geotechnical materials using digital imaging technology;

[0015] Based on the image of the specific region, the matrix and pore portions are distinguished using a binarization method;

[0016] The overall porosity is obtained by measuring the percentage of the pore portion in the overall image of the specific region.

[0017] Based on the overall porosity, the pore size distribution characteristics of the soil and rock materials are obtained through a continuous pore size distribution algorithm.

[0018] Preferably, the method for obtaining the inherent permeability of rock and soil materials based on the pore size distribution characteristics includes:

[0019]

[0020] In the formula, Let the radius of the corresponding pipeline be R. i The porosity occupied by the pores, A is the cross-sectional area of ​​the porous medium, m is the number of channels formed by all the pores, n is the number of pores with different diameters, H is the height of the sample in the flow direction, and L is the height of the sample in the flow direction. i τ is the length of the pipeline. i The tortuosity of the pipeline.

[0021] Preferably, the method for determining the minimum allowable pore size under a preset fluid pressure based on the relationship between fluid pressure and pore size of soil and rock materials includes:

[0022]

[0023] In the formula, γ f For capillary surface tension, P f This represents the fluid pressure difference within the capillary tube.

[0024] Preferably, the method for obtaining the effective permeability at the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size allowed to pass through at the preset fluid pressure includes:

[0025]

[0026] In the formula, τ is the tortuosity corresponding to this porosity.

[0027] The present invention also provides an effective permeability calculation system that takes into account ingress pressure, comprising: an image acquisition module, a feature acquisition module, an inherent permeability acquisition module, a preset permeability acquisition module, a pore size acquisition module, and an effective permeability acquisition module;

[0028] The image acquisition module is used to acquire a binarized image of the soil and rock material;

[0029] The feature acquisition module is used to acquire the pore size distribution characteristics of the soil and rock materials based on the binarized image;

[0030] The inherent permeability acquisition module is used to obtain the inherent permeability of the rock and soil material based on the pore size distribution characteristics.

[0031] The preset permeability acquisition module is used to estimate the change in tortuosity that affects the inherent permeability by using the relationship between porosity and tortuosity, and to obtain the inherent permeability that meets the preset requirements.

[0032] The aperture acquisition module is used to determine the minimum aperture that can be passed under a preset fluid pressure based on the relationship between fluid pressure and pore size of soil and rock materials.

[0033] The effective permeability acquisition module is used to obtain the effective permeability under the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size that can be passed under the preset fluid pressure.

[0034] Preferably, the feature acquisition module includes: a region image unit, a binarization unit, a comparison unit, and a calculation unit;

[0035] The regional image unit is used to acquire images of specific regions of soil and rock materials using digital imaging technology;

[0036] The binarization unit is used to distinguish the matrix and pore portions based on the image of the specific region using a binarization method;

[0037] The comparison unit is used to obtain the overall porosity by the percentage of the pore portion in the overall image of the specific region;

[0038] The calculation unit is used to obtain the pore size distribution characteristics of the soil and rock material based on the overall porosity and through a continuous pore size distribution algorithm.

[0039] Preferably, in the inherent permeability acquisition module, the process of obtaining the inherent permeability of the rock and soil material based on the pore size distribution characteristics includes:

[0040]

[0041] In the formula, Let the radius of the corresponding pipeline be R. iThe porosity occupied by the pores, A is the cross-sectional area of ​​the porous medium, m is the number of channels formed by all the pores, n is the number of pores with different diameters, H is the height of the sample in the flow direction, and L is the height of the sample in the flow direction. i τ is the length of the pipeline. i The tortuosity of the pipeline.

[0042] Preferably, in the aperture acquisition module, the process of determining the minimum allowable aperture under a preset fluid pressure based on the relationship between fluid pressure and pore size of the soil material includes:

[0043]

[0044] In the formula, γ f For capillary surface tension, P f This represents the fluid pressure difference within the capillary tube.

[0045] Preferably, in the effective permeability acquisition module, the process of obtaining the effective permeability under the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size allowed to pass through under the preset fluid pressure includes:

[0046]

[0047] In the formula, τ is the tortuosity corresponding to this porosity.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] This invention considers the relationship between capillary pore size and pressure, improving the accurate description of fluid seepage behavior. It can predict the effective permeability under different pressure gradients, improve accuracy, and enable the understanding and prediction of underground fluid transport characteristics. Attached Figure Description

[0050] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are 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.

[0051] Figure 1 This is a flowchart illustrating an effective permeability calculation method considering entry pressure according to an embodiment of the present invention.

[0052] Figure 2 This invention converts the original image of non-dense soil and rock material into a binarized image.

[0053] Figure 3This is a schematic diagram of the pore size distribution characteristics obtained after binarization of non-dense soil and rock materials in an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram comparing the effective permeability of non-dense soil and rock materials under different water pressures in embodiments of the present invention;

[0055] Figure 5 This is the original image of dense sandstone according to an embodiment of the present invention;

[0056] Figure 6 This is a binarized image of dense sandstone from an embodiment of the present invention;

[0057] Figure 7 This is a schematic diagram of the pore size distribution obtained after binarization of dense sandstone in an embodiment of the present invention;

[0058] Figure 8 This is a schematic diagram illustrating the changes in effective permeability of dense sandstone under different pressures in an embodiment of the present invention. Detailed Implementation

[0059] 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.

[0060] 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.

[0061] Example 1

[0062] like Figure 1 As shown, the present invention provides a method for calculating effective permeability considering ingress pressure, comprising the following steps:

[0063] Obtain a binarized image of the soil and rock material;

[0064] Based on the binarized image, the pore size distribution characteristics of the soil and rock materials are obtained;

[0065] Based on the pore size distribution characteristics, the inherent permeability of rock and soil materials is obtained;

[0066] By analyzing the relationship between porosity and tortuosity, the change in tortuosity that affects the inherent permeability can be predicted, thereby obtaining the inherent permeability that meets the preset requirements.

[0067] Based on the relationship between fluid pressure and pore size of soil and rock materials, determine the minimum allowable pore size under the preset fluid pressure;

[0068] The effective permeability at the preset fluid pressure is obtained based on the inherent permeability that meets the preset requirements and the minimum pore size that can be passed under the preset fluid pressure.

[0069] In this embodiment, the method for obtaining the pore size distribution characteristics of soil and rock materials based on binarized images includes:

[0070] Digital imaging technology is used to obtain images of specific areas of soil and rock materials, that is, to obtain images reflecting the surface structural features of soil and rock materials through scanning electron microscopy (SEM).

[0071] Based on images of specific regions, the matrix and pore portions are distinguished using a binarization method.

[0072] The overall porosity is obtained by measuring the percentage of the pore portion in the overall image of a specific region;

[0073] Based on the pore region portion of the image, a continuous pore size distribution algorithm is used in two dimensions. That is, the pore region is filled with circles of different sizes. The radius of the circle can be continuously increased from 1 until the radius of the circle reaches the edge of the pore. Then, by calculating the proportion of pore area independently occupied by circles of different radii, the pore size distribution characteristics of the soil and rock material (i.e. the proportion of pores of different sizes) can be obtained.

[0074] In this embodiment, the method for obtaining the inherent permeability of rock and soil materials based on pore size distribution characteristics includes:

[0075] A pore can be considered as a combination of a series of orifice-like channels. Considering Poiseuille's law, we have...

[0076]

[0077] In the formula, Q i For flow rate, m 3 / s;R i L is the radius of the pipeline, in meters; ΔP is the pressure difference between the two ends, in Pa; μ is the dynamic viscosity, in Pa·s; L i Let m be the length of the pipeline.

[0078] Therefore, it is generally considered that the total flow rate is equal to the sum of the flow rates in the pipeline, that is...

[0079]

[0080] In the formula, m represents the number of pipes converted from all the pores.

[0081] At the same time, according to Darcy's law,

[0082]

[0083] In the formula, k is the inherent permeability of the soil and rock material, and m2 A is the cross-sectional area of ​​the porous medium, in m². 2 H is the height in the direction of sample flow, in meters (m).

[0084] Combining (1)-(3) we have

[0085]

[0086] In the formula, Let the radius of the corresponding pipeline be R. i The porosity occupied by the pores, A is the cross-sectional area of ​​the porous medium, m is the number of channels formed by all the pores, n is the number of pores with different diameters, H is the height of the sample in the flow direction, and L is the height of the sample in the flow direction. i τ is the length of the pipeline. i The tortuosity of the pipeline.

[0087] In this embodiment, τ i =L i / H represents the tortuosity of the pipeline. For surface structure images of soil and rock materials obtained through scanning electron microscopy (SEM), tortuosity is usually considered to be 1 (because it is a two-dimensional image, there is no concept of thickness, and thickness can be considered as a unit of 1). However, this treatment ignores the complexity of the pore structure, which will undoubtedly lead to an increase in permeability assessment. To solve this problem, the change in tortuosity can be predicted by the relationship between porosity and tortuosity, as shown in the equation.

[0088]

[0089] here Let τ be the overall porosity, and τ be the tortuosity corresponding to that porosity.

[0090] In this way, the permeability of the sample can be obtained (the inherent permeability that meets the preset requirements, which is closer to the true value). This method takes all pore sizes into account. However, in reality, when the radius of the capillary is small, the surface tension of the liquid will cause a significant "liquid pad" to form at the inlet of the pipe. This pad will prevent the liquid from entering the capillary further. This phenomenon is called capillary cutoff, or "suction limit".

[0091] The capillary cutoff phenomenon can be explained by Laplace pressure, which is caused by the pressure difference between the inside and outside of the capillary. When the capillary radius is very small, surface tension causes the pressure inside the capillary to drop to a level lower than the external pressure. This results in a suction effect that prevents liquid from continuing to enter the capillary. Because of this phenomenon, the contribution of each pore to fluid flow is actually related to pressure; when the pressure is low, small pores cannot serve as channels for fluid flow. Therefore, to effectively account for the influence of fluid flow, the relationship between pressure and pore size needs to be considered.

[0092] The occurrence of capillary cutoff can be calculated using the Young-Laplace equation, which describes the relationship between the fluid pressure difference within the capillary and the capillary radius and surface tension.

[0093]

[0094] Therefore, for a given fluid pressure, the first step should be to determine the minimum allowable orifice diameter, i.e.

[0095]

[0096] In the formula, γ f For capillary surface tension, P f This represents the fluid pressure difference within the capillary tube.

[0097] In this embodiment, based on the inherent permeability that meets preset requirements and the minimum pore size allowed to pass through under a preset fluid pressure, and considering the tortuosity as an overall tortuosity for simplicity, the method for obtaining the effective permeability under the preset fluid pressure includes:

[0098]

[0099] Example 2

[0100] The present invention also provides an effective permeability calculation system that takes into account ingress pressure, comprising: an image acquisition module, a feature acquisition module, an inherent permeability acquisition module, a preset permeability acquisition module, a pore size acquisition module, and an effective permeability acquisition module;

[0101] The image acquisition module is used to acquire binary images of soil and rock materials;

[0102] The feature acquisition module is used to acquire the pore size distribution characteristics of the soil and rock materials based on the binarized image;

[0103] The inherent permeability acquisition module is used to obtain the inherent permeability of the rock and soil material based on the pore size distribution characteristics.

[0104] The preset permeability acquisition module is used to estimate the change in tortuosity that affects the inherent permeability by using the relationship between porosity and tortuosity, and to obtain the inherent permeability that meets the preset requirements.

[0105] The aperture acquisition module is used to determine the minimum aperture that can be passed under a preset fluid pressure based on the relationship between fluid pressure and pore size of soil and rock materials.

[0106] The effective permeability acquisition module is used to obtain the effective permeability under the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size that can be passed under the preset fluid pressure.

[0107] In this embodiment, the feature acquisition module includes: a region image unit, a binarization unit, a comparison unit, and a calculation unit;

[0108] Regional image units are used to acquire images of specific regions of geotechnical materials using digital imaging technology;

[0109] The binarization unit is used to distinguish the matrix and pore portions based on the image of the specific region using a binarization method;

[0110] The comparison unit is used to obtain the overall porosity by the percentage of the pore portion in the overall image of the specific region;

[0111] The calculation unit is used to obtain the pore size distribution characteristics of the soil and rock material based on the overall porosity and through a continuous pore size distribution algorithm.

[0112] In this embodiment, the process of obtaining the inherent permeability of soil and rock materials based on pore size distribution characteristics in the inherent permeability acquisition module includes:

[0113]

[0114] In the formula, Let the radius of the corresponding pipeline be R. i The porosity occupied by the pores, A is the cross-sectional area of ​​the porous medium, m is the number of channels formed by all the pores, n is the number of pores with different diameters, H is the height of the sample in the flow direction, and L is the height of the sample in the flow direction. i τ is the length of the pipeline. i The tortuosity of the pipeline.

[0115] In this embodiment, the process of determining the minimum allowable pore size under a preset fluid pressure in the pore size acquisition module, based on the relationship between fluid pressure and pore size of the soil material, includes:

[0116]

[0117] In the formula, γ f For capillary surface tension, P fThis represents the fluid pressure difference within the capillary tube.

[0118] In this embodiment, the process of obtaining the effective permeability at the preset fluid pressure in the effective permeability acquisition module, based on the inherent permeability that meets preset requirements and the minimum pore size allowed to pass through at the preset fluid pressure, includes:

[0119]

[0120] In the formula, τ is the tortuosity corresponding to this porosity.

[0121] Example 3

[0122] The specific implementation process of this invention is as follows:

[0123] Step 1: As Figure 2 As shown, a binarized image of the soil and rock material is obtained. After obtaining the image of the soil and rock material through a scanning electron microscope, the image is segmented by a binarization algorithm to obtain a binarized image. In this way, the pore part is black and the matrix part is white (this invention mainly focuses on the pore part).

[0124] Step 2: As Figure 3 As shown, based on the binarized image, the continuous aperture distribution algorithm is used. That is, for the aperture part (black part) of the binarized image, circles of different sizes are filled. The radius of the circle starts from 1 and continues to increase until the size of the circle touches the edge of the aperture area. In this way, the proportion of the aperture area occupied by the corresponding circle can be obtained, and its aperture distribution characteristics can be obtained.

[0125] Step 3: Determine the minimum pore size of the fluid under different pressures according to formula (7) in Example 1. The groundwater flow studied here has a surface tension of 0.072 N / m.

[0126] When the fluid pressure is 0.05 MPa, its minimum orifice diameter is:

[0127]

[0128] When the fluid pressure is 0.1 MPa, its minimum orifice diameter is

[0129]

[0130] When the fluid pressure increases to 0.5 MPa, its minimum orifice diameter is:

[0131]

[0132] When the fluid pressure increases to 1 MPa, its minimum orifice diameter is

[0133]

[0134] Therefore, the effective permeability of water can be obtained based on the minimum pressure, and compared with commonly used methods, such as... Figure 4 As shown.

[0135] from Figure 4 The results show that when the water pressure is low, the effective permeability is significantly lower than that obtained using methods that generally do not consider pressure. However, when the water pressure reaches 0.5 MPa or higher, the results gradually approach those obtained using current methods. This demonstrates that considering the inlet pressure corresponding to different pore sizes is crucial for studying the accurate effective porosity of geotechnical materials.

[0136] Example 4

[0137] The specific technical solution of this embodiment is as follows: when the minimum pore size calculated under the fluid pressure is greater than the maximum pore size obtained through the image, the permeability corresponding to this pressure is 0. As can be seen from the above formula (8), no flow occurs. Flow will occur when the pressure increases to the point that the calculated minimum flow pore size is less than the maximum pore size obtained through the image. The calculation method is the same as the algorithm in Implementation Case 3, as follows:

[0138] The study here examines the flow of groundwater in dense sandstone, such as... Figure 5 The image shown is a digital image of dense sandstone. Its binarized image was obtained using a binarization method, as shown below. Figure 6 As shown, the aperture is obtained by performing an aperture distribution-based algorithm. Figure 7 As shown. For water, its surface tension is 0.072 N / m. When the fluid pressure is 0.05 MPa, the minimum pore size calculated according to formula (7) is 2.88 μm, which is greater than the maximum pore size of 1.62 μm obtained from the image. Figure 7 If the pressure is 0.1 MPa, then no flow occurs, and according to formula (8), the permeability is 0 at this pressure. When the fluid pressure is 0.1 MPa, the minimum pore size is 1.44 μm, which is less than the maximum pore size of 1.62 μm obtained from the image. Flow occurs at this time, and the effective permeability of the fluid can be calculated according to the method described in formula (8). When the fluid pressure reaches 0.5 MPa and 1 MPa, the minimum pore sizes are 0.288 μm and 0.144 μm respectively according to formula (7). The effective permeability is calculated using formula (8) respectively. Figure 8 As shown, it is clear that only when the pressure is greater than 0.5 MPa does it gradually approach the permeability calculated by general methods, effectively reflecting the fluid flow conditions allowed by different pore sizes.

[0139] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for calculating effective permeability considering ingress pressure, characterized in that, Includes the following steps: Obtain a binarized image of the soil and rock material; Based on the binarized image, the pore size distribution characteristics of the soil and rock materials are obtained; Based on the aforementioned pore size distribution characteristics, the inherent permeability of the rock and soil materials is obtained; By analyzing the relationship between porosity and tortuosity, the change in tortuosity that affects the inherent permeability can be predicted, thereby obtaining the inherent permeability that meets the preset requirements. Based on the relationship between fluid pressure and pore size of soil and rock materials, determine the minimum allowable pore size under the preset fluid pressure; Based on the inherent permeability that meets the preset requirements and the minimum pore size that can be passed under the preset fluid pressure, the effective permeability under the preset fluid pressure is obtained; Based on the relationship between fluid pressure and pore size in soil and rock materials, methods for determining the minimum allowable pore size under a preset fluid pressure include: ， In the formula, For capillary surface tension, The pressure difference of the fluid inside the capillary tube; The method for obtaining the effective permeability at the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size allowed to pass through at the preset fluid pressure includes: ， In the formula, This represents the tortuosity corresponding to this porosity. The radius of the corresponding pipeline is Ri The porosity occupied by the pores; The change in tortuosity can be predicted by the relationship between porosity and tortuosity, using the following formula: ， in, For the overall porosity, This represents the tortuosity corresponding to this porosity.

2. The method for calculating effective permeability considering entry pressure according to claim 1, characterized in that, Based on the binarized image, a method for obtaining the pore size distribution characteristics of soil and rock materials includes: Acquire images of soil and rock materials using digital imaging technology; Based on the image, the matrix and pore portions are distinguished using a binarization method; The overall porosity is obtained by measuring the percentage of the pore portion relative to the total image. Based on the overall porosity, the pore size distribution characteristics of the soil and rock materials are obtained through a continuous pore size distribution algorithm.

3. The effective permeability calculation method considering entry pressure according to claim 1, characterized in that, Methods for obtaining the inherent permeability of rock and soil materials based on the aforementioned pore size distribution characteristics include: ， In the formula, The radius of the corresponding pipeline is Ri The porosity occupied by the pores, A The cross-sectional area of ​​the porous medium. m The number of pipes converted from all pores. n The number of pores with different pore sizes. H The height is the height in the direction of sample flow. For the length of the pipeline, i The tortuosity of the pipeline.

4. An effective permeability calculation system that takes into account inlet pressure, characterized in that, include: The module includes an image acquisition module, a feature acquisition module, an inherent permeability acquisition module, a preset permeability acquisition module, an pore size acquisition module, and an effective permeability acquisition module. The image acquisition module is used to acquire a binarized image of the soil and rock material; The feature acquisition module is used to acquire the pore size distribution characteristics of the soil and rock materials based on the binarized image; The inherent permeability acquisition module is used to obtain the inherent permeability of the rock and soil material based on the pore size distribution characteristics. The preset permeability acquisition module is used to estimate the change in tortuosity that affects the inherent permeability by using the relationship between porosity and tortuosity, and to obtain the inherent permeability that meets the preset requirements. The aperture acquisition module is used to determine the minimum aperture that can be passed under a preset fluid pressure based on the relationship between fluid pressure and pore size of soil and rock materials. The effective permeability acquisition module is used to obtain the effective permeability under the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size that can be passed under the preset fluid pressure. In the aperture acquisition module, the process of determining the minimum allowable aperture under a preset fluid pressure based on the relationship between fluid pressure and pore size of soil and rock materials includes: ， In the formula, For capillary surface tension, The pressure difference of the fluid inside the capillary tube; In the effective permeability acquisition module, the process of obtaining the effective permeability under the preset fluid pressure based on the inherent permeability that meets the preset requirements and the minimum pore size allowed to pass through under the preset fluid pressure includes: ， In the formula, This represents the tortuosity corresponding to this porosity. The radius of the corresponding pipeline is R i The porosity occupied by the pores; The change in tortuosity can be predicted by the relationship between porosity and tortuosity, using the following formula: ， in, For the overall porosity, This represents the tortuosity corresponding to this porosity.

5. The effective permeability calculation system considering entry pressure according to claim 4, characterized in that, The feature acquisition module includes: a region image unit, a binarization unit, a comparison unit, and a calculation unit; The regional image unit is used to acquire images of soil and rock materials using digital imaging technology; The binarization unit is used to distinguish between matrix and pore portions based on the image using a binarization method; The comparison unit is used to obtain the overall porosity by the percentage of the pore portion in the overall image; The calculation unit is used to obtain the pore size distribution characteristics of the soil and rock material based on the overall porosity and through a continuous pore size distribution algorithm.

6. The effective permeability calculation system considering entry pressure according to claim 4, characterized in that, In the inherent permeability acquisition module, the process of obtaining the inherent permeability of the rock and soil material based on the pore size distribution characteristics includes: ， In the formula, The radius of the corresponding pipeline is Ri The porosity occupied by the pores, A The cross-sectional area of ​​the porous medium. m The number of pipes converted from all pores. n The number of pores with different pore sizes. H The height is the height in the direction of sample flow. For the length of the pipeline, i The tortuosity of the pipeline.

Images