Conglomerate oil reservoir equivalent permeability calculation method based on seepage space transformation

Abstract

The invention provides a conglomerate oil reservoir equivalent permeability calculation method based on seepage space transformation, and relates to the technical field of oil exploitation, and the method is implemented through five steps: constructing an equivalent permeability model considering gravel morphology and arrangement, and determining fracture characteristics; calculating effective porosity under different modes according to the granularity composition quantization parameters; determining the permeability of the matrix and the fracture unit, and calculating the fracture opening; seepage space transformation is applied, and a Laplace equation is adopted to simplify and process the anisotropic seepage problem; and developing verification software, ensuring the effectiveness of the model, and performing error analysis by comparing with physical simulation. Gravel particle form classification and corresponding crack parameter setting are refined, an effective porosity calculation formula under bimodal and complex-modal pore structures is introduced, and the permeability of each component is accurately calculated through a mathematical model. The method has important value for guiding effective development of unconventional oil and gas resources, improving the recovery ratio and optimizing a gas drive mining strategy.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, specifically to a method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation. Background Technology

[0002] In the field of oil and gas field development, especially when exploiting conglomerate reservoirs with complex pore structures, rock permeability, as a key parameter, exhibits significant anisotropy. This anisotropy is mainly caused by two factors: first, sedimentary anisotropy formed by sedimentation, where the non-uniformity of the spatial distribution and arrangement of gravel particles leads to differences in permeability in different directions; second, fracture anisotropy caused by fracture activity, where some conglomerate reservoirs have natural fracture networks that further enhance the directionality of reservoir permeability.

[0003] In specific cases of tight conglomerate reservoirs, the complex pore structure includes bimodal and multimodal morphologies, and the rock grains vary in shape. The gravels are also filled with sand and a certain proportion of mud. These factors collectively contribute to the strong heterogeneity and anisotropy of conglomerate reservoirs. Particularly noteworthy is the more pronounced anisotropy of permeability when the gravels are elliptical and their long axes are not aligned, or when a fracture system is present.

[0004] Currently, in the research on horizontal well fracturing and production enhancement, the influence of permeability anisotropy on the pressure field and seepage field is not sufficiently studied. Most existing methods only use simplified models to estimate the equivalent permeability. Although they can reflect the influence of permeability on seepage law to a certain extent, they are insufficient in terms of accuracy and comprehensiveness and cannot accurately describe the influence of permeability anisotropy on the actual seepage path. Summary of the Invention

[0005] The purpose of this invention is to provide a method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation. The core technical problem to be solved is: how to establish an accurate method for calculating the equivalent permeability of anisotropic conglomerate reservoirs, taking into account dual-mode and multi-mode pore structures and fracture distribution, so as to improve the accuracy of scheme design and production capacity prediction, and effectively guide the efficient development of such reservoirs.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation includes the following steps:

[0008] S1: Establish an equivalent permeability calculation model for conglomerate reservoirs with complex pore structures: Based on the shape and arrangement of gravel particles, construct an equivalent permeability calculation model under complex pore structures, and clarify the direction, length and spacing of fractures;

[0009] S2: Quantitative parameter calculation: Based on the above model, calculate the content of each particle size component (gravel, sand, mud) in the conglomerate reservoir. Based on these contents and the average particle diameter, solve the effective porosity of the conglomerate matrix according to the different cases of dual mode (sand, mud) and complex mode (gravel, sand, mud).

[0010] S3: Permeability determination: Using the grain size composition and effective porosity obtained in S2, the permeability of the conglomerate matrix and the permeability of the fracture unit are further calculated. Based on the principle that the same characteristic unit has the same equivalent permeability, the average aperture of the fracture in the unit containing the fracture is obtained.

[0011] S4: Application of the seepage space transformation method: Transforms complex anisotropic seepage problems into Laplace equations for solving, enabling simulation of actual seepage paths and patterns;

[0012] S5: Software Development and Verification: Based on the methods in S1-S4, develop a computational module and verify the effectiveness and practicality of the computational model by comparing it with the physical simulation results and performing error analysis.

[0013] Furthermore: In step S1, the shape and arrangement of the gravel particles are divided into three cases, and their corresponding crack directions, lengths, and spacings are as follows:

[0014] Case 1: The gravel particles are mainly round, the direction of the cracks is parallel to the direction of the maximum horizontal principal stress, the length of a single crack is the average diameter of the gravel, and the crack spacing is the average diameter of the gravel.

[0015] Scenario 2: The gravel particles are mainly elliptical, the cracks extend parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel.

[0016] Scenario 3: If the gravel particles are mainly elliptical, then the direction of the crack extension is parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel.

[0017] Furthermore: In S2, the effective porosity of the conglomerate matrix is ​​calculated as follows:

[0018] For dual-mode (sand, mud): Φ d =Φ s -f m ;

[0019] For complex modes (gravel, sand, mud): Φ e =Φ s -(1-Φ s )f s -f m;

[0020] Where: Φ s Porosity of sand;

[0021] f m For: the particle size composition content of mud;

[0022] f s For: the particle size composition content of sand.

[0023] Furthermore: In S3, the permeability of the conglomerate matrix is ​​calculated as follows:

[0024]

[0025] In the formula: Φ represents porosity;

[0026] f c For: the content of grain size components;

[0027] f m For: the particle size composition content of mud;

[0028] f s For: the particle size distribution of sand;

[0029] d c : The average diameter of the gravel particles;

[0030] d m : The average diameter of mud particles;

[0031] d s : The average diameter of sand particles.

[0032] Furthermore: In S3, the permeability of the fracture element is calculated as follows:

[0033]

[0034] In the formula: k fi Let: the permeability of the i-th group of fractures, mD;

[0035] k m : Matrix permeability, mD.

[0036] Furthermore, in S3, the calculation method for the equivalent permeability of a single unit is as follows:

[0037] Crack permeability can be calculated using the following formula:

[0038]

[0039] In the formula: b1 is the average aperture of the i-th group of cracks, in mm;

[0040] d1 represents the average crack spacing of the i-th group of cracks, in mm.

[0041] To achieve the same permeability for all cells and the same aperture for each individual fracture, then:

[0042] K 非均质单元 =K 裂缝单元

[0043] Assuming the aperture of each crack is b, solving the above equations yields:

[0044]

[0045] The intrinsic permeability k within the fracture is calculated using b. f :

[0046]

[0047] Furthermore: The specific steps of S4 are:

[0048] S401: Perform seepage space transformation:

[0049] First, establish the governing equations:

[0050]

[0051] Then, set the boundary conditions:

[0052]

[0053] S402: Transformation of anisotropic and equivalent isotropic seepage space:

[0054]

[0055] S403: Semi-analytical model of fracture permeability:

[0056]

[0057] In the formula: Q - flow rate obtained from experimental testing, m 3 ;k f－ Crack permeability, ×10 -3 μm 2 ;k y - Matrix permeability, ×10 -3 μm 2 μ - fluid viscosity, mPa·s; Δp - fluid pressure change, MPa; h - characteristic element thickness, m; K(m) - first-kind complete elliptic integral with parameter m; K'(m) - first-kind complete elliptic integral with parameter (1-m); L” is the length of the characteristic element in isotropic space, m; W” is the width of the characteristic element in isotropic space, m.

[0058] Furthermore: S5 uses MATLAB for programming development.

[0059] Furthermore: The programming flow for calculating the equivalent permeability of anisotropic conglomerate reservoirs under seepage space transformation in S5 is as follows:

[0060] S501: Input basic parameters: First, you need to input a series of basic parameters, including Q, μ, h, W, L, k. y , β and Δp; here, Q is the flow rate obtained from experimental testing, m 3 μ - fluid viscosity, mPa·s; h - model thickness, m; W - width of the characteristic element in isotropic space, m; L - length of the characteristic element in isotropic space, m; β - angle between the crack development direction and the horizontal direction, °; ​​Δp - fluid pressure change, MPa;

[0061] S502: Initial permeability given in the direction parallel to the fracture: Based on the parameters in S501, an initial permeability value k is given in the direction parallel to the fracture. x0 ;

[0062] S503: Analytical calculation of R = W' / L' and γ: Given the value of g, iteratively solve T = W' / L'; here, W' is the width of the characteristic unit in the anisotropic space, m; L' is the length of the characteristic unit in the anisotropic space, m; the minimum interior angle πγ of the isotropic parallelogram seepage space, therefore γ is the minimum interior angle πγ / π.

[0063] S504: Check if R equals T: If the calculation result R equals T, proceed to the next step; otherwise, jump to S503 to re-given the value of g and iteratively solve T = W' / L'.

[0064] S505: Determine the value of g and solve for W” / L”;

[0065] S506: Calculate the equivalent permeability k e Then use the above information to calculate the equivalent permeability k. e ;

[0066] S507: Calculate the permeability kx in the direction parallel to the fracture: The last step is to calculate the permeability kx in the direction parallel to the fracture based on ke;

[0067] S508: Determine k x Is k x0 If yes, proceed to the next step; otherwise, switch to S502 to reset k. x0 ;

[0068] S508: End of Run: When all steps are completed, the program ends, and the result of k under the current conditions can be determined. xand k f value.

[0069] Compared with the original technology, the present invention has the following beneficial effects:

[0070] I. This invention improves the accuracy and efficiency of seepage research in the development of unconventional oil reservoirs: By establishing a complex modal pore structure model, the shape, size, and arrangement of gravel particles, as well as the orientation and size of fractures, are considered in detail to accurately calculate anisotropic permeability, reflecting the true seepage characteristics inside the reservoir; by introducing third-order tensor theory, the variation of permeability in three-dimensional space is fully considered, overcoming the limitations of traditional equivalent simplified models in describing complex anisotropic permeability; by using the seepage space transformation method, the complex anisotropic seepage problem is transformed into an isotropic problem that is easy to solve, improving the calculation speed and accuracy, thereby assisting in more scientific and reasonable reservoir management decisions.

[0071] II. Accurately predict the miscibility pressure and phase change patterns during the gas-driven reservoir development process: Based on factors such as crude oil composition, reservoir pressure, and temperature, the aforementioned precise permeability calculation model is used to simulate reservoir pressure and seepage conditions at different stages; through mathematical model analysis of seepage patterns, the influence of various variables on reservoir pressure and phase change during gas-driven development is revealed, thereby providing accurate prediction data; based on the prediction results, the gas-driven production design scheme is optimized, such as rationally controlling the gas injection rate and selecting the optimal production well layout, to maximize reservoir recovery and production efficiency. Attached Figure Description

[0072] Figure 1 This is a flowchart of one embodiment of the present invention;

[0073] Figure 2 A flowchart of a programming procedure for calculating the equivalent permeability of anisotropic conglomerate reservoirs with varying seepage space. Detailed Implementation

[0074] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0075] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0076] A method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation includes the following steps:

[0077] S1: Establish an equivalent permeability calculation model for conglomerate reservoirs with complex pore structures: Based on the shape and arrangement of gravel particles, construct an equivalent permeability calculation model under complex pore structures, and clarify the direction, length and spacing of fractures;

[0078] S2: Quantitative parameter calculation: Based on the above model, calculate the content of each particle size component (gravel, sand, mud) in the conglomerate reservoir. Based on these contents and the average particle diameter, solve the effective porosity of the conglomerate matrix according to the different cases of dual mode (sand, mud) and complex mode (gravel, sand, mud).

[0079] S3: Permeability determination: Using the grain size composition and effective porosity obtained in S2, the permeability of the conglomerate matrix and the permeability of the fracture unit are further calculated. Based on the principle that the same characteristic unit has the same equivalent permeability, the average aperture of the fracture in the unit containing the fracture is obtained.

[0080] S4: Application of the seepage space transformation method: Transforms complex anisotropic seepage problems into Laplace equations for solving, enabling simulation of actual seepage paths and patterns;

[0081] S5: Software Development and Verification: Based on the methods in S1-S4, develop a computational module and verify the effectiveness and practicality of the computational model by comparing it with the physical simulation results and performing error analysis.

[0082] In some embodiments: In step S1, the shape and arrangement of gravel particles are divided into three cases, and their corresponding crack directions, lengths, and spacings are as follows:

[0083] Case 1: The gravel particles are mainly round, the direction of the cracks is parallel to the direction of the maximum horizontal principal stress, the length of a single crack is the average diameter of the gravel, and the crack spacing is the average diameter of the gravel.

[0084] Scenario 2: The gravel particles are mainly elliptical, the cracks extend parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel.

[0085] Scenario 3: If the gravel particles are mainly elliptical, then the direction of the crack extension is parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel.

[0086] In one embodiment: In S2, the effective porosity of the conglomerate matrix is ​​calculated as follows:

[0087] For dual-mode (sand, mud): Φ d =Φ s -f m ;

[0088] For complex modes (gravel, sand, mud): Φ e =Φ s -(1-Φ s )f s -f m ;

[0089] Where: Φ s Porosity of sand;

[0090] f m For: the particle size composition content of mud;

[0091] f s For: the particle size composition content of sand.

[0092] In other embodiments: In S3, the permeability of the conglomerate matrix is ​​calculated as follows:

[0093]

[0094] In the formula: Φ represents porosity;

[0095] f c For: the content of grain size components;

[0096] f m For: the particle size composition content of mud;

[0097] f s For: the particle size distribution of sand;

[0098] d c : The average diameter of the gravel particles;

[0099] d m : The average diameter of mud particles;

[0100] d s : The average diameter of sand particles.

[0101] In other embodiments: In S3, the permeability of the fracture element is calculated as follows:

[0102]

[0103] In the formula: k fi Let: the permeability of the i-th group of fractures, mD;

[0104] k m : Matrix permeability, mD.

[0105] In other embodiments: In S3, the equivalent permeability of the unit cell is calculated as follows:

[0106] Crack permeability can be calculated using the following formula:

[0107]

[0108] In the formula: b1 is the average aperture of the i-th group of cracks, in mm;

[0109] d1 represents the average crack spacing of the i-th group of cracks, in mm.

[0110] To achieve the same permeability for all cells and the same aperture for each individual fracture, then:

[0111] K 非均质单元 =K 裂缝单元

[0112] Assuming the aperture of each crack is b, solving the above equations yields:

[0113]

[0114] The intrinsic permeability k within the fracture is calculated using b. f :

[0115]

[0116] In other embodiments, the specific steps of S4 are as follows:

[0117] S401: Perform seepage space transformation:

[0118] First, establish the governing equations:

[0119]

[0120] Then, set the boundary conditions:

[0121]

[0122] S402: Transformation of anisotropic and equivalent isotropic seepage space:

[0123]

[0124]

[0125] S403: Semi-analytical model of fracture permeability:

[0126]

[0127] In the formula: Q - flow rate obtained from experimental testing, m 3 ;k f－ Crack permeability, ×10 -3 μm 2 ;k y - Matrix permeability, ×10 -3 μm 2 μ - fluid viscosity, mPa·s; Δp - fluid pressure change, MPa; h - characteristic element thickness, m; K(m) - first-kind complete elliptic integral with parameter m; K'(m) - first-kind complete elliptic integral with parameter (1-m); L” is the length of the characteristic element in isotropic space, m; W” is the width of the characteristic element in isotropic space, m.

[0128] In other embodiments: S5 uses MATLAB for programming development.

[0129] In other embodiments: the programming flow for calculating the equivalent permeability of anisotropic conglomerate reservoirs under seepage space transformation in S5 is as follows:

[0130] S501: Input basic parameters: First, you need to input a series of basic parameters, including Q, μ, h, W, L, k. y , β and Δp; here, Q is the flow rate obtained from experimental testing, m 3 μ - fluid viscosity, mPa·s; h - model thickness, m; W - width of the characteristic element in isotropic space, m; L - length of the characteristic element in isotropic space, m; β - angle between the crack development direction and the horizontal direction, °; ​​Δp - fluid pressure change, MPa;

[0131] S502: Initial permeability given in the direction parallel to the fracture: Based on the parameters in S501, an initial permeability value k is given in the direction parallel to the fracture. x0 ;

[0132] S503: Analytical calculation of R = W' / L' and γ: Given the value of g, iteratively solve T = W' / L'; here, W' is the width of the characteristic unit in the anisotropic space, m; L' is the length of the characteristic unit in the anisotropic space, m; the minimum interior angle πγ of the isotropic parallelogram seepage space, therefore γ is the minimum interior angle πγ / π.

[0133] S504: Check if R equals T: If the calculation result R equals T, proceed to the next step; otherwise, jump to S503 to re-given the value of g and iteratively solve T = W' / L'.

[0134] S505: Determine the value of g and solve for W” / L”;

[0135] S506: Calculate the equivalent permeability k e Then use the above information to calculate the equivalent permeability k. e ;

[0136] S507: Calculate the permeability kx in the direction parallel to the fracture: The last step is to calculate the permeability kx in the direction parallel to the fracture based on ke;

[0137] S508: Determine k x Is k x0 If yes, proceed to the next step; otherwise, switch to S502 to reset k. x0 ;

[0138] S508: End of Run: When all steps are completed, the program ends, and the result of k under the current conditions can be determined. x and k f value.

[0139] The following specific embodiment of the present invention is provided to demonstrate the beneficial effects of the present invention:

[0140] The shape and percentage content of gravel, sandstone, and mudstone particles in the selected characteristic unit cells were statistically analyzed, and the porosity calculation model of complex modal (gravel, sand, mudstone) rock blocks was used: Φ e =Φ s -(1-Φ s )f s -f m The effective porosity of this feature unit was calculated to be 8%.

[0141] Based on the calculation of effective porosity and combined with the average particle size of various types of particles, the permeability calculation formula for heterogeneous units is applied.

[0142]

[0143] The calculated permeability of the heterogeneous unit is 0.69 μm. 2 Based on the principle that the equivalent permeability of the same characteristic unit is equal, it can be known that the equivalent permeability of the characteristic unit containing the crack is also 0.69 μm. 2 .

[0144] The physical simulation model is a square with a side length of 200mm on the plane, therefore W / L = 1, k y =0.4μm 2 Here, β takes the value of 0°.

[0145] Assume k x =1.18μm 2 We can obtain W' / L' and γ as 0.5822 and 0.1032, respectively; then, given different values ​​of m, when the calculated result of W' / L' for a certain value of m is different from that of a given k... x When the calculation results are the same, a fixed value of m is chosen, and then the value of m is substituted into K(m) (a complete elliptic integral of the first kind with parameter m) and K'(m) (a complete elliptic integral of the first kind with parameter (1-m)) respectively, to obtain their values, and then substituted into the equation.

[0146]

[0147] The flow rate data can be calculated. Comparing this flow rate data with the flow rate obtained from experimental tests under the same conditions, if the error is within an acceptable range, k can be considered acceptable. x The chosen value is reasonable. Therefore, the equivalent permeability of the fractured element in the direction parallel to the fracture can be determined as k. x Therefore, the fracture permeability k can be obtained. f These parameters can be used to calculate the permeability values ​​of isotropic and anisotropic seepage spaces, respectively.

[0148] The calculation results for the anisotropic seepage space are shown in Table 1. The mean pressure and pressure gradient are the boundary conditions used in experimental testing and permeability calculation, k xexp k is the permeability value obtained from experimental testing. xcal The permeability value calculated using the calculation model established in this patent has an error of: (experimental test value (k)) xexp )-(Calculated value (k) xcal )) / Experimental test value (k) xexp The calculation results show that the permeability k obtained from the experimental test data is calculated as follows: (1) × 100%. xexp k calculated using the semi-analytical model established using this patent xcal The high degree of agreement and small error indicate that the above calculation method is accurate and reasonable.

[0149] Table 1 Comparison of permeability obtained from experimental conversion and semi-analytical model calculations.

[0150]

[0151] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation, characterized in that: Includes the following steps: S1: Establish an equivalent permeability calculation model for conglomerate reservoirs with complex pore structures: Based on the shape and arrangement of gravel particles, construct an equivalent permeability calculation model under complex pore structures, and clarify the direction, length and spacing of fractures; S2: Quantitative parameter calculation: Based on the above model, calculate the content of each particle size component (gravel, sand, mud) in the conglomerate reservoir. Based on these contents and the average particle diameter, solve the effective porosity of the conglomerate matrix according to the different cases of dual mode (sand, mud) and complex mode (gravel, sand, mud). S3: Permeability determination: Using the grain size composition and effective porosity obtained in S2, the permeability of the conglomerate matrix and the permeability of the fracture unit are further calculated. Based on the principle that the same characteristic unit has the same equivalent permeability, the average aperture of the fracture in the unit containing the fracture is obtained. S4: Application of the seepage space transformation method: Transforms complex anisotropic seepage problems into Laplace equations for solving, enabling simulation of actual seepage paths and patterns; S5: Software Development and Verification: Based on the methods in S1-S4, develop a computational module and verify the effectiveness and practicality of the computational model by comparing it with the physical simulation results and performing error analysis.

2. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 1, characterized in that: In step S1, the shape and arrangement of the gravel particles are divided into three cases, and their corresponding crack directions, lengths, and spacings are as follows: Scenario 1: The gravel particles are mainly round, the direction of the cracks is parallel to the direction of the maximum horizontal principal stress, the length of a single crack is the average diameter of the gravel, and the crack spacing is the average diameter of the gravel. Scenario 2: The gravel particles are mainly elliptical, the cracks extend parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel. Scenario 3: If the gravel particles are mainly elliptical, then the direction of the crack extension is parallel to the major axis of the ellipse, the length of a single crack is the average major axis length of the gravel, and the crack spacing is the average minor axis length of the gravel.

3. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 1, characterized in that: In S2, the effective porosity of the conglomerate matrix is ​​calculated as follows: For dual-mode (sand, mud): Φ d =Φ s -f m ; For complex modes (gravel, sand, mud): Φ e =Φ s -(1-Φ s )f s -f m ; In the formula: Φ s Porosity of sand; f m For: the particle size composition content of mud; f s For: the particle size composition content of sand.

4. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 1, characterized in that: In S3, the permeability of the conglomerate matrix is ​​calculated as follows: In the formula: Φ represents porosity; f c For: the content of grain size components; f m For: the particle size composition content of mud; f s For: the particle size distribution of sand; d c : The average diameter of the gravel particles; d m : The average diameter of mud particles; d s : The average diameter of sand particles.

5. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 4, characterized in that: In S3, the permeability of the fracture element is calculated as follows: In the formula: k fi Let: the permeability of the i-th group of fractures, mD; k m : Matrix permeability, mD.

6. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 5, characterized in that: In S3, the equivalent permeability of a single unit is calculated as follows: Crack permeability can be calculated using the following formula: In the formula: b i Let: the average aperture of the i-th group of cracks, in mm; d i Let: the average crack spacing of the i-th group of cracks, in mm; To achieve uniform permeability across all cells and identical aperture for each individual fracture, then: K 非均质单元 =K 裂缝单元 Assuming the aperture of each crack is b, solving the above equations yields: The intrinsic permeability k within the fracture is calculated using b. f :

7. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 1, characterized in that: The specific steps of S4 are: S401: Perform seepage space transformation: First, establish the governing equations: Then, set the boundary conditions: S402: Transformation of anisotropic and equivalent isotropic seepage space: S403: Semi-analytical model of fracture permeability: In the formula: Q - flow rate obtained from experimental testing, m 3 ;k f－ Crack permeability, ×10 -3 μm 2 ;k y - Matrix permeability, ×10 -3 μm 2 μ - fluid viscosity, mPa·s; Δp - fluid pressure change, MPa; h - characteristic element thickness, m; K(m) - first-kind complete elliptic integral with parameter m; K'(m) - first-kind complete elliptic integral with parameter (1-m); L” is the length of the characteristic element in isotropic space, m; W” is the width of the characteristic element in isotropic space, m.

8. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 1, characterized in that: S5 uses MATLAB for programming development.

9. The method for calculating the equivalent permeability of conglomerate reservoirs based on seepage space transformation according to claim 8, characterized in that: The programming flow for calculating the equivalent permeability of anisotropic conglomerate reservoirs under seepage space transformation in S5 is as follows: S501: Input basic parameters: First, you need to input a series of basic parameters, including Q, μ, h, W, L, k. y , β and Δp; here, Q is the flow rate obtained from experimental testing, m 3 μ - fluid viscosity, mPa·s; h - model thickness, m; W - width of the characteristic element in isotropic space, m; L - length of the characteristic element in isotropic space, m; β - angle between the crack development direction and the horizontal direction, °; ​​Δp - fluid pressure change, MPa; S502: Initial permeability given in the direction parallel to the fracture: Based on the parameters in S501, an initial permeability value k is given in the direction parallel to the fracture. x0 ; S503: Analytical calculation of R = W' / L' and γ: Given the value of g, iteratively solve T = W” / L'; Here, W' is the width of the characteristic unit in the anisotropic space, m; L' is the length of the characteristic unit in the anisotropic space, m; the minimum interior angle πγ of the isotropic parallelogram seepage space, therefore γ is the minimum interior angle πγ / π; S504: Check if R equals T: If the calculation result R equals T, proceed to the next step; otherwise, jump to S503 to re-given the value of g and iteratively solve T = W' / L'. S505: Determine the value of g and solve for W” / L”; S506: Calculate the equivalent permeability k e Then, the equivalent permeability k is calculated using the calculation results from S501 to S505. e ; S507: Calculate the permeability kx in the direction parallel to the fracture: The last step is to calculate the permeability kx in the direction parallel to the fracture based on ke; S508: Determine k x Is k x0 If yes, proceed to the next step; otherwise, switch to S502 to reset k. x0 ; S508: End of Execution: When all steps are completed, the program terminates, and the result of k under the current conditions can be determined. x and k f value.

Images