Anisotropic shale hydraulic-chemical coupling parameter test inversion method based on grid search

Abstract

The invention relates to an anisotropic shale hydraulic-chemical coupling parameter test inversion method based on grid search, and belongs to the field of petroleum drilling engineering and rock mechanics and engineering. The invention discloses an anisotropic shale hydraulic-chemical coupling parameter test inversion method based on grid search. The method comprises the following steps: step S10, carrying out a pore pressure transmission test experiment under the action of anisotropic shale hydraulic-chemical coupling; step S20, establishing a pressure transfer finite element model under the anisotropic shale hydraulic-chemical coupling effect; and step S30, in combination with a grid search method and pore pressure transfer test experimental data, assigning a solution domain basic physical property parameter, applying a boundary condition and dividing a finite element mapping grid to the pressure transfer finite element model respectively, and inverting an optimal hydraulic-chemical coupling parameter. According to the method, the problem that the hydraulic-chemical coupling parameters of the anisotropic shale cannot be quickly and accurately determined by a conventional method is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a grid search-based anisotropic shale hydraulic-chemical coupling parameter test inversion method, and belongs to the fields of oil drilling engineering, rock mechanics and engineering. BACKGROUND

[0002] With the increasing depletion of conventional oil and gas resources, shale oil and gas has become increasingly important in the global energy pattern. Horizontal well drilling technology and volume fracturing technology are the only means for the commercialization of shale oil and gas. However, during horizontal drilling, shale borehole instability is serious. Borehole instability will lead to complex accidents such as sticking and burying of the drill pipe, which seriously limits the safe and efficient development of shale oil and gas resources. Shale is a chemically active porous medium rich in clay. When the chemically active porous medium is in contact with drilling fluid, a chemical swelling / contraction effect occurs, leading to borehole instability. This phenomenon is called chemical osmosis. Chemical osmosis occurs due to chemical imbalance between pore fluid in the formation and drilling fluid entering the formation, which will cause a semi-permeable membrane-like effect inside the shale, allowing only part of the ions to pass through. Under the conditions of overbalanced drilling (hydraulic action) and high solute concentration drilling fluid (chemical action), the occurrence of hydraulic transmission and chemical osmosis leads to an increase in pore pressure, thus leading to borehole instability in shale formations.

[0003] Therefore, in order to solve the problem of borehole instability in shale formations, it is necessary to carry out pressure transmission experiments under hydraulic-chemical coupling and determine the relationship between the hydraulic-chemical coupling parameters of drilling fluid and shale, so as to clarify the borehole instability mechanism of shale formations. However, it is difficult to quickly and accurately determine the hydraulic-chemical coupling parameters in the coupling model. Traditional pressure transmission experiments generally use two core samples to carry out pressure transmission experiments under pure hydraulic action and pure chemical action, respectively, and are used to test and invert the hydraulic-chemical coupling parameters such as permeability, solute diffusion coefficient and reflection coefficient. This testing method cannot avoid the influence of sample differences. In addition, for anisotropic shale, the hydraulic-chemical coupling parameters in the parallel bedding and vertical bedding directions are often different. Traditional pressure transmission experiments not only cannot avoid the influence of sample differences, but also often cannot invert the hydraulic-chemical coupling parameters of anisotropic shale. SUMMARY

[0004] In view of the above problems, the present application mainly overcomes the deficiencies in the prior art and proposes a grid search-based anisotropic shale hydraulic-chemical coupling parameter test inversion method.

[0005] The technical solution provided by the present application to solve the above technical problems is: a grid search-based anisotropic shale hydraulic-chemical coupling parameter test inversion method, comprising the following steps: Step S10, carry out the pore pressure transmission test experiment under the anisotropic shale hydraulic-chemical coupling; Step S20, establish the pressure transmission finite element model under the anisotropic shale hydraulic-chemical coupling; The pressure transmission control equation of the pressure transmission finite element model is:

[0006]

[0007] Wherein,

[0008]

[0009]

[0010]

[0011] In the formula, M Biot modulus, GPa; p Pore pressure, MPa; ω Chemical-stress coupling parameter, dimensionless; α Biot coefficient tensor, dimensionless; C Compliance matrix, GPa -1 ; β 1Chemical-seepage coupling coefficient, dimensionless; k Permeability tensor, m 2 ; η Fluid viscosity, Pa·s; Reflection coefficient, dimensionless; π Chemical osmotic pressure, MPa; S σ Storage coefficient, GPa -1 ; γ Chemical action related coefficient, dimensionless; N Chemical coefficient of stress quantity, dimensionless; R Molar gas constant, J / (mol·K); x 0Initial reference salt molar fraction, dimensionless; c s Molar concentration, mol / L; T 0Absolute temperature, K; ϕ Porosity, dimensionless; v 0Initial molar volume of solution, L / mol; superscript T represents matrix transposition; Step S30: Combining the mesh search method and the experimental data of pore pressure transmission test, assign values ​​to the basic physical property parameters of the solution domain, apply boundary conditions and divide the finite element mapping mesh for the pressure transmission finite element model, and invert the optimal hydraulic-chemical coupling parameters.

[0012] A further technical solution is that the specific steps for conducting the pressure transmission test experiment under the hydraulic-chemical coupling of anisotropic shale in step S10 are as follows: Step S11, Applying Confining Pressure: After the sample is placed into the triaxial sealed chamber, a confining pressure of 15 MPa is applied to it, denoted as... p c ; Step S12, Shale saturation test stage under pure hydraulic action: Circulate a mass fraction of [missing value] at the upper end of the sample. C A NaCl solution of 0% is simultaneously injected at a pressure of 3 MPa, denoted as . p 0; After the upstream and downstream pressures are balanced, continue to circulate the liquid for at least 4 hours and monitor the downstream discharged liquid. Only after confirming that no air bubbles are discharged can saturation be determined to be complete. Step S13, Shale Pressure Transmission Test Stage under Pure Hydraulic Action: Maintain the upper circulation mass fraction of the sample at [value missing]. C A NaCl solution of 0% is injected simultaneously at an injection pressure of 10 MPa, denoted as . p m When the pressure at the lower end of the sample rises to the injection pressure p m Record the curve of the pressure change at the lower end over time to observe the effect of hydraulic loading on the pressure distribution of the sample. Step S14, Experimental stage of shale pressure transmission test under pure chemical action: A mass fraction of [missing information] is circulated at the upper end of the sample. C m NaCl solution, while maintaining injection pressure p m The pressure remains unchanged; record the curve of the lower end pressure changing over time to observe the effect of chemical loading on the pressure distribution of the sample.

[0013] A further technical solution is that the sample is a cylindrical shale rock sample drilled along or perpendicular to the bedding planes.

[0014] A further technical solution is that the specific process of step S20 is as follows: based on plane strain, sample shape and boundary conditions, the geometric model can be simplified into a two-dimensional rectangle, and then based on the pressure transmission mathematical model under the hydraulic-chemical coupling of anisotropic shale, a finite element model of pressure transmission under the hydraulic-chemical coupling of anisotropic shale is established.

[0015] A further technical solution is that the specific process of step S30 includes: Step S31, pre-processing the pore pressure transmission test experimental data; Step S32, setting the permeability parameter set k values , the reflection coefficient parameter D svalues and the solute diffusion coefficient parameter . Step S33, permeability inversion in the hydraulic loading stage: in the hydraulic loading stage, the pressure transmission is mainly controlled by the seepage field; the permeability parameter set is traversed in sequence k values ; for each k value, the anisotropic hydraulic-chemical coupling finite element model is called to use the Galerkin method to approximate the pressure transmission control equation under the anisotropic shale hydraulic-chemical coupling, obtain the algebraic equation set required for finite element solution, and calculate the simulated pore pressure distribution; then the absolute average error of the simulation result and the experimental data is calculated; the k value that makes the absolute average error minimum is recorded as the optimal permeability parameter in this stage; Step S34, solute diffusion and reflection coefficient inversion in the chemical loading stage: in the chemical loading stage, the permeability is set to the optimal value in step S33, and the reflection coefficient parameter D svalues and the solute diffusion coefficient parameter are traversed; for each combination of D s and , the optimal k obtained in step S33 is combined, the finite element model is called to simulate the pressure transmission process in the chemical loading stage; the parameter combination that makes the absolute average error minimum is recorded as the optimal solution in this stage. D s .

[0016] Further technical solutions are that the value range and step length of the rock permeability, the reflection coefficient and the solute diffusion coefficient are respectively set in step S32 to form the corresponding permeability parameter set k values , the reflection coefficient parameter D svalues and the solute diffusion coefficient parameter .

[0017] Further technical solutions are that the calculation formula of the absolute average error is as follows:

[0018] In the formula, P is the predicted pore pressure, MPa; p exp ​​The measured pore pressure is in MPa. n This represents the number of measured pore pressure data points. error This represents the absolute average error.

[0019] The beneficial effects of this invention: This invention utilizes two specific sampling angles ( β Pressure transmission experiments were conducted on samples at 0° and 90°. By combining the grid search method and the anisotropic hydraulic-chemical coupling finite element model, the optimal hydraulic-chemical coupling parameters (anisotropic permeability, solute diffusion coefficient, and reflection coefficient) were inverted, overcoming the difficulty of quickly and accurately determining the hydraulic-chemical coupling parameters of anisotropic shale by conventional methods. Attached Figure Description

[0020] Figure 1 A schematic diagram of a cylindrical rock sample obtained from drilling; Figure 2 for β =0° rock sample test results diagram; Figure 3 for β =90° rock sample test results diagram; Figure 4 Set up a graph for the geometric model, finite mesh generation, and boundary conditions; Figure 5 Determined by grid search method β =0° and β Hydraulic-chemical coupling parameter diagram of the optimal hydraulic loading stage for rock samples at 90°; Figure 6 For the hydraulic loading stage ( β Comparison of experimental and simulation results under the condition of 0°; Figure 7 For the chemical loading stage ( β Comparison of experimental and simulation results under the condition of 0°; Figure 8 For the hydraulic loading stage ( β Comparison of experimental and simulation results under the condition of 90° (=90°); Figure 9 For the chemical loading stage ( β Comparison of experimental and simulation results under the condition of 90° (=90°). Detailed Implementation

[0021] 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 embodiments of the invention, 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.

[0022] The application provides an anisotropic shale hydraulic-chemical coupling parameter test inversion method based on a grid search, and comprises the following steps: Step S10, a pore pressure transmission test experiment under anisotropic shale hydraulic-chemical coupling is carried out. Step S11, a test shale core is prepared; cylindrical shale samples are drilled along the bedding and perpendicular to the bedding, and the size of the cylindrical shale sample is Φ50*100 mm.

[0023] Step S12, a confining pressure stage is applied: after the sample is loaded into a triaxial sealing chamber, a confining pressure of 15 MPa is applied to the sample, denoted as p c .

[0024] Step S13, a shale saturation experiment stage under pure hydraulic action: NaCl solution with a mass fraction of C 0=5% is circulated on the upper end of the sample, and an injection pressure of 3 MPa is applied, denoted as p 0; after the upstream and downstream pressures are balanced, the experiment continues to circulate and inject liquid for at least 4 hours, and the downstream discharged liquid is monitored to confirm that no bubbles are discharged before determining that the saturation is completed.

[0025] Step S14, a shale pressure transmission test experiment stage under pure hydraulic action: NaCl solution with a mass fraction of C 0=5% is circulated on the upper end of the sample, and an injection pressure of 10 MPa is applied, denoted as p m ; when the pressure at the lower end of the sample rises to the injection pressure p m , the pressure change curve of the lower end with time is recorded to observe the influence of hydraulic loading on the pressure distribution of the sample.

[0026] Step S15, a shale pressure transmission test experiment stage under pure chemical action: NaCl solution with a mass fraction of C m =20% is circulated on the upper end of the sample, and the injection pressure p m remains unchanged; the pressure change curve of the lower end with time is recorded to observe the influence of chemical loading on the pressure distribution of the sample.

[0027] Step S30, a pressure transmission finite element model under anisotropic shale hydraulic-chemical coupling is established. According to the plane strain, the sample shape and the boundary conditions, the geometric model can be simplified into a two-dimensional rectangle, and based on the pressure transmission mathematical model under anisotropic shale hydraulic-chemical coupling, the pressure transmission finite element model under anisotropic shale hydraulic-chemical coupling is established.

[0028] Specific boundary condition setting: (1) hydraulic loading stage: upstream pressure and solution mass fraction are respectively p m and C 0, the initial value of the whole domain is p 0 and C 0. (2) Chemical loading stage: upstream pressure and solution mass fraction are respectively p m and C m , the initial value of the whole domain is p m and C 0.

[0029] Where the pressure transmission mathematical model under the anisotropic shale hydraulic-chemical coupling is established; The specific steps are as follows: Step 1, establish the pressure transmission control equation under the anisotropic shale hydraulic-chemical coupling: (1) (2) Wherein, (3) (4) (5) (6) In the formula: M Biot modulus, GPa; p Pore pressure, MPa; ω Chemical-stress coupling parameter, dimensionless; α Biot coefficient tensor, dimensionless; C Compliance matrix, GPa -1 ; β 1 is the chemical-seepage coupling coefficient, dimensionless; k Permeability tensor, m 2 ; η Fluid viscosity, Pa·s; Reflection coefficient, dimensionless; π Chemical osmotic pressure, MPa; S σ Storage coefficient, GPa -1 ; γ Chemical action related coefficient, dimensionless; N Chemical coefficient of the amount of substance, dimensionless; R Molar gas constant, J / (mol·K); x0 is the initial reference salt molar fraction, dimensionless; c s is the molar concentration, mol / L; T 0 is the absolute temperature, K; ϕ is the porosity, dimensionless; v 0 is the initial molar volume of the solution, L / mol; the superscript T represents matrix transposition.

[0030] Step S2, using the Galerkin method to approximate the pressure transfer control equation under the action of the anisotropic shale hydraulic-chemical coupling, wherein the finite element solution format of the pressure transfer control equation; (7) wherein, (8) (9) (10) (11) (12) (13) (14) (15) In the formula: N P is the pore pressure shape function, dimensionless; N π is the chemical osmotic pressure shape function, dimensionless; B p is the pore pressure gradient matrix, dimensionless; B π is the chemical osmotic pressure gradient matrix, dimensionless; p and π are vectors of unknown variables p and π respectively; p t and π t are time derivatives of unknown variables p and π respectively; F p , F π are fluid source and sink vectors and solute source and sink vectors respectively.

[0031] Step S40, combining the grid search method and the pressure transfer finite element model under the action of the anisotropic shale hydraulic-chemical coupling, respectively assigning the pressure transfer finite element model with the basic physical property parameters of the solution domain, applying boundary conditions and dividing the finite element mapping grid, finally calculating the pore pressure distribution, and using the pressure transfer experimental data to invert the optimal hydraulic-chemical coupling parameters; The specific inversion process is as follows: (1) experimental data preparation: obtaining pressure transmission experimental data under the action of hydraulic-chemical coupling, and pre-processing the experimental data, including denoising, time alignment and the like, so as to facilitate subsequent comparison.

[0032] (2) parameter space setting: setting the value range and step length of rock permeability, reflection coefficient and solute diffusion coefficient respectively, to form a corresponding discrete parameter set; (3) permeability inversion in the hydraulic loading stage: in the hydraulic loading stage, it is assumed that the pressure transmission is mainly controlled by the seepage field. The permeability parameter set is traversed in turn k values ; for each k value, the anisotropic hydraulic-chemical coupling finite element model is called to simulate the pressure transmission process in the hydraulic loading stage; the error between the simulation result and the experimental data is calculated; the k value that minimizes the absolute average error is recorded as the optimal permeability parameter in this stage.

[0033] (16) In the formula: is the predicted pore pressure, MPa; p exp is the measured pore pressure, MPa; n is the number of measured pore pressure data; error is the absolute average error; (4) solute diffusion and reflection coefficient inversion in the chemical loading stage: in the chemical loading stage, it is assumed that the permeability is the optimal value in step (2), and the D svalues and are traversed, for each combination of D s and , the finite element model is called to simulate the pressure transmission process in the chemical loading stage in combination with the optimal k obtained in step (2); the D s and parameter combination that minimizes the error is recorded as the optimal solution in this stage.

[0034] (5) output optimal parameters: the obtained optimal parameter combination (permeability, solute diffusion coefficient and reflection coefficient) is taken as the inversion result corresponding to the experimental data, for subsequent analysis and verification.

[0035] Embodiment Step S10, prepare a test shale core, drill a cylindrical shale sample along the bedding and perpendicular to the bedding, the size of the cylindrical shale sample is Ф50*100mm, and the drilled cylindrical shale sample is as shown in Figure 1 .

[0036] Step S20, carry out pressure transmission test experiment of anisotropic hydraulic-chemical coupling, and the experimental results are as shown in Figure 2 、 3 .

[0037] From Figure 2 、 3 , it can be seen that in the saturated sample stage and the hydraulic loading stage, the pressure at the lower end of the sample increases with time, and the pressure increase rate gradually decreases, and finally remains consistent with the upper end pressure. In the chemical loading stage, the pressure at the lower end of the sample decreases with time, and the pressure decrease rate gradually decreases, and finally remains stable. By comparing Figure 2 and Figure 3 , it can be seen that the pressure evolution rate of the hydraulic-chemical coupling experiment at different angles is obviously different. This shows that the shale has strong anisotropy; Step S30, establish a pressure transmission finite element model under the anisotropic shale hydraulic-chemical coupling respectively, assign the basic physical parameters of the solution domain, apply boundary conditions and divide the finite element mapping grid Figure 4 (a); the boundary conditions of the upper end fluid pressure and mass fraction and the initial value in the whole domain are as shown in Figure 4 b to 4d; Step S40, combine the grid search method and the pressure transmission finite element model under the anisotropic shale hydraulic-chemical coupling, and use the pressure transmission experimental data to invert the optimal hydraulic-chemical coupling parameters; (1) Experimental data preparation: obtain the original data of the hydraulic-chemical coupling pressure transmission experiment, and pretreat the experimental data, including denoising, time alignment and other operations, so as to facilitate subsequent comparison.

[0038] (2) Parameter space setting: respectively set the value range and step length of the rock permeability, reflection coefficient and solute diffusion coefficient to form the corresponding discrete parameter set; (3) Permeability inversion in the hydraulic loading stage: in the hydraulic loading stage, it is assumed that the pressure transmission is mainly controlled by the seepage field. The permeability parameter set k values is traversed in turn; for each k value, the anisotropic hydraulic-chemical coupling finite element model is called to simulate the pressure transmission process in the hydraulic loading stage; the absolute average error between the simulation result and the experimental data is calculated; the k value that makes the absolute average error minimum is recorded as the optimal permeability parameter in this stage.

[0039] (4) Solute diffusion coefficient and reflection coefficient inversion in the chemical loading stage: in the chemical loading stage, it is assumed that the permeability is the optimal value in step (2), and the Dsvalues and For each group D s and , combined with the optimal k obtained in step (2), call the finite element model to simulate the pressure transmission process in the chemical loading stage; record the D s and parameter combination as the optimal solution of this stage.

[0040] (5) Output the optimal parameters: take the obtained optimal parameter combination (permeability, solute diffusion coefficient, and reflection coefficient) as the inversion result corresponding to the experimental data for subsequent analysis and verification. The optimal parameter combination result is shown in Figure 5 . It can be seen from Figure 5 that for the shale sample with β = 0°, the permeability is 1.3e-20 m 2 , the reflection coefficient is 0.17, and the solute diffusion coefficient is 2e-9 m 2 / s. For the shale sample with β = 90°, the permeability is 6e-20 m 2 , the reflection coefficient is 0.25, and the solute diffusion coefficient is 6e-9 m 2 / s.

[0041] Step S50, verify the accuracy of the inversion of anisotropic hydraulic-chemical coupling parameters; in order to verify the correctness and accuracy of the grid search method combined with the finite element model to invert the hydraulic-chemical coupling parameters, the best hydraulic-chemical coupling parameters are substituted into the anisotropic hydraulic-chemical coupling finite element model to simulate the pressure at different stages and different times, and the simulation results (solid line) are compared with the measured pressure transmission data (solid point). The relative error of the solid point-solid line is shown in Figures 6-9 . It can be seen from the figure that the simulated pressure under the best hydraulic-chemical coupling parameter combination is basically consistent with the actual pressure transmission experimental data.

[0042] The above description is not intended to limit the present application in any form. Although the present application has been disclosed by the above examples, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above examples according to the technical essence of the present application are within the scope of the technical solution of the present application.

Claims

1. A grid-search-based method for testing and inverting hydraulic-chemical coupling parameters of anisotropic shale, characterized in that, Includes the following steps: Step S10: Conduct pore pressure transmission test experiments under the hydraulic-chemical coupling effect of anisotropic shale; Step S20: Establish a finite element model of pressure transmission under the hydraulic-chemical coupling of anisotropic shale; The pressure transmission control equation of the pressure transmission finite element model is: in, In the formula: M Here is the Biot modulus, in GPa; p Pore ​​pressure, MPa; ω is a chemical-stress coupling parameter, and is dimensionless; α Let be the Biot coefficient tensor, which is dimensionless; C Here is the compliance matrix, GPa -1 ; β 1 is the chemical-percolation coupling coefficient, which is dimensionless; k Let m be the permeability tensor. 2 ; η Where is the fluid viscosity, Pa·s; is the reflection coefficient, which is dimensionless; π Chemical osmotic pressure, MPa; S σ Storage coefficient, GPa -1 ; γ These are coefficients related to chemical reactions and are dimensionless. N The chemical coefficient is dimensionless and has no force. R is the molar gas constant, J / (mol·K); x 0 represents the initial reference salt mole fraction, which is dimensionless; c s Molar concentration, mol / L; T 0 represents absolute temperature, in K. ϕ Porosity is dimensionless. v 0 represents the initial molar volume of the solution, in L / mol; the superscript T indicates matrix transpose. Step S30: Combining the mesh search method and the experimental data of pore pressure transmission test, assign values ​​to the basic physical property parameters of the solution domain, apply boundary conditions and divide the finite element mapping mesh for the pressure transmission finite element model, and invert the optimal hydraulic-chemical coupling parameters.

2. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 1, characterized in that, The specific steps for conducting the pressure transmission test experiment under the anisotropic hydraulic-chemical coupling of shale in step S10 are as follows: Step S11, Applying Confining Pressure: After the sample is placed into the triaxial sealed chamber, a confining pressure of 15 MPa is applied to it, denoted as... p c ; Step S12, Shale saturation test stage under pure hydraulic action: Circulate a mass fraction of [missing value] at the upper end of the sample. C A NaCl solution of 0% is simultaneously injected at a pressure of 3 MPa, denoted as . p 0; After the upstream and downstream pressures are balanced, continue to circulate the liquid for at least 4 hours and monitor the downstream discharged liquid. Only after confirming that no air bubbles are discharged can saturation be determined to be complete. Step S13, Shale Pressure Transmission Test Stage under Pure Hydraulic Action: Maintain the upper circulation mass fraction of the sample at [value missing]. C A NaCl solution of 0% is injected simultaneously at an injection pressure of 10 MPa, denoted as . p m When the pressure at the lower end of the sample rises to the injection pressure p m Record the curve of the pressure change at the lower end over time to observe the effect of hydraulic loading on the pressure distribution of the sample. Step S14, Experimental stage of shale pressure transmission test under pure chemical action: A mass fraction of [missing information] is circulated at the upper end of the sample. C m NaCl solution, while maintaining injection pressure p m The pressure remains unchanged; record the curve of the lower end pressure changing over time to observe the effect of chemical loading on the pressure distribution of the sample.

3. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 2, characterized in that, The sample is a cylindrical shale rock sample drilled along or perpendicular to the bedding planes.

4. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 1, characterized in that, The specific process of step S20 is as follows: Based on plane strain, sample shape and boundary conditions, the geometric model can be simplified into a two-dimensional rectangle. Then, based on the pressure transmission mathematical model under the hydraulic-chemical coupling of anisotropic shale, a finite element model of pressure transmission under the hydraulic-chemical coupling of anisotropic shale is established.

5. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 1, characterized in that, The specific process of step S30 includes: Step S31: Preprocess the experimental data of pore pressure transmission test; Step S32: Set the permeability parameter set k values Reflection coefficient parameters D svalues and solute diffusion coefficient parameter ; Step S33, Permeability Inversion during Hydraulic Loading Stage: During the hydraulic loading stage, it is assumed that pressure transmission is mainly controlled by the seepage field; the permeability parameter set is traversed sequentially. k values For each k The anisotropic hydraulic-chemical coupled finite element model is invoked, and the Galerkin method is used to approximate the pressure transmission control equations under anisotropic shale hydraulic-chemical coupling to obtain the algebraic equations required for finite element solution. The simulated pore pressure distribution is then calculated. The absolute average error between the simulation results and experimental data is then calculated, and the value that minimizes the absolute average error is recorded. k The value is used as the optimal penetration rate parameter for this stage; Step S34, Solute diffusion and reflection coefficient inversion during chemical loading: In the chemical loading stage, the permeability is set to the optimal value in step S33, and the reflection coefficient parameters are iterated. D svalues and solute diffusion coefficient parameter For each group D s and The combination, combined with the optimal result obtained in step S33 k The finite element model was used to simulate the pressure transmission process during the chemical loading stage; the result that minimized the absolute average error was recorded. D s and The parameter combination serves as the optimal solution for this stage.

6. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 5, characterized in that, In step S32, the value ranges and step sizes for rock permeability, reflection coefficient, and solute diffusion coefficient are set respectively to form a corresponding permeability parameter set. k values Reflection coefficient parameters D svalues and solute diffusion coefficient parameter .

7. The method for testing and inverting anisotropic shale hydraulic-chemical coupling parameters based on grid search according to claim 5, characterized in that, The formula for calculating the absolute average error is: In the formula: To predict pore pressure, MPa; p exp The measured pore pressure is in MPa. n This represents the number of measured pore pressure data points. error This represents the absolute average error.

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