A method for predicting the morphology of acid-etched wall surfaces based on a mathematical model

Abstract

The present invention provides a method for predicting the acid-etched wall surface morphology based on a mathematical model, which relates to the technical field of petroleum engineering. The method uses a three-dimensional laser scanner and fluid finite element software to perform three-dimensional modeling on the fracture surface of a rock slab to obtain a fracture space model. Based on the fracture space model, the pressure field and velocity field of the fracture space model are coupled and solved to obtain the distribution of fluid flow dynamics parameters in the fracture. The distribution of fluid flow dynamics parameters in the fracture is input into the constructed acid-rock reaction mathematical model to obtain the dissolution mass of each wall node. Using the dissolution mass of each wall node, the corresponding dissolution depth of the wall is obtained. Using the fracture space model, the influence of the corresponding dissolution depth of the wall is removed to obtain the acid-etched wall surface morphology, thus completing the prediction of the acid-etched wall surface morphology. The present invention solves the problem that it is impossible to carry out research on the etching morphology under different acid injection conditions on the same wall surface.

Description

Technical Field

[0001] This specification relates to the technical field of petroleum engineering, and particularly relates to a method for predicting the acid-etched wall morphology based on a mathematical model. Background Art

[0002] At present, the development of carbonate rock oil and gas in the market has been oriented towards deep layers. The resource volume of deep carbonate rock oil and gas accounts for about 70% of the total world oil and gas resources. To this day, deep carbonate rock oil and gas are still an indispensable part of energy supply. However, the problems commonly faced in the development of deep carbonate rock reservoirs are deep burial, strong heterogeneity, high environmental temperature, and high closure pressure. After acid fracturing of deep carbonate rock reservoirs, there are often problems such as weak acid-etched fracture conductivity and short duration of production increase effect. The main reason is that the acid-etched wall morphology restricts the oil and gas channels after fracture closure, which may lead to limited oil and gas flow. Therefore, the acid-etched fracture wall morphology is one of the determining factors for acid-etched fracture conductivity and an important parameter for predicting and judging the acid fracturing effect.

[0003] Currently, the main method for studying the surface morphology of acid-etched fractures is to obtain the acid-etched rock surface through acid liquid flow experiments and then use laser scanning to achieve digitization, so as to conduct research on acid-etched fractures under different conditions. However, due to the strong heterogeneity of carbonate rocks, the initial fracture surfaces obtained from each experimental sample vary greatly, and the traditional research method cannot study the etching characteristics under different acid liquid injection conditions on the same wall surface. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, the method for predicting the acid-etched wall morphology based on a mathematical model provided by the present invention solves the problem that the etching morphology under different acid liquid injection conditions cannot be studied on the same wall surface.

[0005] In order to achieve the above invention purpose, the technical solution adopted by the present invention is: A method for predicting the acid-etched wall morphology based on a mathematical model, including:

[0006] S1: Using a three-dimensional laser scanner and fluid finite element software, perform three-dimensional modeling on the fracture surface of the rock slab to obtain a fracture space model;

[0007] S2: Based on the preset conditions and fluid injection parameters of the fracture space model, use the finite volume method principle to couple and solve the pressure field and velocity field of the fracture space model to obtain the distribution of fluid flow dynamics parameters in the fracture;

[0008] S3: Based on the relevant theories of boundary layer, natural diffusion, and convective mass transfer of acid liquid in the fracture, construct a mathematical model of acid-rock reaction controlled by mass transfer;

[0009] S4: Input the distribution of the fluid flow dynamics parameters in the crack into the acid-rock reaction mathematical model to obtain the corrosion mass of each wall node.

[0010] S5: Analyze the corresponding relationship with the point corrosion depth using the corrosion mass of each wall node to obtain the corresponding corrosion depth of the wall.

[0011] S6: Use the crack space model to remove the influence of the corresponding corrosion depth of the wall to obtain the acid-etched wall morphology, thus completing the prediction of the acid-etched wall morphology.

[0012] The beneficial effects of the present invention are as follows: The processor uses the crack space model and the acid-rock reaction mathematical model to predict the corresponding corrosion depth of the wall, obtains the acid-etched wall morphology, and completes the prediction of the acid-etched wall morphology. By using a three-dimensional laser scanner to obtain the digital model of the real crack surface morphology and importing it into the fluid finite element modeling software to obtain the real crack space model, the experimental workload is greatly simplified, the experimental samples and experimental costs are saved, and the problem that the etching morphology research under different acid injection conditions cannot be carried out on the same wall surface is solved; by using the crack space model and the acid-rock reaction mathematical model, the accuracy and efficiency of the acid-etched wall prediction can also be improved.

[0013] Further, the S1 includes:

[0014] Use a three-dimensional laser scanner to scan the Brazilian split rock plate to obtain the 3D point cloud data of the real rock surface.

[0015] Use fluid finite element software to finely model the 3D point cloud data of the real rock surface to obtain a meshed crack space model.

[0016] Based on the relevant theories of the acid liquid boundary layer, natural diffusion, and convective mass transfer in the crack, a calculation model for the acid-rock reaction rate under the comprehensive parameter conditions considering formation temperature, acid liquid viscosity, acid liquid concentration, acid liquid flow rate, and crack width is established, greatly improving the accuracy of the model calculation results.

[0017] Further, the S3 includes:

[0018] Based on the boundary layer theory of the acid liquid in the crack, use the relationship between the acid liquid flow rate, pumping displacement, and Reynolds number to calculate the critical Reynolds number.

[0019] Based on the natural diffusion theory of the acid liquid in the crack, use the influence of acid liquid concentration, acid liquid viscosity, and formation high temperature on the acid liquid diffusion during acid liquid flow to calculate the diffusion coefficient.

[0020] Based on the convective mass transfer theory of the acid liquid in the crack, obtain the convective mass transfer coefficient of laminar flow in the formation crack.

[0021] Using the critical Reynolds number, the diffusion coefficient, and the convective mass transfer coefficient, obtain the effective mass transfer coefficient of the acid solution in the formation fracture;

[0022] Based on the effective mass transfer coefficient of the acid solution in the formation fracture, use Fick's first law and the acid-rock reaction chemical equation to construct a mathematical model of the acid-rock reaction controlled by mass transfer.

[0023] By considering comprehensive parameters such as formation temperature, acid solution viscosity, acid solution flow rate, and fracture width, it is more in line with the actual formation conditions and the calculation results are more accurate.

[0024] Furthermore, the expression for the critical Reynolds number is:

[0025] ;

[0026] The expression for the diffusion coefficient is:

[0027] ;

[0028] The expression for the convective mass transfer coefficient is:

[0029] ;

[0030] Where, represents the critical Reynolds number, represents the pumping displacement, represents the acid solution density, represents the average fracture height, represents the acid solution viscosity, represents the diffusion coefficient, represents the natural constant in exponential form, represents the formation temperature, represents the acid solution concentration, represents the convective mass transfer coefficient, represents the fracture width, represents the acid solution flow rate, represents the kinematic viscosity of the acid solution.

[0031] Furthermore, the expression for the effective mass transfer coefficient of the acid solution is:

[0032] ;

[0033] The expression for the mathematical model of the acid-rock reaction is:

[0034] ;

[0035] ;

[0036] Where, represents the effective mass transfer coefficient of the acid solution, represents the crack width, represents the acid fluid flow rate, represents the acid fluid density, represents the acid fluid viscosity, represents the natural constant, represents the formation temperature, represents the acid fluid concentration, represents the calcite dissolution rate of the corresponding node, represents the dolomite dissolution rate of the corresponding node.

[0037] A real crack space model was established using a three-dimensional laser scanner and a finite element software for fluid mechanics. After numerical simulation, the distribution of fluid parameters on the crack surface was obtained. Combining with the acid-rock reaction mathematical model, the dissolution mass of a single node on the crack surface was obtained, making the analysis of the dissolution law on the crack surface more refined and specific.

[0038] Further, the S4 includes:

[0039] Using a three-dimensional laser scanner and a fluid finite element software, the average node coverage area, calcite content, and dolomite content were obtained;

[0040] Inputting the distribution of the fluid flow dynamics parameters in the crack, the average node coverage area, the calcite content, and the dolomite content into the acid-rock reaction mathematical model, the dissolution mass of each wall node was obtained.

[0041] Using the finite element mesh division idea, the crack surface mesh was nodeized, and the control area of a single node was calculated, making the subsequent dissolution calculation refined to specific nodes and more in line with the actual formation conditions.

[0042] Further, the expression for the average node coverage area is:

[0043] ;

[0044] Where, represents the average node coverage area, represents the wall area, represents the number of wall mesh nodes.

[0045] Using the dissolution mass calculation formula and the dissolution depth calculation formula, the dissolution height of each wall node at different times can be obtained, thus establishing the dynamic dissolution process of the acid fluid in the crack and predicting the acid-etched wall surface morphology at different times.

[0046] Further, the expression for the dissolution mass of each wall node is:

[0047] ;

[0048] Where, Indicates the corrosion mass of each wall node, Indicates the calcite content, Indicates the calcite corrosion rate of the corresponding node, Indicates the dolomite content, Indicates the dolomite corrosion rate of the corresponding node, Indicates the average coverage area of the node, Indicates the acid fluid flow simulation time.

[0049] Furthermore, the expression for the corrosion depth corresponding to the wall surface is:

[0050] ;

[0051] Wherein, Indicates the corrosion depth corresponding to the wall surface, Indicates the point corrosion mass, Indicates the average coverage area of the node, Indicates the acid fluid density. Brief Description of the Drawings

[0052] This specification will be further described in the form of exemplary embodiments, and these exemplary embodiments will be described in detail through the drawings. These embodiments are not restrictive. In these embodiments, the same numbers represent the same structures, where:

[0053] Figure 1 is an exemplary flowchart of a method for predicting the acid-etched wall surface morphology based on a mathematical model according to some embodiments of this specification. Detailed Embodiments

[0054] The following describes the detailed embodiments of the present invention to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the detailed embodiments. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions created using the concept of the present invention are within the scope of protection.

[0055] Embodiment

[0056] Figure 1 is an exemplary flowchart of a method for predicting the acid-etched wall surface morphology based on a mathematical model according to some embodiments of this specification. As Figure 1 shown, the process includes the following steps. In some embodiments, the process can be executed by a processor.

[0057] S1: Use a three-dimensional laser scanner and fluid finite element software to perform three-dimensional modeling on the fractured surface of the rock slab to obtain a fracture space model.

[0058] A three-dimensional laser scanner is an instrument for scanning and obtaining rock surface information.

[0059] A fluid finite element software is used to model the rock surface to obtain a fracture space model.

[0060] A fracture space model is a three-dimensional space model reflecting the fracture information of the rock surface. For example, the fracture space model may include grid nodes for dividing the wall surface.

[0061] In some embodiments, the processor may use a three-dimensional laser scanner to scan a rock slab to obtain three-dimensional point cloud data of the real rock surface; and use fluid finite element software to finely model the three-dimensional point cloud data of the real rock surface to obtain a meshed fracture space model.

[0062] The three-dimensional point cloud data of the real rock surface is data reflecting the point cloud distribution on the surface of the real rock slab. For example, the three-dimensional point cloud data of the real rock surface may include the three-dimensional point cloud data of a Brazilian split rock surface.

[0063] In some embodiments, the processor may import the three-dimensional point cloud data of the real rock surface into three-dimensional reverse modeling software to obtain a three-dimensional wall model.

[0064] A three-dimensional wall model is a three-dimensional model reflecting the surface structure of the real rock surface.

[0065] In some embodiments, the processor may perform surface curvature and grid construction on the three-dimensional wall model to obtain a surface-curved three-dimensional wall model.

[0066] A meshed fracture space model is a three-dimensional space model with grid information reflecting the fracture information of the rock surface.

[0067] In some embodiments, the processor may use fluid finite element software to process the surface-curved three-dimensional wall model and mesh the processed model to obtain a meshed fracture space model.

[0068] S2: Based on the preset conditions of the fracture space model and the fluid injection parameters, use the principle of the finite volume method to couple and solve the pressure field and velocity field of the fracture space model to obtain the distribution of fluid flow dynamics parameters in the fracture.

[0069] Preset conditions are given hypothetical conditions for simplifying the prediction model. For example, the preset conditions may include that each input parameter is not affected by temperature, the acid-rock reaction heat is not considered, the heat conduction between the wall model and the acid solution is not considered, the filtration of the acid solution is not considered, and no deformation occurs in the wall model, etc.

[0070] Fluid injection parameters are the initial conditions and boundary conditions required for the prediction model. For example, fluid injection parameters may include initial condition injection duration, acid density, acid viscosity, injection flow rate, formation temperature, average fracture height, pumping displacement, etc. and boundary conditions such as selecting the inlet and outlet types.

[0071] In some embodiments, the processor may obtain the initial conditions and boundary conditions based on the scanning of the rock slab fracture surface.

[0072] The principle of the finite volume method is a method for calculating numerical values in fluid mechanics by using the conservation equation in integral form.

[0073] The distribution of fluid flow dynamics parameters in the fracture is data reflecting the acid flow velocity distribution on the fracture surface using a three-axis coordinate.

[0074] In some embodiments, the processor may use the principle of the finite volume method to solve the fracture space model based on preset conditions and fluid injection parameters to obtain the distribution of fluid flow dynamics parameters in the fracture.

[0075] S3: Based on the relevant theories of the boundary layer, natural diffusion, and convective mass transfer of acid in the fracture, construct a mathematical model of acid-rock reaction controlled by mass transfer.

[0076] The boundary layer theory of acid in the fracture is a theory reflecting the influence of viscous forces on the movement of the fluid.

[0077] The natural diffusion theory of acid in the fracture is a theory reflecting the natural movement and diffusion of the fluid.

[0078] The convective mass transfer theory of acid in the fracture is a theory reflecting the mass transfer between the fluid and the solid wall surface.

[0079] The mathematical model of acid-rock reaction controlled by mass transfer is a mathematical model reflecting the movement of acid and the reaction between acid and the rock surface.

[0080] In some embodiments, the processor may calculate the critical Reynolds number based on the boundary layer theory of acid in the fracture using the relationship between acid flow velocity, pumping displacement, and Reynolds number; calculate the diffusion coefficient based on the natural diffusion theory of acid in the fracture using the influence of acid concentration, acid viscosity, and formation high temperature on acid diffusion during acid flow; obtain the convective mass transfer coefficient of laminar flow in the formation fracture based on the convective mass transfer theory of acid in the fracture; obtain the effective mass transfer coefficient of acid in the formation fracture using the critical Reynolds number, the diffusion coefficient, and the convective mass transfer coefficient; and construct a mathematical model of acid-rock reaction controlled by mass transfer based on the effective mass transfer coefficient of acid in the formation fracture using Fick's first law and the chemical equation of acid-rock reaction.

[0081] The critical Reynolds number is a parameter used to determine the flow regime of acid fluid. For example, when the Reynolds number is less than 2,300, it can be laminar flow; when the Reynolds number is between 2,300 and 4,000, it can be transitional flow; when the Reynolds number is greater than 4,000, it can be turbulent flow. When the Reynolds number of the acid fluid flow in the fracture is less than 500, it can indicate that the flow of the acid fluid in the fracture is mainly laminar flow.

[0082] In some embodiments, the expression of the critical Reynolds number can be:

[0083] ;

[0084] Wherein, represents the critical Reynolds number, represents the pumping rate, represents the density of the acid fluid, represents the average fracture height, represents the viscosity of the acid fluid.

[0085] The diffusion coefficient is a parameter describing the diffusion of acid fluid flow.

[0086] In some embodiments, the expression of the diffusion coefficient can be:

[0087] ;

[0088] Wherein, represents the diffusion coefficient, represents the exponential form of the natural constant, represents the formation temperature, represents the acid fluid concentration.

[0089] The convective mass transfer coefficient is a parameter describing the reaction between the acid fluid and the rock surface in laminar flow in the formation fracture.

[0090] In some embodiments, the expression of the convective mass transfer coefficient can be:

[0091] ;

[0092] Wherein, represents the convective mass transfer coefficient, represents the fracture width, represents the acid fluid flow velocity, represents the kinematic viscosity of the acid fluid.

[0093] The effective mass transfer coefficient of the acid fluid is a parameter reflecting the mass transfer ability of hydrogen ions from the acid fluid to the rock surface and determining the rock dissolution rate during acid fracturing.

[0094] In some embodiments, the expression of the effective mass transfer coefficient of the acid fluid can be:

[0095] ;

[0096] Among them, represents the effective mass transfer coefficient of the acid solution, represents the fracture width, represents the flow rate of the acid solution, represents the density of the acid solution, represents the viscosity of the acid solution, represents the natural constant, represents the formation temperature, represents the acid solution concentration.

[0097] Fick's first law is a law that describes the diffusion mass flow rate per unit time through a unit cross-sectional area perpendicular to the diffusion direction.

[0098] The acid-rock reaction chemical equation is a chemical equation that reflects the material changes caused by the acid-salt reaction.

[0099] In some embodiments, the expression of the acid-rock reaction mathematical model can be:

[0100] ;

[0101] ;

[0102] Among them, represents the calcite dissolution rate of the corresponding node, represents the dolomite dissolution rate of the corresponding node.

[0103] S4: Input the distribution of the fluid flow dynamics parameters in the fracture into the acid-rock reaction mathematical model to obtain the dissolution mass of each wall node.

[0104] The dissolution mass of each wall node is mass data that reflects the loss of the rock surface at the wall node after being corroded by the acid solution.

[0105] In some embodiments, the processor can use a three-dimensional laser scanner and fluid finite element software to obtain the average node coverage area, calcite content, and dolomite content; input the distribution of the fluid flow dynamics parameters in the fracture, the average node coverage area, the calcite content, and the dolomite content into the acid-rock reaction mathematical model to obtain the dissolution mass of each wall node.

[0106] The average node coverage area is data that reflects the average value of the coverage areas of each node.

[0107] In some embodiments, the expression of the average node coverage area can be:

[0108] ;

[0109] Among them, Represents the average coverage area of nodes, Represents the wall area, Represents the number of wall grid nodes

[0110] The calcite content is the amount of calcite contained in the rock wall within each node.

[0111] The dolomite content is the amount of dolomite contained in the rock wall within each node.

[0112] In some embodiments, the processor can use a three-dimensional laser scanner to scan the rock slab to obtain the calcite content and dolomite content corresponding to each node.

[0113] In some embodiments, the expression for the corrosion mass of each wall node can be:

[0114] ;

[0115] Wherein, Represents the corrosion mass of each wall node, Represents the calcite content, Represents the calcite corrosion rate of the corresponding node, Represents the dolomite content, Represents the dolomite corrosion rate of the corresponding node, Represents the average coverage area of nodes, Represents the acid fluid flow simulation time.

[0116] S5: Using the corrosion mass of each wall node, analyze the corresponding relationship with the point corrosion depth to obtain the corrosion depth corresponding to the wall.

[0117] The corrosion depth corresponding to the wall is data reflecting the depth change of the wall after corrosion.

[0118] In some embodiments, the expression for the corrosion depth corresponding to the wall can be:

[0119] ;

[0120] Wherein, Represents the corrosion depth corresponding to the wall, Represents the point corrosion mass, Represents the average coverage area of nodes, Represents the acid fluid density.

[0121] S6: Using the crack space model, remove the influence of the corrosion depth corresponding to the wall to obtain the acid-etched wall morphology, and complete the prediction of the acid-etched wall morphology.

[0122] The acid-etched wall morphology is the wall morphology reflecting the rock slab wall after being corroded by the acid fluid.

[0123] In some embodiments, the processor may process the corresponding grid in the fracture space model by using the obtained erosion depth of each grid wall surface to obtain the wall surface morphology after acid etching.

[0124] In some embodiments of the present specification, the processor uses the fracture space model and the acid-rock reaction mathematical model to predict the corresponding erosion depth of the wall surface, obtain the wall surface morphology after acid etching, and complete the prediction of the acid-etched wall surface morphology. In this way, the experimental workload is greatly simplified, the experimental samples and experimental costs are saved, and the problem that the etching morphology cannot be studied under different acid injection conditions on the same wall surface is solved; by using the fracture space model and the acid-rock reaction mathematical model, the accuracy and prediction efficiency of acid-etched wall surface prediction can also be improved.

Claims

1. A method for predicting the morphology of acid-etched wall based on a mathematical model, characterized in that: include: S1: Use a 3D laser scanner and fluid finite element software to perform 3D modeling on the crack surface of the rock plate to obtain a crack space model; S2: Based on the preset conditions of the fracture space model and the fluid injection parameters, the pressure field and the velocity field of the fracture space model are coupled and solved using the finite volume method principle to obtain the distribution of the fluid flow dynamics parameters in the fracture; S3: Based on the boundary layer, natural diffusion and convective mass transfer theories of acid fluid in fractures, a mathematical model of acid-rock reaction controlled by mass transfer is constructed; S4: inputting the distribution of fluid flow dynamics parameters in the fracture into the acid-rock reaction mathematical model to obtain the dissolution mass of each wall node; S5: using the dissolution mass of each wall node, analyzing the corresponding relationship with the point dissolution depth, and obtaining the corresponding dissolution depth of the wall; S6: using the fracture space model, removing the influence of the corresponding dissolution depth of the wall, obtaining the wall morphology after acid etching, and completing the prediction of the acid-etched wall morphology.

2. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 1, characterized in that: The S1 includes: Use a 3D laser scanner to scan the rock slab and obtain the 3D point cloud data of the real rock surface; The three-dimensional point cloud data of the real rock surface is finely modeled using fluid finite element software to obtain a gridded fracture space model.

3. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 1, characterized in that: The S3 includes: Based on the boundary layer theory of acid in cracks, the critical Reynolds number is calculated by using the relationship between acid flow rate, pumping displacement and Reynolds number. Based on the natural diffusion theory of acid in fractures, the diffusion coefficient is calculated by using the influence of acid concentration, acid viscosity and formation high temperature on the diffusion of acid during acid flow. Based on the convective mass transfer theory of acid solution in fractures, the convective mass transfer coefficient of laminar flow in formation fractures is obtained. Using the critical Reynolds number, the diffusion coefficient and the convection mass transfer coefficient, an effective mass transfer coefficient of the acid fluid in the formation fracture is obtained; Based on the effective mass transfer coefficient of the acid in the formation fractures, a mass transfer controlled acid-rock reaction mathematical model is constructed using Fick's first law and the acid-rock reaction chemical equation.

4. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 3, characterized in that: The expression of the critical Reynolds number is: ； The expression of the diffusion coefficient is: ； The expression of the convective mass transfer coefficient is: ； in, represents the critical Reynolds number, Indicates the pump displacement. represents the density of acid liquid, Indicates the average seam height, Indicates the viscosity of the acid. represents the diffusion coefficient, represents the natural constant exponential form, represents the formation temperature, Indicates the acid concentration, represents the convective mass transfer coefficient, represents the crack width, Indicates the acid flow rate, Indicates the kinematic viscosity of the acid.

5. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 3, characterized in that: The expression of the effective mass transfer coefficient of the acid solution is: ； The expression of the acid-rock reaction mathematical model is: ； ； in, represents the effective mass transfer coefficient of acid solution, represents the crack width, Indicates the acid flow rate, represents the density of acid liquid, Indicates the viscosity of the acid. represents a natural constant, represents the formation temperature, Indicates the acid concentration, represents the calcite dissolution rate of the corresponding node, Indicates the dolomite dissolution rate of the corresponding node.

6. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 1, characterized in that: The S4 includes: The average coverage area of ​​nodes, calcite content, and dolomite content were obtained using a 3D laser scanner and fluid finite element software; The distribution of fluid flow dynamics parameters in the fracture, the average coverage area of ​​the nodes, the calcite content and the dolomite content are input into the acid-rock reaction mathematical model to obtain the dissolution quality of each wall node.

7. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 6, characterized in that: The expression of the average coverage area of ​​the nodes is: ； in, represents the average coverage area of ​​nodes, represents the wall area, Represents the number of wall mesh nodes.

8. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 6, characterized in that: The expression of the dissolution quality of each wall node is: ； in, represents the dissolution quality of each wall node, Indicates the calcite content, represents the calcite dissolution rate of the corresponding node, Indicates the dolomite content, represents the dolomite dissolution rate of the corresponding node, represents the average coverage area of ​​nodes, Indicates the acid flow simulation time.

9. The method for predicting the acid-etched wall morphology based on a mathematical model according to claim 1, characterized in that: The expression of the wall surface corresponding to the dissolution depth is: ； in, Indicates the corresponding dissolution depth of the wall. Indicates the quality of point dissolution, represents the average coverage area of ​​nodes, Indicates the density of acid liquid.

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