Fracture-vug type reservoir acid fracturing effect evaluation method and device, storage medium and processor

Abstract

The invention relates to the field of exploration and development of oil and gas reservoirs, and discloses a fracture-vug type reservoir acid fracturing effect evaluation method and device, a storage medium and a processor, and the method comprises the steps: carrying out the mesh generation of a fracture and a karst cave body, and obtaining an embedded fracture-vug body model; based on a discontinuous stress method and a discontinuous displacement method, constructing a stress field mechanical model corresponding to the embedded fracture-cavity body model; establishing a geomechanical model, a chemical reaction flow model and a crack propagation model corresponding to the embedded fracture-cavity body model, wherein the crack propagation model is obtained based on the stress field mechanical model; and obtaining a multi-field coupling acid fracturing model according to the geomechanical model, the chemical reaction flow model and the fracture propagation model, and solving the multi-field coupling acid fracturing model to obtain an acid fracturing effect evaluation result of the fracture-cavity reservoir. As the discontinuous factors of the stress of the karst cave body and the discontinuous factors of the displacement at the crack are considered when the acid fracturing effect is evaluated, the accuracy of the acid fracturing effect evaluation of the carbonate fractured-vuggy reservoir can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas reservoir exploration and development, in particular to a fracture-cave type reservoir acid fracturing effect evaluation method, a fracture-cave type reservoir acid fracturing effect evaluation device, a machine readable storage medium and a processor. BACKGROUND

[0002] Deep and ultra-deep carbonate fracture-cave type oil and gas reservoirs are the key to increasing oil and gas resources, and therefore, efficient development of such oil and gas reservoirs is of great significance. Among them, acid fracturing reconstruction is an indispensable means to realize efficient development of carbonate fracture-cave type oil and gas reservoirs. Through acid fracturing reconstruction, on the one hand, the reservoir damage caused by well construction in the near wellbore can be clearly understood, and on the other hand, the poor connectivity or non-connectivity of the reservoir can be connected by artificial fractures, greatly improving the connectivity between the reservoirs.

[0003] At present, numerical simulation technology is one of the most effective means to evaluate acid fracturing effect, which can be used to evaluate different acid effective action time, effective action distance, acid concentration distribution law in the direction of fracture length, and calculate dynamic fracture expansion change, acid etching fracture length and conductivity, so as to guide the optimization scheme of acid fracturing.

[0004] However, the existing numerical model for evaluating acid fracturing effect is relatively simple and considers fewer factors, such as not considering the influence of stress discontinuity of cave body on stress distribution, fracture diversion expansion, multi-fracture competition expansion and self-organization evolution process of wormhole in etched fracture, and the influence of displacement discontinuity at the fracture on multi-fracture competition expansion and self-organization evolution process of wormhole in etched fracture, which makes it difficult to accurately evaluate the acid fracturing effect of carbonate fracture-cave type reservoir. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the acid fracturing effect of carbonate fracture-cave type reservoir cannot be accurately evaluated in the prior art, and to provide a fracture-cave type reservoir acid fracturing effect evaluation method, device, storage medium and processor.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a fracture-cave type reservoir acid fracturing effect evaluation method, comprising:

[0007] Grid partitioning is performed on the fractures and cave bodies, and an embedded fracture-cave body model is obtained based on the grid partitioning results and the matrix;

[0008] Based on the non-continuous stress method and the non-continuous displacement method, a stress field mechanics model corresponding to the embedded fracture-cave body model is constructed;

[0009] A geological mechanics model, a chemical reaction flow model and a fracture expansion model corresponding to the embedded fracture-cave body model are established, and the fracture expansion model is obtained based on the stress field mechanics model;

[0010] obtaining a multi-field coupling acid fracturing model corresponding to the embedded fracture-cave model according to the geomechanical model, the chemical reaction flow model and the fracture propagation model, and solving the multi-field coupling acid fracturing model to obtain an acid fracturing effect evaluation result of the fracture-cave reservoir.

[0011] In the embodiment of the present application, the grid division of the fracture and the cave body comprises:

[0012] The fracture is divided by a two-dimensional triangular grid, and the cave body is divided by a three-dimensional tetrahedral grid.

[0013] In the embodiment of the present application, the stress field mechanical model corresponding to the embedded fracture-cave model is constructed based on the non-continuous stress method and the non-continuous displacement method, and the geomechanical model, the chemical reaction flow model and the fracture propagation model corresponding to the embedded fracture-cave model are established.

[0014] The stress field change caused by the fluid pressure change of the cave body is calculated by the non-continuous stress method, and the stress field change caused by the deformation of the fracture is calculated by the non-continuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded fracture-cave model.

[0015] In the embodiment of the present application, the geomechanical model corresponding to the embedded fracture-cave model is established based on the geomechanical equation.

[0016] In the embodiment of the present application, the chemical reaction flow model corresponding to the embedded fracture-cave model is established based on the mass conservation equation, the convection-diffusion equation and the auxiliary equation.

[0017] In the embodiment of the present application, the auxiliary equation comprises at least one of the mass transport equation of the acid in the pore network, the strain displacement equation, the stress strain equation, the fracture constitutive equation and the Darcy seepage equation.

[0018] The second aspect of the present application provides a fracture-cave reservoir acid fracturing effect evaluation device, comprising:

[0019] The grid division module is configured to divide the fracture and the cave body by a grid, and obtain an embedded fracture-cave model based on the grid division result and the matrix.

[0020] The model construction module is configured to construct a stress field mechanical model corresponding to the embedded fracture-cave model based on the non-continuous stress method and the non-continuous displacement method, and establish a geomechanical model, a chemical reaction flow model and a fracture propagation model corresponding to the embedded fracture-cave model, wherein the fracture propagation model is obtained based on the stress field mechanical model.

[0021] The solving module is configured to obtain a multi-field coupling acid fracturing model corresponding to the embedded fracture-cave model according to the geomechanical model, the chemical reaction flow model and the fracture propagation model, solve the multi-field coupling acid fracturing model, and obtain the acid fracturing effect evaluation result of the fracture-cave reservoir.

[0022] In the embodiments of the present application, the model construction module is configured to calculate the stress field change caused by the fluid pressure change of the cave body by using a non-continuous stress method and calculate the stress field change caused by the fracture deformation by using a non-continuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded fracture-cave model.

[0023] The third aspect of the present application provides a processor configured to execute the acid fracturing effect evaluation method of the fracture-cave reservoir.

[0024] The fourth aspect of the present application provides a machine readable storage medium having instructions stored thereon, the instructions, when executed by a processor, cause the processor to be configured to execute the acid fracturing effect evaluation method of the fracture-cave reservoir.

[0025] Through the above technical solution, the fracture and the cave body are meshed, the embedded fracture-cave model is obtained based on the meshing result and the matrix, the stress field mechanical model corresponding to the embedded fracture-cave model is constructed based on the non-continuous stress method and the non-continuous displacement method, the geomechanical model, the chemical reaction flow model and the fracture propagation model corresponding to the embedded fracture-cave model are established, the fracture propagation model is obtained based on the stress field mechanical model, the multi-field coupling acid fracturing model corresponding to the embedded fracture-cave model is obtained according to the geomechanical model, the chemical reaction flow model and the fracture propagation model, the multi-field coupling acid fracturing model is solved, and the acid fracturing effect evaluation result of the fracture-cave reservoir is obtained. Since the influence of the stress discontinuity of the cave body on the stress distribution, the fracture diversion and expansion, the multi-fracture competition and expansion and the self-organizing evolution process of the wormhole in the etched fracture, and the influence of the displacement discontinuity of the fracture on the multi-fracture competition and expansion and the self-organizing evolution process of the wormhole in the etched fracture are considered when the acid fracturing effect is evaluated, the accuracy of the acid fracturing effect evaluation of the carbonate fracture-cave reservoir can be improved.

[0026] Other features and advantages of the embodiments of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0028] Figure 1A flowchart of a method for evaluating acid fracturing effect of a fracture-cave type reservoir according to an embodiment of the present application is shown schematically.

[0029] Figure 2 A three-dimensional grid dissection of a fracture and a cave body according to an embodiment of the present application is shown schematically.

[0030] Figure 3 A stress field mechanical model constructed based on a non-continuous stress method and a non-continuous displacement method according to an embodiment of the present application is shown schematically.

[0031] Figure 4-1 A dissection effect diagram of a three-dimensional fracture and a three-dimensional cave body according to an embodiment of the present application is shown schematically, Figure 4-2 A simulation effect diagram of complex fracture propagation according to an embodiment of the present application is shown schematically.

[0032] Figure 5 A generalized model of various three-dimensional combined faults according to an embodiment of the present application is shown schematically.

[0033] Figure 6 A structure of a dissolved cave in a single faulted fracture for a strip-shaped fault combination according to an embodiment of the present application is shown schematically.

[0034] Figure 7 A structure of a dissolved cave in a single faulted fracture for a plate-shaped fault combination according to an embodiment of the present application is shown schematically.

[0035] Figure 8 A structure of a dissolved cave in a single faulted fracture for a sandwich-shaped fault combination according to an embodiment of the present application is shown schematically.

[0036] Figure 9 A structural block diagram of an acid fracturing effect evaluation device for a fracture-cave type reservoir according to an embodiment of the present application is shown schematically.

[0037] Figure 10 An internal structure diagram of a computer device according to an embodiment of the present application is shown schematically.

[0038] Legend of reference signs

[0039] 210-dissection module; 220-model construction module; 230-solution module; A01-processor; A02-network interface; A03-internal memory; A04-display screen; A05-input device; A06-non-volatile storage medium; B01-operating system; B02-computer program. DETAILED DESCRIPTION

[0040] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the specific implementation described herein is only used to explain and illustrate the embodiments of the present application, and should not be used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0041] If the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those of ordinary skill in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0042] As described in the background, deep and ultra-deep carbonate fracture-cave oil and gas reservoirs are the key to increasing oil and gas resources, and therefore, efficient development of such oil and gas reservoirs is of great significance. Deep and ultra-deep carbonate fracture-cave oil and gas reservoirs have a high-temperature, high-pressure, and high-stress environment, and the strong heterogeneity and strong anisotropy brought by the widely developed different scale fractures, faults, and caves in the reservoir bring many technical challenges to the efficient development of such oil and gas reservoirs. Among them, acid fracturing is an indispensable means to achieve efficient development of carbonate fracture-cave oil and gas reservoirs. Through acid fracturing, on the one hand, the reservoir damage caused by well construction in the near wellbore can be clearly understood, and on the other hand, the poor or non-communicating reservoirs can be connected by artificial fractures, greatly improving the connectivity between reservoirs. At present, numerical simulation technology is one of the most effective means to evaluate acid fracturing effect, which can be used to evaluate different acid effective action time, effective action distance, acid concentration distribution rule in the direction of fracture length, and calculate dynamic fracture expansion change, acid etching fracture length and conductivity, etc., so as to guide the optimization scheme of acid fracturing. However, the current acid fracturing numerical simulation software is basically based on the classical acid fracturing theory, and its application in carbonate fracture-cave reservoirs is poor. For example, the current numerical model for evaluating acid fracturing effect is mostly based on the assumption of simple fracture morphology, or does not consider the influence of cave bodies on fluid flow and rock deformation, or only treats the cave body as a fluid pressure equipotential body without considering the stress distribution characteristics around the cave body, and does not consider the local non-uniformity of the stress field, which leads to the inability to accurately predict the complex mechanical behavior of carbonate fracture-cave reservoirs such as fracture around cave, cave stringing, and cave trapping during acid fracturing. In practical application, the main factors affecting the development of acid fracturing numerical simulation include: self-organizing competition and expansion simulation of dissolution wormholes, influence of non-uniform dissolution seam roughness on conductivity, acid loss mechanism, prediction technology of multi-etching seam competition and expansion under stress shadow, three-dimensional acid fracturing mechanism and numerical simulation technology, and influence mechanism of fracture-cave composite medium on acid fracturing. The current numerical model for evaluating acid fracturing effect is relatively simple and considers fewer factors, such as not considering the influence of stress discontinuity of cave bodies on stress distribution, fracture diversion and expansion, multi-fracture competition and expansion, and self-organizing evolution process of wormholes in etching seams, and the influence of displacement discontinuity at the fracture on multi-fracture competition and expansion and self-organizing evolution process of wormholes in etching seams, which makes it difficult to accurately evaluate the acid fracturing effect of carbonate fracture-cave reservoirs.

[0043] To this end, an embodiment of the present application provides a fracture-cave reservoir acid fracturing effect evaluation method, as shown in Figure 1 The fracture-cave reservoir acid fracturing effect evaluation method can include the following steps:

[0044] Step 101, grid division is performed on the fractures and cave bodies, and an embedded fracture-cave body model is obtained based on the grid division results and the matrix.

[0045] In the embodiment of the present application, the grid division of the cracks and the cave bodies in step 101 can include: two-dimensional triangular grid division of the cracks, and three-dimensional tetrahedral grid division of the cave bodies. In specific implementation, the cracks can be described by using a spatial polygon (also referred to as a three-dimensional polygon surface), and the cave bodies can be described by using an ellipsoid. For the spatial polygon, the polygon boundary point coordinates and the key spatial point coordinates on the surface can be input, and for the ellipsoid, the long axis, the medium axis, the short axis and the center point coordinates of the ellipsoid can be input, then the triangular grid division program of the entity of the corresponding type is called through the Gmsh application program interface (API) to divide the polygon surface and the three-dimensional ellipsoid surface, thereby realizing the three-dimensional numerical characterization of the cracks and the cave bodies.

[0046] In actual application, the division process can include step (a), step (b) and step (c), and the details are as follows:

[0047] Step (a), input the characteristic data of the cracks and the cave bodies. Since the cracks are simplified as a three-dimensional polygon surface, the corresponding input characteristic data can include a series of boundary node coordinates Pi (Pxi, Pyi, Pzi) and a series of interpolation point coordinates Ii (Ixi, Iyi, Izi). Among them, the points capable of reflecting the curvature characteristics of the cracks are selected as the interpolation points, thereby the three-dimensional surface crack characteristics can be grasped, and the cracks can be accurately described. Since the cave bodies are simplified as an ellipsoid, the corresponding input characteristic data can include the center point coordinates O (x, y, z) of the ellipsoid, the long semi-axis a, the medium semi-axis b and the short semi-axis c.

[0048] Step (b), grid division setting. Based on the input characteristic data in step (1), the triangular grid division program built in Gmsh can be used to implement the division. Gmsh provides two-dimensional triangular grid division application program interface (API) and three-dimensional tetrahedral grid division application program interface (API) for spatial surfaces and three-dimensional entities, after the operations such as adding a spatial point (addPoint ()), adding a line segment (addLine ()), adding an arc line (addEllipseArc ()), adding a surface (addSurfaceFilling ()), based on the grid division command (mesh::generate ()), the three-dimensional polygon surface grid corresponding to the cracks and the three-dimensional tetrahedral grid corresponding to the cave bodies can be generated.

[0049] Step (c), outputting the meshing result. After the mesh is generated, the mesh data (including nodes, line segments, surfaces, etc.) will be stored in the Gmsh internal array, and all data information of the above elements can be obtained by calling the data function. In order to facilitate the output of the meshing result, the present application provides two types of output program interfaces, including Tecplot and MeshLab. According to the built-in data format, the corresponding data extraction and data output functions are designed by using C++, and the three-dimensional meshing effect can be displayed by using Tecplot and MeshLab. As shown in FIG. 8, it is a schematic diagram of three-dimensional meshing of cracks and cave bodies in an embodiment of the present application. As shown in FIG. 9, the left side is the geometric boundary information of the mesh input, and the right side is the meshing result obtained according to the input data. Figure 2 Figure 2

[0050] In the embodiment of the present application, the embedded fracture-cave body model based on the meshing result and the matrix in step 101 can include: embedding the fracture and the cave body into the matrix based on the mesh data of the fracture and the mesh data of the cave body to form the embedded fracture-cave body model.

[0051] Step 102, constructing a stress field mechanics model corresponding to the embedded fracture-cave body model based on the non-continuous stress method and the non-continuous displacement method.

[0052] In the embodiment of the present application, the stress field mechanics model corresponding to the embedded fracture-cave body model based on the non-continuous stress method and the non-continuous displacement method can include: calculating the stress field change caused by the change of the fluid pressure of the cave body by using the non-continuous stress method and calculating the stress field change caused by the deformation of the fracture by using the non-continuous displacement method, so as to obtain the stress field mechanics model corresponding to the embedded fracture-cave body model.

[0053] Regarding the calculation of the stress field change caused by the change of the fluid pressure of the cave body by using the non-continuous stress method:

[0054] In the specific implementation, the area integral of the calculation unit in the infinite space can be performed by using the Kelvin solution to calculate the induced stress field generated by the deformation of the cave body. Wherein, the displacement u i The stress σ ij can be expressed by the following formula (1), formula (2) and formula (3):

[0055]

[0056] In the above formula (1)-formula (9), u1, u2, u3 represent the displacement along three directions, and the unit is m; σ​​11 , σ 22 , σ 33 , σ 12 , σ 23 , σ 13 is the stress tensor; G is the shear modulus with the unit of Pa; v is the Poisson's ratio, (i = 1, 2, 3) is the expression of the integral kernel function of the discrete element corresponding to the solution cavity, as shown in the following formula (10); (i = 1, 2, 3; j = 1, 2, 3) represents the kernel function the first-order partial derivative of the coordinate j; (i = 1, 2, 3; j = 1, 2, 3; k = 1, 2, 3) represents the kernel function the second-order partial derivative of the coordinates j and k in turn; (i = 1, 2, 3; j = 1, 2, 3; k = 1, 2, 3; l = 1, 2, 3) represents the kernel function the third-order partial derivative of the coordinates j, k and l in turn; x refers to the coordinate, and x3 refers to the coordinate in the third direction.

[0057]

[0058] wherein R is the area of the sub-element; P i (i = 1, 2, 3) is the virtual stress, wherein P1, P2 and P3 all need to be substituted into the calculation once; (x1, x2, x3) is the local coordinate system of the element, x1, x2 and x3 respectively refer to the coordinate values in three directions; (ξ, η, 0) is the coordinate system in which the loading point is located.

[0059] Regarding the calculation of the stress field change caused by the deformation of the crack by using the discontinuous displacement method:

[0060] The discontinuous displacement method is used to calculate the induced stress field generated by the crack, that is, the discontinuous displacement method is used to calculate the induced stress field generated by the deformation of the crack.

[0061] In specific implementation, the discontinuous displacement of the crack can be considered physically as the difference between the displacements of the corresponding points on the upper and lower surfaces of the crack in the normal direction thereof (x3 direction). In actual application, the upper and lower surfaces of the crack can be respectively defined as x3 = 0 + and x3 = 0 - , then the discontinuous displacement D i = (D1, D2, D3) across the upper and lower surfaces of the crack can be represented by the following formula (11), formula (12) and formula (13):

[0062] D1(x1, x2, 0) = u1(x1, x2, 0 - )-u1(x1, x2, 0 +) (11) ;

[0063] D2(x1,x2,0) = u2(x1,x2,0 - ) - u2(x1,x2,0 + ) (12) ;

[0064] D3(x1,x2,0) = u3(x1,x2,0 - ) - u3(x1,x2,0 + ) (13) ;

[0065] In the above formula (11) - formula (13), D1, D2, D3 respectively represent the non-continuous displacement amount of the crack element in three directions, with the unit of m; the above formula (11), formula (12) and formula (13) respectively represent the relative displacement size of the upper and lower surfaces of the crack element in three different directions, that is, the non-continuous displacement amount, in the element local coordinate system with the element normal direction as the direction 3.

[0066] The mathematical expressions of stress and strain can be obtained by integrating the non-continuous displacement on the calculation element, and the generalized mathematical expression of the non-continuous displacement can be shown in the following formula (14), formula (15), formula (16), formula (17), formula (18), formula (19), formula (20), formula (21) and formula (22):

[0067] u1 = { [-2(1-v)ψ 1,3 -x3ψ 1,11 ]-x3ψ 2,12 -[(1-2v)ψ 3,1 +x3ψ 3,13 ]} (14) ;

[0068] u2 = {-x3ψ 1,12 +[2(1-v)ψ 2,3 -x3ψ 2,22 ]-[(1-2v)ψ 3,2 +x3ψ 3,23 ]} (15) ;

[0069] u3 = {-(1-2v)ψ 1,1 -x3ψ 1,13 +[(1-2v)ψ 2,2 +x3ψ 2,23 ]+[2(1-v)ψ 3,3 -x3ψ 3,33 ]} (16) ;

[0070]

[0071] σ 22 = 2G{[2vψ1,13 - x3ψ 1,122 + [2ψ 2,23 - x3ψ 2,222 + ψ 3,33 + x3ψ 3,11 - x3ψ 3,223 ]} (18).

[0072] σ 33 = 2G{[-x3ψ 1,133 - x3ψ 2,233 + ψ 3,33 - x3ψ 3,333 ]} (19).

[0073] σ 12 = 2G{[(1 - v)ψ 1,23 - x3ψ 1,112 + (1 - v)ψ 2,13 - x3ψ 2,122 - (1 - 2v)ψ 3,12 + x3ψ 3,123 ]} (20).

[0074] σ 23 = 2G{[-vψ 1,12 - x3ψ 1,123 + ψ 2,23 + vψ 2,11 - x3ψ 2,223 - x3ψ 2,233} (21).

[0075] σ 13 = 2G{[ψ 1,33 + vψ 1,22 - x3ψ 1,113 - vψ 2,12 - x3ψ 2,123 - x3ψ 3,133} (22).

[0076] In the above equations (14) - (22), ψ i (i = 1, 2, 3) is an expression of the integral kernel function of the discrete element corresponding to the crack, as shown in the following equation (23); ψ i,j (i = 1, 2, 3; j = 1, 2, 3) represents the first-order partial derivative of the kernel function ψ i with respect to the coordinate j; ψ i,jk (i = 1, 2, 3; j = 1, 2, 3; k = 1, 2, 3) represents the second-order partial derivative of the kernel function ψ i with respect to the coordinates j and k in turn; and ψ i,jkl(i = 1, 2, 3; j = 1, 2, 3; k = 1, 2, 3; l = 1, 2, 3) represent the kernel function ψ i The third-order partial derivative of the coordinate j, k and l is derived in turn.

[0077]

[0078] In the above formula (23), R is the area of the joint unit, D i (i = 1, 2, 3) is a non-continuous displacement, wherein D1, D2, D3 need to be substituted into the calculation; (x1, x2, x3) is a local coordinate system of the unit, x1, x2, x3 respectively indicate the coordinate values in three directions; (ξ, η, 0) is a coordinate system in which the loading point is located.

[0079] As Figure 3 shown, it is a stress field mechanical model diagram constructed based on the non-continuous stress method and the non-continuous displacement method in an embodiment of the present application. Figure 3 In the figure, the blue area represents a crack, the red area represents a cave, the arrow represents the direction of action, Pn is the internal pressure of the cave, Dn and Ds respectively represent the normal and shear direction non-continuous displacement, and Γσ represents the line load.

[0080] By constructing the stress field mechanical model of the embedded fracture-cave body model based on the non-continuous stress method and the non-continuous displacement method, the non-continuous stress method and the non-continuous displacement method can be used to calculate the stress distribution, so that the changes caused by the existing cracks and caves to the stress field under different fluid pressures can be accurately calculated, and the control effect of the changes of the stress field on the three-dimensional crack etching turning can also be obtained. Compared with the traditional finite element method and the discrete element method, the method provided in the embodiment of the present application has higher precision and faster calculation speed, and can allow the crack propagation path to be arbitrarily turned, and also considers the mechanical-chemical coupling control.

[0081] In step 103, a geological mechanics model, a chemical reaction flow model and a crack propagation model corresponding to the embedded fracture-cave body model are established, and the crack propagation model is obtained based on the stress field mechanical model.

[0082] Regarding the geological mechanics model:

[0083] In the embodiment of the present application, the deformation of the rock mass can be described by using continuous medium mechanics, and the following assumptions are made: ① the deformation of the solid is linear elastic; ② the deformation of the solid is a quasi-static process; ③ the deformation of the solid is very small relative to the entire seepage region, that is, the small deformation assumption; and ④ it is constant temperature during the mining process. Based on these assumptions, the following geological mechanics equation (24) can be obtained, and the geological mechanics model corresponding to the embedded fracture-cave body model is established based on the geological mechanics equation.

[0084]

[0085] In the above formula (24), For the divergence operator, C dr ρ is the fourth-order elastic drainage bulk modulus, in Pa; ε is the strain tensor; b is the Boit coefficient; p is the pore pressure, in Pa; δ is the second-order Kronecker tensor; φ is the porosity, which represents the ratio of pore volume to total volume of the rock under the current deformation condition; ρ f Fluid density, in kg / m³ 3 ;ρ s Density of rock, in kg / m³ 3 g is the gravitational vector, with units of m / s². 2 u is the displacement vector, in meters, and is an unknown quantity.

[0086] Regarding chemical reaction flow models:

[0087] In this embodiment of the application, a chemical reaction flow model corresponding to the embedded slit body model can be established based on the mass conservation equation, the convection-diffusion equation, and auxiliary equations.

[0088] (i) Regarding the mass conservation equation: In the case of a source and sink, the difference between the mass of the fluid in the control volume and the mass of the fluid flowing out of the control volume is equal to the mass source and sink term. Therefore, the mass conservation equation (i.e. the mass balance equation) can be shown in the following formulas (25) and (26):

[0089]

[0090] In the above formulas (25) and (26), ∈ represents volumetric strain; w represents crack aperture in meters; t represents simulation time in seconds; M represents Biot modulus in Pa; ν m The velocity of the fluid in the matrix, in m / s; v f The velocity of the fluid in the crack is expressed in m / s; Q is the volumetric flow rate source / sink, expressed in m³ / s. 3 / s; → indicates the flow direction, q is the volumetric flow rate between the crack and the matrix, and between cracks, in m³ / s. 3 / s; the subscripts m and f represent the matrix and crack, respectively.

[0091] In practical implementation, it can be assumed that the flow of fluid in the matrix and the crack follows Darcy's law and Poiseuille's law, respectively. Then, the average flow velocity through the matrix can be expressed as shown in the following formula (27), and the average flow velocity through the crack can be expressed as shown in the following formula (28):

[0092]

[0093] In the above formulas (27) and (28), k m The permeability of the matrix is ​​expressed in mD; k f The permeability of the fracture is expressed in mD; k f =w 2 / 12; I is the second-order unit tensor, μ is the fluid viscosity, and the unit is cP; ρ f Fluid density, in kg / m³ 3 .

[0094] (ii) Regarding the convection-diffusion equation: This convection-diffusion equation can characterize the mass transfer law of the flow system during fluid flow. In the embodiments of this application, the convection-diffusion equation can specifically be a convection-diffusion equation containing chemical reactions. By establishing a convection-diffusion equation containing chemical reactions, the convection caused by local pore size changes and local dissolution reactions on the fracture surface in the matrix and fracture system can be characterized. The convection-diffusion equation (specifically a convection-diffusion equation containing chemical reactions) can be shown as follows: (29) and (30)

[0095]

[0096] In the above formulas (29) and (30), φ is porosity, and C f and C s These represent the acid concentrations within the pores and at the solid-liquid interface, respectively, in mol / m³. 3 ;D e The dispersion coefficient tensor of the matrix, in units of m. 2 / s;k c α is the local mass exchange coefficient, with units of 1 / s; v q represents the specific surface area, expressed in units of 1 / m². m q f These correspond to the solute source and sink terms in the rock mass mechanism and fractures, respectively, with units of mol / m³. 3 / s;D ef The dispersion coefficient tensor of the crack is expressed in m. 2 / s.

[0097] In practical applications, the porosity changes caused by dissolution, pressure, and stress variations can be represented by the following formula (31):

[0098]

[0099] In the above formula (31), C f and C s These represent the acid concentrations within the pores and at the solid-liquid interface, respectively, in mol / m³. 3 ;D e The dispersion coefficient tensor, in units of m.2 / s;k c This is the local mass exchange coefficient, with units of 1 / s; a v R is the surface area per unit volume available for chemical reaction, expressed in 1 / m²; R is the kinetic energy number, expressed in mol / m². 2 α is the solubility parameter of the acid, with units of kg / mol; K s This represents the bulk modulus of the matrix particles, expressed in units of 1 / Pa.

[0100] (iii) Regarding auxiliary equations: In the embodiments of this application, auxiliary equations may include at least one of the following: the mass transport equation of acid in the porous network, the strain-displacement equation, the stress-strain equation, the fracture constitutive equation, and the Darcy flow equation. Preferably, auxiliary equations may include the mass transport equation of acid in the porous network, the strain-displacement equation, the stress-strain equation, the fracture constitutive equation, the Darcy flow equation, etc. The strain-displacement equation may also be called the strain-displacement equation, and the stress-strain equation may also be called the stress-strain equation.

[0101] The mass transport equation of acid in the porous network can be shown in the following formulas (32), (33) and (34):

[0102]

[0103] In the above formulas (32), (33), and (34), S h r is the Sherwood number or dimensionless mass transfer coefficient. P k is the average pore radius in meters. c D is the mass transport coefficient between the Darcy scale and the pore scale, with units of 1 / s; m The effective molecular expansion coefficient of the acid at any shear rate is expressed in m. 2 / s;S h∞ For asymptotic Sherwood number; m p Re is the ratio of pore length to radius; p is the Reynolds number at the pore size, and is the ratio of inertial force to viscous force. , where v is the dynamic viscosity, in cP; α is the Schmidt number; os D is a constant coefficient that depends on pore connectivity. eX The longitudinal (X-direction) dispersion coefficient, in meters. 2 / s;D eT The lateral (Y or Z direction) dispersion coefficient, in meters. 2 / s;λ x and λ T It is a constant coefficient that depends on the pore structure.

[0104] In the Darcy model, the physicochemical parameters of rocks (including local pore size, pore surface area, and permeability) depend on the pore structure. Therefore, the variation of physicochemical parameters can be considered by establishing the relationship between pore structure and physicochemical parameters (Carman-Kozeny equation). The Darcy flow equation can be shown in the following formulas (35) and (36):

[0105]

[0106] In formulas (35) and (36) above, K0 is the initial average permeability, in meters. 2 φ0 is the initial average porosity; φ is the current porosity; r0 is the initial average pore radius in meters; a0 is the initial specific surface area in cubic meters (L / m); β is the expansion coefficient, K, r P a v These are the current average penetration rates (in meters). 2 ), pore radius (in meters) and specific surface area (in cubic meters per square meter).

[0107] Regarding fracture propagation models (also known as fracture propagation models for fractured reservoirs):

[0108] In this embodiment, a crack propagation model is obtained based on a stress field mechanics model. Specifically, the cave body can be discretized using a discontinuous stress method based on triangular elements, and the cracks can be discretized using a discontinuous displacement method based on triangular elements to simulate crack propagation and the resulting geostress disturbance. More specifically, obtaining the crack propagation model based on the stress field mechanics model may include steps (i), (ii), and (iii):

[0109] Step (1): Calculate the induced stress generated at any point in space by the cave body and cracks in the stress field mechanical model.

[0110] In practice, the embedded cavern and cracks can be discretized into a series of triangular units. Each triangular element is divided into upper and lower faces. Then, the induced stress generated at any point in space by the Crouch fundamental solution and the Kelvin solution can be obtained. Among them, the induced stress generated at any point in space by the cave and the crack can be expressed as shown in the following formula (37):

[0111]

[0112] In the above formula (37), A is the influence coefficient and Π is the discontinuous displacement stress. When solving the induced stress generated by the cave body at any point in space, n, s, t represent the discontinuous stress in the normal, strike and dip directions under the local coordinates of a certain triangular unit, respectively. When solving the induced stress generated by the crack at any point in space, n, s, t represent the discontinuous displacement in the normal, strike and dip directions under the local coordinates of a certain triangular unit, respectively. This represents the induced stress along the ζ direction generated at element i; This represents the discontinuous stress in element j along the n direction; This represents the influence coefficient of the induced stress along the ζ direction generated by the discontinuous stress in element j along the n direction in element i, and so on.

[0113] The stress intensity factor at the crack tip element can be obtained from the discontinuous displacement of the crack tip element. Specifically, the stress intensity factor at the crack tip element can be obtained based on the following formula (38):

[0114]

[0115] In the above formula (38), β n =β s =E / [4(1-v 2 )], β t =E / [4(1+v)], where E is Young's modulus in Pa; v is Poisson's ratio; ξ = 0.806 is an empirical calibration parameter; and r is the distance from the geometric center of the crack tip element to the crack tip in meters.

[0116] Step (2): Calculate the crack propagation rate.

[0117] In practical implementation, the crack propagation rate can be calculated using the Paris scaling rate. Specifically, the crack propagation rate can be calculated based on the following formulas (39) and (40):

[0118] ΔL=L max (K eq / K IC ) m (39);

[0119]

[0120] In the above formulas (39) and (40), ΔL and L max These are the current crack propagation length and the maximum allowable propagation length, respectively, in meters; K I K II and K IIIThese represent the fracture toughness of Type I, Type II, and Type III fractures, respectively, in MPa; γ0 is the crack propagation angle, in rad; m = 1.0 is an empirical parameter of the model; K eq K is the equivalent stress concentration factor. IC The critical fracture toughness is given. For ease of calculation, the model specifies that the equivalent stress intensity factor satisfies (1-θ)K. IC ≤K eq ≤(1+θ)K IC At time (θ=0.05), the crack expands.

[0121] In practical applications, the crack propagation direction is determined by both the crack-induced stress and the far-field stress. Therefore, according to the maximum circumferential stress criterion, the crack propagation angle γ0 satisfies the following formulas (41) and (42):

[0122]

[0123] In the above formulas (41) and (42), σ'1 is the circumferential stress in Pa; γ is the crack propagation angle in rad; and the subscript γ = γ0 indicates the crack propagation angle when the maximum circumferential stress is obtained.

[0124] Step (3): Based on the induced stress and the crack propagation rate, the crack propagation model is obtained.

[0125] Step 104: Based on the geomechanical model, the chemical reaction flow model, and the fracture propagation model, obtain the multi-field coupled acid fracturing model corresponding to the embedded fracture-vuggy reservoir model. Solve the multi-field coupled acid fracturing model to obtain the acid fracturing effect evaluation results of the fracture-vuggy reservoir.

[0126] In practical applications, acid fracturing in fractured-vuggy oil and gas reservoirs involves rock mass deformation, chemical reaction flow, and fracture propagation, representing a typical multi-physical and multi-chemical field coupled problem. This application establishes a multi-field coupled acid fracturing model that considers rock mass deformation, chemical reaction flow, and fracture propagation, and performs multi-field coupled solutions to achieve accurate, efficient, and practical multi-field coupled acid fracturing simulation. Specifically, the geomechanical model reflects the rock mass deformation during acid fracturing, the chemical reaction flow model reflects the chemical reaction flow during acid fracturing, and the fracture propagation model reflects the fracture propagation during acid fracturing.

[0127] In practical implementation, the geomechanical model, chemical reaction flow model, and fracture propagation model can be coupled by conserving fluid mass in the fracture and exchanging stress boundaries. Specifically, the geomechanical model and the chemical reaction flow model can be coupled to obtain a rock mass fluid-structure interaction model. During the solution process, iterative solutions are performed between the rock mass fluid-structure interaction model and the fracture propagation model.

[0128] The specific solution process can be summarized as follows:

[0129] First, initial guesses are given for the fracture width, initial fracture stiffness, fluid pressure, and stress distribution. Then, the fluid pressure, acid concentration, and effective stress on the fracture wall are solved using the finite element-finite volume method. Within each iteration step, the fracture boundary stress condition set constructed from the obtained physical environment is used as the stress boundary condition for the fracture propagation model, further calculating the fracture width, fracture permeability, fracture stiffness, and fracture-induced stress. Conversely, the fracture parameters obtained from the fracture propagation model are fed back to the rock mass fluid-structure interaction model to correct the fluid pressure and stress fields. Iterative calculations are performed according to the above process until the changes in fracture parameters, fluid pressure, acid concentration, and stress meet the pre-defined convergence conditions, then the calculation proceeds to the next time step. Before proceeding to the next time step, the fracture is checked according to the fracture propagation criteria. If the propagation conditions are met, the fracture propagation distance and propagation angle are given according to the aforementioned criteria, and propagation fracture elements are added at the fracture tip. Simultaneously, the physical quantities calculated at the end of the time step are used as initial guesses for the same iterative calculation until convergence. If the propagation conditions are not met, the calculation proceeds directly to the next time step. The above two calculation cycles are repeated until the calculation time reaches the given requirement, at which point the calculation ends and the acid fracturing effect evaluation result of the fractured-vuggy reservoir is obtained.

[0130] It is understood that the acid fracturing effect evaluation method for fractured-vuggy reservoirs provided in the above embodiments of this application includes: meshing fractures and karst caves, and obtaining an embedded fractured-vuggy model based on the meshing results and matrix; constructing a stress field mechanical model corresponding to the embedded fractured-vuggy model based on discontinuous stress and discontinuous displacement methods; establishing a geomechanical model, a chemical reaction flow model, and a fracture propagation model corresponding to the embedded fractured-vuggy model, wherein the fracture propagation model is obtained based on the stress field mechanical model; obtaining a multi-field coupled acid fracturing model corresponding to the embedded fractured-vuggy model based on the geomechanical model, the chemical reaction flow model, and the fracture propagation model; solving the multi-field coupled acid fracturing model to obtain the acid fracturing effect evaluation result of the fractured-vuggy reservoir. Because the evaluation of acid fracturing effects takes into account the influence of stress discontinuity in the cavernous body on stress distribution, fracture propagation, competitive propagation of multiple fractures, and the self-organized evolution of wormholes in etched fractures, as well as the influence of displacement discontinuity at fractures on competitive propagation of multiple fractures and the self-organized evolution of wormholes in etched fractures, the accuracy of acid fracturing effect evaluation for carbonate fractured-vuggy reservoirs can be improved.

[0131] In other words, addressing the problem that current numerical models for acid fracturing in fractured-vuggy reservoirs are too simplistic to effectively simulate stress disturbances and fracture propagation caused by existing cavities and fractures, this application provides a method for evaluating the effectiveness of acid fracturing in fractured-vuggy reservoirs based on discontinuous stress and discontinuous displacement. This method utilizes a three-dimensional mesh generation technique for fractures and cavities, generating corresponding computational meshes according to their given locations, shapes, and sizes. Then, this mesh generation technique is combined with three-dimensional discontinuous stress and three-dimensional discontinuous displacement methods. By fusing discontinuous stress-displacement boundary element and finite element methods, and using a numerical-analytical hybrid solution method, the method can describe the real-time changes in the stress field and explicitly track the propagation of complex three-dimensional fractures or fracture networks. This allows for the understanding of the effects of cavities and fractures on the stress field under different fluid pressures and their control over fracture propagation. Consequently, it can accurately simulate the etch propagation of fractures during acid fracturing in fractured-vuggy reservoirs, as well as the complex mechanical behaviors of propagating fractures such as circumferential, interconnected, and trapped cavities, thus revealing the effect of fracture etch propagation on the interconnection of existing cavities.

[0132] like Figure 4-1 The image shown is a cross-sectional view of a three-dimensional crack and a three-dimensional cave in a specific embodiment of this application. Figure 4-2 The image shown is a simulation diagram of complex crack propagation in a specific embodiment of this application.

[0133] The following will describe the acid fracturing effect evaluation method for fractured reservoirs provided in the above embodiments of this application, in conjunction with specific simulation processes and simulation results. It should be understood that the following examples are merely specific implementation methods and do not imply undue limitation on the solution of this application.

[0134] Using the acid fracturing effect evaluation method for fractured-vuggy reservoirs provided in the above embodiments of this application, three typical fracture-dissolved body types (including banded, flat, and sandwich-shaped traps) from the Tahe Oilfield were selected as simulation objects. Banded fracture-dissolved bodies refer to a combination of multiple Type I fractures or Type II fractures originating from deep layers, predominantly flower-shaped fractures. Flat fracture-dissolved bodies refer to a fracture type consisting of relatively scattered Type III fractures combined with Type II fractures, with Type II fractures being the dominant type. Sandwich-shaped fracture-dissolved bodies refer to a fracture type consisting of multiple Type II and Type III fractures that are relatively parallel or form a network between Type I fractures.

[0135] In practical applications, the cause of fault dissolution may be atmospheric precipitation seeping down along the fault or deep fluids flowing up along the bottom fault. In this example, we tentatively consider the deep fluids flowing from the bottom fault to the shallower parts, causing gradual dissolution of the combined fault. Figure 5 The diagram shows a generalized model of various three-dimensional combined faults. This model is used to simulate the control of faults and bedding on the formation of fault-soluble bodies. Figure 5(a) is a generalized model and mesh generation of a banded fractured solution. Figure 5 (b) is a generalized model and mesh generation of a plate-shaped fractured solution. Figure 5 (a) is a generalized model and mesh generation of a sandwich-shaped fractured solution.

[0136] In this example, the simulation area is 140 m (X direction) × 100 m (Y direction) × 100 m (Z direction). The initial average aperture of the initial fault (or bedding) is 0.1 mm. Dissolving fluid flows continuously from the bottom to the top of the model under a pressure difference of 20 m. The model is surrounded by an impermeable boundary. Simulation parameters related to the chemical reactions and chemical equilibrium of carbonate rocks are shown in Table 1. Considering that the aperture varies in different parts of the fault, typically following a Gaussian distribution, a roughness of 1.5 (i.e., the ratio of the variance to the mean of the aperture) is introduced in this example.

[0137] Table 1 List of Main Simulation Parameters

[0138] Simulation parameters Values Equilibrium concentration C eq (mol / m 3 )]]> 3.41 CO2partial pressure P (MPa) 0.50 Initial temperature T (°C) 10 Diffusion coefficient D (m 2 / s) 3.6E-10 Initial fracture width d (mm) 0.1 Rainfall recharge (mm / year) 1000 Fracture system permeability (mD) 1.1e+05 Matrix block permeability (mD) 1.0 Maximum crack length L max (m)]]> 80 Maximum crack width H max (m)]]> 30

[0139] For strip fault assemblages, corrosive liquids pass through the bottom fault under the action of hydraulic gradients, and the dissolution cavities continuously extend into the interior of several branch faults at higher positions, causing different degrees of dissolution in the higher faults, and eventually forming a complex, interconnected system of dissolution cavities. Figure 6 The structure of dissolution cavities within a single fault is illustrated. This result demonstrates that dissolution cavities within a single fault can also form complex cavitation structures, indicating significant differential dissolution within the same fault. Figure 6 (a) shows the crack erosion expansion morphology of the banded fractured body after 35 years of erosion. Figure 6 (b) shows the crack erosion expansion morphology of the banded fractured body after 62 years of erosion. Figure 6 (c) shows the crack erosion expansion morphology of the banded fractured body after 118 years of erosion. Figure 6 (d) shows the crack erosion extension morphology of the strip-shaped fractured body after 205 years of erosion.

[0140] For flat-plate fault combinations Figure 7 It exhibits a more complex solution cavity structure, with differential dissolution occurring not only within the nearly parallel faults but also, when the faults and bedding planes intersect, the solution cavities extend horizontally along the bedding planes, forming interconnected solution fracture-cavity units consisting of nearly vertical and horizontal solution cavities. Figure 7 (a) shows the crack erosion propagation morphology of a flat fractured body after 30 years of erosion. Figure 7 (b) shows the crack erosion propagation morphology of the flat fractured body after 56 years of erosion.Figure 7 (c) shows the crack erosion propagation morphology of a flat fractured body after 78 years of erosion. Figure 7 (d) shows the crack erosion extension morphology of a flat fractured body after 105 years of erosion.

[0141] The formation of branching cavities is helpful in explaining some unique phenomena in the Tarim Oilfield and understanding its dissolution process. For example, a "beaded" phenomenon is often observed in the original seismic profile perpendicular to the fault-dissolved body; this phenomenon is related to the non-uniformity and branching cavities formed during the dissolution process. Figure 8 Taking the simulated sandwich-like fractured body as an example, when cut along a direction perpendicular to the X-axis, the "beaded" structure will be observed. Among them, Figure 8 (a) shows the crack erosion expansion morphology of a sandwich-shaped fractured body after 30 years of erosion. Figure 8 (b) shows the crack erosion propagation morphology of the sandwich-shaped fractured body after 56 years of erosion. Figure 8 (c) shows the crack erosion propagation morphology of the sandwich-shaped fractured body after 98 years of erosion. Figure 8 (d) shows the fracture erosion extension morphology of a sandwich-shaped fractured body after 175 years of dissolution. Secondly, practice shows that "wherever the fracture extends, the reservoir develops." This is because the fault provides a rapid channel for soluble liquids and also provides a site for differential dissolution, which is conducive to the rapid formation of branched dissolution caves inside the fault and quickly penetrates the entire fault.

[0142] Therefore, the solutions provided by the above embodiments of this application can provide an efficient and reliable research method for the evolution process and acid fracturing etching process of fractured-vuggy carbonate reservoirs. Through simulation of the dissolution and propagation of three-dimensional fractures in typical fault-dissolved bodies, it is clarified that the cavities also undergo significant etching and propagation within the bedding planes and eventually connect with branch cavities within the fault, ultimately forming a dissolution fracture-vuggy system with a complex spatial distribution. These simulation results have significant theoretical and engineering application value.

[0143] Based on the same inventive concept, such as Figure 9 As shown, Figure 9 This schematically illustrates a structural block diagram of an acid fracturing effect evaluation device for fractured reservoirs according to an embodiment of this application. In one embodiment, an acid fracturing effect evaluation device 200 for fractured reservoirs is provided, including a partitioning module 210, a model building module 220, and a solution module 230, wherein:

[0144] The meshing module 210 is used to mesh the cracks and caverns, and to obtain an embedded crack and cavern model based on the meshing results and the matrix.

[0145] The model building module 220 is used to construct the stress field mechanical model corresponding to the embedded fracture cavity model based on the discontinuous stress method and the discontinuous displacement method; and to establish the geomechanical model, chemical reaction flow model and crack propagation model corresponding to the embedded fracture cavity model, wherein the crack propagation model is obtained based on the stress field mechanical model.

[0146] The solver module 230 is used to obtain the multi-field coupled acid fracturing model corresponding to the embedded fracture-vuggy reservoir model based on the geomechanical model, the chemical reaction flow model and the fracture propagation model, solve the multi-field coupled acid fracturing model, and obtain the acid fracturing effect evaluation result of the fracture-vuggy reservoir.

[0147] In one embodiment, the subdivision module 210 is used to subdivide the cracks into two-dimensional triangular meshes and the cave body into three-dimensional tetrahedral meshes.

[0148] In one embodiment, the model building module 220 is used to calculate the stress field change caused by the change in fluid pressure in the cavern using a discontinuous stress method and to calculate the stress field change caused by crack deformation using a discontinuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded cavern model.

[0149] In one embodiment, the model building module 220 is used to establish a geomechanical model corresponding to the embedded fracture-cavity model based on the geomechanical equations.

[0150] In one embodiment, the model building module 220 is used to establish a chemical reaction flow model corresponding to the embedded cavity model based on the mass conservation equation, the convection-diffusion equation, and auxiliary equations.

[0151] In one embodiment, the auxiliary equations include at least one of the following: the mass transport equation of acid in the porous network, the strain-displacement equation, the stress-strain equation, the fracture constitutive equation, and the Darcy flow equation.

[0152] The fractured reservoir acid fracturing effect evaluation device includes a processor and a memory. The above-mentioned segmentation module 210, model construction module 220 and solution module 230 are all stored in the memory as program units. The processor executes the above-mentioned program modules stored in the memory to realize the corresponding functions.

[0153] The processor contains a core, which retrieves the corresponding program unit from memory. One or more cores can be configured, and by adjusting the core parameters, fast and efficient modeling and computation can be achieved at the entire chip scale.

[0154] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0155] This application provides a machine-readable storage medium storing a program that, when executed by a processor, implements the aforementioned method for evaluating the acid fracturing effect of fractured reservoirs.

[0156] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 10 As shown in the figure, the computer device includes a processor A01, a network interface A02, a display screen A04, an input device A05, and a memory (not shown) connected via a system bus. The processor A01 provides computing and control capabilities. The memory includes internal memory A03 and a non-volatile storage medium A06. The non-volatile storage medium A06 stores an operating system B01 and a computer program B02. The internal memory A03 provides an environment for the operation of the operating system B01 and the computer program B02 stored in the non-volatile storage medium A06. The network interface A02 is used for communication with external terminals via a network connection. When the computer program is executed by the processor A01, it implements a method for evaluating the acid fracturing effect of fractured reservoirs. The display screen A04 can be a liquid crystal display or an e-ink display. The input device A05 can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0157] Those skilled in the art will understand that Figure 10 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0158] In one embodiment, the acid fracturing effect evaluation device for fractured reservoirs provided in this application can be implemented as a computer program, which can be implemented in various ways, such as... Figure 10 The computer device shown runs on this system. The computer device's memory can store the various program modules that make up the intelligent scheduling device for this construction task, for example... Figure 9The diagram shows the partitioning module 210, model building module 220, and solution module 230. The computer program comprised of these modules enables the processor to execute the steps in the acid fracturing effect evaluation method for fractured reservoirs according to the various embodiments of this application described in this specification.

[0159] Figure 10 The computer equipment shown can be used as follows Figure 9 The execution method of the segmentation module 210, model building module 220 and solution module 230 in the fractured reservoir acid fracturing effect evaluation device shown.

[0160] This application provides a device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps:

[0161] The cracks and caverns are meshed, and an embedded crack-cave model is obtained based on the meshing results and the matrix.

[0162] Based on the discontinuous stress method and the discontinuous displacement method, a stress field mechanical model corresponding to the embedded slit body model is constructed.

[0163] Establish the geomechanical model, chemical reaction flow model, and fracture propagation model corresponding to the embedded fracture cavity model, wherein the fracture propagation model is obtained based on the stress field mechanical model;

[0164] Based on the geomechanical model, the chemical reaction flow model, and the fracture propagation model, a multi-field coupled acid fracturing model corresponding to the embedded fracture-vuggy reservoir model is obtained. The multi-field coupled acid fracturing model is solved to obtain the acid fracturing effect evaluation results of the fracture-vuggy reservoir.

[0165] In one embodiment, the meshing of the cracks and caverns includes:

[0166] The cracks are divided into two-dimensional triangular meshes, and the cave body is divided into three-dimensional tetrahedral meshes.

[0167] In one embodiment, constructing the stress field mechanical model corresponding to the embedded slot body model based on the discontinuous stress method and the discontinuous displacement method includes:

[0168] The stress field changes caused by the fluid pressure changes in the cavern are calculated using the discontinuous stress method, and the stress field changes caused by crack deformation are calculated using the discontinuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded cavern model.

[0169] In one embodiment, a geomechanical model corresponding to the embedded fissure cave model is established based on geomechanical equations.

[0170] In one embodiment, a chemical reaction flow model corresponding to the embedded slit-cavity model is established based on the mass conservation equation, the convection-diffusion equation, and auxiliary equations.

[0171] In one embodiment, the auxiliary equations include at least one of the following: the mass transport equation of acid in the porous network, the strain-displacement equation, the stress-strain equation, the fracture constitutive equation, and the Darcy flow equation.

[0172] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0173] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0174] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0175] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0176] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0177] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0178] Computer-readable media include both permanent and non-permanent, removable and non-removable media, which can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0179] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0180] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for evaluating the acid fracturing effect of fractured-vuggy reservoirs, characterized in that, include: The cracks and caverns are meshed, and an embedded crack-cave model is obtained based on the meshing results and the matrix. Based on the discontinuous stress method and the discontinuous displacement method, a stress field mechanical model corresponding to the embedded slit body model is constructed. Establish the geomechanical model, chemical reaction flow model, and fracture propagation model corresponding to the embedded fracture cavity model, wherein the fracture propagation model is obtained based on the stress field mechanical model; Based on the geomechanical model, the chemical reaction flow model, and the fracture propagation model, a multi-field coupled acid fracturing model corresponding to the embedded fracture-vuggy reservoir model is obtained. The multi-field coupled acid fracturing model is solved to obtain the acid fracturing effect evaluation results of the fracture-vuggy reservoir.

2. The method for evaluating the acid fracturing effect of fractured reservoirs according to claim 1, characterized in that, The meshing of cracks and caverns includes: The cracks are divided into two-dimensional triangular meshes, and the cave body is divided into three-dimensional tetrahedral meshes.

3. The method for evaluating the acid fracturing effect of fractured-vuggy reservoirs according to claim 1, characterized in that, The stress field mechanical model corresponding to the embedded slot body model is constructed based on the discontinuous stress method and the discontinuous displacement method, including: The stress field changes caused by the fluid pressure changes in the cavern are calculated using the discontinuous stress method, and the stress field changes caused by crack deformation are calculated using the discontinuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded cavern model.

4. The method for evaluating the acid fracturing effect of fractured reservoirs according to claim 1, characterized in that, A geomechanical model corresponding to the embedded fissure cave model is established based on the geomechanical equations.

5. The method for evaluating the acid fracturing effect of fractured reservoirs according to claim 1, characterized in that, A chemical reaction flow model corresponding to the embedded slit-cavity model is established based on the mass conservation equation, the convection-diffusion equation, and auxiliary equations.

6. The method for evaluating the acid fracturing effect of fractured reservoirs according to claim 5, characterized in that, The auxiliary equations include at least one of the following: the mass transport equation of acid in the porous network, the strain-displacement equation, the stress-strain equation, the fracture constitutive equation, and the Darcy flow equation.

7. A device for evaluating the acid fracturing effect of a fractured reservoir, characterized in that, include: The meshing module is used to mesh cracks and caverns, and to obtain an embedded crack and cavern model based on the meshing results and the matrix. The model building module is used to construct the stress field mechanical model corresponding to the embedded fracture cavity model based on the discontinuous stress method and the discontinuous displacement method; and to establish the geomechanical model, chemical reaction flow model and crack propagation model corresponding to the embedded fracture cavity model, wherein the crack propagation model is obtained based on the stress field mechanical model. The solution module is used to obtain the multi-field coupled acid fracturing model corresponding to the embedded fracture-vuggy reservoir model based on the geomechanical model, the chemical reaction flow model and the fracture propagation model, and to solve the multi-field coupled acid fracturing model to obtain the acid fracturing effect evaluation results of the fracture-vuggy reservoir.

8. The acid fracturing effect evaluation device for fractured reservoirs according to claim 7, characterized in that, The model building module is used to calculate the stress field changes caused by the change in fluid pressure in the cavern using the discontinuous stress method and to calculate the stress field changes caused by crack deformation using the discontinuous displacement method, so as to obtain the stress field mechanical model corresponding to the embedded cavern model.

9. A processor, characterized in that, It is configured to perform the method for evaluating the acid fracturing effect of fractured reservoirs according to any one of claims 1 to 6.

10. A machine-readable storage medium storing instructions thereon, characterized in that, When executed by a processor, this instruction causes the processor to be configured to perform the method for evaluating the acid fracturing effect of fractured reservoirs according to any one of claims 1 to 6.

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