Construction method and device of unstructured grid model, storage medium and processor

Abstract

The embodiment of the invention provides a construction method and device of an unstructured grid model, a storage medium and a processor, and belongs to the technical field of oil and gas reservoir geological modeling. The method comprises the steps of firstly establishing an unstructured surface grid of a contour surface of a karst cave medium in the fracture-vug type reservoir, effectively simplifying the unstructured surface grid through an edge collapse algorithm, and then inserting data of a fracture medium in the fracture-vug type reservoir by taking the simplified unstructured surface grid as a boundary constraint to construct an unstructured grid model. In the karst cave characterization stage, an iterative algorithm based on collapse error measurement is used for carrying out iterative simplification on an outer contour curved surface grid, so that the complexity is effectively reduced, and the basic geometric characteristics of an initial model are still kept. In the fracture characterization stage, the structural data of the fracture medium are inserted point by point, so that the points and the medium surfaces on the unstructured grid and the fracture-cavity medium are doubly attached, the fine characterization of the complex multi-scale medium is effectively realized, and the efficiency and the stability of the three-dimensional unstructured grid generation process are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas reservoir geological modeling, and in particular to a method, device, storage medium and processor for constructing an unstructured grid model of a fracture-cavity reservoir. Background Art

[0002] In the field of geological modeling and numerical simulation of oil and gas reservoirs, as geological models continue to become more refined and complex, grid technology has also undergone a series of developments. In order to deal with complex structural description problems such as faults and pinch-outs, the reservoir grid model has developed corner grid technology from the original orthogonal rectangular grid; in order to characterize artificial fractures, local encrypted grid technology has been further developed on the basis of corner grids and widely used in major commercial simulators; unstructured grids have been gradually introduced into the field of reservoir numerical simulation in the 1990s due to their grid flexibility to solve the fine characterization of discrete fracture networks.

[0003] At present, due to the advantages of simple generation method, good orthogonality and high computational efficiency, structured grids such as rectangular grids or corner grids are still the most common grid models in the field of reservoir modeling. However, for fracture-cavity reservoirs where a large number of multi-scale media such as fractures and caves are interwoven and developed, traditional structured grids are difficult to achieve precise and effective representation, resulting in distortion of geological models and low subsequent simulation accuracy, and are no longer applicable; while the mainstream unstructured grid modeling method in the field of reservoir modeling lacks special treatment for fracture-cavity reservoirs with more complex morphological contours. When dealing with a large number of fractures and cave complex media, it is necessary to use a large number of unstructured grids to describe geometric features such as medium contours, which greatly increases the computational workload and causes a large number of problems in data access and geometric operation efficiency of points, lines and surfaces, and it is difficult to achieve unstructured grid segmentation for such reservoirs. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a method by which complex media with cracks and holes can be precisely characterized while meeting the requirements of geometric calculation efficiency.

[0005] In order to achieve the above object, an embodiment of the present invention provides a method for constructing an unstructured grid model, which is used to construct an unstructured grid model of a fracture-vuggy reservoir, comprising:

[0006] Obtaining geometric topological structure data sets X1 and X2 that respectively characterize the cave medium and fracture medium in the fracture-cavity reservoir;

[0007] Based on X1, an unstructured surface mesh representing the contour surface of the cave medium is initialized;

[0008] Traverse each edge of the unstructured surface mesh, collapse each edge into a new vertex, and determine the position of the new vertex when the position of the new vertex meets the preset collapse error, so as to simplify the unstructured surface mesh; and

[0009] Taking the simplified unstructured surface mesh as the boundary constraint, construct an unstructured mesh model based on X2.

[0010] Optionally, X1 includes: the coordinates of the outer contour feature points of the karst medium and the geometric topological relationship between the outer contour feature points; X2 includes: the coordinates of the fracture feature points of the fracture medium and the geometric topological relationship between the fracture feature points.

[0011] Furthermore, both X1 and X2 are expressed in explicit format, including all points, lines, surfaces, all intersection points of lines, and all intersection lines of surfaces.

[0012] Optionally, the single mesh of the initialized unstructured surface mesh is a triangular mesh surface, preferably obtained based on the Delaunay triangulation algorithm.

[0013] Furthermore, the factors affecting the collapse error include: the distance between the new vertex and the plane of each associated triangular mesh, the average area of the adjacent triangular meshes before each edge collapse, and the regularity of the adjacent triangular meshes before each edge collapse.

[0014] Furthermore, the calculation formula for the collapse error is:[[]]

[0015]

[0016] In the formula, collapse the opposite edge (v i , v j ), and the set of triangular meshes Planes(i,j) associated with the edge (v i , v j ) forms a region. The position of the new vertex generated after the collapse of the edge (v i , v j ) is [x, y, z, 1] T , is the collapse error brought by the collapse of the edge (v i , v j );

[0017] is the position to the sum of the squares of the distances from the plane of each triangular mesh in the set Planes(i,j);

[0018] is the edge (v i , v j)The average area of adjacent triangular meshes before collapse; and

[0019] For edge (v i , v j ) The average regularity of adjacent triangular meshes before collapse.

[0020] Optionally, with the simplified unstructured surface mesh as the boundary constraint, based on X2, construct an unstructured grid model, including:

[0021] Using the simplified unstructured surface mesh as the boundary constraint, generate an initial unstructured grid model, where each mesh surface of the unstructured surface mesh is one of the surfaces of the initial unstructured grid model; and

[0022] Based on a predetermined meshing algorithm, insert the crack feature points of each crack in X2 into the initial unstructured grid model point by point.

[0023] Furthermore, each mesh surface of the unstructured surface mesh is triangular, and each single grid of the unstructured grid model is a tetrahedron obtained based on the Delaunay triangulation algorithm.

[0024] On the other hand, the present invention provides a device for constructing an unstructured grid model, used to construct an unstructured grid model of a fracture-vug reservoir, including:

[0025] A data acquisition module, which acquires a geometric topology structure dataset X1 representing the karst medium in the fracture-vug reservoir and a geometric topology structure dataset X2 representing the fracture medium in the fracture-vug reservoir;

[0026] A surface mesh generation module, which initializes an unstructured surface mesh representing the contour surface of the karst medium based on X1;

[0027] A surface mesh simplification module, which traverses each edge of the unstructured surface mesh, collapses each edge into a new vertex, and determines the position of the new vertex when the position of the new vertex meets a preset collapse error, to simplify the unstructured surface mesh; and

[0028] A grid model construction module, which constructs an unstructured grid model based on X2 with the simplified unstructured surface mesh as the boundary constraint.

[0029] Optionally, X1 includes: the coordinates of the outer contour feature points of the karst medium and the geometric topology relationship between the outer contour feature points; X2 includes: the coordinates of the crack feature points of the fracture medium and the geometric topology relationship between the crack feature points; both X1 and X2 are expressed in explicit format, including all points, lines, surfaces, all intersection points of lines, and all intersection lines of surfaces.

[0030] Optionally, the initialized unstructured surface mesh is obtained based on the Delaunay triangulation algorithm.

[0031] Furthermore, the factors affecting the collapse error include: the distance between the new vertex and the plane of each triangular mesh it is associated with, the average area of the adjacent triangular meshes before each edge collapse, and the regularity of the adjacent triangular meshes before each edge collapse.

[0032] Furthermore, the calculation formula for the collapse error is:

[0033]

[0034] In the formula, when collapsing the opposite edge (v i ,v j ), the set of triangular meshes Planes(i,j) associated with the edge (v i ,v j ) forms a region, and the position of the new vertex generated after the collapse of the edge (v i ,v j ) is [x,y,z,1] T , is the collapse error brought about by the collapse of the edge (v i ,v j );

[0035] is the sum of the squares of the distances from the position to the plane of each triangular mesh in the set Planes(i,j);

[0036] is the average area of the adjacent triangular meshes before the collapse of the edge (v i ,v j ); and

[0037] is the average value of the regularity of the adjacent triangular meshes before the collapse of the edge (v i ,v j ).

[0038] On the other hand, the present invention provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to cause a machine to execute the method for constructing an unstructured grid model of the present application.

[0039] On the other hand, the present invention provides a processor, characterized in that it is used to run a program, wherein when the program is run, it is used to execute the method for constructing an unstructured grid model of the present application.

[0040] Through the above technical solution, first establish an unstructured surface mesh of the contour surface of the cave medium in the fracture-vuggy reservoir, and effectively simplify the unstructured surface mesh through the edge collapse algorithm. Then, taking the simplified unstructured surface mesh as the boundary constraint, insert the data of the fracture medium in the fracture-vuggy reservoir to construct an unstructured grid model. In the cave characterization stage, the outer contour surface mesh is iteratively simplified based on the collapse error metric iterative algorithm, effectively reducing the complexity, and while reducing the number of meshes, still maintaining the basic geometric features of the initial model. In the fracture characterization stage, the structural data of the fracture medium is inserted point by point. The generated unstructured grid not only fits the points on the fracture-vuggy medium, but also fits the medium surface itself, effectively realizing the fine characterization of complex multi-scale media, and also improving the efficiency and stability of the region in the three-dimensional unstructured grid generation process.

[0041] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0043] Figure 1 is a schematic flowchart of an embodiment of the method for constructing an unstructured grid model of the present invention;

[0044] Figure 2 is a schematic flowchart of simplifying the unstructured surface mesh in another embodiment of the method for constructing an unstructured grid model of the present invention;

[0045] Figure 3 is Figure 2 the three-dimensional fracture-vuggy reservoir model of the implementation object in the embodiment;

[0046] Figure 4 is from Figure 3 a schematic diagram of extracting the outer contour data of the cave medium from the three-dimensional fracture-vuggy reservoir model;

[0047] Figure 5 is from Figure 3 a schematic diagram of extracting the outer contour data of the fracture medium from the three-dimensional fracture-vuggy reservoir model;

[0048] Figure 6 (a) - (c) are schematic diagrams of the effect of iterative simplification according to Figure 2 the simplification process;

[0049] Figure 7 is the three-dimensional fracture-vuggy reservoir unstructured grid model finally constructed according to the present invention; and

[0050] Figure 8 It is a component structure diagram of an embodiment of the device for constructing an unstructured grid model of the present invention. Detailed implementation manners

[0051] The following will describe in detail the specific implementation manners of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0052] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0053] The embodiments of the present invention provide a method for constructing an unstructured grid model, which can be used to construct an unstructured grid model for a multi-scale reservoir, and can take into account the operation efficiency, characterization accuracy and process stability of the constructed model. Especially for a complex fracture-cavity reservoir, it can be double-fitted with the points and surfaces of the karst cave medium and the fracture medium, and realize the fine characterization of the complex multi-scale medium. The process of this embodiment is as Figure 1 shown, and includes the following steps:

[0054] Step 1: Obtain geometric topology structure data sets X1 and X2 that respectively represent the karst cave medium and the fracture medium in the fracture-cavity reservoir;

[0055] The above geometric topology structure data sets X1 and X2 respectively correspond to the karst cave medium and the fracture medium in the fracture-cavity reservoir, and both X1 and X2 include the characteristic point coordinates of the outer contour of the corresponding karst cave / fracture medium and the geometric topology relationship between the characteristic points of the outer contour, that is, the definition of the characteristic points, lines, surfaces, intersection points, intersection lines, etc. of the outer contour.

[0056] Obtaining X1 and X2 can be to extract the characteristic points of the outer contour of the karst cave medium and the fracture medium and the geometric topology relationship between the characteristic points from a three-dimensional fracture-cavity reservoir model respectively. For example, all points, lines, surfaces and their intersection points and intersection lines in the definition data set X1 in explicit format are defined, that is, the illegal intersection of geometric monomers without definition is not allowed.

[0057] Step 2: Initialize an unstructured surface grid representing the contour surface of the karst cave medium based on X1;

[0058] Step 3: Traverse each edge of the unstructured surface grid, collapse each edge into a new vertex, and determine the position of the new vertex when the position of the new vertex meets a preset collapse error, so as to simplify the unstructured surface grid;

[0059] Step 2-3 is the karst cave characterization stage. For fractured-vuggy reservoirs, the details of the outer contour of the karst cave medium are usually very rich, and the number of unstructured grids required to achieve high-quality characterization is usually extremely large, so simplification is needed. To solve this problem, an edge-collapse iterative algorithm improved based on quadratic error metric is mainly used. The goal of the algorithm is to reduce the complexity of the grid by reducing the number of points, edges, and faces of the grid within a certain error range.

[0060] Therefore, in Step 2, first establish an unstructured surface grid of the contour surface of the initial karst cave medium based on the geometric topology structure dataset X1 of the karst cave medium, and then in Step 3, iteratively simplify the unstructured outer contour surface grid established in Step 2 based on the iterative algorithm of collapse error metric to reduce the complexity of the unstructured surface grid, and while reducing the number of grids, try to maintain the basic geometric features of the initial model based on the constraints of the collapse error metric.

[0061] In Step 2, for example, each single grid in the unstructured surface grid can be obtained according to the Delaunay triangulation algorithm. That is, each single grid in the unstructured surface grid is a triangle, each triangular single grid is a face, and all the triangular single grids form a three-dimensional surface, and this three-dimensional surface fits the outer contour surface of the karst cave medium in the fractured-vuggy reservoir.

[0062] It should be noted that the Delaunay triangulation algorithm is just an unstructured grid algorithm, and the present invention is not limited to obtaining unstructured grids by this method. For the introduction of the Delaunay triangulation algorithm, refer to the description in the prior art literature, and it will not be elaborated here.

[0063] Step 4: Based on X2, construct an unstructured grid model with the simplified unstructured surface grid as the boundary constraint.

[0064] This is the crack characterization stage. Based on the simplified unstructured surface mesh in step 3, the structural data X2 of the crack medium can be inserted point by point in the local area to generate a three-dimensional unstructured volume mesh (which can also be simply referred to as an unstructured mesh). The unstructured mesh generation methods include regular division method, modified octree method, constrained Delaunay method, etc. In one implementation, it is obtained by using the constrained Delaunay tetrahedral meshing algorithm. For the introduction of the constrained Delaunay tetrahedral meshing algorithm, refer to the description in the prior art literature and will not be elaborated here. Specifically, using the point-by-point insertion algorithm based on Delaunay triangulation, each crack data point is inserted point by point into the initial unstructured volume mesh in turn, and finally the target unstructured volume mesh is obtained. The point-by-point insertion algorithm of Delaunay triangulation can adopt various methods such as Bowyer Watson algorithm, Lawson algorithm, etc. For the introduction of the point-by-point insertion algorithm, refer to the description in the related technology and will not be elaborated here.

[0065] The unstructured mesh generated according to the above steps not only fits the points on the fracture-vug medium, but also fits the medium surface itself, effectively realizing the fine characterization of complex multi-scale media, and also improving the efficiency and stability of the region in the process of generating the three-dimensional unstructured mesh.

[0066] Based on this embodiment, there is also a preferred implementation of the construction method of the unstructured mesh model of the present invention. In some embodiments, the factors affecting the collapse error include: the distance between the new vertex and the plane of each associated triangular mesh, the average area of the adjacent triangular meshes of each edge before collapse, and the regularity of the adjacent triangular meshes of each edge before collapse.

[0067] In some embodiments, the calculation formula of the collapse error is:

[0068]

[0069] In the formula, for the collapse of the opposite side (v i ,v j ), the set of triangular meshes Planes(i,j) associated with the edge (v i ,v j ) forms a region, and the position i ,v j ) after the collapse of the edge (v i ,v j ) to generate a new vertex is [x,y,z,1] T , is the collapse error brought by the collapse of the edge (v i ,v j );

[0070] is the position The sum of the squares of the distances to the planes of each associated triangular face mesh p in the set Planes(i,j);

[0071] is the average area of the m triangular face meshes adjacent to the collapsed edge (v i , v j ), and A k is the area of the k-th triangular face mesh adjacent to the collapsed edge (v i , v j );

[0072] is the average regularity of the m triangular face meshes of the adjacent faces of the collapsed edge (v i , v j ), and R k is the regularity of the k-th triangular face mesh of the adjacent faces of the collapsed edge (v i , v j ).

[0073] It should be noted that can also be replaced by the minimum value among the regularities of the m triangular face meshes of the adjacent faces of the collapsed edge (v i , v j ).

[0074] The following introduces a preferred embodiment in conjunction with Figure 2-7 . The implementation steps include:

[0075] First step, respectively according to the medium partition information of the three-dimensional fracture-vug reservoir model, obtain the characteristic point coordinates of the outer contours of the two media, i.e., solution cavities and fractures, of the three-fracture-vug reservoir model and the data set X1, X2 of their mutual geometric topological relationships.

[0076] The three-dimensional fracture-vug reservoir model generally refers to a three-dimensional geological model obtained by relying on geological modeling methods. This method usually constructs the two media of solution cavities and fractures separately and then merges them. The characteristic point data set of each medium can be obtained according to the original modeling information.

[0077] In Figure 3 shows a three-dimensional model of a typical fracture-vug reservoir unit. In the model, the red and yellow areas represent solution cavities of different scales, and the light green and dark green represent fractures of different scales; Figure 4 and Figure 5 respectively show the outer contours of the two media of solution cavities and fractures extracted from this three-dimensional fracture-vug reservoir model.

[0078] Second step, respectively perform explicit format expressions on all the data in the data sets X1 and X2 to obtain the explicit data sets PLC X1 and PLC X2 of the solution cavities and fractures.

[0079] The definition of the explicit format is that all points, lines, planes in the data set PLC X and their intersection points and intersection lines need to be defined in the data set PLC X, that is, the illegal intersection of geometric monomers without definition is not allowed. During the specific instance operation, it is necessary to check the characteristic point data sets X1 and X2 of the two media of the karst cave and the crack to ensure that any intersection points, intersection lines, and intersection planes formed when the cracks intersect with each other, the cracks intersect with the karst caves, and the karst caves intersect with each other in the data set are defined in the data set itself, that is, the intersection points, intersection lines, and intersection planes belong to the data set itself.

[0080] In the third step, based on the explicit data set PLC X1 of the karst cave, a high-quality unstructured surface mesh that can finely represent the outer contour surface of the karst cave is obtained. Among them, any point, line, and plane geometric monomer in the data set PLC X1 is the vertex, grid edge, or grid surface of the unstructured surface mesh.

[0081] The unstructured mesh of the outer contour surface of the karst cave refers to the unstructured mesh generated for the outer contour surface of the target karst cave. In this embodiment, a high-quality unstructured triangular mesh is obtained according to the Delaunay triangulation algorithm, such as Figure 6 (a) shows the unstructured triangular mesh generated for the outer contour of a specific karst cave in the fracture-vug unit. It should be noted that the Delaunay triangulation algorithm is just an unstructured mesh algorithm and is not limited to obtaining the unstructured mesh by this method. For the introduction of the Delaunay triangulation algorithm, refer to the description in the related technology and will not be elaborated here.

[0082] In the fourth step, combine Figure 2 The iterative process of the edge collapse algorithm shown in the figure is used to simplify the unstructured surface mesh of the outer contour of the karst cave, and the simplified unstructured surface mesh of the outer contour of the karst cave is obtained.

[0083] For fracture-vug reservoirs, the details of the outer contour of the karst cave medium are usually very rich, and the number of unstructured meshes required to achieve high-quality representation is usually very large, so simplification is needed. To solve this problem, an edge collapse iterative algorithm based on the improvement of the quadratic error metric as shown in Figure 2 is used. The goal of the algorithm is to replace the edge that meets the collapse requirements with a new vertex, reducing the number of points, edges, and faces of the mesh within a certain error range, so as to achieve the purpose of reducing the mesh complexity.

[0084] Traverse each edge in the unstructured surface mesh obtained in the third step, and denote the current edge as: edge (v i , v j ), and the edge (v i , v j)The set of associated face meshes is denoted as Planes(i,j). In this embodiment, the face meshes are triangular face meshes, but the present invention is not limited thereto. Planes(i,j) forms a region that will collapse the edge (v i , v j ) to generate the position of the new vertex denoted as [x, y, z, 1] T , then the collapse error caused by this edge collapse is defined and calculated using the following formula:

[0085]

[0086]

[0087]

[0088]

[0089]

[0090] where, is the position of the new vertex to the sum of the squares of the distances from each associated triangular face mesh p in the set of triangular face meshes Planes(i,j) to the face where it is located; is the average area of the m triangular face meshes adjacent to the collapsed edge (v i , v j ), A k is the area of the k-th triangular face mesh adjacent to the collapsed edge (v i , v j ); is the average regularity of the m triangular face meshes adjacent to the face of the collapsed edge (v i , v j ), R k is the regularity of the k-th triangular face mesh adjacent to the face of the collapsed edge (v i , v j ), l1, l2, l3 are the three side lengths of the k-th triangular face mesh, and l1 ≤ l2 ≤ l3.

[0091] Specifically, implementing the above iterative algorithm to traverse each edge can be as follows: Traverse the unstructured face meshes of the outer contour of the karst cave in sequence, calculate the collapse error of each mesh edge, sort the collapse errors by magnitude, perform an edge collapse operation on the edge with the smallest collapse error, that is, merge two points into one point, connect other points connected to the collapsed edge to the new vertex, delete the degenerate edges and points, update the collapse errors of the affected edges and the new vertex, and re-sort. Iterate in this way until the simplification goal is achieved. As Figure 2 shown, the iterative algorithm process is as follows:

[0092] ①Read the unstructured grid point, line, and face data that needs to be simplified;

[0093] ②Calculate the position of the new vertex with the minimum collapse error for each edge and the corresponding collapse error;

[0094] ③Sort the collapse errors in ascending order;

[0095] ④Take out the edge with the minimum error for edge collapse operation, connect other points connected to the collapsed edge to the new vertex, delete the degenerate edges and points, and update the collapse error, new vertex, and collapse order of the affected edges;

[0096] ⑤If the simplification requirement is met, end the iterative algorithm and input the structured grid point, line, and face data after iteration; if the simplification requirement is not met, go to ④ and continue the simplification.

[0097] As Figure 6 shown in (a)–(c), simplify the unstructured surface grid of the outer contour of the karst cave in (a) according to the iterative method. According to the simplification targets of reducing the number of grids by 3 / 4 and 19 / 20 respectively, after optimizing the iterative process, the simplified unstructured surface grids of the outer contour of the karst cave in (b) and Figure 6 (c) are obtained respectively, and the number of triangular grids is reduced from 20,000 to 5,000 and 1,000 respectively. Figure 6 (b) and Figure 6 (c) are obtained respectively, and the number of triangular grids is reduced from 20,000 to 5,000 and 1,000 respectively.

[0098] In the fifth step, using the simplified unstructured surface grid of the outer contour of the karst cave as the boundary constraint, generate the initial unstructured volume grid.

[0099] The three-dimensional unstructured volume grid generation methods include the regular division method, the modified octree method, the constrained Delaunay method, etc. In this embodiment, the initial unstructured volume grid is generated by using the constrained Delaunay tetrahedron meshing algorithm and is of the Delaunay tetrahedron grid type. This step can be understood as taking all the vertices in the simplified unstructured surface grid of the outer contour of the karst cave as auxiliary points and constructing a Delaunay tetrahedron grid as the initial unstructured volume grid, where each grid face of the unstructured surface grid is one of the faces of the initial volume grid. For the introduction of the constrained Delaunay tetrahedron meshing algorithm, see the description in the related technology and will not be elaborated here.

[0100] In the sixth step, insert the data set PLC X2 of the cracks point by point in the local area into the initial unstructured volume grid to obtain the target three-dimensional unstructured volume grid.

[0101] As Figure 7As shown in the figure, in this embodiment, the point-by-point insertion algorithm based on Delaunay triangulation is adopted, and each crack data point is successively inserted point by point into the initial unstructured tetrahedral mesh, and finally the target unstructured tetrahedral mesh is obtained.

[0102] In this step, each time a crack data point is inserted into the tetrahedral mesh, all tetrahedral elements in the circumscribed sphere of the tetrahedral mesh that contain the crack data point x to be inserted are first deleted to form a cavity V x , and the point x to be inserted is connected to the vertices of the outer bounding surface of the cavity V x to generate a new tetrahedral mesh. This process can be understood as that each time a crack data point is inserted into the tetrahedral mesh, the tetrahedral mesh will be locally adjusted, and after multiple adjustments, the target tetrahedral mesh is generated.

[0103] The point-by-point insertion algorithm based on Delaunay triangulation can adopt various methods such as the Bowyer Watson algorithm and the Lawson algorithm. For the introduction of the point-by-point insertion algorithm, refer to the description in the related technology, which will not be elaborated here.

[0104] Compared with the prior art, the technical advantages of this embodiment are as follows:

[0105] (1) An optimization method for the outer contour of the fracture-cavity model is proposed. Through the iterative algorithm based on error measurement, the outer contour surface mesh of the karst cave is iteratively simplified, effectively reducing the complexity, keeping the original basic geometric features of the model while reducing the number of meshes, meeting the requirements of the subsequent numerical simulation operation efficiency, and being more suitable for the access and geometric operation efficiency requirements of a large number of point, line, and surface data of fractures and cavities;

[0106] (2) A method for improving the generation efficiency and fineness of unstructured meshes for complex fracture-cavity reservoirs is realized. On the basis of the effective simplification of the outer contour surface mesh of the karst cave, in the fracture characterization stage, by locally inserting crack data points point by point, the generated unstructured volume mesh not only fits the points on the fracture-cavity medium, but also fits the medium surface itself, effectively realizing the fine characterization of complex multi-scale media. The strategy of local point-by-point insertion also improves the efficiency and stability of the region in the process of generating three-dimensional unstructured meshes.

[0107] The embodiment of the present invention provides a device for constructing an unstructured mesh model, such as Figure 8As shown in the figure, it includes a data acquisition module, a surface mesh generation module, a surface mesh simplification module, and a mesh model construction module. Among them, the data acquisition module acquires a geometric topology structure data set X1 representing the karst cave medium in the fracture-vuggy reservoir, and a geometric topology structure data set X2 representing the fracture medium in the fracture-vuggy reservoir; the surface mesh generation module initializes an unstructured surface mesh representing the contour surface of the karst cave medium based on X1; the surface mesh simplification module traverses each edge of the unstructured surface mesh, collapses each edge into a new vertex, and determines the position of the new vertex when the position of the new vertex meets the preset collapse error, thereby simplifying the unstructured surface mesh; the mesh model construction module constructs an unstructured mesh model based on X2 with the simplified unstructured surface mesh as the boundary constraint.

[0108] In some embodiments, the geometric topology structure data set X1 obtained by the data acquisition module includes: the coordinates of the outer contour feature points representing the karst cave medium and the geometric topology relationship between the outer contour feature points; X2 includes: the coordinates of the fracture feature points representing the fracture medium and the geometric topology relationship between the fracture feature points; both X1 and X2 are expressed in explicit format, including all points, lines, surfaces, all intersection points of lines, and all intersection lines of surfaces.

[0109] In some embodiments, the surface mesh generation module obtains the initialized unstructured surface mesh based on X1 and the Delaunay triangulation algorithm. That is, each single mesh in the unstructured surface mesh is a triangle, each triangular single mesh is a surface, and all the triangular single meshes form a three-dimensional surface, and this three-dimensional surface fits the outer contour surface of the karst cave medium in the fracture-vuggy reservoir.

[0110] In some embodiments, the factors affecting the collapse error include: the distance between the new vertex and the plane where each associated triangular mesh is located, the average area of the adjacent triangular meshes before each edge collapse, and the regularity of the adjacent triangular meshes before each edge collapse.

[0111] In some embodiments, the calculation formula for the collapse error is:

[0112]

[0113] In the formula, when collapsing the opposite side (v i ,v j ), the set of triangular meshes Planes(i,j) associated with the edge (v i ,v j ) constitutes a region, and the position i ,v j ) after collapsing the edge (v is [x,y,z,1] T , is the edge (vi , v j ) The collapse error caused by the collapse;

[0114] is the position The sum of the squares of the distances to the planes of each associated triangular face mesh p in the set Planes(i, j);

[0115] is the collapsed edge (v i , v j ) The average area of the m triangular face meshes adjacent to it, A k is the collapsed edge (v i , v j ) The area of the k-th triangular face mesh adjacent to it;

[0116] is the collapsed edge (v i , v j ) The average regularity of the m triangular face meshes of the adjacent faces, R k is the collapsed edge (v i , v j ) The regularity of the k-th triangular face mesh of the adjacent faces.

[0117] It should be noted that can also be replaced by the minimum value among the regularities of the m triangular face meshes of the adjacent faces of the collapsed edge (v i , v j ).

[0118] The embodiment of the present invention also provides a device for constructing an unstructured grid model. The device for constructing the unstructured grid model includes a processor and a memory. The above data acquisition module, face mesh generation module, face mesh simplification module, and grid model construction module, etc., are all stored in the memory as program units, and the corresponding functions are realized by the processor executing the above program units stored in the memory.

[0119] The processor contains a kernel, and the kernel retrieves the corresponding program units from the memory. One or more kernels can be set, and by adjusting the kernel parameters, the fine characterization of the fracture-vug complex medium can be achieved while meeting the geometric operation efficiency requirements.

[0120] The memory may include non-permanent memory in a computer-readable medium, forms such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.

[0121] An embodiment of the present invention provides a storage medium, on which a program is stored, and when the program is executed by a processor, the method for constructing an unstructured grid model of the present application is implemented.

[0122] An embodiment of the present invention provides a processor, which is used to run a program, wherein when the program runs, the method for constructing an unstructured grid model of the present application is executed.

[0123] An embodiment of the present invention provides a device, which includes a processor, a memory, and a program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for constructing an unstructured grid model of the present application are implemented. The device herein may be a server, a PC, a PAD, a mobile phone, etc.

[0124] The present application also provides a computer program product, which is suitable for executing a program initialized with the steps of the method for constructing an unstructured grid model of the present application when executed on a data processing device.

[0125] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented 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.

[0126] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0127] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide for implementing the steps in a process Figure 1 a process or multiple processes and / or blocks Figure 1 or multiple blocks, to perform the functions specified in the process

[0129] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0130] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0131] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can store information by any method or technology. The information can be computer-readable instructions, data structures, program modules, 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, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0132] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, commodity or device comprising the element.

[0133] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for constructing an unstructured grid model, which is used to construct an unstructured grid model of a fracture-cavity reservoir, including: Obtain geometric topology structure datasets X1 and X2 respectively characterizing the cavern medium and fracture medium in the fracture-vuggy reservoir; Based on the X1, initialize an unstructured surface mesh characterizing the contour surface of the cavern medium; Traverse each edge of the unstructured surface mesh, collapse each edge into a new vertex, and determine the position of the new vertex when the position of the new vertex meets a preset collapse error, so as to simplify the unstructured surface mesh; And Using the simplified unstructured surface mesh as a boundary constraint, based on the X2, construct the unstructured grid model.

2. The method for constructing an unstructured grid model according to claim 1, wherein The X1 includes: the coordinates of the outer contour feature points characterizing the cavern medium and the geometric topology relationship between the outer contour feature points; and The X2 includes: the coordinates of the fracture feature points characterizing the fracture medium and the geometric topology relationship between the fracture feature points.

3. The method for constructing an unstructured grid model according to claim 2, wherein Both the X1 and the X2 are expressed in explicit format, including all points, lines, surfaces, all intersection points of lines, and all intersection lines of surfaces.

4. The method for constructing an unstructured grid model according to claim 1, wherein The single grid of the initialized unstructured surface mesh is a triangular grid surface.

5. The method for constructing an unstructured grid model according to claim 4, wherein The factors affecting the collapse error include: the distance between the new vertex and the plane where each associated triangular grid is located, the average area of the adjacent triangular grids before each edge collapse, and the regularity of the adjacent triangular grids before each edge collapse.

6. The method for constructing an unstructured grid model according to claim 5, wherein The calculation formula of the collapse error is: wherein, for the opposite side (v i , v j ), collapse is performed, and the set of triangular meshes Planes(i,j) associated with the side (v i , v j ) forms a region, and the position of the new vertex generated after the collapse of the side (v i , v j ) is [x, y, z, 1] T , is the collapse error brought about by the collapse of the side (v i , v j ); for the position the sum of the squares of the distances to the planes of each triangular mesh in the set Planes(i, j); is the average area of the adjacent triangular meshes before the collapse of the edge (v i , v j ); and is the average of the regularity degrees of the adjacent triangular meshes before the collapse of the edge (v i , v j ).

7. The method for constructing an unstructured grid model according to claim 1, wherein The constructing the unstructured grid model with the simplified unstructured surface mesh as a boundary constraint and based on the X2 includes: Using the simplified unstructured surface mesh as a boundary constraint to generate an initial unstructured grid model, where each grid surface of the unstructured surface mesh is one of the surfaces of the initial unstructured grid model; and Based on a predetermined meshing algorithm, insert the fracture feature points of each fracture in the X2 into the initial unstructured grid model point by point.

8. The method for constructing an unstructured grid model according to claim 7, wherein Each grid surface of the unstructured surface mesh is a triangle, and each single grid of the unstructured grid model is a tetrahedron obtained based on the Delaunay triangulation algorithm.

9. An apparatus for constructing an unstructured grid model, which is used to construct an unstructured grid model of a fracture-cavity reservoir, including: A data acquisition module, which acquires a geometric topology structure dataset X1 characterizing the cavern medium in the fracture-vuggy reservoir and a geometric topology structure dataset X2 characterizing the fracture medium in the fracture-vuggy reservoir; A surface mesh generation module, which initializes an unstructured surface mesh characterizing the contour surface of the cavern medium based on the X1; A surface mesh simplification module, which traverses each edge of the unstructured surface mesh, collapses each edge into a new vertex, and determines the position of the new vertex when the position of the new vertex meets a preset collapse error, and simplifies the unstructured surface mesh; And A grid model construction module, which constructs the unstructured grid model with the simplified unstructured surface mesh as a boundary constraint and based on the X2.

10. The apparatus for constructing an unstructured grid model according to claim 9, wherein The X1 includes: the coordinates of the outer contour feature points characterizing the cavern medium and the geometric topology relationship between the outer contour feature points; The X2 includes: the coordinates of the fracture feature points characterizing the fracture medium and the geometric topology relationship between the fracture feature points; and Both the X1 and the X2 are in explicit format expressions, including all points, lines, planes, all intersection points of lines, and all intersection lines of planes.

11. The construction device of the unstructured grid model according to claim 9, wherein, The initialized unstructured surface mesh is obtained based on the Delaunay triangulation algorithm.

12. The construction device of the unstructured grid model according to claim 11, wherein, The factors affecting the collapse error include: the distance between the new vertex and the plane where each associated triangular mesh is located, the average area of the adjacent triangular meshes before each edge collapse, and the regularity of the adjacent triangular meshes before each edge collapse.

13. The construction device of the unstructured grid model according to claim 12, wherein, The calculation formula for the collapse error is: wherein, for the opposite side (v i , v j ), collapse is performed, and the set of triangular meshes Planes(i,j) associated with the side (v i , v j ) forms a region, and the position of the new vertex generated after the collapse of the side (v i , v j ) is [x, y, z, 1] T , is the collapse error brought about by the collapse of the side (v i , v j ); to the position the sum of the squares of the distances to the planes where each triangular mesh in the set Planes(i, j) is located; is the average area of the adjacent triangular meshes before the collapse of the edge (v i , v j ); and is the average of the regularity degrees of the adjacent triangular meshes before the collapse of the edge (v i , v j ).

14. A machine-readable storage medium having instructions stored thereon for causing a machine to execute: the method for constructing an unstructured grid model according to any one of claims 1-8.

15. A processor, wherein, For running a program, wherein when the program is run, it is used to execute: the method for constructing an unstructured grid model as described in any one of claims 1-8.

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