Three-dimensional geomechanical modeling method and system for complex geological body based on corner point grid

Abstract

The application discloses a complex geologic body three-dimensional geomechanics modeling method and system based on a corner point grid, and the method comprises the following steps: establishing a geometric framework of strata and a propagation framework of fault surfaces; calculating gradient values of points in the strata; establishing a geologic body geometric model of each stratum, and dividing a geologic body grid M1; forming a comprehensive grid M3 for mechanical calculation of a reservoir geologic body-fault surface according to the propagation framework of the fault surfaces and the geologic body grid M1; performing physical property parameter assignment and mechanical parameter assignment on each solid element in the comprehensive grid M3, and performing mechanical parameter assignment on each fault surface element in the comprehensive grid M3; establishing an outer framework of the comprehensive grid M3, and applying a ground stress load, a dead weight load and a boundary displacement constraint on the outer framework of the comprehensive grid M3; and saving a data body obtained in the foregoing steps into a three-dimensional geologic model data file which can be directly read by a solver. The application realizes fine simulation of a reservoir geologic mechanics problem.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas reservoir geomechanics and engineering technology, and more specifically, relates to a three-dimensional geomechanical modeling method and system for complex geological bodies based on corner grids. Background Technology

[0002] In oil and gas reservoir engineering, fault structures are common in reservoir rocks. The formation stress caused by injection and production activities often leads to instability of the reservoir, especially the faults, which in turn causes engineering accidents such as water channeling in the oilfield, leakage in the gas storage facility, and wellbore instability. The mechanical stability of the reservoir under alternating injection and production loads is an important factor to consider when determining the injection and production pressure of the oilfield and the operating pressure of the gas storage facility.

[0003] Using specialized mechanical calculation software to analyze the stress evolution of reservoirs and faults during injection and production activities is a prerequisite for assessing the stability of reservoirs and faults. However, general-purpose mechanical calculation software such as Ansys, Abaqus, and Flac3D struggle to create detailed geological models, particularly failing to reflect the discontinuous geological phenomena commonly found in oil and gas reservoirs, such as stratigraphic pinch-outs and faults. Furthermore, these software programs assign mechanical parameters to geological bodies in a layered or regional manner, failing to reflect the high degree of heterogeneity in reservoir mechanical parameters.

[0004] Petrel, a reservoir geological modeling software, can create a fine-grained corner mesh model of the target area, but this mesh cannot be directly used for mechanical calculations. The main reason is that the nodes in the corner mesh are discontinuous at any corner, violating the requirement of geological body continuity in mechanical calculations. Furthermore, the rigid connection between the fault sides cannot account for the relative displacement that can occur on either side of the fault, and the corner mesh lacks an explicit fault plane, making it impossible to apply mechanical properties such as tangential stiffness and normal stiffness that reflect the mechanical properties of the fault. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to propose a three-dimensional geomechanical modeling method and system for complex geological bodies based on corner grids. This method transforms corner grids into finite element grids for mechanical calculations, leveraging the advantages of reservoir geological modeling software for detailed reservoir and fault modeling, while also utilizing the powerful computational capabilities of general-purpose mechanical calculation software to achieve detailed simulation of reservoir geomechanical problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes, the method comprising the following steps: Establish the geometric framework of the strata and the extended framework of the fault planes; Calculate the gradient value at each point within the formation; Using the geometric framework of the strata, the extension framework of the fault planes, and the gradient values ​​as constraints, we establish the geological body geometric model of each stratum and divide the geological body into grids M1. Based on the extended framework of the fault plane and the geological body grid M1, a comprehensive grid M3 for mechanical calculation of reservoir-fault plane is formed; Assign physical and mechanical parameters to each solid element in the composite mesh M3, and assign mechanical parameters to each fault plane element in the composite mesh M3; Establish the outer frame of the composite grid M3, and apply ground stress load, self-weight load and boundary displacement constraint on the outer frame of the composite grid M3. Based on the solver used in the numerical simulation, the composite mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints are combined into a three-dimensional geomechanical model data volume and saved as a three-dimensional geological model data file that can be directly read by the solver.

[0007] Preferably, the method for three-dimensional geomechanical modeling of complex geological bodies based on corner meshes specifically includes the following steps: Step 1: Determine the distribution range of reservoir geological bodies and fault attitude based on the geometric information of corner grids, and establish the geometric framework of strata and the extension framework of fault planes. Step 2: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data, and mechanical experimental data, interpolate and calculate the gradient values ​​at each point within the formation; Step 3: Using the geometric framework of the strata, the extension framework of the fault plane, and the gradient value as constraints, establish the geological body geometric model of each stratum and divide the geological body into grids M1; Step 4: Based on the extended framework of the fault plane and the geological body grid M1, the fault plane grid M2 is formed. The fault plane grid M2 and the geological body grid M1 are combined to form the reservoir-fault plane mechanical calculation integrated grid M3. Step 5: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data and mechanical experimental data, the interpolation method is used to assign physical property parameters and mechanical parameters to each solid element in the composite grid M3. For each fault plane element in the composite grid M3, the mechanical parameters are assigned based on the structural surface experimental data. Step 6: Establish the outer frame of the composite grid M3. Based on the measurement data of regional geostress and the burial depth of the geological body, apply geostress load, self-weight load and boundary displacement constraint to the outer frame of the composite grid M3. Step 7: Based on the solver used in the numerical simulation, combine the integrated mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints into a three-dimensional geomechanical model data volume and save it as a three-dimensional geological model data file that can be directly read by the solver.

[0008] Preferably, the three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes further includes: After step 1, the geometric framework of the strata and the extension framework of the fault plane are extended according to the area under study, with the extension range being 5 times or more the area under study.

[0009] Preferably, step 2 includes the following steps: Step 201: Establish the physical property parameter distribution field using the physical property parameters contained in the corner grid; Step 202: Verify and correct the parameter distribution field using seismic interpretation data, well logging interpretation data, and mechanical experimental data; Step 203: Select the longitudinal and transverse step sizes, establish a grid, use the physical and mechanical parameters contained in the corner grid as the interpolation source data, and use the coordinates of the grid points as the interpolation coordinate data. Use the Kriging interpolation method to calculate the physical and mechanical parameters at each grid point. Then, based on the longitudinal and transverse step sizes of the grid, calculate the gradients of the physical and mechanical parameters, and use the maximum value of the gradient of each parameter as the gradient value of the grid point.

[0010] Preferably, step 3 includes the following steps: Step 301: Based on the cutting relationship of the fault extension to the strata, obtain the extension framework of the fault plane, divide the stratigraphic framework into regions, and establish the geometric framework of the strata. Step 302: Establish the geological geometric model of each stratum using the geometric framework of the strata and the extended framework of fault planes; Step 303: Set the mesh size range, local refinement factor, and lower limit of the quality factor for the geological body geometric model based on the gradient value; Step 304: Use the Delaunay algorithm to generate a hexahedral mesh for the geological body geometric model, forming the geological body mesh M1.

[0011] Preferably, step 3 further includes: After step 303, a mesh quality check is performed, and cells with quality factors below the lower limit are corrected and adjusted.

[0012] Preferably, step 3 further includes: After step 304, based on the geometric information such as the node coordinates, unit shape and unit size of the corner grid, the discontinuity of the strata is analyzed. At the discontinuity points, the geological body grid M1 is subdivided and the tetrahedral or wedge-shaped units are transitioned to obtain a fine grid of the reservoir geological body.

[0013] Preferably, step 4 includes the following steps: Step 401: For each group of fault planes in the extended framework of the fault plane, select the grid nodes of the pre-divided geological body grid M1 on the fault plane. Step 402: Use the Delaunay algorithm to connect the selected mesh nodes into a quadrilateral mesh, and use triangular meshes or quadrilateral meshes at the boundaries; Step 403: For each fault plane, match the quadrilateral meshes on both sides of the fault plane to form a fault plane mesh group, and combine each fault plane mesh group to form a fault plane mesh M2. Step 404: Combine the fault plane grid M2 with the geological body grid M1 to form the geological body-fault plane mechanical calculation integrated grid M3.

[0014] Preferably, step 4 further includes: After step 404, the matching degree of the grids on both sides of the fault plane is detected. If the mutual embedding or separation distance of the grids on both sides exceeds the tolerance, local adjustment is performed.

[0015] Preferably, step 5 includes the following steps: Step 501: Calculate the center point coordinates of each solid element in the composite mesh M3, and find the position of its corresponding corner grid. Step 502: Based on the physical property parameters of the corner grid, combined with seismic interpretation data and well logging interpretation data, the physical property parameters of each solid element in the composite grid M3 are assigned using the interpolation method. Combined with mechanical experimental data, the mechanical parameters of each solid element in the composite grid M3 are assigned. The physical property parameters include porosity, saturation, and permeability; the mechanical parameters include density, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. Step 503: For each fault plane element in the synthetic mesh M3, assign mechanical parameters based on the structural plane experimental data. The mechanical parameters include the tangential stiffness and normal stiffness of the structural plane.

[0016] Preferably, step 5 further includes: After step 503, a parameter assignment consistency check is performed. The relative deviation between the physical property parameters assigned to each entity element and the physical property parameters based on the corner grid, combined with the parameters obtained from seismic interpretation data and well logging interpretation data, is checked. The relative deviation between the mechanical parameters assigned to each entity element and the mechanical experimental data is also checked. If the deviation exceeds the tolerance, the values ​​are re-interpolated and reassigned.

[0017] Preferably, step 6 includes the following steps: Step 601: Select the outer surface, top surface, and bottom surface of mesh M3, establish the outer frame of mesh M3 composed of the outer surface, top surface, and bottom surface, and calculate the inner normal direction of the outer surface. Step 602: Decompose the measured ground stress along the inner normal and tangent directions of each outer surface and apply it to each outer surface; Step 603: Calculate the self-weight of the overlying rock layer based on the burial depth of the geological body, and apply the self-weight of the overlying rock layer as a self-weight load to the top surface; Step 604: Apply boundary displacement constraints to the bottom surface.

[0018] Preferably, step 6 further includes: After step 604, according to the calculation requirements, other loads are applied to the outer frame of grid M3, including fluid pressure and injection-production periodic stress.

[0019] This invention also discloses a three-dimensional geomechanical modeling system for complex geological bodies with faults based on corner grids, comprising: First building block: used to establish the geometric framework of the strata and the extended framework of the fault plane; Calculation unit: Used to calculate the gradient value at various points within the formation; The second building unit is used to establish the geological body geometric model of each stratum and divide the geological body into grids M1, constrained by the geometric framework of the strata, the extension framework of the fault plane, and the gradient value. The third building unit is used to form a comprehensive grid M3 for mechanical calculation of reservoir geological bodies and fault planes based on the extended framework of the fault plane and the geological body grid M1. Assignment Unit: Used to assign physical and mechanical parameters to each solid element in the composite mesh M3, and to assign mechanical parameters to each fault plane element in the composite mesh M3; The fourth building block is used to establish the outer frame of the composite mesh M3, and to apply ground stress load, self-weight load and boundary displacement constraints on the outer frame of the composite mesh M3. Storage unit: Used to combine the synthetic mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load and boundary displacement constraints into a three-dimensional geomechanical model data volume according to the solver used in the numerical simulation, and save it as a three-dimensional geological model data file that can be directly read by the solver.

[0020] The beneficial effects of this invention are as follows: This invention transforms corner point meshes into finite element meshes for mechanical calculations. It leverages the advantages of reservoir geological modeling software for detailed reservoir and fault modeling, while also utilizing the powerful computational capabilities of general-purpose mechanical calculation software to achieve precise simulation of reservoir geomechanical problems. By employing discontinuous meshes to describe the connection between the fault sides, relative slippage of the geological bodies on both sides of the fault can be achieved. This avoids the problem of excessive stiffness at the interrupted plane in the calculation, realizing flexible slippage on both sides of the fault and more accurately characterizing the flexible relative slippage phenomenon on both sides of the fault during injection and production.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart of a three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes according to an embodiment of the present invention is shown.

[0024] Figure 2 The original corner mesh is shown in an embodiment of the present invention for a three-dimensional geomechanical modeling method for complex geological bodies based on a corner mesh.

[0025] Figure 3 A stratigraphic geometry frame, a fault extension frame, and a stratigraphic bedding frame are shown according to an embodiment of the present invention.

[0026] Figure 4 A geometric model of a geological body including faults is shown in a three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to an embodiment of the present invention.

[0027] Figure 5 The geological body grid M1, which is divided according to the geometric model of the geological body, is shown.

[0028] Figure 6 The integrated grid M3 for mechanical calculations of reservoir geological bodies and fault planes is shown.

[0029] Figure 7 The composite mesh M3 with an outer frame is shown.

[0030] Figure 8 The grid, which includes faults, strata, and an outer framework, is shown after parameter assignment. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figure 1 As shown: This invention discloses a three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes. The method includes the following steps: Establish the geometric framework of the strata and the extended framework of the fault planes; Calculate the gradient value at each point within the formation; Using the geometric framework of the strata, the extension framework of the fault planes, and the gradient values ​​as constraints, a geometric model of the geological body of each stratum is established, and the geological body grid M1 is divided. Based on the extended framework of the fault plane and the geological body grid M1, a comprehensive grid M3 for mechanical calculation of reservoir-fault plane is formed; Assign physical and mechanical parameters to each solid element in the composite mesh M3, and assign mechanical parameters to each fault plane element in the composite mesh M3; Establish the outer frame of the composite grid M3, and apply ground stress load, self-weight load and boundary displacement constraint on the outer frame of the composite grid M3. Based on the solver used in the numerical simulation, the composite mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints are combined into a three-dimensional geomechanical model data volume and saved as a three-dimensional geological model data file that can be directly read by the solver.

[0033] This invention transforms corner point meshes into finite element meshes for mechanical calculations. It leverages the advantages of reservoir geological modeling software for detailed reservoir and fault modeling, while also utilizing the powerful computational capabilities of general-purpose mechanical calculation software to achieve precise simulation of reservoir geomechanical problems. By employing discontinuous meshes to describe the connection between the fault sides, relative slippage of the geological bodies on both sides of the fault can be achieved. This avoids the problem of excessive stiffness at the interrupted plane in the calculation, realizing flexible slippage on both sides of the fault and more accurately characterizing the flexible relative slippage phenomenon on both sides of the fault during injection and production.

[0034] The modeling method of the present invention is described in detail below: A method for three-dimensional geomechanical modeling of complex geological bodies based on corner meshes, the method specifically includes the following steps: Step 1: Determine the distribution range of reservoir geological bodies and fault attitude based on the geometric information of corner grids, and establish the geometric framework of strata and the extension framework of fault planes. like Figure 2 and Figure 3 As shown: Figure 2 The original corner mesh of a three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh, according to an embodiment of the present invention, is shown. Figure 2 It can be seen that: mesh x The grid number is 442. y The grid number is 390, the total number of strata is 33, and it contains one major fault. Figure 3 A stratigraphic geometry frame, a fault extension frame, and a stratigraphic bedding frame are shown according to an embodiment of the present invention.

[0035] Preferably, the geometric framework of the strata and the extension framework of the fault plane are extended according to the area under study, and the extension range is 5 times or more of the area under study.

[0036] Step 2: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data, and mechanical experimental data, interpolate and calculate the gradient values ​​at each point within the formation; Specifically, step 2 includes the following steps: Step 201: Establish the physical property parameter distribution field using the physical property parameters contained in the corner grid; Step 202: Verify and correct the parameter distribution field using seismic interpretation data, well logging interpretation data, and mechanical experimental data; Step 203: Select the longitudinal step size and the transverse step size (generally 1 / 100 of the entire computational area), establish a grid, use the physical property parameters and mechanical parameters contained in the corner grid as the interpolation source data, and use the coordinates of the grid points as the interpolation coordinate data. Use the Kriging interpolation method to calculate the physical property parameters and mechanical parameters at each grid point; then, based on the longitudinal and transverse step sizes of the grid, calculate the gradients of the physical property parameters and mechanical parameters, and use the maximum value of the gradient of each parameter as the gradient value of the grid point.

[0037] Step 3: Using the geometric framework of the strata, the extension framework of the fault plane, and the gradient value as constraints, establish the geological body geometric model of each stratum and divide the geological body into grids M1; like Figure 4 and Figure 5 As shown: Figure 4 A geometric model of a geological body including faults is shown in a three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to an embodiment of the present invention. Figure 5 The geological body grid M1, which is divided according to the geometric model of the geological body, is shown.

[0038] Specifically, step 3 includes the following steps: Step 301: Based on the cutting relationship of the fault extension to the strata, obtain the extension framework of the fault plane, divide the stratigraphic framework into regions, and establish the geometric framework of the strata. Step 302: Establish the geological geometric model of each stratum using the geometric framework of the strata and the extended framework of fault planes; Step 303: Set the mesh size range, local refinement factor, and lower limit of the quality factor for the geological body geometric model based on the gradient value; Step 304: Use the Delaunay algorithm to generate a hexahedral mesh for the geological body geometric model, forming the geological body mesh M1.

[0039] Preferably, step 3 further includes: after step 303, performing a mesh quality check and correcting and adjusting cells with quality factors below the lower limit.

[0040] Preferably, step 3 further includes: after step 304, based on the geometric information such as the node coordinates, unit shape and unit size of the corner grid, analyzing the discontinuity of the formation, subdividing the geological body grid M1 at the discontinuity points, and transitioning the tetrahedral or wedge-shaped units to obtain a fine grid of the reservoir geological body. The discontinuity includes formation pinch-out and missing (this step is the preferred option, but it can be omitted in actual application).

[0041] Step 4: Based on the extended framework of the fault plane and the geological body grid M1, the fault plane grid M2 is formed. The fault plane grid M2 and the geological body grid M1 are combined to form the reservoir-fault plane mechanical calculation integrated grid M3. like Figure 6 As shown: Figure 6 The integrated grid M3 for mechanical calculations of reservoir geological bodies and fault planes is shown.

[0042] Specifically, step 4 includes the following steps: Step 401: For each group of fault planes in the extended framework of the fault plane, select the grid nodes of the pre-divided geological body grid M1 on the fault plane. Step 402: Use the Delaunay algorithm to connect the selected mesh nodes into a quadrilateral mesh, and use triangular meshes or quadrilateral meshes at the boundaries; Step 403: For each fault plane, match the quadrilateral meshes on both sides of the fault plane to form a fault plane mesh group, and combine each fault plane mesh group to form a fault plane mesh M2. Step 404: Combine the fault plane grid M2 with the geological body grid M1 to form the geological body-fault plane mechanical calculation integrated grid M3.

[0043] Preferably, step 4 further includes: After step 404, the matching degree of the grids on both sides of the fault plane is detected. If the mutual embedding or separation distance of the grids on both sides exceeds the tolerance, local adjustment is performed.

[0044] Step 5: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data and mechanical experimental data, the interpolation method is used to assign physical property parameters and mechanical parameters to each solid element in the composite grid M3. For each fault plane element in the composite grid M3, the mechanical parameters are assigned based on the structural surface experimental data. Specifically, step 5 includes the following steps: Step 501: Calculate the center point coordinates of each solid element in the composite mesh M3, and find the position of its corresponding corner grid. Step 501: Calculate the center point coordinates of each solid element in the composite mesh M3, and find the position of its corresponding corner grid. Step 502: Based on the physical property parameters of the corner grid, combined with seismic interpretation data and well logging interpretation data, the physical property parameters of each solid element in the composite grid M3 are assigned using the interpolation method. Combined with mechanical experimental data, the mechanical parameters of each solid element in the composite grid M3 are assigned. The physical property parameters include porosity, saturation, and permeability; the mechanical parameters include density, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. Step 503: For each fault plane element in the synthetic mesh M3, assign mechanical parameters based on the structural plane experimental data. The mechanical parameters include the tangential stiffness and normal stiffness of the structural plane.

[0045] Preferably, step 5 further includes: After step 503, a parameter assignment consistency check is performed. The relative deviation between the physical property parameters assigned to each entity element and the physical property parameters based on the corner grid, combined with the parameters obtained from seismic interpretation data and well logging interpretation data, is checked. The relative deviation between the mechanical parameters assigned to each entity element and the mechanical experimental data is also checked. If the deviation exceeds the tolerance, the values ​​are re-interpolated and reassigned.

[0046] Step 6: Establish the outer frame of the composite grid M3. Based on the measurement data of regional geostress and the burial depth of the geological body, apply geostress load, self-weight load and boundary displacement constraint to the outer frame of the composite grid M3. like Figure 7 As shown, Figure 7 The composite mesh M3, which forms the outer frame, is shown. (See figure.) Figure 8 As shown, Figure 8 The grid, which includes faults, strata, and an outer framework, is shown after parameter assignment.

[0047] Specifically, step 6 includes the following steps: Step 601: Select the outer surface, top surface, and bottom surface of mesh M3, establish the outer frame of mesh M3 composed of the outer surface, top surface, and bottom surface, and calculate the inner normal direction of the outer surface. Step 602: Decompose the measured ground stress along the inner normal and tangent directions of each outer surface and apply it to each outer surface; Step 603: Calculate the self-weight of the overlying rock layer based on the burial depth of the geological body, and apply the self-weight of the overlying rock layer as a self-weight load (overlying load) to the top surface; Step 604: Apply boundary displacement constraints to the bottom surface.

[0048] Preferably, step 6 further includes: After step 604, according to the calculation requirements, other loads are applied to the outer frame of grid M3, including fluid pressure and injection-production periodic stress.

[0049] Step 7: Based on the solver used in the numerical simulation, combine the integrated mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints into a three-dimensional geomechanical model data volume and save it as a three-dimensional geological model data file that can be directly read by the solver.

[0050] This invention also discloses a three-dimensional geomechanical modeling system for complex geological bodies with faults based on corner grids, comprising: First building block: used to establish the geometric framework of the strata and the extended framework of the fault plane; Calculation unit: Used to calculate the gradient value at various points within the formation; The second building unit is used to establish the geological body geometric model of each stratum and divide the geological body into grids M1, constrained by the geometric framework of the strata, the extension framework of the fault plane, and the gradient value. The third building unit is used to form a comprehensive grid M3 for mechanical calculation of reservoir geological bodies and fault planes based on the extended framework of the fault plane and the geological body grid M1. Assignment Unit: Used to assign physical and mechanical parameters to each solid element in the composite mesh M3, and to assign mechanical parameters to each fault plane element in the composite mesh M3; The fourth building block is used to establish the outer frame of the composite mesh M3, and to apply ground stress load, self-weight load and boundary displacement constraints on the outer frame of the composite mesh M3. Storage unit: Used to combine the synthetic mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load and boundary displacement constraints into a three-dimensional geomechanical model data volume according to the solver used in the numerical simulation, and save it as a three-dimensional geological model data file that can be directly read by the solver.

[0051] The functions and implementation methods of each unit in the three-dimensional geomechanical modeling system for complex geological bodies with faults based on corner grids of the present invention correspond to the functions and implementation methods of each step in the three-dimensional geomechanical modeling method for complex geological bodies with faults based on corner grids of the present invention, therefore, they will not be repeated here.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes, characterized in that, The method includes the following steps: Establish the geometric framework of the strata and the extended framework of the fault planes; Calculate the gradient value at each point within the formation; Using the geometric framework of the strata, the extension framework of the fault planes, and the gradient values ​​as constraints, a geometric model of the geological body of each stratum is established, and the geological body grid M1 is divided. Based on the extended framework of the fault plane and the geological body grid M1, a comprehensive grid M3 containing reservoir geological body-fault plane mechanical calculations is formed. Assign physical and mechanical parameters to each solid element in the composite mesh M3, and assign mechanical parameters to each fault plane element in the composite mesh M3; Establish the outer frame of the composite grid M3, and apply ground stress load, self-weight load and boundary displacement constraint on the outer frame of the composite grid M3. Based on the solver used in the numerical simulation, the composite mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints are combined into a three-dimensional geomechanical model data volume and saved as a three-dimensional geological model data file that can be directly read by the solver; the method specifically includes the following steps: Step 1: Determine the distribution range of reservoir geological bodies and fault attitude based on the geometric information of corner grids, and establish the geometric framework of strata and the extension framework of fault planes. Step 2: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data, and mechanical experimental data, interpolate and calculate the gradient values ​​at each point within the formation; Step 3: Using the geometric framework of the strata, the extension framework of the fault plane, and the gradient value as constraints, establish the geological body geometric model of each stratum and divide the geological body into grids M1; Step 4: Based on the extended framework of the fault plane and the geological body grid M1, the fault plane grid M2 is formed. The fault plane grid M2 and the geological body grid M1 are combined to form the reservoir-fault plane mechanical calculation integrated grid M3. Step 4 includes the following steps: Step 401: For each group of fault planes in the extended framework of the fault plane, select the grid nodes of the pre-divided geological body grid M1 on the fault plane. Step 402: Use the Delaunay algorithm to connect the selected mesh nodes into a quadrilateral mesh, and use triangular meshes or quadrilateral meshes at the boundaries; Step 403: For each fault plane, match the quadrilateral meshes on both sides of the fault plane to form a fault plane mesh group, and combine each fault plane mesh group to form a fault plane mesh M2. Step 404: Combine the fault plane grid M2 with the geological body grid M1 to form the geological body-fault plane mechanical calculation integrated grid M3; Step 5: Based on the physical property parameters of the corner grid, combined with seismic interpretation data, well logging interpretation data and mechanical experimental data, the interpolation method is used to assign physical property parameters and mechanical parameters to each solid element in the composite grid M3. For each fault plane element in the composite grid M3, the mechanical parameters are assigned based on the structural surface experimental data. Step 5 includes the following steps: Step 501: Calculate the center point coordinates of each solid element in the composite mesh M3, and find the position of its corresponding corner grid. Step 502: Based on the physical property parameters of the corner grid, combined with seismic interpretation data and well logging interpretation data, the physical property parameters of each solid element in the composite grid M3 are assigned using interpolation. Combined with mechanical experimental data, the mechanical parameters of each solid element in the composite grid M3 are assigned. The physical property parameters include porosity, saturation, and permeability; the mechanical parameters include density, elastic modulus, Poisson's ratio, cohesion, and internal friction angle. Step 503: For each fault plane element in the synthetic mesh M3, assign mechanical parameters based on the structural plane experimental data; where the mechanical parameters include the tangential stiffness and normal stiffness of the structural plane; Step 6: Establish the outer frame of the composite grid M3. Based on the measurement data of regional geostress and the burial depth of the geological body, apply geostress load, self-weight load and boundary displacement constraint to the outer frame of the composite grid M3. Step 7: Based on the solver used in the numerical simulation, combine the integrated mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load, and boundary displacement constraints into a three-dimensional geomechanical model data volume and save it as a three-dimensional geological model data file that can be directly read by the solver.

2. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Also includes: After step 1, the geometric framework of the strata and the extension framework of the fault plane are extended according to the area under study, with the extension range being 5 times or more the area under study.

3. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Step 2 includes the following steps: Step 201: Establish the physical property parameter distribution field using the physical property parameters contained in the corner grid; Step 202: Verify and correct the parameter distribution field using seismic interpretation data, well logging interpretation data, and mechanical experimental data; Step 203: Select the longitudinal and transverse step sizes, establish a grid, use the physical and mechanical parameters contained in the corner grid as the interpolation source data, and use the coordinates of the grid points as the interpolation coordinate data. Use the Kriging interpolation method to calculate the physical and mechanical parameters at each grid point. Then, based on the longitudinal and transverse step sizes of the grid, calculate the gradients of the physical and mechanical parameters, and use the maximum value of the gradient of each parameter as the gradient value of the grid point.

4. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Step 3 includes the following steps: Step 301: Based on the cutting relationship of the fault extension to the strata, obtain the extension framework of the fault plane, divide the stratigraphic framework into regions, and establish the geometric framework of the strata. Step 302: Establish the geological geometric model of each stratum using the geometric framework of the strata and the extended framework of fault planes; Step 303: Set the mesh size range, local refinement factor, and lower limit of the quality factor for the geological body geometric model based on the gradient value; Step 304: Use the Delaunay algorithm to generate a hexahedral mesh for the geological body geometric model, forming the geological body mesh M1.

5. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 4, characterized in that, Step 3 also includes: After step 303, a mesh quality check is performed, and cells with quality factors below the lower limit are corrected and adjusted.

6. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 4, characterized in that, Step 3 also includes: After step 304, based on the geometric information of the corner grid, the discontinuity of the strata is analyzed. At the discontinuity points, the geological body grid M1 is subdivided, and the tetrahedral or wedge-shaped units are transitioned to obtain a fine grid of the reservoir geological body.

7. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Step 4 also includes: After step 404, the matching degree of the grids on both sides of the fault plane is detected. If the mutual embedding or separation distance of the grids on both sides exceeds the tolerance, local adjustment is performed.

8. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Step 5 further includes: After step 503, a parameter assignment consistency check is performed. The relative deviation between the physical property parameters assigned to each entity element and the physical property parameters based on the corner grid, combined with the parameters obtained from seismic interpretation data and well logging interpretation data, is checked. The relative deviation between the mechanical parameters assigned to each entity element and the mechanical experimental data is also checked. If the deviation exceeds the tolerance, the values ​​are re-interpolated and reassigned.

9. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 1, characterized in that, Step 6 includes the following steps: Step 601: Select the outer surface, top surface, and bottom surface of mesh M3, establish the outer frame of mesh M3 composed of the outer surface, top surface, and bottom surface, and calculate the inner normal direction of the outer surface. Step 602: Decompose the measured ground stress along the inner normal and tangent directions of each outer surface and apply it to each outer surface; Step 603: Calculate the self-weight of the overlying rock layer based on the burial depth of the geological body, and apply the self-weight of the overlying rock layer as a self-weight load to the top surface; Step 604: Apply boundary displacement constraints to the bottom surface.

10. The three-dimensional geomechanical modeling method for complex geological bodies based on corner mesh according to claim 9, characterized in that, Step 6 also includes: After step 604, according to the calculation requirements, other loads are applied to the outer frame of grid M3, including fluid pressure and injection-production periodic stress.

11. A three-dimensional geomechanical modeling system for complex geological bodies containing faults based on corner meshes, used for executing the three-dimensional geomechanical modeling method for complex geological bodies based on corner meshes according to any one of claims 1-10, characterized in that, include: First building block: used to establish the geometric framework of the strata and the extended framework of the fault plane; Calculation unit: Used to calculate the gradient value at various points within the formation; The second building unit is used to establish the geological body geometric model of each stratum and divide the geological body into grids M1, constrained by the geometric framework of the strata, the extension framework of the fault plane, and the gradient value. The third building unit is used to form a comprehensive grid M3 for mechanical calculation of reservoir geological bodies and fault planes based on the extended framework of the fault plane and the geological body grid M1. Assignment Unit: Used to assign physical and mechanical parameters to each solid element in the composite mesh M3, and to assign mechanical parameters to each fault plane element in the composite mesh M3; The fourth building block is used to establish the outer frame of the composite mesh M3, and to apply ground stress load, self-weight load and boundary displacement constraints on the outer frame of the composite mesh M3. Storage unit: Used to combine the synthetic mesh M3, physical parameters, mechanical parameters, geostress load, self-weight load and boundary displacement constraints into a three-dimensional geomechanical model data volume according to the solver used in the numerical simulation, and save it as a three-dimensional geological model data file that can be directly read by the solver.

Images