Fault contact boundary processing method and device in structure recovery process

Abstract

The embodiment of the invention provides a fault contact boundary processing method and device in a structure recovery process, and relates to the technical field of structure geology. The method comprises the following steps: acquiring a tetrahedral grid structure which corresponds to geological data and conforms to geomechanical and geometric characteristics; determining an initial stratum of structural recovery simulation, and generating a spring vector of each mass point and an adjacent mass point for each mass point in the initial stratum; the spring vector is used for representing the mechanical relationship between the mass points; fault top line node relation setting is carried out according to fault information stored in the fault binary tree management system; under the constraint of the fault top line node relation, establishing a mass point corresponding relation between a main disc and an auxiliary disc in the fault plane; and under the limitation of the mass point corresponding relation, the positions of the mass points are updated based on the spring vectors, and primary structure recovery simulation of the initial stratum is formed. According to the method, an algorithm principle, technical guarantee and tool guarantee are provided for industrial production application such as subsequent crack modeling.

Description

Technical Field

[0001] This application relates to the technical field of structural geology, and specifically relates to a method for processing fault contact boundaries during structural restoration, a device for processing fault contact boundaries during structural restoration, an electronic device, and a corresponding storage medium. Background Technique

[0002] The study of geological structure restoration refers to performing de-faulting and de-folding operations on a geological model that describes the current underground geological state. Through the restored geological model, characteristics such as the geometric shape of the ancient geological landform can be reproduced. The restoration method based on geomechanics is the current mainstream method. Since it is difficult to reproduce the true form of crustal movement at the reservoir level or even the basin level in laboratory-scale physical simulation experiments, the numerical simulation method has become the most important technology and tool in the study of geological structure restoration.

[0003] Traditional geological structure restoration methods often rely on two basic assumptions, namely the geometric deformation assumption and the Newtonian kinematics assumption. After more than a century of precipitation and accumulation, these methods have made great progress in aspects such as cross-section restoration, stratigraphic horizon restoration, and three-dimensional model restoration. Among them, cross-section restoration is one of the earliest developed structure restoration methods, and some scholars tend to call it the "balancing method". Its core idea is to simplify the result of stratum deformation in a compressive environment into the change of the aspect ratio of area or volume conservation. The restoration of stratigraphic horizons aims to restore the stratigraphic horizons with faults and folds to the horizontal initial deposition state. The advantage of this method is that the displacement caused by flattening the current stratigraphic horizons can be roughly inversely estimated to obtain the force that generates faults and folds. Therefore, this method is actually a preliminary exploration of the numerical simulation research method of in-situ stress. The overall restoration of three-dimensional strata has always been the focus and difficulty of structure restoration research. So far, all published three-dimensional restoration methods are based on the assumption of minimum deformation and default that the strata before and after deformation comply with the principle of volume conservation. Since the 21st century, with the continuous increase in computing power, the structure restoration method based on geomechanics simulation has gradually developed. Different from the aforementioned methods, the key to the structure restoration method based on in-situ stress simulation lies in the setting of boundary conditions. Deformation details such as fracture position, shape, and size are determined by the forward process of rock mechanics, rather than being artificially set. The advantage of this method is that its simulation process is "from ancient to modern", so whether the boundary adjustment setting is correct can be judged by whether its result is similar to the current geological structure pattern. Researchers can restore a complete and realistic geological evolution process through the simulation results.

[0004] Although certain progress has been made in the study of geological structure restoration, and it has shown irreplaceability in case studies such as terrain deformation prediction, fracture and fluid prediction, due to the extremely complex underground geological conditions, the current geological structure form is often the comprehensive result of multiple stages of tectonic movements and the action of the in-situ stress field. There are still the following problems in the current geological structure restoration methods:

[0005] (1) The assumptions such as volume conservation adopted by traditional geological structure restoration methods are often extreme simplifications of the current underground geological situation. Therefore, only qualitative and semi-quantitative formation restoration results can be obtained for the formations restored by traditional methods, and details are easily missing. Moreover, the research idea of traditional structure restoration methods is to reverse infer the ancient structure form from the current geological structure form. However, the ancient structure form itself is unknown. Therefore, such methods lack quantitative evaluation criteria.

[0006] (2) Traditional methods often have their own drawbacks in application scenarios. For example, the cross-section restoration method confines the formation deformation to a two-dimensional cross-section plane and assumes that the deformation in the third dimension can be ignored, resulting in difficulty in expanding this method to three-dimensional structure restoration research. Especially in areas with strike-slip faults, this method will not be applicable; the formation bedding restoration method can achieve three-dimensional structure restoration effects by superimposing formation bedding at multiple depths. However, since the deformation restoration in its three-dimensional space is not carried out as a whole, the academic community often classifies the three-dimensional structure form results established only based on bedding restoration as "2.5"-dimensional models; the three-dimensional formation restoration method is limited by its complex operation process and strict assumption conditions. Currently, it can only provide two deformation modes, namely minimum deformation and flexural slip, and its applicable scenarios are also limited.

[0007] (3) Although in-situ stress simulation means can achieve structure restoration in three-dimensional space through the mechanical response simulation of rocks and formations, the boundary conditions set at the beginning of the simulation are often not unique and need to be artificially optimized, which will lead to certain subjectivity in the simulation results.

[0008] (4) Since the structure restoration method based on in-situ stress simulation means is monopolized by commercial software, the most core fault contact processing algorithm part in the structure restoration process has been encrypted and has formed a technical barrier, increasing the difficulty of three-dimensional structure restoration research based on geomechanics in China. Summary of the Invention

[0009] The purpose of the embodiments of this application is to provide a method and device for processing fault contact boundaries during structure restoration, providing an algorithm principle, technology and tool guarantee for subsequent industrial production applications such as fracture modeling, so as to solve at least some of the problems in the background technology.

[0010] To achieve the above object, a method for processing the fault contact boundary during the structural restoration process is provided in this application. The method includes: obtaining a tetrahedral mesh structure corresponding to geological data that conforms to geomechanical and geometric characteristics; determining the starting formation of the structural restoration simulation, and generating spring vectors for each particle in the starting formation with its adjacent particles; the spring vectors are used to characterize the mechanical relationship between particles; according to the fault information stored in the fault binary tree management system, setting the node relationship of the fault top line; under the constraint of the node relationship of the fault top line, establishing the particle correspondence between the main disk and the auxiliary disk within the fault plane; under the limitation of the particle correspondence, updating the positions of each particle based on the spring vectors to form a primary structural restoration simulation of the starting formation.

[0011] Preferably, obtaining a tetrahedral mesh structure corresponding to geological data that conforms to geomechanical and geometric characteristics includes: using 3D seismic data as the data basis, performing 3D geological structure interpretation within the target formation with well-seismic calibration as the constraint, and providing complete boundary conditions through the superposition of faults and horizons; analyzing and determining the fault stages and cross-cutting sequence information based on the contact relationships between faults and between faults and horizons, and managing fault data through a binary tree management system; generating a tetrahedral mesh structure that conforms to geomechanical and geometric characteristics using the fault contact boundary information.

[0012] Preferably, generating spring vectors for each particle in the starting formation with its adjacent particles includes: within the starting formation, generating spring vectors for each particle with its adjacent particles along the boundary of the tetrahedral mesh; the spring vectors within the formation are divided into body springs, fault springs, and top surface springs according to the types of the two end particles.

[0013] Preferably, setting the node relationship of the fault top line according to the fault information stored in the fault binary tree management system includes: determining the fault name within the starting formation and retrieving the fault binary tree management system; sequentially determining the main disk and the auxiliary disk on both sides of the fault according to the retrieval result; setting the node relationship between the intersection plane top line and the main and auxiliary disk top lines for the faults intersecting with the starting formation.

[0014] Preferably, establishing the particle correspondence between the main disk and the auxiliary disk within the fault plane under the constraint of the node relationship of the fault top line includes: after setting the node relationship of the fault top line, sequentially setting the particle pairs between the main disk particles and the auxiliary disk particles within the fault plane according to the length and direction of the projection vector; the main disk particle and the auxiliary disk particle in the particle pair have a corresponding relationship; determining the force on a certain particle based on the spring vector of the certain particle and the corresponding particle based on the particle pair.

[0015] Preferably, under the limitation of the corresponding relationship of the mass points, updating the positions of each mass point based on the spring vector to form a primary structural restoration simulation of the starting formation, including: flattening the top surface, and obtaining the stress and strain conditions between the mass points by the finite element numerical simulation method under the constraint of the spring vector; solving the displacement of each mass point through Hooke's law or neo-Hooke's law; moving each mass point in the three-dimensional model along the total stress direction according to the displacement calculation result to form a primary structural restoration simulation of the starting formation; and updating the surface and body grid states, and re-analyzing the fault contact relationship according to the structural restoration result to update the fault binary tree management system.

[0016] Preferably, the method further includes: if there are multiple stages of fault combinations in the starting formation, selecting the fault groups in sequence according to the primary and secondary relationships for iterative simulation.

[0017] Preferably, after completing the structural restoration simulation of the starting formation, the method further includes: stripping the starting formation, and sequentially selecting the overlying formations of the starting formation for structural restoration simulation.

[0018] In the present application, there is also provided a device for processing the fault contact boundary during the structural restoration process. The device includes: a grid construction module for obtaining a tetrahedral grid structure corresponding to geological data that conforms to the characteristics of geomechanics and geometry; a vector analysis module for determining the starting formation of the structural restoration simulation and generating a spring vector between each mass point in the starting formation and its adjacent mass points; the spring vector is used to characterize the mechanical relationship between the mass points; a relationship setting module for setting the relationship of the top line nodes of the fault according to the fault information stored in the fault binary tree management system; a corresponding relationship module for establishing the corresponding relationship between the main plate and the auxiliary plate within the fault plane under the constraint of the relationship of the top line nodes of the fault; and a result generation module for updating the positions of each mass point based on the spring vector under the limitation of the corresponding relationship of the mass points to form a primary structural restoration simulation of the starting formation.

[0019] In the present application, there is also provided an electronic device, including: at least one processor; a memory connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the at least one processor realizes the steps of the method for processing the fault contact boundary during the structural restoration process described above by executing the instructions stored in the memory.

[0020] In the present application, there is also provided a machine-readable storage medium, on which instructions are stored, and when the instructions are executed by a processor, the processor is configured to execute the steps of the method for processing the fault contact boundary during the structural restoration process described above.

[0021] In this application, a computer program product is also provided, including a computer program which, when executed by a processor, implements the steps of the method for processing the fault contact boundary in the aforementioned structure restoration process.

[0022] The above technical solution has the following beneficial effects:

[0023] (1) Traditional geological structure restoration methods often conduct flattening and back-stripping studies of strata based on qualitative understandings such as geological models, and the results are difficult to quantitatively evaluate. This application proposes and applies the spring method to handle the mechanical connection relationships of each particle in the stratum. After solving through the finite element method, the stress field results in the stratum after structure restoration can be obtained. By comparing with real data such as the fracture density, aperture, dip, and strike observed today, the structure restoration results can be quantitatively evaluated.

[0024] (2) Traditional three-dimensional geological structure restoration methods have problems such as huge computational amounts and excessive computer times. The spring method provided in this application adopts a point-to-point processing means, which can effectively transform three-dimensional space calculations into one-dimensional calculations around a single particle, greatly improving the computational efficiency while ensuring the accuracy of three-dimensional space calculations.

[0025] (3) By applying the spring method provided in this application to form springs between each particle in the stratum, the springs can continuously exist and continuously provide mechanical connection relationships before the stratum is stripped, enabling researchers to independently determine the number of iterations of the stratum structure restoration according to the structure restoration results combined with information such as geological cognition and fault structure.

[0026] Other features and advantages of the embodiments of this application will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 1 Schematically shows a schematic diagram of the steps of the method for processing the fault contact boundary in the structure restoration process according to an embodiment of this application;

[0029] Figure 2 It is a schematic diagram of the technical process for successively conducting structure restoration research on each stratum from top to bottom in an embodiment of this application;

[0030] Figure 3 It is a display effect diagram of the input fault boundary and the fault management system based on a binary tree in an embodiment of this application;

[0031] Figure 4Schematic diagram of a tetrahedral mesh generated for a research target layer segment under the constraint of fault boundary information in the implementation mode of this application;

[0032] Figure 5 Schematic diagram of the process of setting the relationship of the top line nodes of a single fault in the implementation mode of this application;

[0033] Figure 6 Schematic diagram of the process of setting the corresponding relationship of mass points within the fault plane after setting the relationship of the top line nodes in the implementation mode of this application;

[0034] Figure 7 Schematic diagram of the action process of the mechanical conduction mechanism of the spring vector in the implementation mode of this application;

[0035] Figure 8 Schematic diagram of the structural restoration process for formation Lc in the implementation mode of this application;

[0036] Figure 9 Schematic diagram of the structural restoration results for multiple formations sequentially in the implementation mode of this application;

[0037] Figure 10 Schematic diagram of the calculation results of the in-situ stress field obtained during the structural restoration process in the implementation mode of this application;

[0038] Figure 11 Schematically shows the structural diagram of the fault contact boundary processing device during the structural restoration process according to the implementation mode of this application. Detailed implementation mode

[0039] The following will describe in detail the specific implementation mode of the embodiments of this application with reference to the accompanying drawings. It should be understood that the specific implementation mode described here is only used to illustrate and explain the embodiments of this application, and is not used to limit the embodiments of this application.

[0040] Figure 1 Schematically shows the step diagram of the fault contact boundary processing method during the structural restoration process according to the implementation mode of this application. As Figure 1 shown, a fault contact boundary processing method during a structural restoration process includes:

[0041] S01. Obtain a tetrahedral mesh structure that conforms to geomechanical and geometric characteristics corresponding to geological data;

[0042] S02. Determine the starting formation for the structural restoration simulation, and generate spring vectors for each mass point within the starting formation and its adjacent mass points; the spring vectors are used to characterize the mechanical relationship between the mass points;

[0043] S03. Set the relationship of the top line nodes of the fault according to the fault information stored in the fault binary tree management system;

[0044] S04. Under the constraint of the node relationship of the fault top line, establish the particle correspondence between the main plate and the auxiliary plate within the fault plane;

[0045] S05. Under the limitation of the particle correspondence, update the positions of each particle based on the spring vector to form the first tectonic restoration simulation of the starting formation.

[0046] In the above embodiments, the displacement can be calculated from the overall contact situation of the two plates of the fault plane, and the processing selection and deformation process of the fault branch can be defined according to different levels of fault branches. Finally, the functions of de - folding and de - faulting in three - dimensional space are realized layer by layer according to the formation sequence, and the geological structure restoration research is completed.

[0047] Figure 2 This is a schematic diagram of the technical process for successively conducting tectonic restoration research on each formation from top to bottom in the embodiments of the present application. It includes steps such as geological structure interpretation of the target formation section in the study area, setting boundary conditions, etc., until the formation Lc is peeled off and the underlying formation (formation Lc + 1) is selected.

[0048] In some embodiments of the present application, obtaining a tetrahedral mesh structure that conforms to the characteristics of geomechanics and geometry for geological data includes: using three - dimensional seismic data as the data basis, performing three - dimensional geological structure interpretation within the target formation with well - seismic calibration as the constraint, and providing complete boundary conditions through the superposition of faults and formation surfaces; analyzing and determining fault stages and cross - cutting sequence information based on the contact relationships between faults and between faults and formation surfaces, and managing fault data through a binary tree management system; generating a tetrahedral mesh structure that conforms to the characteristics of geomechanics and geometry using the fault contact boundary information. The specific tetrahedral mesh structure is constructed through the following steps.

[0049] S101: Geological structure interpretation, setting boundary condition data. Using three - dimensional seismic data as the data basis, performing fine three - dimensional geological structure interpretation within the target formation with well - seismic calibration as the constraint, including formation surface interpretation results, fault interpretation results, etc. Through the superposition of faults and formation surfaces, complete boundary conditions are provided for the fault contact boundary processing method. In this step, the fault contact boundary refers to the contact boundaries between faults of different levels and between faults and formation surfaces. Correctly setting boundary condition data can promote the rapid matching of nodes within the same formation surface.

[0050] S102: Tectonic data analysis, obtaining fault boundary information. Analyze and determine information such as fault stages and cross - cutting sequences based on the contact relationships between faults and between faults and formation surfaces, and manage fault data through a binary tree management system. Figure 3 This is the display effect diagram of the fault boundary input in the embodiments of the present application and the fault management system based on a binary tree; asFigure 3 As shown in (a) of , this fault contains three faults, namely F1, F2, and F3. Through the analysis of fault boundary information, information such as the intersection relationship and the main - auxiliary relationship between faults can be stored and managed by the binary - tree system reservoir. The auxiliary fault is the leaf node of the main fault, and the obtained fault binary tree is as shown in (b) of . In this step, the data management system based on the binary - tree algorithm first connects the truncated faults to the truncating faults in the form of child nodes and comprehensively manages the fault data through a multi - layer tree structure.

[0051] S103: Generate a tetrahedral mesh structure based on fault boundary information. Comprehensively utilize fault contact boundary information, such as the intersection relationship between faults and the intersection relationship between faults and horizons, to generate a tetrahedral mesh structure that conforms to the geomechanical and geometric characteristics for a study area with complex structures. In this step, the generated tetrahedral mesh structure needs to conform to the geomechanical and geometric characteristics. For example, in a relatively large area with homogeneous and gently varying anisotropy, tetrahedral meshes with larger monomer volumes are generated, while in positions with strong inhomogeneity, tetrahedral meshes with smaller monomer volumes are generated. Figure 4 This is a schematic diagram of the tetrahedral mesh generated for the target layer segment under the constraint of fault boundary information in the embodiment of the present application. As Figure 4 shown, it shows the tetrahedral meshes under faults 14, 15, and 16.

[0052] In some embodiments of the present application, generating spring vectors for each particle in the starting formation and its adjacent particles includes: within the starting formation, generating spring vectors for each particle along the boundary of the tetrahedral mesh to its adjacent particles; the spring vectors within the layer are divided into body springs, fault springs, and top - surface springs according to the types of the two - end particles. Specifically, first, determine that the starting formation is the formation currently undergoing tectonic restoration, denoted as Lc (Current Layer). Within this starting formation, generate spring vectors for each particle along the boundary of the tetrahedral mesh to its adjacent particles, and these spring vectors can accurately represent the mechanical relationship between particles. Among them, the spring vectors within the layer are divided into three spring types according to the types of the two - end particles: body springs (Tet Spring) connecting the tetrahedral model, fault springs (Fault Spring) connecting the main and auxiliary fault blocks, and top - surface springs (Attachment Spring) fixing the top surface.

[0053] In some embodiments of the present application, according to the fault information stored in the fault binary tree management system, the setting of the fault top line node relationship is carried out, including: determining the fault name in the starting formation and retrieving the fault binary tree management system; successively determining the main plate and the auxiliary plate on both sides of the fault according to the retrieval result; setting the node relationship between the intersection plane top line and the main and auxiliary plate top lines for the fault intersecting with the starting formation. Specifically, it includes: determining the fault name in formation Lc and retrieving the binary tree management system, and successively determining the main and auxiliary plates on both sides of the fault according to the retrieval result; setting the node relationship between the intersection plane top line and the main and auxiliary plate top lines for the fault intersecting with formation Lc. The main and auxiliary plates refer to the two sides of the formation disconnected by the fault. Generally, the side with activity is set as the auxiliary plate. In the binary tree structure, the main and auxiliary plates are expressed as: the parent node is the main plate and the child node is the auxiliary plate. The intersection plane of the fault and the formation is a positive parallelogram plane approximately the same as the fault plane, and its top line is a straight line. Generally, its height is set as the maximum value of the structural height in formation Lc. The main and auxiliary top lines of the fault are irregular line types. When setting the node relationship, first flatten the main and auxiliary top lines to the intersection plane top line, and mark the relevant relationship between the nodes through the node positions in the main and auxiliary top lines. Figure 5 This is a schematic diagram of the process of setting the top line node relationship of a single fault in the embodiment of the present application. As Figure 5 shown, use P s to represent any node in the top line of the auxiliary plate of a certain fault, and use P m to represent the node on the main plate top line corresponding to point P s . In the present application, it is set that point P m can be located on the boundary of the tetrahedral mesh or at the node of the tetrahedral mesh. When processing the top line nodes, the two-end marking method is used to represent the local top line. The coordinates of P m are represented as the weighted sum of the two end nodes of the local top line:

[0054]

[0055] The vector V between point P m and point P s is the projection vector, which can be represented in the same coordinate system as:

[0056]

[0057] where n is the serial number of the two end points of the local top line.

[0058] In some embodiments of the present application, under the constraint of the fault top-line node relationship, a corresponding relationship between the mass points of the main plate and the auxiliary plate within the fault plane is established, including: after setting the fault top-line node relationship, setting the pairs of mass points of the main plate and the auxiliary plate within the fault plane in sequence according to the length and direction of the projection vector; there is a corresponding relationship between the mass point of the main plate and the mass point of the auxiliary plate in the pair; determining the force on a certain mass point based on the spring vector of the certain mass point and the corresponding mass point of the pair. Specifically, with the fault top-line node relationship as the constraint, a correlation between the points on the fault main plate section and the mass points on the fault auxiliary plate section is established to form pairs of mass points connecting the two fault plates. The establishment of the main and auxiliary plate mass point pairs plays a decisive role in the result of the structural restoration simulation. After setting the fault top-line node relationship, pairs of mass points of the main plate and the auxiliary plate within the fault plane are set in sequence according to the length and direction of the projection vector V. Figure 6 FIG. is a schematic diagram of the setting process of the corresponding relationship between the mass points within the fault plane after setting the top-line node relationship in the embodiment of the present application. As Figure 6 shown, in this step, the fault planes of the two plates are approximately two-dimensional extensions of the fault top-lines of the two plates along the fault dip direction. The local fault plane is analogized to the local top-line and marked by three mass points of a tetrahedron. The mass point P m on the fault main plate and the projection vector between the pairs of mass points are similar to the top-line node processing process, and only n needs to be extended to n ∈ [1; 2; 3].

[0059] Set that at this time, each mass point in the three-dimensional space covered by the formation L c has reached a mechanical equilibrium state through the combined mechanical action of the spring vectors connected to it. Therefore, the mechanical relationship in its three-dimensional space can be simplified to a one-dimensional spring connection relationship. Use P0 to represent a certain mass point within the layer, and P i to represent the mass point connected to P0. The spring vector between the mass points can transmit the force on the mass point P0 to the adjacent node P i . The magnitude of the force on each mass point is the sum of the forces transmitted by its adjacent mass points, which can be expressed as:

[0060]

[0061] where, represents the spring vector connecting the pair of mass points P0 - P i ; k 0，i represents the corresponding spring stiffness; represents the natural length of the spring in the relaxed state; represents the length of the spring when it is under force.

[0062] In some embodiments of the present application, under the limitation of the corresponding relationship of the mass points, based on the spring vector, the positions of each mass point are updated to form a primary structural restoration simulation of the starting formation, including: flattening the top surface, and obtaining the stress and strain conditions between the mass points by the finite element numerical simulation method under the constraint of the spring vector; solving the displacement of each mass point through Hooke's law or Neo-Hooke's law; moving each mass point in the three-dimensional model along the total stress direction according to the calculation result of the displacement to form a primary structural restoration simulation of the starting formation; and updating the surface and volume mesh state, and re-analyzing the fault contact relationship according to the structural restoration result to update the fault binary tree management system.

[0063] Specifically, the Total Lagrangian formulation is adopted as the solution target of the finite element method:

[0064]

[0065] Where P is the nominal stress, ρ0 is the density of the formation rock before restoration, is the mathematical divergence in the unrecovered space, b is the body stress, is the acceleration vector. The above formula is the strong form of the Total Lagrangian formulation. The finite element method completes the local solution by equivalently converting it into the weak form of each "element". The solution object after conversion can be expressed as:

[0066]

[0067] Where M is the mass matrix; F is the force on the mass point, which can be calculated by the spring method in step S5; is the external force; C is the damping matrix; is the velocity. According to the static assumption of the finite element method, the above formula is independent of the time state, so it can be further simplified to:

[0068]

[0069] Combined with Hooke's law, when the formation undergoes small to medium-scale deformation, the stress-strain relationship is linear. Therefore, the displacement of each mass point in the formation can be obtained by the following formula:

[0070]

[0071] Where K is the stiffness matrix.

[0072] In this step, the Neo-Hookean law is used to solve the stress-strain relationship of the formation when it fractures or undergoes large-scale deformation. The stress-strain relationship of the formation will change from a linear relationship to a non-linear one, and Hooke's law will no longer apply. In this embodiment, a hyperelastic medium is introduced to simulate the formation state around the fault and in the area of large-scale deformation. The corresponding hyperelastic model selects the Neo-Hookean law. Under this condition, the internal stress of the formation generated is the second Piola-Kirchhoff stress, and its potential energy expression is:

[0073]

[0074] where C is the right Cauchy-Green tensor; I are the invariants of the Cauchy-Green tensor C, including three components I1, I2, and I3:

[0075] I1(C) = trace(C); I3(C) = det(C)

[0076] And ψ represents the potential energy, which can be eliminated by introducing the deformation gradient G. After elimination, the potential energy expression is transformed into:

[0077] S = λln(J)C -1 +μ(I - C -1 );

[0078] J = det(G) = det(G T );

[0079] The corresponding stress-strain relationship can be approximately expressed as:

[0080] F = S·G T

[0081] It cannot be directly solved in the non-linear stress-strain relationship Therefore, the displacement u of each particle in the formation can be obtained by optimizing the residual equation:

[0082]

[0083] In this step, the finite element numerical method includes two solution algorithms, namely the Newton-Raphson method and the L-BGFS Quasi-Newton method. Both of these methods can be used to iteratively solve the residual equation f(u) = 0. At the (t + 1)-th iteration step, the Taylor series expansion of f can be expressed as:

[0084]

[0085] wherein

[0086]

[0087] the stiffness matrix K int is the tangential stiffness matrix; K ext is the load stiffness matrix. According to the principle of Newton's iteration method, the iteration starts from time step t = 0, and at each subsequent time step t+1, the abscissa of the intersection of the tangent line of f at the abscissa u t is calculated and set as u t+1 for the next time step iteration calculation until u t+1 -u t is less than the preset threshold, at which point the iteration ends, and the resulting displacement is:

[0088]

[0089] To reduce the number of iteration steps for quick solution, the correct setting of u0 is crucial. This application combines the advantages of linear solution and sets the linear solution result as u0, that is:

[0090]

[0091] When using Newton's iteration method for solution, a second-order Taylor series expansion is required at the stationary point, and the second-order partial derivative of f(u) is calculated. For a complex mesh system, the second-order partial derivative is a Hessian matrix of size T×T. When the number of iteration steps reaches a certain amount, the inversion of this Hessian matrix will be very complex. This application introduces the L-BGFS quasi-Newton iteration method to solve this problem. The L-BGFS quasi-Newton iteration method first uses an iteration matrix D t to replace the Hessian matrix, and its iteration expression is:

[0092]

[0093] wherein, D0 is set as the identity matrix; Δu t+1：t = u t+1 -u t ; Δg t+1：t is the gradient difference between u t+1 and u t . When D t+1 reaches a certain threshold, the iteration stops, and D t+1 is the approximate Hessian matrix. To make the iteration process of D t+1 more memory-saving, this application stores the values of the most recent several iterations (default value is 100) for approximate calculation of the Hessian matrix. Figure 7Schematic diagram of the action process of the mechanical conduction mechanism of the spring vector in the embodiment of the present application. As Figure 7 shown, (a) is a schematic diagram of the position distribution of the main and auxiliary fault blocks on both sides of the fault (black solid line); (b) is the generation of spring vectors between the mass points of the main and auxiliary fault blocks on both sides of the fault; (c) is to set the relationship between the top line nodes and the mass points on the fault plane and pull the point pairs to the same position; (d) is to pull the other mass points affected by the movement of the point pairs according to the mechanical mechanism; (e) is to flatten the top surface of the formation, and each mass point moves under the constraints of the boundary conditions and the spring vectors; (f) is that each mass point in the main and auxiliary fault blocks reaches the mechanical equilibrium state after solving the global mechanical equilibrium state by the finite element method.

[0094] In some embodiments of the present application, after step S05, the method further includes: if there are multiple stages of fault combinations in the starting formation, the fault groups are sequentially selected according to the main and auxiliary relationships for iterative simulation. The iterative simulation herein refers to repeating the above steps S01 to S05 until a result that conforms to the geological law is obtained. The result that conforms to the geological law in this step is a general term and needs to be analyzed differently according to the general situation of different work areas. For example, in the process of tectonic restoration of a fault with a large fault throw and the strata it cuts through in the example, after the first tectonic restoration of the uppermost strata, there is a large gap between the restored main and auxiliary fault planes, which is contrary to the geological simulation. Therefore, multiple tectonic restorations are required to improve the restoration result. Figure 8 Schematic diagram of the tectonic restoration process for formation Lc in the embodiment of the present application. As Figure 8 shown, (a) is a tetrahedral mesh generated for the experimental work area by combining the interpretation results of the fault and the formation plane; (b) is to set the corresponding relationship between the top line nodes and the mass points on the fault plane; (c) is to pull the points at both ends of the point pair to the same position according to the corresponding relationship; (d) is to flatten the top surface of the formation; (e) is the morphology of the work area after solving the global mechanical equilibrium state by the finite element method. It can be seen from the results that there is a large gap between the faults, which does not conform to the geological understanding, and iterative calculation is required; (f) is the tectonic restoration result after iterative calculation.

[0095] In some embodiments of the present application, after completing the tectonic restoration simulation of the starting formation, the method further includes: stripping the starting formation, and sequentially selecting the overlying formations of the starting formation for tectonic restoration simulation. Strip the Lc formation, and sequentially select the overlying formation Lc+1 for tectonic restoration simulation. Repeat the foregoing steps for the Lc+1 formation until the tectonic restoration research of the entire study area is completed. Figure 9 Schematic diagram of the tectonic restoration results of multiple formations sequentially in the embodiment of the present application. As Figure 9 shown, (a) is the tectonic restoration result after flattening formation L c ; (b) is the result after stripping formation L c and then flattening formation L c+1The structural restoration result; (c) is to strip the formation L c+1 After that, flatten the formation L c+2 The structural restoration result; (d) is to strip the formation L c+2 After that, flatten the formation L c+3 The structural restoration result; (e) is to strip the formation L c+3 After that, flatten the formation L c+4 The structural restoration result; (f) is to strip the formation L c+4 After that, flatten the formation L c+5 The structural restoration result.

[0096] Figure 10 This is a schematic diagram of the calculation result of the in-situ stress field obtained during the structural restoration process in the embodiment of the present application. As Figure 10 shown, (a) is the in-situ stress field of the first principal stress direction obtained after flattening and solving the formation Lc; (b) is a schematic diagram of the force direction in the in-situ stress field of the first principal stress direction; (c) is the in-situ stress field of the second principal stress direction obtained after flattening and solving the formation Lc; (d) is a schematic diagram of the force direction in the in-situ stress field of the second principal stress direction; (e) is the in-situ stress field of the third principal stress direction obtained after flattening and solving the formation Lc; (f) is a schematic diagram of the force direction in the in-situ stress field of the third principal stress direction.

[0097] Through the above embodiments, the structural restoration result can be quantitatively evaluated, and while ensuring the accuracy of the three-dimensional space calculation, the calculation efficiency can be greatly improved, and at the same time, the number of iterations of the formation structure restoration can be independently determined.

[0098] Based on the same inventive concept, the embodiment of the present application also provides a device for processing the fault contact boundary during the structural restoration process. Figure 11 Schematically shows a structural diagram of the device for processing the fault contact boundary during the structural restoration process according to the embodiment of the present application. As Figure 11 shown, the device includes: a grid construction module for obtaining a tetrahedral grid structure that conforms to the characteristics of geomechanics and geometry corresponding to geological data; a vector analysis module for determining the starting formation of the structural restoration simulation and generating spring vectors between each particle in the starting formation and its adjacent particles; the spring vectors are used to characterize the mechanical relationship between particles; a relationship setting module for setting the relationship of the fault top line nodes according to the fault information stored in the fault binary tree management system; a correspondence relationship module for establishing a particle correspondence relationship between the main disk and the auxiliary disk in the fault plane under the constraint of the fault top line node relationship; and a result generation module for updating the positions of each particle based on the spring vectors under the limitation of the particle correspondence relationship to form a primary structural restoration simulation of the starting formation.

[0099] In some alternative embodiments, obtaining a tetrahedral mesh structure that conforms to the characteristics of geomechanics and geometry for geological data includes: using 3D seismic data as the data basis, performing 3D geological structure interpretation within the target formation with well-seismic calibration as the constraint, and providing complete boundary conditions through the superposition of faults and horizons; analyzing and determining fault stages and cross-cutting sequence information based on the contact relationships between faults and between faults and horizons, and managing fault data through a binary tree management system; generating a tetrahedral mesh structure that conforms to the characteristics of geomechanics and geometry using the fault contact boundary information.

[0100] In some alternative embodiments, generating spring vectors for each particle in the starting formation and its adjacent particles includes: within the starting formation, generating spring vectors for each particle and its adjacent particles along the boundary of the tetrahedral mesh; the spring vectors within the layer are divided into body springs, fault springs, and top surface springs according to the types of the two end particles.

[0101] In some alternative embodiments, setting the relationship of the top line nodes of the fault according to the fault information stored in the fault binary tree management system includes: determining the fault names in the starting formation and retrieving the fault binary tree management system; successively determining the hanging wall and footwall on both sides of the fault according to the retrieval results; setting the relationship between the top line of the intersection plane and the top line nodes of the hanging wall and footwall for the faults intersecting with the starting formation.

[0102] In some alternative embodiments, under the constraint of the relationship of the top line nodes of the fault, establishing the corresponding relationship between the particles in the hanging wall and the footwall within the fault plane includes: after setting the relationship of the top line nodes of the fault, successively setting the particle pairs between the particles in the hanging wall and the footwall within the fault plane according to the length and direction of the projection vector; there is a corresponding relationship between the particle in the hanging wall and the particle in the footwall in the particle pair; determining the force on a certain particle based on the spring vector of the certain particle and the corresponding particle based on the particle pair.

[0103] In some alternative embodiments, under the limitation of the corresponding relationship of the particles, updating the positions of each particle based on the spring vectors to form a primary tectonic restoration simulation of the starting formation includes: flattening the top surface, obtaining the stress and strain conditions between the particles by the finite element numerical simulation method under the constraint of the spring vectors; solving the displacement of each particle through Hooke's law or Neo-Hooke's law; moving each particle in the 3D model along the total stress direction according to the calculation result of the displacement to form a primary tectonic restoration simulation of the starting formation; and updating the state of the tetrahedral mesh, re-analyzing the fault contact relationship according to the tectonic restoration result, and updating the fault binary tree management system.

[0104] In some alternative embodiments, the device further includes: if there are multiple-stage fault combinations in the starting formation, successively selecting fault groups according to the hanging wall-footwall relationship for iterative simulation.

[0105] In some alternative embodiments, after completing the tectonic restoration simulation of the starting formation, the apparatus further includes: stripping the starting formation and sequentially selecting the underlying formations of the starting formation for tectonic restoration simulation.

[0106] For the specific definitions of the various functional modules in the fault contact boundary processing apparatus during the above tectonic restoration process, reference may be made to the definitions of the fault contact boundary processing method during the tectonic restoration process in the foregoing text, which will not be elaborated herein. Each module in the above apparatus can be implemented in whole or in part by software, hardware, and their combination. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to the above modules. It also overcomes the deficiencies of the existing tectonic restoration technology and achieves the technical effect of true three-dimensional tectonic restoration.

[0107] In some embodiments of the present application, an electronic device is further provided, including: at least one processor; a memory connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the at least one processor executes the steps of the fault contact boundary processing method during the tectonic restoration process described above. The control module or processor here has the functions of numerical calculation and logical operation, and it at least has a central processing unit CPU with data processing capabilities, a random access memory RAM, a read-only memory ROM, a variety of I / O ports, and an interrupt system, etc. The processor contains a kernel, and the kernel retrieves the corresponding program unit from the memory. One or more kernels can be set, and the foregoing method can be implemented by adjusting the kernel parameters. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of, for example, read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip. The electronic device is preferably a chip.

[0108] In an embodiment provided by the present application, a machine-readable storage medium is provided, and instructions are stored on the machine-readable storage medium, and when the instructions are executed by a processor, the processor is configured to execute the steps of the fault contact boundary processing method during the tectonic restoration process described above.

[0109] In an embodiment provided by the present application, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps of the fault contact boundary processing method during the tectonic restoration process described above are implemented.

[0110] 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 take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0111] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (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 flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, 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 means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0112] 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 instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such 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 steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0114] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0115] The memory may include non-permanent memory in the computer-readable medium, in the form of 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 a computer-readable medium.

[0116] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0117] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0118] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for processing the fault contact boundary during the construction restoration process, characterized in that, The method includes: Obtaining a tetrahedral mesh structure corresponding to geological data that conforms to geomechanical and geometric characteristics; Determining the starting formation for tectonic restoration simulation, and generating spring vectors for each particle in the starting formation with its adjacent particles; the spring vectors are used to characterize the mechanical relationship between particles; Performing fault top-line node relationship setting according to the fault information stored in the fault binary tree management system; Establishing a particle correspondence relationship between the main plate and the auxiliary plate within the fault plane under the constraint of the fault top-line node relationship; Updating the positions of each particle based on the spring vectors under the limitation of the particle correspondence relationship to form a primary tectonic restoration simulation of the starting formation.

2. The method according to claim 1, wherein Obtaining a tetrahedral mesh structure corresponding to geological data that conforms to geomechanical and geometric characteristics includes: Taking 3D seismic data as the data basis, performing 3D geological structure interpretation within the target formation with well-seismic calibration as the constraint, and providing complete boundary conditions through the superposition of faults and horizons; Analyzing and determining fault episode and cross-cutting sequence information based on the contact relationships between faults and between faults and horizons, and managing fault data through a binary tree management system; Generating a tetrahedral mesh structure that conforms to geomechanical and geometric characteristics using fault contact boundary information.

3. The method according to claim 1, characterized in that, Generating spring vectors for each particle in the starting formation with its adjacent particles includes: Within the starting formation, generating spring vectors for each particle with its adjacent particles along the boundary of the tetrahedral mesh; the spring vectors within the layer are divided into body springs, fault springs, and top surface springs according to the different types of particles at both ends.

4. The method according to claim 1, characterized in that Performing fault top-line node relationship setting according to the fault information stored in the fault binary tree management system includes: Determining the fault names within the starting formation and retrieving the fault binary tree management system; Sequentially determining the main plate and the auxiliary plate on both sides of the fault according to the retrieval results; Setting the relationship between the top line of the intersection plane and the top line nodes of the main and auxiliary plates for the faults intersecting with the starting formation.

5. The method according to claim 1, wherein Establishing a particle correspondence relationship between the main plate and the auxiliary plate within the fault plane under the constraint of the fault top-line node relationship includes: After setting the fault top-line node relationship, sequentially setting the particle pairs of the main plate particles and the auxiliary plate particles within the fault plane according to the length and direction of the projection vector; the main plate particles and the auxiliary plate particles in the particle pair have a corresponding relationship; Determining the force on a certain particle based on the spring vector of the certain particle and the corresponding particle based on the particle pair.

6. The method according to claim 1, wherein Updating the positions of each particle based on the spring vectors under the limitation of the particle correspondence relationship to form a primary tectonic restoration simulation of the starting formation includes: Flattening the top surface, and obtaining the stress and strain conditions between particles by the finite element numerical simulation method under the constraint of the spring vectors; Solving the displacement of each particle through Hooke's law or neo-Hooke's law; Moving each particle in the 3D model along the total stress direction according to the displacement calculation result to form a primary tectonic restoration simulation of the starting formation; And updating the state of the face-body mesh, and re-analyzing the fault contact relationship according to the tectonic restoration result, and updating the fault binary tree management system.

7. The method according to claim 1, wherein The method further includes: if there are multiple-phase fault combinations in the starting underlying layer, fault groups are sequentially selected according to the primary-secondary relationship for iterative simulation.

8. The method according to claim 1, wherein After completing the structural restoration simulation of the starting formation, the method further includes: Stripping the starting formation, and sequentially selecting the underlying formations of the starting formation for structural restoration simulation.

9. A fault contact boundary processing device for a structural restoration process, characterized in that, The device includes: A grid construction module, configured to obtain a tetrahedral grid structure corresponding to geological data and conforming to geomechanical and geometric characteristics; A vector analysis module, configured to determine the starting formation for structural restoration simulation, and generate spring vectors between each particle in the starting formation and its adjacent particles; the spring vectors are used to characterize the mechanical relationship between the particles; A relationship setting module, configured to perform fault top-line node relationship setting according to the fault information stored in the fault binary tree management system; A corresponding relationship module, configured to establish a particle corresponding relationship between the main plate and the auxiliary plate within the fault plane under the constraint of the fault top-line node relationship; and A result generation module, configured to update the positions of each particle based on the spring vectors under the limitation of the particle corresponding relationship, and form a primary structural restoration simulation of the starting formation.

10. An electronic device, characterized in that, Including: At least one processor; A memory, connected to the at least one processor; Wherein, the memory stores instructions executable by the at least one processor, and the at least one processor realizes the steps of the fault contact boundary processing method in the structural restoration process described in any one of claims 1 to 8 by executing the instructions stored in the memory.

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