Discrete-element-based three-dimensional fault / fracture network modeling method and device under backlash pushing and covering system

Abstract

The invention discloses a discrete element-based three-dimensional fault / fracture network modeling method and device under a backlash pushing and covering system, and relates to the technical field of three-dimensional fault modeling, and the method comprises the steps: building an initialized fault plane model based on the seismic logging information parameters of a target region; extracting stratum parameters of the target area, and determining a deformation process in combination with an equilibrium profile recovery method; the method comprises the following steps: calibrating mesoscopic parameters of discrete elements according to stratum parameters, depositing a first discrete element model, optimizing and generating a second discrete element model, setting boundary conditions to carry out back-flushing pushing-covering simulation, comparing an output result of the second discrete element model with an actual geological section, adjusting model parameters until the output result and the actual geological section are matched, and establishing a three-dimensional fault and fracture network. And analyzing and establishing spatial distribution characteristics of the target area, and carrying out dynamic evaluation and trend prediction on the activity of the three-dimensional fault. According to the method, the geomechanical model is fused, the subjectivity of manual interpretation is overcome, and the problems of fault tip extension and the like in grid reconstruction are effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional fault modeling research, and in particular to a three-dimensional fault / crack network modeling method and device in a thrust-nappe system based on discrete elements. Background Art

[0002] Faults and fractures, as important products of geological tectonic activities, are key geological elements that control the migration, accumulation and accumulation of oil and gas. Faults refer to structures in which rock layers are broken and significantly displaced by tectonic stress, while fractures characterize discontinuous interfaces formed by rock fractures. The complex network system composed of the two not only directly affects the distribution of oil and gas reservoir space, but also has a continuous transformation effect on the integrity of the trap and the fluid conductivity through the dynamic evolution process. Therefore, constructing a three-dimensional fault / fracture network model has become a core technical link in deciphering the structural control mechanism of oil and gas exploration and development.

[0003] The current three-dimensional geological modeling faces two challenges: on the one hand, the surface and deep fault / fracture systems have significant spatial heterogeneity and geometric discontinuity, and their original three-dimensional observation data often show fragmented characteristics. The complex fault structures cut each other, causing the continuity of the strata to be severely damaged. Various spatial interpolation algorithms and surface model and volume model fault construction methods are no longer applicable; on the other hand, traditional modeling methods are mostly limited to static layered structure reconstruction, which greatly increases the difficulty and complexity of modeling when constructing complex fault models with many layers, and it is difficult to effectively characterize the thrust-nappe system formed by the superposition of multiple tectonic movements. Especially when it comes to complex processes such as fault tip stress singularity, multi-fault interactive extension, and dynamic reorganization of fracture networks, conventional modeling techniques often lead to significant deviations in prediction results due to problems such as difficult grid reconstruction and missing evolution processes. This limitation is particularly prominent in oil and gas basins with strong tectonic transformation characteristics, making it impossible to fundamentally solve the multi-solution problem of two-dimensional structural interpretation through simple three-dimensional visualization.

[0004] The basic idea of ​​discrete element simulation is to regard a single discrete particle at the microscopic scale inside the material as a discrete unit, and the particle aggregate as a collection of several discrete units. The mechanical behavior of material science is simulated through a series of discrete units. It has great advantages in studying the rupture of discontinuous media and large deformation problems. The three-dimensional fault / crack modeling technology of thrust-nappe system based on the discrete element method improves the traditional modeling paradigm. This method integrates dynamic elements such as the evolution of stress fields and fault nucleation and expansion laws in geological history into the modeling process, and uses discrete element numerical simulation to reproduce the structural deformation sequence. The three-dimensional geological modeling constructed by this research method and device is leaping from static description to dynamic prediction, providing a new technical method for oil and gas exploration in complex structural areas. Summary of the invention

[0005] In view of the fact that the existing three-dimensional fault fracture modeling methods based on seismic data have significant limitations when facing complex deformation areas such as thrust tectonic belts, such as complex fault structure distribution, strong spatial heterogeneity, fragmented geological data, and the inability of traditional methods to dynamically invert the fracture evolution process, it is difficult to balance the spatial accuracy and geological rationality of the model, and the prediction results have large deviations. In addition, conventional grid reconstruction has problems such as indescribable stress singularities and modeling obstacles in dealing with fault tip ruptures, fault intersection expansion, and dynamic evolution of fractures, so the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to construct a high-precision three-dimensional modeling method that combines geomechanical mechanisms, can dynamically simulate the formation and evolution process of fault cracks, and is suitable for thrust-nappe tectonic belts, so as to achieve accurate characterization of the spatiotemporal distribution characteristics of complex fault systems and dynamic evaluation of fault activity, and overcome the shortcomings of traditional methods in modeling accuracy, reconstruction of evolutionary processes, and expression of multi-period structural superposition.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements, which comprises: Based on the seismic logging data parameters of the target area, an initial fault plane model is constructed, and a basic fault point set data is extracted along the strike direction of the initial fault plane model using an encrypted gridding method; Extract the stratigraphic parameters of the target area and combine them with the balanced profile restoration method to determine the deformation process of the target area in the historical period; Calibrate the microscopic parameters of the discrete element according to the formation parameters, deposit the first discrete element model, construct the fault function, and optimize and generate the second discrete element model; Based on the second discrete element model, boundary conditions are set to perform thrust simulation, and by comparing the output result of the second discrete element model with the actual geological profile, the model parameters are adjusted until the two match; Based on the simulation results, a three-dimensional fault and fracture network is established, the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area are analyzed and established, and the activity of the three-dimensional fault is dynamically evaluated and trend predicted.

[0008] As a preferred solution of the three-dimensional fault / fracture network modeling method in the thrust-nappe system based on discrete elements of the present invention, the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area are established and analyzed based on the matched model results, and the activity of the three-dimensional fault is dynamically evaluated and the trend is predicted, including: Based on the particle coordinates of the second discrete element model evolution results and the relative position vectors between particles, the displacement gradient tensors of different particles are derived; According to the particle displacement gradient tensor of the second discrete element model evolution result, the strain tensors of different sections are plotted to obtain the three-dimensional faults distributed in space; Based on the bonding relationship between particles in the evolution results of the second discrete element model, it is determined whether the bonding between particles is broken; According to the judgment result, the time, location and type of inter-particle bonding failure are recorded, wherein the types include tensile failure and shear failure; Marking the bonding state between particles as a crack initiation point, wherein the crack initiation point is a situation where the bonding state between particles changes from a bonding compression state or a bonding tension state to a non-bonded contact state or a state where interaction is lost; The characteristics of the tensile rupture type and the shear rupture type are analyzed, wherein the tensile rupture type is characterized by damage perpendicular to the direction of the maximum principal stress; and the shear rupture type is characterized by damage developing along the direction of the minimum principal stress; Based on the progress of the loading process, the information of inter-particle bonding failure is continuously updated to establish a crack network database, wherein the crack network database includes the coordinates of particles where bonding failure has occurred, the failure time and the failure type; Based on the fracture network database, a fracture network quantitative analysis is performed to calculate statistical indicators, wherein the statistical indicators include fracture density, average fracture length and fracture direction distribution; The spatial distribution characteristic diagram of the fracture network under different spatiotemporal evolutions is drawn by using the statistical indicators.

[0009] As a preferred solution of the three-dimensional fault / fracture network modeling method under the thrust-nappe system based on discrete elements of the present invention, wherein: based on the second discrete element model, boundary conditions are set to perform thrust-nappe simulation, and by comparing the output result of the second discrete element model with the actual geological profile, the model parameters are adjusted until the two match, including: The trailing edge of the second discrete element model is set as an active boundary, and the remaining boundaries are set as fixed boundaries; applying motion to the active boundary with reference to the fault displacement amount and the balance profile recovery shortening amount in the target area; Controlling the movement of the active boundary, when the extrusion amount equal to the shortening amount restored by the equilibrium section is reached, stopping the operation of the second discrete element model; Extracting simulation results of the second discrete element model, and comparing the simulation results with the actual geological profile for consistency; If the simulation result does not match the actual geological profile, fine-tune the discrete element particle parameters or boundary motion, and repeat the above steps until the simulation result matches the actual geological profile; If the simulation result matches the actual geological profile, a three-dimensional fault / fracture network construction is performed.

[0010] As a preferred solution of the three-dimensional fault / fracture network modeling method in the thrust-nappe system based on discrete elements of the present invention, wherein: the mesoscopic parameters of the discrete elements are calibrated according to the formation parameters, a first discrete element model is deposited, a fault function is constructed, and a second discrete element model is optimized and generated, including: Establishing a microscopic parameter system of discrete elements, wherein the microscopic parameter system includes particle parameters and particle bonding parameters; Determine the state relationship between adjacent particles of discrete elements, and calibrate the microscopic parameters of the particle materials of each formation through triaxial compression test, wherein the state relationship includes the bond compression state, the bond tension state, the unbonded contact state, and the state where the particles lose interaction; Based on the space corresponding to the target area, particles with a normal distribution of radius are randomly distributed, and the corresponding relationship between the microscopic parameters of the particles and the macroscopic properties of the formation is established, and physical properties and interaction parameters are assigned to each particle, wherein the physical properties include radius and density; and the interaction parameters include normal stiffness, shear stiffness and friction coefficient; Allow the endowed particles to settle freely until the system is stable, record the position parameters of each formation particle, and complete the construction of the first discrete element model; Based on the calibrated particle bonding parameters and the formation information of the target area, setting a bonding relationship between the particles of the first discrete element model; Refining the first discrete element model to establish microscopic parameters and mechanical relationships of particles at different levels in the target area; According to the fault point set data Fault, a main fault model function isInsideFault is established, wherein the main fault model function is used to determine whether any particle coordinate pt is located inside the fault point set Fault; Based on the judgment results, the bonding between particles on the fault plane is eliminated, and the friction coefficient between particles on the fault plane is reduced to form the second discrete element model.

[0011] As a preferred solution of the three-dimensional fault / fracture network modeling method under the thrust-nappe system based on discrete elements of the present invention, wherein: extracting the stratigraphic parameters of the target area, combining the balanced profile recovery method, and determining the deformation process of the target area in the historical period, including: Based on the initialized fault plane model, collecting drilling data of the target area, and obtaining core samples from the drilling data; Conducting laboratory analysis on the core samples to determine physical property parameters of different formations, wherein the physical property parameters include lithology, porosity and permeability; Collecting and analyzing well logging data of the target area to obtain detailed information of the underground formation, wherein the well logging data includes resistivity logging data and natural gamma ray logging data; Analyze seismic profile data to extract information about different strata in the target area, wherein the information about different strata includes stratum lithology, mechanical parameters, and spatial distribution characteristics; the mechanical parameters include elastic modulus and Poisson's ratio; Comprehensively analyzing the information of the different strata, the physical property parameters and the detailed information to obtain complete stratum parameters of the target area; Based on the complete formation parameters, the target area is modeled using a balanced profile recovery method; Determine the deformation process of the target area in the historical period by using the balanced profile restoration method, and identify the multi-stage activity of the fault; A quantitative comparative analysis is performed between the restored equilibrium profile generated by the equilibrium profile restoration method and the original profile, and the compression deformation displacement caused by each period of fault activity is calculated.

[0012] As a preferred solution of the three-dimensional fault / fracture network modeling method in the thrust-nappe system based on discrete element in the present invention, wherein: the method for constructing the initialization fault surface model is: Acquiring seismic logging data parameters of the target area and preprocessing the seismic logging data parameters; Based on the pre-processed seismic logging data parameters, seismic sections that clearly show the target fault characteristics are selected, with priority given to areas showing displacement; Based on the seismic profile, extract coordinate data, layer data, and fault data; Analyze the seismic profile to identify and extract relevant parameters of the main faults with large displacement and in the direction of compression, wherein the relevant parameters include the inclination of the fault plane, the dip angle of the fault plane, the slip distance along the fault plane, the slip direction along the fault plane, and the relative displacement of the strata on both sides of the fault; Based on the relevant parameters, extracting the spatial three-dimensional geometric shape of the main fault; The three-dimensional geometric shape of the space is processed by using an encrypted grid method; Based on the processed three-dimensional geometric shape, the basic fault point set data is extracted along the strike direction of the main fault. The basic fault point set data is assumed to be Fault, including n three-dimensional points S={p 1 , p 2 ,…,p n}, where p n is the nth 3D point on the fault plane; An initialization fault plane model is constructed according to the basic fault point set data.

[0013] In a second aspect, the present invention provides a three-dimensional fault / crack network modeling device in a thrust-nappe system based on discrete elements, comprising: A fault module constructs an initial fault plane model based on the seismic logging data parameters of the target area, and extracts basic fault point set data along the strike direction of the initial fault plane model using an encrypted gridding method; The inversion module is used to extract stratigraphic information and deformation process by observing the geology of the target area and analyzing the seismic data in the area, and to invert the seismic analysis map and the spatial evolution process of the fault; A model module, calibrating discrete element microscopic parameters according to the formation parameters, depositing a first discrete element model, constructing a fault function, and optimizing to generate a second discrete element model; A deformation module, based on the second discrete element model, sets boundary conditions to perform thrust simulation, and adjusts model parameters by comparing the output result of the second discrete element model with the actual geological profile until the two match; The modeling module establishes and analyzes the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area based on the matched model results, and dynamically evaluates and predicts the activity of the three-dimensional faults.

[0014] In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, it implements any step of the above-mentioned discrete element-based three-dimensional fault / crack network modeling method in a thrust-nappe system.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned discrete element-based three-dimensional fault / fracture network modeling method in a thrust-nappe system is implemented.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: by introducing the discrete element method to dynamically simulate the fault fracture system, the problem of difficulty in accurately describing the fault tip rupture and expansion behavior due to the difficulty in grid reconstruction in traditional modeling is effectively avoided; by integrating geomechanical parameters and tectonic evolution processes in the modeling process, a spatiotemporal coupling relationship between pre-existing faults and new fractures is established, and a quantitative analysis of the multi-period structural superposition effect is achieved; at the same time, a closed-loop modeling process from structural sign inversion to future structural evolution prediction is established, which significantly improves the geological rationality and predictive ability of three-dimensional spatial distribution modeling of complex fault systems, and provides scientific and reliable technical support for the identification of hidden structures, fault plugging evaluation and structural reservoir control mechanism research in oil and gas exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them: Figure 1 Schematic diagram of the process of three-dimensional fault / fracture network modeling method in thrust-nappe system based on discrete element method.

[0018] Figure 2 It is a sedimentary model for the three-dimensional fault / fracture network modeling method in the thrust-nappe system based on discrete element.

[0019] Figure 3 Particle contact and bonding relationships for a discrete element-based three-dimensional fault / fracture network modeling approach in a thrust-nappe system.

[0020] Figure 4 The evolution of the equilibrium profile is an example of the discrete element-based approach to modeling the three-dimensional fault / fracture network in a thrust-nappe system.

[0021] Figure 5 Schematic diagram of the simulation device structure for the three-dimensional fault / crack network modeling method in the thrust-nappe system based on discrete elements.

[0022] Figure 6 The discrete element geological model is compared with the actual geological conditions in the example area shown in the discrete element-based three-dimensional fault / fracture network modeling method in the thrust-nappe system.

[0023] Figure 7 This is the stress-strain curve of the simulated stratum based on the discrete element method of three-dimensional fault / fracture network modeling in the thrust-nappe system.

[0024] Figure 8 Seismic section of the Mazatagh tectonic belt as an example of the discrete element-based three-dimensional fault / fracture network modeling method in the thrust-nappe system.

[0025] Fig. 9 An example fault combination diagram of the discrete element-based three-dimensional fault / fracture network modeling method in a thrust-nappe system.

[0026] Fig.10 A fault longitudinal section diagram showing an example of the discrete element-based three-dimensional fault / fracture network modeling approach for thrust-nappe systems.

[0027] Fig.11 Fault cross-section diagram showing an example of the discrete element-based approach to modeling a three-dimensional fault / fracture network in a thrust-nappe system.

[0028] Fig.12Example fracture density statistics for a discrete element-based approach to modeling a 3D fault / fracture network in a thrust-nappe system. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0033] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Example 1 Reference Figure 1~Figure 5 , which is the first embodiment of the present invention, provides a three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements, comprising: S1: Based on the seismic logging data parameters of the target area, an initial fault plane model is constructed, and the basic fault point set data is extracted along the strike direction of the initial fault plane model using the encrypted gridding method.

[0036] Specifically, the method for constructing the initial fault plane model is to obtain the seismic logging data parameters of the target area and preprocess the seismic logging data parameters.

[0037] In an optional implementation, the seismic logging data parameters of the target area are obtained through geological survey and seismic data analysis, and the seismic logging data parameters are preprocessed using Petrol and LandMark software, including noise removal and reflection wave extraction.

[0038] Furthermore, based on the pre-processed seismic logging data parameters, seismic profiles that clearly show the characteristics of the target fault are selected, with priority given to areas showing displacement; based on the seismic profiles, coordinate data, stratification data, and fault data are extracted; the seismic profiles are analyzed to identify and extract relevant parameters of major faults with large displacements and in the direction of compression, wherein the relevant parameters include the dip of the fault plane, the dip angle of the fault plane, the sliding distance along the fault plane, the sliding direction along the fault plane, and the relative displacement of the strata on both sides of the fault; based on the relevant parameters, the spatial three-dimensional geometric shapes of the major faults are extracted; and the spatial three-dimensional geometric shapes are processed using an encrypted gridding method.

[0039] Preferably, based on the processed three-dimensional geometric shape of the space, basic fault point set data is extracted along the strike direction of the main fault. Let the basic fault point set data be Fault, including n three-dimensional points S={p 1 , p 2 ,…,p n}, where p n is the nth 3D point on the fault plane; Furthermore, an initial fault plane model is constructed based on the basic fault point set data.

[0040] S2: Extract the stratigraphic parameters of the target area and combine them with the balanced profile recovery method to determine the deformation process of the target area in the historical period.

[0041] Specifically, drilling data of the target area are collected and core samples are obtained from the drilling data; the core samples are subjected to laboratory analysis to determine the physical property parameters of different formations, where the physical property parameters include lithology, porosity and permeability; logging data of the target area are collected and analyzed to obtain detailed information on the underground formations, where the logging data include resistivity logging data and natural gamma-ray logging data.

[0042] It should be noted that the detailed information of underground strata includes stratum thickness, lithological boundaries and fluid saturation.

[0043] Furthermore, the seismic profile data is analyzed to extract information on different strata in the target area, including lithology, mechanical parameters and spatial distribution characteristics; mechanical parameters include elastic modulus and Poisson's ratio; the information, physical property parameters and detailed information of different strata are comprehensively analyzed to obtain the complete stratum parameters of the target area; based on the complete stratum parameters, the target area is modeled using the balanced profile recovery method.

[0044] It should be noted that the balance profile recovery method is implemented through the balance profile recovery software, wherein the balance profile recovery software is 3dmove.

[0045] Furthermore, Figure 4 As shown in the figure, the deformation process of the target area in the historical period is determined by the balanced profile restoration method, and the multi-stage activity of the fault is identified; the restored balanced profile generated by the balanced profile restoration method is quantitatively compared with the original profile, and the compression deformation displacement caused by each stage of fault activity is calculated.

[0046] S3: Calibrate the microscopic parameters of the discrete element according to the formation parameters, deposit the first discrete element model, construct the fault function, and optimize and generate the second discrete element model.

[0047] Specifically, Figure 2 As shown, a discrete element micro-parameter system is established, wherein the discrete element micro-parameter system includes particle parameters and particle bonding parameters.

[0048] It should be noted that the particle parameters describe the mechanical properties of the particles themselves and the contact behavior between the particles; the particle bonding parameters describe the bonding effect between the particles and are suitable for simulating cemented materials (such as consolidated rocks). The relationship between the contact and bonding between the particles is as follows: Figure 3 shown.

[0049] In an optional embodiment, a particle-to-particle contact constitutive model is established based on the Hertz-Mindlin theory, in which particles are given elastic-friction contact characteristics; the mechanical response of particles in contact is defined, including normal stress and interparticle shear stress , where the normal stress and the normal stiffness between particles are The overlap between particles Related; interparticle shear stress and interparticle shear stiffness and the shear offset of the particle center Related; and The values ​​are all nonlinear quantities related to the contact area of ​​overlapping particles and the particle shear modulus and Poisson's ratio related.

[0050] Furthermore, the state relationship between adjacent particles of the discrete element is determined, and the microscopic parameters of the granular materials in each formation are calibrated through triaxial compression test tests, where the state relationship includes the bonding compression state, the bonding tension state, the unbonded contact state, and the state in which the particles lose interaction.

[0051] As shown in the example, the radius expansion method is used to establish a 1:1:2 initial model in the triaxial compression test. In the initial model, the top and bottom walls move toward the center of the sample at the same speed, and different confining pressures are set around them. The stress-strain curve of the triaxial compression test sample at a strain of 20% is obtained, and the cohesion, friction coefficient and other parameters of the sample are obtained by post-processing the stress-strain curve. The corresponding relationship between the microscopic parameters of the particles and the macroscopic properties of the formation is established.

[0052] Furthermore, based on the space corresponding to the target area, particles with a normal distribution of radius are randomly distributed, and the corresponding relationship between the microscopic parameters of the particles and the macroscopic properties of the formation is established, and each particle is assigned physical properties and interaction parameters, where the physical properties include radius and density; the interaction parameters include normal stiffness, shear stiffness and friction coefficient. The assigned particles are allowed to settle freely until the system is stable, and the position parameters of each formation particle are recorded to complete the construction of the first discrete element model.

[0053] Specifically, based on the calibrated particle bonding parameters and the formation information of the target area, a bonding relationship is set between the particles of the first discrete element model.

[0054] It should be noted that the bonding relationship defines the failure criterion of inter-particle bonding through the parameters of bond strength, tensile strength and internal friction angle.

[0055] Furthermore, the first discrete element model is refined to establish the microscopic parameters and mechanical relationships of particles in different layers of the target area. According to the fault point set data Fault, the main fault model function isInsideFault is established, where the main fault model function is used to determine whether any particle coordinate pt is located inside the fault point set Fault.

[0056] It should be noted that when the particle coordinate pt is located inside the fault plane defined by the fault point set Fault, the main fault model function isInsideFault returns a true value; when the particle coordinate pt is located outside the fault plane defined by the fault point set Fault, the main fault model function isInsideFault returns a false value.

[0057] Furthermore, based on the judgment result, the bonding between particles on the fault plane is eliminated, and the friction coefficient between particles on the fault plane is reduced to form a second discrete element model.

[0058] S4: Based on the second discrete element model, boundary conditions are set to perform thrust simulation, and by comparing the output results of the second discrete element model with the actual geological profile, the model parameters are adjusted until the two match.

[0059] Specifically, boundary conditions are set to perform thrust simulation, including: setting the rear edge of the second discrete element model as an active boundary and the remaining boundaries as fixed boundaries; applying movement to the active boundary with reference to the fault displacement in the target area and the shortening amount of the equilibrium section recovery; controlling the movement of the active boundary, and stopping the operation of the second discrete element model when the extrusion amount equals the shortening amount of the equilibrium section recovery is reached.

[0060] Furthermore, the simulation results of the second discrete element model are extracted, and the consistency of the simulation results is compared with the actual geological profile; if the simulation results do not match the actual geological profile, the discrete element particle parameters or boundary movement are fine-tuned, and the above steps are repeated until the simulation results match the actual geological profile; if the simulation results match the actual geological profile, the three-dimensional fault / fracture network construction is executed.

[0061] S5: Based on the matched model results, establish and analyze the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area, and dynamically evaluate and predict the activity of the three-dimensional faults.

[0062] Specifically, based on the particle coordinates of the evolution results of the second discrete element model and the relative position vectors between the particles, the displacement gradient tensors of different particles are derived; based on the particle displacement gradient tensors of the evolution results of the second discrete element model, the strain tensors of different sections are drawn to obtain the three-dimensional faults distributed in space.

[0063] Furthermore, the three-dimensional faulting includes: dividing the space of the second discrete element model into control volumes for each particle, where particle i is at an initial position of , the current location is , the position of neighbor particle j is ; Assign a unit to each particle, where the unit includes all the spatial points closest to this particle. , satisfying the condition: for all particle points .

[0064] Furthermore, based on the position of the particle in the reference state and the current state, the displacement vector and the relative position vector are calculated. The relevant formulas are as follows: ; in, is the displacement vector of particle j relative to particle i, is the position vector of particle j relative to particle i, is the displacement vector of particle j, is the displacement vector of particle i, is the position coordinate of particle j in the current state, is the position coordinate of particle j in the initial reference state, is the position coordinate of particle i in the current state, is the position coordinate of particle i in the initial reference state.

[0065] Furthermore, the displacement gradient tensor is calculated based on the displacement vector and the relative position vector. The specific formula is as follows: ; in, is the displacement gradient tensor of particle i, is the position vector of particle j relative to particle i.

[0066] Preferably, the strain tensor is calculated based on the displacement gradient tensor, and the strain tensor distribution of different sections is plotted to obtain a three-dimensional fault with spatial distribution.

[0067] It should be noted that the specific formula of the strain tensor is as follows: ; in, is the strain tensor of particle i, is the displacement gradient tensor of particle i, is the transpose of the displacement gradient tensor of particle i.

[0068] Specifically, based on the bonding relationship between the particles in the evolution result of the second discrete element model, it is determined whether the bonding between the particles is destroyed.

[0069] It should be noted that if the stress value is greater than the preset bonding strength, it is determined that the bonding between the particles is broken; if the stress value is less than or equal to the preset bonding strength, it is determined that the bonding between the particles is not broken.

[0070] Furthermore, the time, location and type of inter-particle bond failure are recorded according to the judgment results, wherein the types include tensile fracture and shear fracture; the inter-particle bond state is marked as a crack initiation point, wherein the crack initiation point is the situation where the inter-particle bond state changes from a bond compression state or a bond tension state to a non-bonded contact state or a loss of interaction state.

[0071] Furthermore, the characteristics of the tensile rupture type and the shear rupture type are analyzed, where the tensile rupture type is characterized by damage perpendicular to the direction of the maximum principal stress, and the shear rupture type is characterized by damage developing along the direction of the minimum principal stress.

[0072] Specifically, based on the advancement of the loading process, the information on the bond failure between particles is continuously updated to establish a crack network database, where the crack network database includes the coordinates of particles where bond failure has occurred, the failure time and the failure type; based on the crack network database, a quantitative analysis of the crack network is performed to calculate statistical indicators, where the statistical indicators include crack density, average crack length and crack direction distribution; Furthermore, the spatial distribution characteristics of the fracture network under different spatiotemporal evolutions are drawn through statistical indicators.

[0073] Further, refer to Figure 5 This embodiment also provides a three-dimensional fault / crack network modeling device in a thrust-nappe system based on discrete elements, including: The fault module constructs an initial fault plane model based on the seismic logging data parameters of the target area, and uses the encrypted grid method to extract basic fault point set data along the strike direction of the initial fault plane model; The inversion module is used to extract stratigraphic information and deformation process by observing the geology of the target area and analyzing the seismic data in the area, and to invert the seismic analysis map and the spatial evolution process of the fault; The model module calibrates the discrete element mesoscopic parameters according to the formation parameters, deposits the first discrete element model, constructs the fault function, and optimizes and generates the second discrete element model; The deformation module sets boundary conditions to simulate thrust and push based on the second discrete element model, and adjusts model parameters by comparing the output results of the second discrete element model with the actual geological profile until the two match; The modeling module establishes and analyzes the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area based on the matched model results, and dynamically evaluates and predicts the activity of the three-dimensional faults.

[0074] This embodiment also provides a computer device, which is suitable for the case of a three-dimensional fault / crack network modeling method in a thrust-nappe system based on discrete elements, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement the three-dimensional fault / crack network modeling method in a thrust-nappe system based on discrete elements as proposed in the above embodiment.

[0075] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0076] This embodiment also provides a storage medium having a computer program stored thereon. When the program is executed by a processor, the method for modeling a three-dimensional fault / fracture network in a thrust-nappe system based on discrete elements is implemented as proposed in the above embodiment.

[0077] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0078] In summary, the present invention introduces the discrete element method to dynamically simulate the fault fracture system, effectively avoiding the problem of difficult to accurately characterize the fault tip rupture and expansion behavior due to the difficulty of grid reconstruction in traditional modeling; by integrating geomechanical parameters and tectonic evolution processes in the modeling process, a spatiotemporal coupling relationship between pre-existing faults and new fractures is established, and a quantitative analysis of the multi-period structural superposition effect is achieved; at the same time, a closed-loop modeling process from structural sign inversion to future structural evolution prediction is established, which significantly improves the geological rationality and predictive ability of three-dimensional spatial distribution modeling of complex fault systems, and provides scientific and reliable technical support for the identification of hidden structures, fault plugging evaluation and structural control mechanism research in oil and gas exploration.

[0079] Example 2 Reference Figure 4 , Figure 6~Figure 12 , which is the second embodiment of the present invention, provides a three-dimensional fault / crack network modeling method in a thrust-nappe system based on discrete elements. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0080] The middle section of the southern edge of the Bachu uplift in the western Tarim Basin was taken as the research object, and the typical thrust-nappe structural area where the three major structural belts of Niaoshan, Mazatag and Luostag were intersected was selected as the target area. Due to the superposition and transformation of multiple stages of structures, the fault system in this area is dense and complex, and has typical thrust deformation characteristics. The compression and convergence between multiple structural belts not only leads to the diversity and heterogeneity of the fault system, but also breeds rich oil and gas resources. It is of great significance to clarify the distribution of deep faults and structural styles to improve the efficiency of oil and gas exploration.

[0081] The origin of the Niaoshan tectonic belt can be regarded as the result of the differential evolution of the late advancement rate of the Mazatag tectonic belt in the east and the Lostag tectonic belt in the west. Its structural evolution is mainly simulated and inferred based on the seismic data of the Mazatag and Lostag tectonic belts. To this end, high-resolution seismic profiles are first selected, pre-processed and fault identified, and clear fault reflection features are extracted. Figure 8 As shown in the figure, a main fault F1 thrusting to the north was identified in the Mazatag tectonic belt, and multiple branch thrust faults were observed along the main fault. For each fault, the spatial coordinate information (including horizontal and vertical positions and time / depth) was extracted at the position where the reflection axis of the upper and lower plates was suddenly interrupted or dislocated, and the two-dimensional seismic information was converted into a three-dimensional coordinate point set. Finally, the Rosta fault point set p was constructed respectively. 1 and the Mazatagh fault data point p 2 , providing structural boundary basis for subsequent discrete element modeling.

[0082] In order to accurately construct the mechanical properties of the formation and the fracture evolution process, triaxial compression experiments are further used to calibrate the microscopic parameters of the particles. Figure 7 As shown in the figure, the radius expansion method was used to construct the sample in the experiment, and the top and bottom walls were compressed and loaded at a constant rate. At the same time, the stress-strain response of the sample was tested under a confining pressure of 5-80 MPa, and the curve at 20% strain was recorded. The results showed that the macroscopic response cohesion of the model particles was about 32.8 MPa and the friction angle was 29.4°, which were similar to the brittle formation parameters in the target area, verifying the rationality of the parameter setting.

[0083] In the modeling stage, a spatial container with a size of 20km×15km is first constructed and filled with a calibrated set of particles to simulate the natural sedimentation process of the strata. After the free sedimentation is stable, the top 3.5km is eroded to reflect the history of surface uplift, and the particle position data is output to form the first discrete element model; then, combining the stratum information and fault structure characteristics, a particle bonding relationship with parameters such as bonding strength, tensile strength and internal friction angle is introduced between the particles to simulate the natural cementation structure of the rock strata. By writing the isInsideFault function, the particle position is spatially judged to identify whether it is inside the area defined by the fault plane p1 or p2; if it belongs to the fault plane area, the bonding relationship between the particles is cancelled and the friction coefficient is lowered, thereby simulating the easy sliding characteristics of the fault plane and forming a more realistic second discrete element model; such as Figure 6 As shown, different particle colors can distinguish the fault zone (red) and the brittle strata (blue and green), clearly showing the structural hierarchy of the model. The compression direction is due north. The west side of the fault zone is the main fault plane p1 of the Rostag fault, and the east side of the fault zone is the main fault plane p2 of the Mazatag fault.

[0084] In the process of tectonic deformation simulation, the shortening amount obtained by the balanced profile recovery method is referred to, and the boundary load is applied to the model; the rear edge of the model is set as the active boundary, and the other three sides are fixed boundaries, so that the active boundary is continuously squeezed until the equivalent displacement of the restored profile (such as Figure 4 The deformation shown is 6.59 km), simulating the whole process of structural evolution; comparing the simulation output with the seismic profile results, Fig. 9 and Fig.11 The longitudinal section diagram and Figure 8 The results of earthquake measurements are highly consistent, which verifies the rationality and accuracy of the modeling method. Fig.10 and Fig.11 For details on the cross-section location, see Fig. 9 The simulation results also reveal that Fig. 9 , Fig.10 As shown, at the Rosta fault point set p 1 and the Mazatagh fault data point p 2 Two oblique en-echelon faults are formed between them, and their strikes intersect with the fault systems of the Rostag and Mazatag tectonic belts and eventually disappear. The structural characteristics are consistent with the geometric morphology of the Niaoshan tectonic belt, verifying the existence of the inferred structure.

[0085] In terms of crack modeling, the system tracks the changes in the bond failure state between particles in real time. Whenever the stress between particles exceeds the bond strength and the state changes from "bond compression" or "bond tension" to "no bond" or "loss of interaction", it is determined to be a crack generation event. The system records the time, location and type (tensile rupture or shear rupture) of crack generation and constructs a spatiotemporal evolution crack database. Tensile ruptures often occur in the direction perpendicular to the maximum principal stress, while shear ruptures extend along the direction of the minimum principal stress. Further statistics on the development of cracks in different regions, such as Fig.12 As shown in the figure, with the intensification of boundary compression, the number of fractures in the conversion zone increases rapidly, among which the fracture density in the middle intersection area is the highest. It is inferred that it has excellent reservoir fracture channel characteristics, providing important spatial indicators and target area judgment basis for oil and gas exploration.

[0086] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements, characterized by: include, Based on the seismic logging data parameters of the target area, an initial fault plane model is constructed, and a basic fault point set data is extracted along the strike direction of the initial fault plane model using an encrypted gridding method; Extract the stratigraphic parameters of the target area and combine them with the balanced profile restoration method to determine the deformation process of the target area in the historical period; Calibrate the microscopic parameters of the discrete element according to the formation parameters, deposit the first discrete element model, construct the fault function, and optimize and generate the second discrete element model; Based on the second discrete element model, boundary conditions are set to perform thrust simulation, and by comparing the output result of the second discrete element model with the actual geological profile, the model parameters are adjusted until the two match; Based on the matched model results, the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area are established and analyzed, and the activity of the three-dimensional fault is dynamically evaluated and trend predicted.

2. The three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements according to claim 1, characterized in that: Based on the matched model results, the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area are established and analyzed, and the activity of the three-dimensional fault is dynamically evaluated and trend predicted, including: Based on the particle coordinates of the second discrete element model evolution results and the relative position vectors between particles, the displacement gradient tensors of different particles are derived; According to the particle displacement gradient tensor of the second discrete element model evolution result, the strain tensors of different sections are plotted to obtain the three-dimensional faults distributed in space; Based on the bonding relationship between particles in the evolution results of the second discrete element model, it is determined whether the bonding between particles is broken; According to the judgment result, the time, location and type of inter-particle bonding failure are recorded, wherein the types include tensile failure and shear failure; Marking the bonding state between particles as a crack initiation point, wherein the crack initiation point is a situation where the bonding state between particles changes from a bonding compression state or a bonding tension state to a non-bonded contact state or a state where interaction is lost; The characteristics of the tensile rupture type and the shear rupture type are analyzed, wherein the tensile rupture type is characterized by damage perpendicular to the direction of the maximum principal stress; and the shear rupture type is characterized by damage developing along the direction of the minimum principal stress; Based on the progress of the loading process, the information of inter-particle bonding failure is continuously updated to establish a crack network database, wherein the crack network database includes the coordinates of particles where bonding failure has occurred, the failure time and the failure type; Based on the fracture network database, a fracture network quantitative analysis is performed to calculate statistical indicators, wherein the statistical indicators include fracture density, average fracture length and fracture direction distribution; The spatial distribution characteristic diagram of the fracture network under different spatiotemporal evolutions is drawn by using the statistical indicators.

3. The three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements according to claim 2, characterized in that: Based on the second discrete element model, boundary conditions are set to perform thrust simulation, and by comparing the output result of the second discrete element model with the actual geological profile, the model parameters are adjusted until the two match, including: The trailing edge of the second discrete element model is set as an active boundary, and the remaining boundaries are set as fixed boundaries; applying motion to the active boundary with reference to the fault displacement amount and the balance profile recovery shortening amount in the target area; Controlling the movement of the active boundary, when the extrusion amount equal to the shortening amount restored by the equilibrium section is reached, stopping the operation of the second discrete element model; Extracting simulation results of the second discrete element model, and comparing the simulation results with the actual geological profile for consistency; If the simulation result does not match the actual geological profile, fine-tune the discrete element particle parameters or boundary motion, and repeat the above steps until the simulation result matches the actual geological profile; If the simulation result matches the actual geological profile, a three-dimensional fault / fracture network construction is performed.

4. The three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements according to claim 3, characterized in that: Calibrate the microscopic parameters of the discrete element according to the formation parameters, deposit the first discrete element model, construct the fault function, and optimize and generate the second discrete element model, including: Establishing a microscopic parameter system of discrete elements, wherein the microscopic parameter system includes particle parameters and particle bonding parameters; Determine the state relationship between adjacent particles of discrete elements, and calibrate the microscopic parameters of the particle materials of each formation through triaxial compression test, wherein the state relationship includes the bond compression state, the bond tension state, the unbonded contact state, and the state where the particles lose interaction; Based on the space corresponding to the target area, particles with a normal distribution of radius are randomly distributed, and the corresponding relationship between the microscopic parameters of the particles and the macroscopic properties of the formation is established, and physical properties and interaction parameters are assigned to each particle, wherein the physical properties include radius and density; and the interaction parameters include normal stiffness, shear stiffness and friction coefficient; Allow the endowed particles to settle freely until the system is stable, record the position parameters of each formation particle, and complete the construction of the first discrete element model; Based on the calibrated particle bonding parameters and the formation information of the target area, setting a bonding relationship between the particles of the first discrete element model; Refining the first discrete element model to establish microscopic parameters and mechanical relationships of particles at different levels in the target area; According to the fault point set data Fault, a main fault model function isInsideFault is established, wherein the main fault model function is used to determine whether any particle coordinate pt is located inside the fault point set Fault; Based on the judgment results, the bonding between particles on the fault plane is eliminated, and the friction coefficient between particles on the fault plane is reduced to form the second discrete element model.

5. The three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements according to claim 4, characterized in that: Extract the stratigraphic parameters of the target area and combine them with the balanced profile restoration method to determine the deformation process of the target area in the historical period, including: Based on the initialized fault plane model, collecting drilling data of the target area, and obtaining core samples from the drilling data; Conducting laboratory analysis on the core samples to determine physical property parameters of different formations, wherein the physical property parameters include lithology, porosity and permeability; Collecting and analyzing well logging data of the target area to obtain detailed information of the underground formation, wherein the well logging data includes resistivity logging data and natural gamma ray logging data; Analyze seismic profile data to extract information about different strata in the target area, wherein the information about different strata includes stratum lithology, mechanical parameters, and spatial distribution characteristics; the mechanical parameters include elastic modulus and Poisson's ratio; Comprehensively analyzing the information of the different strata, the physical property parameters and the detailed information to obtain complete stratum parameters of the target area; Based on the complete formation parameters, the target area is modeled using a balanced profile recovery method; Determine the deformation process of the target area in the historical period by using the balanced profile restoration method, and identify the multi-stage activity of the fault; A quantitative comparative analysis is performed between the restored equilibrium profile generated by the equilibrium profile restoration method and the original profile, and the compression deformation displacement caused by each period of fault activity is calculated.

6. The three-dimensional fault / fracture network modeling method in a thrust-nappe system based on discrete elements according to claim 5, characterized in that: The method for constructing the initialization fault plane model is: Acquiring seismic logging data parameters of the target area and preprocessing the seismic logging data parameters; Based on the pre-processed seismic logging data parameters, seismic sections that clearly show the target fault characteristics are selected, with priority given to areas showing displacement; Based on the seismic profile, extract coordinate data, layer data, and fault data; Analyze the seismic profile to identify and extract relevant parameters of the main faults with large displacement and in the direction of compression, wherein the relevant parameters include the inclination of the fault plane, the dip angle of the fault plane, the slip distance along the fault plane, the slip direction along the fault plane, and the relative displacement of the strata on both sides of the fault; Based on the relevant parameters, extracting the spatial three-dimensional geometric shape of the main fault; The three-dimensional geometric shape of the space is processed by using an encrypted grid method; Based on the processed three-dimensional spatial geometric shape, basic fault point set data is extracted along the strike direction of the main fault. The basic fault point set data is assumed to be Fault, including n three-dimensional points S={p1, p2, ..., p n }, where p n is the nth 3D point on the fault plane; An initialization fault plane model is constructed according to the basic fault point set data.

7. A three-dimensional fault / fracture network modeling device for a thrust-nappe system based on discrete elements, based on the three-dimensional fault / fracture network modeling method for a thrust-nappe system based on discrete elements according to any one of claims 1 to 6, characterized in that: include, A fault module constructs an initial fault plane model based on the seismic logging data parameters of the target area, and extracts basic fault point set data along the strike direction of the initial fault plane model using an encrypted gridding method; The inversion module is used to extract stratigraphic information and deformation process by observing the geology of the target area and analyzing the seismic data in the area, and to invert the seismic analysis map and the spatial evolution process of the fault; A model module, calibrating discrete element microscopic parameters according to the formation parameters, depositing a first discrete element model, constructing a fault function, and optimizing to generate a second discrete element model; A deformation module, based on the second discrete element model, sets boundary conditions to perform thrust simulation, and adjusts model parameters by comparing the output result of the second discrete element model with the actual geological profile until the two match; The modeling module establishes and analyzes the spatial distribution characteristics of the three-dimensional fault and fracture network in the target area based on the matched model results, and dynamically evaluates and predicts the activity of the three-dimensional faults.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the discrete element-based three-dimensional fault / crack network modeling method in a thrust-nappe system described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the discrete element-based three-dimensional fault / crack network modeling method in a thrust-nappe system described in any one of claims 1 to 6 are implemented.

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