A Three-Dimensional Joint Mesh Modeling Method Based on the Integrated Concept of Geological Engineering

Abstract

This invention provides a three-dimensional fracture network modeling and numerical simulation integration method based on the integrated geological and engineering concept. The method includes: determining the fracture development status of different fracturing sections based on reservoir geological characteristics and hydraulic fracturing microseismic observation data; determining the main fracture morphology and stimulation area scale of the corresponding fracturing sections based on microseismic interpretation results; establishing a geological model containing a three-dimensional fracture network; performing regional meshing discretization of the geological model; establishing a complex fracture network matching mode; constructing a three-dimensional fracture network seepage model; meshing the seepage model and establishing corresponding solution methods; and analyzing key parameters affecting seepage, and analyzing the influence of different parameters on well productivity. This three-dimensional fracture network modeling and numerical simulation integration method based on the integrated geological and engineering concept can construct an effective simulation of three-dimensional fracture seepage with realistic morphology, accurately characterize complex three-dimensional fracture morphology, and provide good guidance for volumetric fracturing design.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development technology, and in particular to a three-dimensional fracture network modeling and digital modeling method based on the concept of integrated geological engineering. Background Technology

[0002] In recent years, with the deepening of low-permeability oil and gas exploration and development, facing the practical problems of low oil and gas production and difficulty in stabilizing production, oil companies have gradually increased their demand for the application of hydraulic fracturing technology in the exploration and development of unconventional oil and gas reservoirs. Drawing on geological achievements in fracturing engineering is imperative. Focusing on the technological needs of low-permeability oil and gas exploration and development, actively implementing the integrated geological engineering concept, and breaking through the key technological bottlenecks in low-permeability reservoir fracturing design are crucial for achieving efficient reservoir development. Practice shows that vertical segmented fracturing of multi-layered low-permeability reservoirs can effectively improve single-well production. Vertically, through multi-segment fracturing and intra-segment combined fracture network fracturing, the degree of fracture control over the reservoir is increased, which can improve production capacity and delay decline. Different fracture morphologies need to be matched for different reservoir conditions. Fracture monitoring results and production profile test results show that, vertically, due to the influence of pressure, physical properties, etc., co-production with the same fracture properties can lead to fluid supply interference problems.

[0003] Meanwhile, the natural fractures associated with the reservoir and the artificial network fractures generated by volumetric fracturing together constitute an extremely complex multi-scale network system. After volumetric fracturing, the reservoir contains multiple pore systems, including matrix, natural fractures, and network fractures. Each system experiences different stress conditions and internal fluid flow patterns within the reservoir, collectively influencing the development effect of the oil well. Therefore, it is essential to comprehensively consider the impact of fluid flow in a multi-porous medium and clarify the changing patterns of the seepage field during the development of low-permeability reservoirs. Fracture network fracturing is currently the main technology for improving the development effect of low-permeability reservoirs. By establishing a three-dimensional combined fracture network of main fractures and branch fractures in thick reservoirs, the stimulation volume is increased, thereby improving the stimulation effect.

[0004] Currently, most hydraulic fracture modeling methods focus on two-dimensional fracture networks, lacking three-dimensional fracture network modeling methods. It is unclear what changes will occur in the seepage characteristics after forming large-volume complex branch fractures plus main fractures.

[0005] The prior art related to this invention:

[0006] (1) Hydraulic fracture modeling method based on microseismic observation

[0007] Low-permeability oil reservoirs require hydraulic fracturing for economical development due to their low reservoir permeability. After hydraulic fracturing, information such as fracture orientation and length can be determined through microseismic observation, thus characterizing the hydraulic fractures. However, this method generally only determines the approximate morphology of the fractures and cannot obtain information such as their conductivity. Therefore, in practical applications, it is necessary to combine production data to invert fracture information and predict well production dynamics.

[0008] (2) Unconventional oil and gas fracture modeling method based on fracture propagation

[0009] The development of natural fractures, brittleness, and heterogeneity in low-permeability reservoirs, along with fracturing control parameters during construction, collectively determine fracture propagation morphology. By introducing fracture extension and fracturing criteria, a dynamic finite element or discrete element model of fracture propagation can be constructed, enabling a more accurate characterization of the fluid-mechanical coupling properties and thus predicting fracturing fracture morphology. Based on this technology, Schlumberger developed the corresponding software UFM. However, this modeling method requires relevant geological parameters, which are often nondeterministic, affecting the fracture prediction accuracy of such models.

[0010] (3) Crack modeling method based on the concept of equivalence

[0011] Fracture modeling methods based on the equivalent concept are primarily proposed for cases where fracturing results in a stimulated volume. In this method, the focus shifts from the specific details of the fractures themselves to treating the fracturing zone as an equivalent high-conductivity seepage zone with similar permeability properties, exhibiting significant differences in properties compared to the unstimulated zone. Current models based on this approach include trilinear flow models, pentalinear flow models, and composite models. These methods typically treat the fracture network as a two-dimensional model, where both hydraulic fractures and stimulated zones traverse the entire reservoir. However, they are incapable of modeling complex three-dimensional fracture networks.

[0012] (4) Analytical / Semi-analytical solutions

[0013] The most common analytical model for volumetric fracturing horizontal wells is the linear flow model. Based on equivalent flow theory, it assumes a fracture shape and simplifies the flow within the fractures to linear or radial flow, treating the fracture network as a high-permeability zone. The number, volume, and permeability of this high-permeability zone characterize the fracture network. This model focuses on capturing the overall fracture network characteristics and flow morphology of the volumetric fracturing horizontal well. A semi-analytical model treats the complex fracture network as a system composed of many small fracture segments. It describes the complex fracture network structure by defining parameters such as the length, orientation, and conductivity of each segment. It couples matrix flow and internal fracture flow for each segment, then iteratively calculates the pressure and flow distribution of that segment to obtain the productivity contribution of a single fracture, thereby predicting the overall productivity of the fracturing horizontal well. Semi-analytical flow models include matrix flow models, internal fracture flow models, and the coupling of matrix flow and internal fracture flow; they can also consider flow and coupling issues within the wellbore. Semi-analytical methods have relatively complex preprocessing, require many model input parameters, and can only solve single-well, single-phase problems, thus having certain limitations.

[0014] (5) Numerical simulation methods

[0015] Compared to analytical / semi-analytical methods, numerical methods are more flexible and capable of handling more complex fracture networks. The DFN (Digital Fracture Network) model is currently widely used. This method simplifies the fracture network system into a multi-fracture or interlaced distribution, including three-dimensional wire mesh models, two-dimensional discrete models, and randomly distributed multi-fracture models. It explicitly defines the location, attitude, geometry, size, width, and porosity / permeability properties of each fracture within the simulation area. While the DFN model can accurately simulate fracture distribution near the well site, its accuracy in describing fractures far from the well site is poor, requiring the use of two-dimensional distribution maps of geological and seismic attributes to constrain the generation of the fracture model. Therefore, this simulation method is only suitable for areas with a large number of imaging wells, and not for areas with a small number of wells.

[0016] Currently, there is a lack of 3D fracture network modeling technology and 3D fracture network seepage models, resulting in unclear development and seepage patterns, which cannot meet the requirements of field fracturing design. The main problems are as follows: 1. Modeling: There is a lack of targeted 3D fracture network modeling methods. Current methods are mostly 2D models or have complex fracture characterization; 2. Physical model: A fully coupled seepage model of multi-stage fracturing fractures + branch fractures + main fractures + reservoir has not yet been established; 3. Fracture spatial structure: Current research focuses on 2D models, and there are few reports on the impact of 3D fracture networks on seepage; 4. Solution methods: Semi-analytical methods cannot be applied to complex fracture models, and numerical methods need to balance speed and accuracy; 5. Parameter optimization: Due to the lack of suitable fracture network analysis tools, it is impossible to quantitatively analyze the impact of parameters on well productivity, and parameters cannot be optimized.

[0017] Chinese patent application CN202011144919.X discloses a method and apparatus for optimizing well network deployment in unconventional oil and gas reservoirs. The method includes: constructing a geological model containing natural fractures for a study area; wherein the geological model containing natural fractures includes geostress parameters; performing integrated geological-engineering fracturing simulation of the study area based on the constructed geological model containing natural fractures and combining fracturing parameters already implemented in the study area to obtain a basic fracture network model; performing microseismic interpretation on wells already in production in the study area to obtain microseismic interpretation results; determining the unsteady flow analysis results of wells already in production in the study area using unsteady flow analysis methods through curve fitting and inversion based on well test data and daily production data; and calibrating the basic fracture network model based on the microseismic interpretation results and the unsteady flow analysis results to obtain a fracture network model for the study area.

[0018] Chinese patent application CN201811146295.8 discloses an optimization method for three-dimensional fracture network fracturing in tight oil horizontal wells, belonging to the field of tight oil exploration and development technology. This method first classifies fractures according to different morphologies; then characterizes parameters based on fracture distribution and development characteristics; derives equivalent permeability expressions for different fracture network morphologies; next, establishes theoretical models for the production capacity of different seepage fracture networks; calculates the impact of different fracture network morphologies on production capacity; and finally selects the optimal fracturing mode based on the analysis of factors affecting production capacity.

[0019] Chinese patent application CN201710689827.1 discloses a method for modeling and simulating multi-scale fracture networks in tight reservoirs. This method includes: Step 1, using a combination of the MINC model and SC mapping to divide the matrix into grids; Step 2, calculating the flow rate between nodes using quasi-steady-state flow; Step 3, performing dimensionality reduction on the large-scale fracture system using the flow equivalence principle; Step 4, simulating the fractures; and Step 5, solving and verifying the multi-scale complex fracture network model.

[0020] The existing technologies described above are significantly different from the present invention and have failed to solve the technical problem we want to address. Therefore, we have invented a new three-dimensional fracture network modeling and digital modeling integrated method based on the concept of integrated geological engineering. Summary of the Invention

[0021] The purpose of this invention is to provide a three-dimensional fracture network modeling and digital modeling method based on the concept of integrated geological engineering, which can meet the development needs of thick and tight oil reservoirs and provide corresponding technical support.

[0022] The objective of this invention can be achieved through the following technical measures: a three-dimensional fracture network modeling and digital modeling integrated method based on the integrated geological engineering concept, which includes:

[0023] Step 1: Determine the fracture development status of different fracturing sections based on reservoir geological characteristics and hydraulic fracturing microseismic observation data;

[0024] Step 2: Determine the main fracture morphology and the scale of the fracturing area for the corresponding fracturing segment based on the microseismic interpretation results of different segments;

[0025] Step 3: Establish a geological model including a three-dimensional fracture network;

[0026] Step 4: Discretize the geological model into a grid for regional movement;

[0027] Step 5: Establish complex mesh matching patterns;

[0028] Step 6: Construct a three-dimensional mesh seepage model;

[0029] Step 7: Mesh the seepage model and establish the corresponding solution method;

[0030] Step 8: Analyze the key parameters affecting seepage and analyze the impact of different parameters on well productivity.

[0031] The objective of this invention can also be achieved through the following technical measures:

[0032] In step 1, the fracture development status of different fracturing sections is determined based on reservoir geological characteristics and hydraulic fracturing microseismic observation data; the reservoir characteristics, development characteristics, fluid characteristics, and fracturing stimulation characteristics of the target area are analyzed, and geological model parameters are extracted; the fracture network development status of different sections after fracturing is analyzed.

[0033] In step 2, the main crack information includes crack length, direction, and flow capacity; the modified volume information includes modified volume scale and flow capacity.

[0034] In step 2, the orientation of the main fracture is determined through microseismic analysis, and the length and conductivity of the main fracture are determined through fracturing construction simulation. The scale and conductivity of the modified area are determined through microseismic observation and fracturing construction simulation.

[0035] In step 3, the geological model includes three regions: the matrix, the main fracture, and the modified area; the matrix system has the lowest permeability, followed by the modified area, and the main fracture has the highest permeability.

[0036] In step 3, in the absence of development in the modified area, the geological model includes two areas: the matrix and the main fracture.

[0037] In step 4, the geological model is discretized by regional meshing; during the discretization process, the mesh near the main fracture is refined; finally, a three-dimensional fracture with a realistic shape is constructed.

[0038] In step 4, a uniform grid system is used in the matrix region, while a grid refinement technique is used near the main crack. That is, the grid is divided according to the actual width of the main crack, and a larger grid is used when the grid is far away from the main crack.

[0039] In step 5, a complex fracture network matching mode is established, mainly establishing a coupling mode of hydraulic primary fracture-secondary fracture-reservoir system. During the coupling process, the permeability of different media should be considered, and the fluid flow direction is from matrix-secondary fracture-primary fracture-wellbore. The fluid flow is considered to be under isothermal conditions, and the fluid is a slightly compressible fluid. The fluid is considered to be a two-phase fluid of water and oil. Based on this, a new mathematical model is established.

[0040] In step 5, the new mathematical model is established as follows:

[0041] (1) Establish the governing equations

[0042] The mass conservation equation in the matrix is:

[0043]

[0044] The mass conservation equation in the crack is:

[0045]

[0046] Where φ is porosity; ρ is fluid density; q m- f represents the flow between the crack and the matrix; q m and q f Ω represents the source and sink terms in the matrix and cracks; t represents time; f and Ω m The fracture and matrix domains are represented by v; v is the flow velocity, m is the matrix, and f is the fracture.

[0047] Seepage satisfies formula (3):

[0048]

[0049] Where v is the flow velocity; μ is the fluid viscosity; k is the permeability; and p is the pressure.

[0050] From equations (1), (2), and (3), we can obtain the continuity equation for the solution domain:

[0051]

[0052] Q v and Q m-f,v Volume source or sink; B is the volume coefficient;

[0053] (2) Numerical simulation model establishment

[0054] By discretizing equation (4) using the finite volume method, we can obtain:

[0055]

[0056] Where the subscript i represents the mesh contact surface; the subscript G represents the mesh number; V b Represents the mesh volume; n represents the time step; d is the conductivity; A is the mesh contact area; d is the distance between the centers of adjacent meshes; Fluid properties were calculated using the harmonic averaging method. The arithmetic mean is used for calculation, where T is the conductivity and Q is the yield.

[0057] In step 6, reservoir parameters, fluid parameters, development parameters, and fracturing stimulation parameters are collected to construct a three-dimensional fracture network seepage model, thereby achieving coupling between the three-dimensional fracture network and the geological model.

[0058] In step 6, during the establishment of the numerical simulation model, the reservoir parameters collected include porosity, permeability, and saturation; fluid parameters include density, viscosity, and compressibility factor; development parameters include well production regime and pressure; fracturing parameters include fracture parameters and construction parameters; based on the collected data, geological models, PVT models, relative permeability models, fluid distribution models, temperature and pressure field models, and production dynamic models are established; the fracture parameters adopt the fracture interpretation results from step 1.

[0059] In step 7, during the numerical simulation model solution process, orthogonal meshes are used to mesh the fractures and reservoir, and mesh refinement technology is used near the fractures; the resulting nonlinear equations are solved using the Newton method.

[0060] In step 8, considering the characteristics of thick oil reservoirs, a physical model is established that can reflect the characteristic parameters of reservoir, fluid, development, and fracturing. The influence of various factors, including primary fracture parameters, secondary fracture parameters, and stimulation areas, on well production and the influence mechanism are studied, and the influence weight of different parameters on production capacity is analyzed.

[0061] This invention presents a three-dimensional fracture network modeling and numerical simulation integration method based on the integrated geological and engineering concept. This method can construct a realistic three-dimensional fracture seepage simulation, accurately characterize complex three-dimensional fracture morphology, and perform sensitivity analysis on parameters affecting production. It provides accurate characterization of complex three-dimensional fracture morphology and offers significant guidance for volumetric fracturing design. This invention fully leverages information from fracture seismic inversion, constrains fracture parameter interpretation models through microseismic events to ensure the accuracy of fracture parameters, and employs an advanced discrete fracture model in the flow simulation model to characterize fractures in different layers of segmented fracturing wells, fully considering the differences between fracture layers. This method has been applied in 20 wells in the Shengli tight oilfield, with production prediction results showing a high degree of agreement with field data, demonstrating significant potential for wider application. Attached Figure Description

[0062] Figure 1 This is a flowchart of a specific embodiment of the three-dimensional fracture network modeling and digital-simulation integration method based on the integrated geological engineering concept of the present invention;

[0063] Figure 2 This is a schematic diagram of the segmented fracturing microseismic observation results in a specific embodiment of the present invention;

[0064] Figure 3 This is a schematic diagram of a geological model considering only the main fracture and the matrix in a specific embodiment of the present invention;

[0065] Figure 4 This is a schematic diagram of a geological model considering three systems in a specific embodiment of the present invention;

[0066] Figure 5 This is a schematic diagram of the coupling between the primary hydraulic fracturing fracture, secondary fracture, and reservoir in a specific embodiment of the present invention.

[0067] Figure 6 This is a schematic diagram of the numerical simulation model establishment process in a specific embodiment of the present invention;

[0068] Figure 7 This is a schematic diagram of the numerical simulation model establishment process in a specific embodiment of the present invention;

[0069] Figure 8 This is a cumulative oil production curve diagram for different number of segments in a specific embodiment of the present invention;

[0070] Figure 9 This is a schematic diagram illustrating the pressure distribution simulated by different number of segments in a specific embodiment of the present invention;

[0071] Figure 10 This is a simulation result diagram of the propagation of four cracks in a specific embodiment of the present invention;

[0072] Figure 11 This is a schematic diagram of the modeling result of a four-segment fracturing three-dimensional fracture network in a specific embodiment of the present invention. Detailed Implementation

[0073] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0074] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0075] like Figure 1 As shown, Figure 1 This is a flowchart of the three-dimensional fracture network modeling and digital modeling integrated method based on the integrated geological engineering concept of the present invention. The three-dimensional fracture network modeling and digital modeling integrated method based on the integrated geological engineering concept includes:

[0076] Step 1: First, determine the fracture development status of different fracturing sections based on reservoir geological characteristics and hydraulic fracturing microseismic observation data;

[0077] Step 2: Determine the main fracture morphology and the scale of the modified area of ​​the corresponding fracturing segment based on the microseismic interpretation results of different segments.

[0078] The main fracture information includes fracture length, orientation, and flow conductivity, while the modified volume information includes modified volume size and flow conductivity.

[0079] Step 3: Establish a geological model containing a three-dimensional fracture network. The geological model includes three areas: matrix, main fracture, and modified area.

[0080] Step 4: Discretize the three regions into a grid, and refine the grid near the main crack during the discretization process.

[0081] Step 5: Establish a complex fracture network matching mode, mainly establishing a coupling mode of hydraulic primary fracture-secondary fracture-reservoir system;

[0082] Step 6: Collect reservoir parameters, fluid parameters, development parameters, and fracturing stimulation parameters, construct a three-dimensional fracture network seepage model, and achieve coupling between the three-dimensional fracture network and the geological model;

[0083] Step 7: Mesh the seepage model and establish the corresponding solution method;

[0084] Step 8: Analyze the key parameters affecting seepage and analyze the impact of different parameters on well productivity.

[0085] The following are several specific embodiments of the application of the present invention.

[0086] Example 1

[0087] In a specific embodiment 1 of the present invention, the three-dimensional fracture network modeling and digital modeling integrated method based on the concept of integrated geological engineering includes:

[0088] Step 1: First, determine the fracture development status of different fracturing sections based on reservoir geological characteristics and hydraulic fracturing microseismic observation data. Firstly, analyze the reservoir characteristics, development characteristics, fluid characteristics, and fracturing stimulation characteristics of the target area, and extract geological model parameters; secondly, analyze the fracture network development status of different sections after fracturing, such as... Figure 2 To obtain the microseismic results of the four segments after fracturing, analysis showed that the fracture orientations of the four segments were basically consistent. The microseismic signal points exhibited a long strip-shaped distribution, meaning the morphology of the modified volume can be assumed to be approximately rectangular.

[0089] Step 2: Based on the microseismic interpretation results of different segments, determine the morphology of the main fracture and the scale of the modified area for the corresponding fracturing segment. Main fracture information includes fracture length, orientation, and conductivity, while modified volume information includes modified volume size and conductivity. The orientation of the main fracture can be determined through microseismic analysis, and parameters such as the length and conductivity of the main fracture can be determined through fracturing construction simulation. The scale and conductivity of the modified area can be determined through microseismic observation and fracturing construction simulation.

[0090] Step 3: Establish a geological model incorporating a three-dimensional fracture network. The geological model includes three regions: matrix, main fracture, and modified zone. It also comprises three systems: the matrix system has the lowest permeability, followed by the modified zone, with the main fracture having the highest. In cases where the modified zone is underdeveloped, the geological model includes only the matrix and main fracture systems. For example... Figure 3 For a geological model considering only the main fracture and matrix, the fracture length is 100m, and the geological model area is 400m × 400m; Figure 4 To simultaneously consider the geological models of the three regions, the modified areas are distributed along the main fracture in a rectangular shape, corresponding to the microseismic results.

[0091] Step 4: Discretize the three regions using a grid, refining the grid near the main fracture during the discretization process. This ultimately constructs a three-dimensional fracture with a realistic morphology. The final step of the invention is to discretize the geological model using a rectangular grid, such as... Figure 3 and Figure 4 A uniform mesh system is used in the matrix region, while a mesh refinement technique is employed near the main fracture. This involves dividing the mesh according to the actual width of the main fracture, with larger mesh sizes used further away from it. Mesh refinement of the main fracture, the modified volume, and the matrix provides crucial information for subsequent flow simulations.

[0092] Step 5: Establish a complex fracture network matching model, mainly establishing a coupling model of hydraulic primary fractures-secondary fractures-reservoir system; such as... Figure 5 The vertical well traverses four sections longitudinally, each of which underwent hydraulic fracturing. The primary and secondary fracture morphologies differ in each section. Using a hydraulic fracturing fracture propagation model, the morphological characteristics of the primary and secondary fractures can be obtained, along with the conductivity of different fractures. During the coupling process, the permeability of different media should be considered, with the fluid flow direction being from the matrix to the secondary fractures, then to the primary fracture, and finally to the wellbore. Fluid flow is considered under isothermal conditions, with the fluid being a slightly compressible fluid, and the fluid being a two-phase mixture of water and oil. As described in the background section, existing discrete fracture simulation techniques cannot account for three-dimensional fracture networks. To address these technical issues, this application establishes the following mathematical model.

[0093] (1) Establish the governing equations

[0094] The mass conservation equation in the matrix is:

[0095]

[0096] The mass conservation equation in the crack is:

[0097]

[0098] Where φ is porosity; ρ is fluid density; q m-f For crossflow between cracks and matrix; q m and q f Ω represents the source and sink terms in the matrix and cracks; t represents time; f and Ω m For the crack and matrix domains.

[0099] Seepage satisfies formula (3):

[0100]

[0101] Where v is the flow velocity; μ is the fluid viscosity; k is the permeability; and p is the pressure.

[0102] From equations (1), (2), and (3), we can obtain the continuity equation for the solution domain:

[0103]

[0104] Q v and Q m-f,v Volume source or sink; B is the volume coefficient.

[0105] (2) Numerical simulation model establishment

[0106] By discretizing equation (4) using the finite volume method, we can obtain:

[0107]

[0108] Where the subscript i represents the mesh contact surface; the subscript G represents the mesh number; V b Represents the mesh volume; n represents the time step; d is the conductivity; A is the mesh contact area; d is the distance between the centers of adjacent meshes; Fluid properties were calculated using the harmonic averaging method. Calculate using the arithmetic mean.

[0109] Step 6: Collect reservoir parameters, fluid parameters, development parameters, and fracturing stimulation parameters to construct a three-dimensional fracture network seepage model, achieving coupling between the three-dimensional fracture network and the geological model. During the numerical simulation model establishment process, it is necessary to collect basic parameters that meet the simulation requirements, mainly including reservoir parameters (porosity, permeability, saturation, etc.), fluid parameters (density, viscosity, compressibility factor, etc.), development parameters (well production regime, pressure, etc.), and fracturing parameters (fracture parameters, construction parameters), etc. Based on the collected data, establish geological models, PVT models, relative permeability models, fluid distribution models, temperature and pressure field models, and production dynamic models, etc. Fracture parameters adopt the fracture interpretation results from Step 1. Figure 6 , which are the modules contained in the model.

[0110] Step 7: Mesh the seepage model and establish the corresponding solution method; during the numerical simulation model solution process, orthogonal meshes are used to mesh the fractures and reservoir, and mesh refinement technology is used near the fractures. The resulting nonlinear equations are solved using the Newton method.

[0111] Step 8: Analyze the key parameters affecting seepage and the influence of different parameters on well productivity. Considering the characteristics of thick reservoirs, establish a physical model that reflects the characteristic parameters of reservoir, fluid, development, and fracturing. Conduct research on the degree and mechanism of influence of various factors (primary fracture parameters, secondary fracture parameters, stimulated areas, etc.) on well production, and analyze the influence weight of different parameters on productivity. Finally, through dynamic analysis of reservoir pressure and well production, the seepage characteristics of the three-dimensional fracture network can be clarified.

[0112] Example 2

[0113] Figure 7 This study interprets the reservoir results of an oil well. The reservoir has a large vertical span, necessitating staged fracturing. Parameters for this well area are collected, and a corresponding 3D fracture network model is established. The well's production rate is shown to vary depending on the number of stages. Figure 8 , Figure 9 The diagram shows the pressure distribution in the study area for different numbers of fracturing stages. It can be seen that three-stage fracturing is more suitable for this well.

[0114] Example 3

[0115] Using the steps described in the invention, a three-dimensional fracture network model of a typical well in Shengli Oilfield was established. Figure 10 The image shows the simulation results of fracture propagation in section 4 of a well in the Shengli Oilfield. Based on the fracturing simulation results, relevant parameters of the main fracture and the stimulated volume were obtained, and a three-dimensional fracture network model was finally established. Figure 11 Left side: Geological model; Right side: Single-layer grid subdivision results.

[0116] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A three-dimensional fracture network modeling and digital modeling integrated method based on the integrated concept of geological engineering, characterized in that, This three-dimensional fracture network modeling and digital simulation integration method based on the integrated geological engineering concept includes: Step 1: Determine the fracture development status of different fracturing sections based on reservoir geological characteristics and hydraulic fracturing microseismic observation data; Step 2: Determine the main fracture morphology and the scale of the fracturing area for the corresponding fracturing segment based on the microseismic interpretation results of different segments; Step 3: Establish a geological model including a three-dimensional fracture network; Step 4: Discretize the geological model into a grid for regional movement; Step 5: Establish complex mesh matching patterns; Step 6: Construct a three-dimensional mesh seepage model; Step 7: Mesh the seepage model and establish the corresponding solution method; Step 8: Analyze the key parameters affecting seepage and analyze the impact of different parameters on well productivity; In step 5, a complex fracture network matching mode is established, mainly establishing a coupling mode of hydraulic primary fracture-secondary fracture-reservoir system; during the coupling process, the permeability of different media should be considered, and the fluid flow direction is from matrix-secondary fracture-primary fracture-wellbore; the fluid flow is considered to be under isothermal environment, the fluid is a slightly compressible fluid, and the fluid is considered to be a two-phase fluid of water and oil, and a new mathematical model is established based on this. In step 5, the new mathematical model is established as follows: (1) Establish the governing equations The mass conservation equation in the matrix is: The mass conservation equation in the crack is: in Porosity; For fluid density; This refers to the flow between the cracks and the matrix; and Source and sink terms in the matrix and cracks; For time; and The fracture and matrix domains are represented by v; v is the flow velocity, m is the matrix, and f is the fracture. Seepage satisfies formula (3): in v It is the flow velocity; μ It is the fluid viscosity; k It's penetration rate; p For pressure; From equations (1), (2), and (3), we obtain the continuity equation for the solution domain: in and Volume source or sink; This is the volume factor; (2) Numerical simulation model establishment The equation (4) is discretized using the finite volume method. Subscript Represents the mesh contact surface; subscript Represents the grid number; Represents the mesh volume; Represents a time step; For conductivity; This represents the contact area of ​​the grid. The distance between the centers of adjacent grid cells; Fluid properties were calculated using the harmonic averaging method. The arithmetic mean is used for calculation, where T is the conductivity and Q is the yield.

2. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 1, the fracture development status of different fracturing sections is determined based on reservoir geological characteristics and hydraulic fracturing microseismic observation data; the reservoir characteristics, development characteristics, fluid characteristics, and fracturing stimulation characteristics of the target area are analyzed, and geological model parameters are extracted; the fracture network development status of different sections after fracturing is analyzed.

3. The three-dimensional fracture network modeling and digital-simulation integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 2, the main crack information includes crack length, direction, and flow capacity; the modified volume information includes modified volume scale and flow capacity.

4. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 3, is characterized in that, In step 2, the orientation of the main fracture is determined through microseismic analysis, and the length and conductivity of the main fracture are determined through fracturing construction simulation. The scale and conductivity of the modified area are determined through microseismic observation and fracturing construction simulation.

5. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 3, the geological model includes three regions: the matrix, the main fracture, and the modified area; the matrix system has the lowest permeability, followed by the modified area, and the main fracture has the highest permeability.

6. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 3, in the absence of development in the modified area, the geological model includes two areas: the matrix and the main fracture.

7. The three-dimensional fracture network modeling and digital modeling method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 4, the geological model is discretized into a grid. During the discretization process, the mesh near the main crack is refined; Finally, a three-dimensional crack with a realistic shape is constructed.

8. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 7, characterized in that, In step 4, a uniform grid system is used in the matrix region, while a grid refinement technique is used near the main crack. That is, the grid is divided according to the actual width of the main crack, and a larger grid is used when the grid is far away from the main crack.

9. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 6, reservoir parameters, fluid parameters, development parameters, and fracturing stimulation parameters are collected to construct a three-dimensional fracture network seepage model, thereby achieving coupling between the three-dimensional fracture network and the geological model.

10. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 9, characterized in that, In step 6, during the establishment of the numerical simulation model, the reservoir parameters collected include porosity, permeability, and saturation; fluid parameters include density, viscosity, and compressibility factor; development parameters include well production regime and pressure; fracturing parameters include fracture parameters and construction parameters; based on the collected data, geological models, PVT models, relative permeability models, fluid distribution models, temperature and pressure field models, and production dynamic models are established; the fracture parameters adopt the fracture interpretation results from step 1.

11. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 7, during the numerical simulation model solution process, orthogonal meshes are used to mesh the fractures and reservoir, and mesh refinement technology is used near the fractures; the resulting nonlinear equations are solved using the Newton method.

12. The three-dimensional fracture network modeling and digital-model integration method based on the integrated geological engineering concept as described in claim 1, characterized in that, In step 8, considering the characteristics of thick oil reservoirs, a physical model is established that can reflect the characteristic parameters of reservoir, fluid, development, and fracturing. The influence of various factors, including primary fracture parameters, secondary fracture parameters, and stimulation areas, on well production and the influence mechanism are studied, and the influence weight of different parameters on production capacity is analyzed.

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