Compact conglomerate hydraulic fracture initiation and expansion simulation optimization method and system

Abstract

The invention discloses a compact conglomerate hydraulic fracture initiation and expansion simulation optimization method and system, and the method comprises the steps: based on a compact conglomerate physical model and a hydraulic fracture expansion fluid-structure interaction control equation, inserting a fracture expansion unit considering interface characteristics and a hydraulic fracture initiation expansion finite element criterion; establishing a hydraulic fracture propagation numerical model of the compact conglomerate; based on the dense conglomerate hydraulic fracture expansion numerical model, fracture initiation and expansion characteristic analysis of hydraulic fractures in the dense conglomerate considering interface characteristics is carried out, and a simulation analysis result is obtained; and the simulation analysis result serves as a theoretical basis for optimization of the hydraulic fracturing scheme of the compact conglomerate reservoir, the hydraulic fracturing scheme of the compact conglomerate reservoir is optimized, and the optimized hydraulic fracturing scheme of the compact conglomerate reservoir is obtained. The fracturing initiation and expansion simulation method of the hydraulic fracture in the compact conglomerate considering the interface characteristics is formed, and a theoretical basis is provided for optimization of a compact conglomerate reservoir hydraulic fracturing scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic fracturing simulation, and in particular to a method and system for simulating and optimizing the initiation and expansion of hydraulic fractures in dense conglomerate. Background Art

[0002] With the continued growth of global energy demand, the development of tight oil and gas resources has become a key focus of oil and gas exploration. Tight conglomerate reservoirs, due to their low permeability, poor overall physical properties, strong heterogeneity, lack of natural fractures, and complex lithofacies, cannot be economically and efficiently developed under conventional mining methods. Hydraulic fracturing is essential to create complex fracture networks to increase production. During horizontal well fracturing of tight conglomerate reservoirs, large horizontal biaxial in-situ stress differences, low natural fracture development, and complex gravel structures lead to difficulties in controlling fracture morphology, low fracture network complexity, and significant interfracture interference. Compared to typical reservoirs such as sandstone or shale, the interface between primary cement and gravel in tight conglomerates exhibits significant mechanical anisotropy, with interfacial strength differences reaching 2-3 orders of magnitude greater than that of the matrix rock. This unique interface structure results in hydraulic fracture initiation location prediction errors exceeding 40% and propagation path deviations exceeding 1.5 times the designed value, severely limiting the accuracy of fracturing design.

[0003] Commonly used numerical simulation methods for hydraulic fracturing include the finite element method (FEM), boundary element method (BEM), peridynamics, phase field method (DEM), and discrete element method (DEM). These methods have different application scenarios, but the four most commonly used numerical methods in hydraulic fracturing simulation are the FEM, BEM, DEM, and phase field method. The FEM, based on fracture mechanics, uses the fracture surface as the internal boundary of the computational cell and calculates the stress intensity factor (SIF) at the fracture tip using the mutual integration method. Combined with the maximum energy release rate criterion, the FEM determines the fracture propagation orientation and determines whether the fracture can continue to propagate. The BEM solves the governing equations for hydraulic fracturing by discretizing the boundaries, efficiently simulating the fracture initiation location and propagation path, and accurately calculating the SIF. It is particularly suitable for analyzing the interaction of multiple fractures in infinite domains or complex geometries. The DEM simulates the hydraulic fracturing process by modeling discrete elements, tracking the contact forces and motion between particles. It can characterize the dynamic propagation of fracture networks and the dynamics of interfacial fractures. It is suitable for analyzing discrete media such as rock, but its computational efficiency is relatively low. The phase field method describes the hydraulic fracturing process by introducing crack propagation order parameters, which can numerically characterize the bifurcation and merging behavior of complex fractures. By combining fracture mechanics and material deformation models, it can achieve high-precision simulation of dynamic fracture propagation under multi-field coupling, and has significant advantages in the analysis of multi-crack interactions in tight reservoirs.

[0004] However, the finite element method (FEM) struggles to represent the discrete characteristics of conglomerate interfaces due to its continuum assumption, leading to singularities in the element stiffness matrix and numerical divergence when cracks propagate along weak interfaces. The boundary element method (BEM) relies on Green's function integration, resulting in a significant computational burden in complex fracture networks and limited multi-field coupling modeling capabilities. While the discrete element method (DEM) can simulate particle breakage, its computational efficiency decreases exponentially with scale and it lacks a continuum-discrete medium coupling mechanism. The phase field method (Phase Field) requires a high-resolution mesh to capture crack details, resulting in high computational costs and strong sensitivity to material parameters. Its multi-physics coupling efficiency remains to be improved. Each method faces limitations in model assumptions and computational bottlenecks, requiring the integration of multi-scale algorithms to overcome these limitations. Furthermore, the interface between primary cement and gravel, prevalent in dense conglomerates, exhibits significant mechanical anisotropy, with interfacial strength differences reaching two to three orders of magnitude compared to that of the matrix rock. Currently, a comprehensive method for modeling the initiation and propagation of hydraulic fractures in dense conglomerates is lacking.

[0005] In view of this, this application is hereby filed. Summary of the Invention

[0006] To further clarify the impact of gravel on the local and macroscopic propagation of hydraulic fractures within the gravel, and to further characterize the distribution patterns of fractures at the reservoir scale, including the degree of inter-well, inter-segment, and inter-fracture stress interference, corresponding numerical simulation analysis was conducted. The present invention aims to provide a method and system for simulating and optimizing the initiation and propagation of hydraulic fractures in tight conglomerate rock. This invention provides a theoretical basis for optimizing hydraulic fracturing schemes in tight conglomerate reservoirs.

[0007] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate, the method comprising: Obtain pre-built tight conglomerate physical models and fluid-solid coupling governing equations for hydraulic fracture propagation; Based on the physical model of dense conglomerate and the fluid-solid coupling governing equations of hydraulic fracture propagation, a numerical model of hydraulic fracture propagation in dense conglomerate is established by inserting a fracture propagation unit that considers interface characteristics and a finite element criterion for hydraulic fracture initiation and propagation. Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the initiation and propagation characteristics of hydraulic fractures in dense conglomerate considering interface characteristics were analyzed, and simulation analysis results were obtained; The simulation analysis results are used as the theoretical basis for optimizing the hydraulic fracturing scheme for tight conglomerate reservoirs. The hydraulic fracturing scheme for tight conglomerate reservoirs is optimized to obtain the optimized hydraulic fracturing scheme for tight conglomerate reservoirs.

[0008] Furthermore, the dense conglomerate physical model uses the Monte Carlo method to randomly generate gravels, forming a dense conglomerate structure with a size of 0.3×0.3m; and a weak surface structure is formed between the dense conglomerate structure and the matrix part.

[0009] Furthermore, the fluid-solid coupling control equation for hydraulic fracture expansion is affected by pore pressure, and the equation is expressed as follows:

[0010] Where, ρ is the rock density; is the total compressibility of the fluid-saturated rock; P is the pore pressure; km is the rock permeability; is the fluid viscosity; Q is the mass flow rate in the rock medium; is the rate of change of pressure over time; is the divergence.

[0011] Furthermore, based on the numerical model of hydraulic fracture propagation in dense conglomerate, the initiation and propagation characteristics of hydraulic fractures in dense conglomerate were analyzed taking into account interface characteristics. The simulation analysis results include: Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the fracture initiation and extension morphology were simulated, and the failure mode of dense conglomerate rock slab was analyzed to obtain the first simulation analysis results; Based on the numerical model of hydraulic fracture propagation in dense conglomerate, under different interface tensile strength conditions, the second simulation analysis result was obtained by simulating the hydraulic fracture propagation through the conglomerate when the interface tensile strength was increased to different values. Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the effects of gravels of different sizes on hydraulic fracture propagation were simulated to obtain the third simulation analysis results; Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the influence of different fracture toughness on hydraulic fracture propagation was simulated, and the fourth simulation analysis result was obtained.

[0012] Furthermore, the crack initiation and extension morphology are simulated, and the failure mode of the dense conglomerate slab is analyzed, including: When the injection condition is the first preset displacement, the hydraulic fracture encounters a gravel during the initiation and expansion process and expands around the gravel; When the injection condition is the second preset flow rate, two fractures are generated based on the simulation calculation of the tight conglomerate hydraulic fracture propagation numerical model: one fracture is the main fracture. When the main fracture propagates downward, it encounters a gravel and continues to extend downward around the gravel to the lower boundary of the tight conglomerate hydraulic fracture propagation numerical model. The fracture stops extending and the model calculation ends. The other fracture is the main fracture. When it propagates downward, it encounters the first gravel, turns right around the gravel, and continues to extend to the right boundary of the model. The second preset displacement is greater than the first preset displacement.

[0013] Furthermore, under different interface tensile strength conditions, the hydraulic fracture propagation through gravel is simulated when the interface tensile strength increases to different values ​​in sequence, including: When the interfacial tensile strength reaches the first preset strength, the hydraulic fracture initiates along the direction of the maximum horizontal principal stress from the left injection point. During the expansion process, the front section mainly expands almost horizontally between the particles. When encountering a gravel with a diameter of the first preset diameter, the fracture expands from the left side of the gravel upward around the interface between the gravel and the matrix to the right side of the gravel, stops expanding around the gravel, and continues to expand parallel to the direction of the maximum horizontal principal stress. When the interface tensile strength increases to the second preset strength, the hydraulic fracture propagates from the left side parallel to the direction of the maximum horizontal principal stress, penetrates the small-sized gravel at the second preset diameter, and continues to extend in an almost horizontal direction to the gravel with the first preset diameter. A slight turn occurs at the interface, and the fracture propagates along the bottom of the gravel and then continues to propagate horizontally. When the interfacial tensile strength continues to increase to the third preset strength, the hydraulic fracture completely penetrates the gravel and extends in a direction parallel to the direction of the maximum horizontal principal stress.

[0014] Furthermore, the hydraulic fracturing scheme for tight conglomerate reservoirs is optimized, including: The relevant formation parameters and fracturing operation parameters of tight conglomerate reservoirs were input into the tight conglomerate hydraulic fracture propagation numerical model to analyze the competitive propagation morphology of multiple fractures in tight conglomerate reservoirs. The analysis of multi-fracture competition expansion morphology includes the influence of different reservoir elastic moduli, different reservoir horizontal stress differences, different reservoir permeabilities and different reservoir construction displacements on the expansion of hydraulic fractures.

[0015] Furthermore, the method further comprises: The established tight conglomerate hydraulic fracture propagation numerical model is verified. If the model accuracy meets the preset requirements, the model verification is completed.

[0016] In a second aspect, the present invention provides a system for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate rock, the system comprising: An acquisition unit for acquiring a pre-built tight conglomerate physical model and a fluid-solid coupling governing equation for hydraulic fracture propagation; A numerical model building unit is used to establish a numerical model of hydraulic fracture propagation in dense conglomerate based on the physical model of dense conglomerate and the fluid-solid coupling governing equations of hydraulic fracture propagation. The numerical model is then inserted into the fracture propagation unit that considers interface characteristics and the finite element criterion for hydraulic fracture initiation and propagation. A simulation analysis unit is used to analyze the initiation and propagation characteristics of hydraulic fractures in dense conglomerate taking into account interface characteristics based on a numerical model of hydraulic fracture propagation in dense conglomerate, and obtain simulation analysis results; The scheme optimization unit is used to use the simulation analysis results as the theoretical basis for optimizing the hydraulic fracturing scheme of the tight conglomerate reservoir, optimize the hydraulic fracturing scheme of the tight conglomerate reservoir, and obtain the optimized hydraulic fracturing scheme of the tight conglomerate reservoir.

[0017] In a third aspect, the present invention further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-mentioned method for simulating and optimizing the initiation and expansion of hydraulic fractures in dense conglomerate.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method and system for simulating and optimizing the initiation and expansion of hydraulic fractures in dense conglomerate. The system further clarifies the influence of gravel on the local expansion of hydraulic fractures in gravel and the macroscopic expansion of fractures, and deeply describes the distribution patterns of fractures between wells, between sections, and between fractures at the reservoir scale, as well as the degree of stress interference between fractures, and conducts corresponding numerical simulation analysis. The present invention forms a set of simulation methods for the initiation and expansion of hydraulic fractures in dense conglomerate that takes into account interface characteristics, providing a theoretical basis for optimizing hydraulic fracturing schemes for dense conglomerate reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 This is a flow chart of a method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to the present invention; Figure 2 This is a detailed flow chart of a method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to the present invention; Figure 3 Schematic diagram of the physical model of dense conglomerate of the present invention; Figure 4 Schematic diagram of crack propagation criterion of the extended finite element method of the present invention; Figure 5 This is a crack opening displacement-load curve diagram of the physical experiment and numerical simulation of the present invention; Figure 6 This is a comparison diagram of the experimental crack extension morphology and the numerically calculated crack morphology under the conditions of unilateral injection with different displacement rates of the present invention; Figure 7 The crack extension morphology of different interface tensile strengths of the present invention; Figure 8 The effect of gravels of different sizes on the expansion of hydraulic fractures in the present invention; Figure 9 The effect of fracture toughness on hydraulic fracture propagation in the present invention, (a) crack propagation morphology, (b) stress distribution area; Figure 10 Schematic diagram of the two-dimensional hydraulic fracture propagation of the present invention, (a) intra-segment multi-cluster fracture propagation model, (b) inter-segment fracture propagation model; Figure 11 The hydraulic fracture extension morphologies under different formation elastic moduli of the present invention are (a) elastic modulus 16.35 GPa, (b) elastic modulus 24.35 GPa, and (c) elastic modulus 32.35 GPa. Figure 12 The crack propagation morphologies under different stress difference conditions of the present invention are: (a) horizontal biaxial stress difference of 1 MPa, (b) horizontal biaxial stress difference of 13 MPa, and (c) horizontal biaxial stress difference of 20.25 MPa. Figure 13 The fracture morphology under different formation permeability conditions of the present invention, (a) 0.1mD fracture expansion morphology, (b) 1mD fracture expansion morphology, (c) 10mD fracture expansion morphology; Figure 14 The crack expansion morphology under different displacement conditions of the present invention, (a) 12m 3 / min, (b) 15m 3 / min; Figure 15 This is a structural block diagram of a system for simulating and optimizing the initiation and expansion of hydraulic fractures in dense conglomerate according to the present invention. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0021] Traditional numerical simulation methods, based on the assumption of an equivalent continuum medium, treat conglomerate as a homogenized material, failing to effectively characterize the discrete characteristics of the gravel-cement interface. Although the discrete element method (DEM) can simulate the interface fracture process, its computational efficiency is difficult to meet engineering scale requirements, and it lacks a description of the coupling mechanism between the macroscopic seepage field and the microscopic fracture. The finite element method (FEM) faces the problem of singular element stiffness matrices when dealing with interface problems. In particular, when cracks propagate along weak interfaces, the calculation results show obvious numerical divergence. Although the cohesive zone model (CZM) developed in recent years can characterize the evolution of interface damage, it still suffers from directional selectivity bias in predicting the propagation path of randomly distributed microcracks in conglomerate.

[0022] Therefore, the present invention first uses the extended finite element method to describe the steering and propagation of hydraulic fractures. Using cohesive elements (a special element type in finite element analysis (FEA) specifically used to simulate interface separation and crack propagation), the paper describes the bonding strength between the rock matrix and gravel (bond strength refers to the adhesion between mineral particles within the rock or between fillers and the rock wall in rock mass structural surfaces), and its influence on the propagation of hydraulic fractures through / around gravel. This paper establishes a numerical model for hydraulic fracture propagation in tight conglomerate rock, and clarifies the main controlling factors of the propagation morphology of multi-segment and multi-cluster fractures in a single well and the interference between fractures. Combined with a multi-well fracturing model (a numerical model used to simulate and analyze hydraulic fracturing operations in multiple wells (usually horizontal wells) simultaneously or sequentially), the paper reveals the propagation morphology of inter-well fractures in tight conglomerate rock under different fracturing sequences. This paper then develops a simulation method for the initiation and propagation of hydraulic fractures in tight conglomerate rock that takes interface characteristics into account, providing a theoretical basis for optimizing hydraulic fracturing schemes for tight conglomerate reservoirs.

[0023] Specifically, the present invention first requires the establishment of a numerical model for hydraulic fracture propagation in dense conglomerate, including constructing a dense conglomerate physical model, establishing the fluid-solid coupling control equation for hydraulic fracture propagation, inserting a fracture propagation unit that considers interface characteristics, and proposing a finite element criterion for hydraulic fracture initiation and propagation. Secondly, after the establishment of the numerical model for hydraulic fracture propagation in dense conglomerate is completed, the accuracy of the numerical model must be verified. Only numerical models that meet the required accuracy can serve as the basis for further analysis. After the model is verified, the initiation and propagation of hydraulic fractures in dense conglomerate that considers interface characteristics are analyzed, including the analysis of the initiation and extension morphology of dense conglomerate fractures, as well as the influence of different interface tensile strengths, gravel sizes, and fracture toughness on hydraulic fracture propagation. Finally, the above simulation results are used as the theoretical basis for optimizing the hydraulic fracturing scheme for dense conglomerate reservoirs, and the hydraulic fracturing scheme for dense conglomerate reservoirs is optimized. After inputting the relevant formation parameters and fracturing operation parameters of the tight conglomerate reservoir into the numerical model, an analysis of the competitive expansion morphology of multiple fractures in the tight conglomerate reservoir was carried out, including the influence of different reservoir elastic moduli, horizontal stress differences, permeability and operation displacement on the expansion of hydraulic fractures. Finally, the optimized hydraulic fracturing scheme for the tight conglomerate reservoir was formed based on the simulation analysis results.

[0024] The key technical points of the present invention are as follows: (1) Numerical model of hydraulic fracture propagation in dense conglomerate Numerical simulation of long horizontal well fracturing involves a porous media-fluid-solid coupled mechanics problem. The initiation and propagation of hydraulic fractures in reservoirs encompass multiple issues, including rock failure and deformation, fracture extension, fracturing fluid flow and filtration within the fractures, and downhole flow distribution. Gravel causes local stress concentrations, interfering with the direction of hydraulic fracture propagation. Therefore, an extended finite element method was employed to account for the diversion of hydraulic fractures. To account for the bond strength between the rock matrix and the gravel surface, cohesive elements were used to describe the contact surface between the gravel and the rock matrix. This deepened the understanding of the impact of gravel on hydraulic fracture propagation and further investigated the propagation of hydraulic fractures between wells, segments, and fractures in tight conglomerate reservoirs. Ultimately, a numerical model for hydraulic fracture propagation in tight conglomerate reservoirs was developed.

[0025] (2) The influence of different gravel characteristics on the propagation morphology of hydraulic fractures The authors describe the initiation and propagation behavior of hydraulic fractures under varying conditions of interfacial tensile strength, gravel particle size, and fracture toughness. Interfacial tensile strength significantly influences whether hydraulic fractures propagate locally around the gravel. When the interfacial tensile strength is less than 1.35 MPa, the fractures locally propagate around the gravel. When the interfacial tensile strength is between 1.35 and 2.7 MPa, the fractures primarily penetrate the gravel in gravels with a median particle size less than 10 mm. When the interfacial tensile strength is greater than 2.7 MPa, the fractures locally propagate through the gravel.

[0026] Gravel size alters the support type of dense conglomerate. When the gravel size is greater than 10 mm, the deflection angle caused by crack propagation around the gravel decreases as the gravel centerline deviates from the matrix model centerline. The larger the gravel size, the larger the initial deflection angle around the gravel. After the propagation around the gravel ends, the crack continues to propagate parallel to the direction of the maximum horizontal principal stress, with a deflection angle of 0°. Therefore, gravel diameter and gravel distribution only affect the local crack direction within the gravel and have no effect on the macroscopic crack extension direction.

[0027] The fracture toughness of gravel has a great influence on the local propagation of cracks through / around gravel. As the fracture toughness of gravel increases, the cracks transform from local penetration through gravel to local around gravel.

[0028] Example 1 like Figure 1 As shown, the present invention provides a method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate, the method comprising: Step 1: Obtain a pre-built tight conglomerate physical model and the fluid-solid coupling governing equations for hydraulic fracture propagation; Step 2: Based on the tight conglomerate physical model and the fluid-solid coupling governing equations for hydraulic fracture propagation, a numerical model for hydraulic fracture propagation in tight conglomerate is established by inserting a fracture propagation unit that considers interface characteristics and a finite element criterion for hydraulic fracture initiation and propagation. Step 3: Based on the numerical model of hydraulic fracture propagation in dense conglomerate, analyze the initiation and propagation characteristics of hydraulic fractures in dense conglomerate taking into account interface characteristics to obtain simulation analysis results; Step 4: Using the simulation analysis results as a theoretical basis for optimizing the hydraulic fracturing scheme for the tight conglomerate reservoir, the hydraulic fracturing scheme for the tight conglomerate reservoir is optimized to obtain an optimized hydraulic fracturing scheme for the tight conglomerate reservoir.

[0029] In this embodiment, since the actual formation gravel is an irregular ellipsoid, it is not conducive to numerical calculation and meshing. In order to improve the meshing accuracy and reduce the amount of calculation, the gravel is set as an ideal sphere. The dense gravel physical model uses the Monte Carlo method to randomly generate gravel to form a dense gravel structure with a size of 0.3×0.3m; wherein, the gravel particle size is defined in the interval (30~50mm), and the particle size distribution is consistent with the actual formation particle size distribution; the thickness of the weak surface structure between the dense gravel structure and the matrix part is defined as 0.5mm. The two-dimensional numerical model of dense gravel (i.e., the dense gravel physical model) is as follows Figure 3 As shown, Figure 3 The middle green area represents the matrix of dense conglomerate, the blue area represents the dense gravel structure, and the red area represents the weak surface structure. The gravel content is 43.2%, which is basically consistent with the reservoir gravel content.

[0030] In this embodiment, the pre-constructed fluid-solid coupling control equation for hydraulic fracture expansion is as follows: A porous medium saturated with fluid can be represented as: (1) Where, σ is the stress, Pa; is strain, dimensionless; σ 0 represents the initial stress, Pa; C is the matrix stiffness, Pa; is the Biot coefficient, dimensionless, P is the pore pressure, Pa; P0 is the initial pore pressure, Pa; I is a unit diagonal matrix and is dimensionless.

[0031] The strain tensor of rock can be expressed in terms of displacement as: (2) Where, u is the displacement vector, m.

[0032] The energy conservation equation for porous media is: (3) In formula (3), ρ is the rock density, ; g is the acceleration due to gravity, .

[0033] The fluid flow control equation is affected by the pore pressure, and the fluid-solid coupling control equation for hydraulic fracture expansion can be expressed as: (4) (5) Where, ρ is the rock density; is the total compressibility coefficient of saturated fluid rock, ; P is the pore pressure; km is the rock permeability, ; is the rock porosity, dimensionless; cm is the rock skeleton compression coefficient, dimensionless; Q is the mass flow rate in the rock medium, ; is the fluid viscosity; Q is the mass flow rate in the rock medium; is the rate of change of pressure over time; is the divergence.

[0034] Taking rock deformation into account, the fluid flow formula can be expressed as: (6) Where, is the rock volume strain, dimensionless; k is the rock skeleton bulk modulus, Pa.

[0035] When the crack extends to the interface, it is necessary to insert a cohesive unit locally to characterize the interface bonding strength. When the rock does not break locally, it is controlled by the traction-displacement law. Figure 4 It can be seen that the maximum tensile stress of the material is the critical point. When the material is not damaged, the tensile stress has not reached the maximum tensile stress, and the material is in the linear elastic change region; when the maximum tensile stress is reached, as the tensile stress continues to increase, the material enters the damage degradation stage, that is, the stiffness of the rock body unit begins to degrade.

[0036] In the initial stage of rock cracking, according to the maximum principal stress criterion, the maximum principal stress ratio is f as follows: (7) Where, is the maximum principal stress borne by the material, MPa; The Macaulay brackets indicate that the cohesive element will not fail under pure compressive stress. is the rated principal stress, MPa.

[0037] When the rock body is in the stiffness damage stage, the material normal traction T can be expressed as: (8) Where, K o is the initial stiffness of rock material, Pa; δ is the displacement during loading, m; δ max is the maximum displacement during loading, m; δ 0. δ f are the displacements at initial damage and complete destruction, m; damage variable D is a scalar that represents the overall damage of the material and is expressed as: (9) The comparison between the external load P and crack opening displacement curve obtained by experiment and the external load P and crack opening displacement curve obtained by numerical simulation is shown in Figure 2. Figure 5. The results show that the curve of unilateral load P and crack opening displacement further clarifies that the accuracy of the two-dimensional crack extension numerical model calculation is highly consistent with the experimental crack extension results, thereby verifying the accuracy of the numerical model. When the experimental load P reaches 4500N, the opening of the plate crack reaches 0.2mm; when the load P in the numerical model reaches 4500N, the crack opening displacement reaches 0.15mm. The crack opening error between the two does not exceed 5%. Subsequently, the slope of the crack opening displacement curve of the experiment and the numerical model decreases synchronously with the decrease of load P, and the crack opening gradually increases. Since the calculation model is a two-dimensional crack extension numerical model and the experiment is a three-dimensional physical model experiment, there is a certain deviation in the process of calculating crack extension, but the deviation is within the allowable range of engineering.

[0038] In this embodiment, based on the numerical model of hydraulic fracture propagation in dense conglomerate, the initiation and propagation characteristics of hydraulic fractures in dense conglomerate are analyzed taking into account the interface characteristics. The simulation analysis results obtained include: (1) Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the fracture initiation and extension morphology were simulated, and the failure mode of dense conglomerate slab was analyzed to obtain the first simulation analysis results; (2) Based on the numerical model of hydraulic fracture propagation in dense conglomerate, under different interface tensile strength conditions, the hydraulic fracture propagation through the conglomerate was simulated with the interface tensile strength increasing to different values ​​in sequence, and the second simulation analysis results were obtained; (3) Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the effects of gravels of different sizes on hydraulic fracture propagation were simulated to obtain the third simulation analysis results; (4) Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the influence of different fracture toughness on the propagation of hydraulic fractures was simulated to obtain the fourth simulation analysis result.

[0039] Specifically, based on the numerical model of hydraulic fracture propagation in dense conglomerate (single-side injection), the fracture initiation and extension morphology are simulated, and the failure mode of dense conglomerate slab is analyzed. The fracture propagation morphology under the first preset displacement (2ml / min) and the second preset displacement (5ml / min) conditions is shown in Figure 6 The hydraulic fracture propagates around the gravel in the local area. The gravel is randomly distributed in the model, and the number of gravels encountered by the fracture varies when it propagates along different paths. This includes: When the injection rate was 2 ml / min, simulations based on a numerical model of hydraulic fracture propagation in dense conglomerate (single-sided injection) revealed that the hydraulic fracture encountered a gravel during initiation and propagation, and then expanded around it. Comparison with the single-sided crack propagation morphology in rock slabs under the same injection conditions revealed that the fracture expanded around the larger gravel when encountering it.

[0040] When the injection rate was 5 ml / min, two fractures were generated based on the numerical model of hydraulic fracture propagation in tight conglomerate rock. One fracture was a main fracture, which encountered a gravel during its downward expansion and continued to extend downward around the gravel until it reached the lower boundary of the numerical model. The fracture stopped extending and the model calculation ended. The other fracture was a main fracture, which encountered the first gravel during its downward expansion and turned right around the gravel before continuing to the right boundary of the model. Comparison with the single-sided fracture propagation experiment under the 5 ml / min injection rate showed that hydraulic fracturing produced two fractures around the gravel: a tensile fracture caused by tensile failure and a shear fracture caused by shear failure that connected to the tensile fracture.

[0041] In this embodiment, under different interface tensile strength conditions, the hydraulic fracture propagation through gravel is simulated when the interface tensile strength is increased to different values. The numerical simulation results of the single-side injection fracture propagation under different interface tensile strength conditions are shown in Figure 2. Figure 7 As shown. Includes: When the interfacial tensile strength is 0.45 MPa, the hydraulic fracture starts from the injection point on the left side along the direction of the maximum horizontal principal stress. During the expansion process, the front section mainly expands almost horizontally between the particles. When encountering a gravel with a diameter of 10 mm, it expands from the left side of the gravel upward around the interface between the gravel and the matrix to the right side of the gravel, stops expanding around the gravel, and continues to expand parallel to the direction of the maximum horizontal principal stress. When the interfacial tensile strength increases to 1.35 MPa, the hydraulic fracture propagates from the left side parallel to the direction of maximum horizontal principal stress, penetrating the 7 mm small-size gravel. It then continues in a nearly horizontal direction to the 10 mm gravel, where it undergoes a slight deflection at the interface. The fracture propagates along the gravel base before continuing horizontally. Notably, for the same 10 mm gravel, the increased interfacial tensile strength changes the pattern of crack propagation within that particular gravel. Under low tensile strength conditions, the crack propagates completely around the gravel. When the tensile strength increases, the crack still tends to propagate around the gravel surface, leading to a slight downward deflection of the hydraulic fracture. However, due to the concentrated hydraulic energy at the interface, tensile failure occurs at the interface, and the hydraulic fracture tip extends beyond the gravel surface. As the hydraulic energy continues to increase, the fracture propagates slightly through the gravel at the gravel base.

[0042] When the interfacial tensile strength continues to increase to 2.70 MPa, the hydraulic fractures completely penetrate the gravel and extend in a direction parallel to the direction of the maximum horizontal principal stress.

[0043] Based on the propagation morphology of hydraulic fractures, the propagation stages of hydraulic fractures in the numerical simulation of two-dimensional dense conglomerate considering the interface structure can be divided into the following parts: (1) the horizontal propagation stage of the fracture within the matrix; (2) the fracture tip encountering the interface structure; (3) the fracture tip blunting stage; (4) the stage of local gravel around / through the gravel; and (5) the stage of continued horizontal propagation of the fracture within the matrix. It can be seen that the interface structure will affect the crack propagation path locally at the gravel edge, but will not change the macroscopic extension trend of the fracture.

[0044] Figure 8 Figure 3 shows the effect of gravel of different sizes on hydraulic fracture propagation. When the gravel size is 10 mm, the small gravel size and high gravel content result in a large number of gravels encountered during hydraulic fracture propagation. As the gravel size increases, the hydraulic fracture gradually shifts from primarily propagating through the gravel to propagating around the gravel. When the gravel size reaches 30 mm, the fracture deflects when encountering gravel during the initial initiation and propagation phase. After propagating around the gravel to the lower surface of the gravel, the hydraulic fracture continues to propagate in the direction of maximum horizontal principal stress. When the particle size increases to 50 mm, the number of gravel particles in the model is reduced to two, and the gravel is staggered, causing the fracture to propagate in a straight line around the gravel in the direction of maximum horizontal principal stress.

[0045] Figure 9 is the effect of fracture toughness on hydraulic crack expansion. When the hydraulic fracture extends through the gravel in a straight line along the direction of the maximum horizontal principal stress, the difficulty of hydraulic fracture extending through the gravel gradually increases with the increase of fracture toughness. When the hydraulic fracture only penetrates the gravel slightly along the top of the gravel. Since the hydraulic fracture dissipates a lot of energy when penetrating the gravel, after the penetration is completed, the hydraulic fracture will eventually expand along the direction of the maximum horizontal principal stress. When the cracks do not penetrate the gravel, they expand locally around the gravel at the top of the gravel and then continue to expand horizontally. Figure 9 (b) shows the regional stress distribution during the hydraulic fracture propagation process. This regional stress distribution indicates that as fracture toughness increases, the ability of the hydraulic fracture to penetrate the gravel decreases during the initial stage. As the fracture propagates around the gravel, stress concentrates at the gravel's edge.

[0046] In this embodiment, the hydraulic fracturing scheme for the tight conglomerate reservoir is optimized, including: The relevant formation parameters and fracturing operation parameters of tight conglomerate reservoirs were input into the tight conglomerate hydraulic fracture propagation numerical model to analyze the competitive propagation morphology of multiple fractures in tight conglomerate reservoirs. The analysis of multi-fracture competition expansion morphology includes the influence of different reservoir elastic moduli, different reservoir horizontal stress differences, different reservoir permeabilities and different reservoir construction displacements on the expansion of hydraulic fractures.

[0047] In this embodiment, the method further includes: The established tight conglomerate hydraulic fracture propagation numerical model is verified. If the model accuracy meets the preset requirements, the model verification is completed.

[0048] In the specific implementation, a certain well was taken as the research object to explore the main controlling factors affecting the expansion of hydraulic fractures between segments (model 1) and between fracture segments (model 2), such as Figure 10 The design displacement is 10-12 m³ / min, the fracturing section length is 89 m, and the basic simulation adopts a three-cluster fracture expansion method with a fracture spacing of 29 m.

[0049] Figure 11 These are simulation results for different elastic moduli in a tight conglomerate reservoir. Three fractures, HF1, HF2, and HF3, extend parallel to the direction of maximum horizontal principal stress. When the elastic modulus is 16.35 GPa, the three fractures extend symmetrically, with a single-sided fracture pattern forming an "M" shape. The average width of the three fractures is 0.83 mm, and the lengths from left to right are 62.5 m, 43.8 m, and 64.3 m, respectively. Fractures HF1 and HF3 on either side extend outward in a crescent-shaped pattern. The fracture tip extension direction and the center fracture extension direction are mutually exclusive. The pore pressure field in the stimulated area is limited, confined to the fracture perimeter. When the elastic modulus is increased to 24.35 GPa, the fracture lengths from left to right are 75.36 m, 53.3 m, and 73.6 m, respectively, with a width of 0.79 mm. The overall fracture width shows little significant change. The curvature of the fractures on either side changes more significantly, especially as the fracture tips extend farther apart. The reservoir pore pressure changes significantly along the midline of the fracture, and the fracturing stimulation range is somewhat expanded compared to the conditions under a formation elastic modulus of 16.35 GPa. When the elastic modulus increases to 32.35 GPa, the fracture length increases to 83.5 m, 63.7 m, and 87.6 m, respectively. The overall fracture width decreases to 0.62 mm. In general, as the elastic modulus of tight conglomerate increases, the extension length of the hydraulic fracture increases. However, the repulsion of the central fracture from the adjacent fractures also increases, resulting in increased deflection and decreased fracture width.

[0050] Figure 12 The simulation results of different horizontal stress differences in tight conglomerate reservoirs are shown in Figure 2. Figure 12 (b) with reference to, Figure 12(a) is the fracture extension curve when the horizontal stress difference is 1 MPa. The calculated fracture lengths are 32.5 m, 20.6 m, and 36.5 m from left to right, and the fracture width is only 0.24 mm. The effect of the fracture on the pore pressure around the formation is much smaller than that when the horizontal biaxial stress difference is 13 MPa. The deflection angles of HF1 and HF3 fractures are large. When the horizontal biaxial stress difference reaches Figure 12 (c) At 20.25 MPa, the fracture length increases significantly, reaching 91.2 m, 65.7 m, and 93.4 m, respectively. The fracture deflection angle decreases significantly, and the fracture extends significantly along the direction of maximum horizontal stress. The fracture width at this point is 1.2 mm. As the horizontal biaxial stress difference increases, the pore pressure in the reservoir also increases, and the concentrated pore pressure distribution area increases from the fracture tip to both sides of the fracture.

[0051] Figure 13 The following are simulation results for different tight conglomerate reservoir permeabilities. Permeability affects the rate of fracturing fluid loss into the reservoir, thus changing the time it takes for the net pressure in the fracture to increase. Figure 13 (a) and (c) compare the fracture propagation morphology under two extreme conditions. Under a permeability of 0.1 md, the formation fracture width is 0.23 mm; under a permeability of 10 md, the fracture width is 1.5 mm. When the reservoir permeability is low, the fluid's penetration rate into the formation is slow, and the pore pressure is concentrated in the fractures around the wellbore perforations. Under a permeability of 0.1 md, the high pore pressure generated by the fracturing fluid is concentrated near the injection point. As the reservoir permeability increases, the high pore pressure generated by the fracturing fluid shifts from the center of the fracture near the injection point toward the fracture tip, and the range of high pore pressure caused by the fracturing fluid continues to expand.

[0052] Figure 14 The simulation results are shown in Figure 2. The simulation results are based on three commonly used displacement rates in the field, namely .in The crack expansion morphology and pore pressure distribution under the conditions are shown in Figure 11 (a) shown. The fracture extension morphology and pore pressure distribution under the displacement condition are shown in Figure 14 Based on the understanding of how horizontal biaxial stress differences in reservoirs affect fracture propagation, under the same geological conditions, a greater pumping rate increases fracture length and width. Under the conditions of 29m cluster spacing and uniform injection between clusters, a greater pumping rate increases the degree to which the central fracture repel the adjacent fractures. When , the deflection angle of the cracks on both sides is 9°; When , the deflection angle of the cracks on both sides is 10°; When the hydraulic fractures were applied, the deflection angles of the fractures on both sides reached 13°. Increasing the pumping rate not only increased the distribution of higher pore pressure in the reservoir, but also enhanced the connectivity between the fractures. The hydraulic fractures' reach in the formation continued to increase, improving the reservoir's permeability.

[0053] The present invention: (1) Based on the established numerical model of hydraulic fracture propagation in dense conglomerate, an extended finite element method is used to consider the direction of hydraulic fractures; to consider the bonding strength between the rock matrix and the gravel surface, a cohesive unit is used to describe the contact surface between the gravel and the rock matrix, and the degree of influence of gravel on the propagation of hydraulic fractures is further studied. (2) According to the influence of different gravel characteristics on the propagation morphology of hydraulic fractures, the interfacial tensile strength has a significant influence on whether the hydraulic fracture propagates locally around the gravel; the gravel diameter and gravel distribution position only affect the local fracture direction of the gravel, and have no effect on the macroscopic extension direction of the fracture; the fracture toughness of the gravel has a significant influence on the local propagation of the fracture through / around the gravel.

[0054] Example 2 like Figure 15 As shown, the difference between this embodiment and embodiment 1 is that this embodiment provides a system for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate rock. This system corresponds one-to-one with the method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate rock in embodiment 1. The system includes: An acquisition unit for acquiring a pre-built tight conglomerate physical model and a fluid-solid coupling governing equation for hydraulic fracture propagation; A numerical model building unit is used to establish a numerical model of hydraulic fracture propagation in dense conglomerate based on the physical model of dense conglomerate and the fluid-solid coupling governing equations of hydraulic fracture propagation. The numerical model is then inserted into the fracture propagation unit that considers interface characteristics and the finite element criterion for hydraulic fracture initiation and propagation. A simulation analysis unit is used to analyze the initiation and propagation characteristics of hydraulic fractures in dense conglomerate taking into account interface characteristics based on a numerical model of hydraulic fracture propagation in dense conglomerate, and obtain simulation analysis results; The scheme optimization unit is used to use the simulation analysis results as the theoretical basis for optimizing the hydraulic fracturing scheme of the tight conglomerate reservoir, optimize the hydraulic fracturing scheme of the tight conglomerate reservoir, and obtain the optimized hydraulic fracturing scheme of the tight conglomerate reservoir.

[0055] The execution process of each unit can be performed according to the process steps of the method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate in Example 1, and will not be described in detail in this embodiment.

[0056] At the same time, the present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for simulating and optimizing the initiation and expansion of hydraulic fractures in dense conglomerate.

[0057] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0058] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0059] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0060] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0061] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate rock, characterized in that: The method includes: Obtain pre-built tight conglomerate physical models and fluid-solid coupling governing equations for hydraulic fracture propagation; Based on the tight conglomerate physical model and the fluid-solid coupling governing equations for hydraulic fracture propagation, a numerical model for hydraulic fracture propagation in tight conglomerate is established by inserting a fracture propagation unit that considers interface characteristics and a finite element criterion for hydraulic fracture initiation and propagation. Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the initiation and propagation characteristics of hydraulic fractures in dense conglomerate are analyzed taking into account interface characteristics to obtain simulation analysis results; The simulation analysis results are used as a theoretical basis for optimizing the hydraulic fracturing scheme for the tight conglomerate reservoir, and the hydraulic fracturing scheme for the tight conglomerate reservoir is optimized to obtain an optimized hydraulic fracturing scheme for the tight conglomerate reservoir.

2. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 1, characterized in that: The dense conglomerate physical model uses the Monte Carlo method to randomly generate gravels, forming a dense conglomerate structure with a size of 0.3×0.3 m; and a weak plane structure is formed between the dense conglomerate structure and the matrix part.

3. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 1, characterized in that: The fluid-solid coupling control equation for the expansion of hydraulic fractures is affected by pore pressure and is expressed as follows: Where, ρ is the rock density; is the total compressibility of the fluid-saturated rock; P is the pore pressure; km is the rock permeability; is the fluid viscosity; Q is the mass flow rate in the rock medium; is the rate of change of pressure over time; is the divergence.

4. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 1, characterized in that: Based on the numerical model of hydraulic fracture propagation in dense conglomerate, the initiation and propagation characteristics of hydraulic fractures in dense conglomerate considering interface characteristics were analyzed, and simulation analysis results were obtained, including: Based on the dense conglomerate hydraulic fracture propagation numerical model, the fracture initiation and extension morphology is simulated, and the failure mode of the dense conglomerate rock plate is analyzed to obtain a first simulation analysis result; Based on the numerical model of hydraulic fracture propagation in dense conglomerate, under different interface tensile strength conditions, the hydraulic fracture propagation through the conglomerate is simulated when the interface tensile strength is successively increased to different values, to obtain a second simulation analysis result; Based on the tight conglomerate hydraulic fracture propagation numerical model, the influence of gravels of different sizes on the hydraulic fracture propagation is simulated to obtain a third simulation analysis result; Based on the dense conglomerate hydraulic fracture propagation numerical model, the influence of different fracture toughnesses on the hydraulic fracture propagation is simulated to obtain a fourth simulation analysis result.

5. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 4, characterized in that: Simulate the crack initiation and extension morphology and analyze the failure mode of dense conglomerate slabs, including: When the injection condition is the first preset displacement, the hydraulic fracture encounters a gravel during the initiation and expansion process and expands around the gravel; When the injection condition is the second preset displacement, two fractures are generated based on the simulation calculation of the tight conglomerate hydraulic fracture propagation numerical model: one fracture is a main fracture, which encounters a gravel when propagating downward and continues to propagate downward around the gravel to the lower boundary of the tight conglomerate hydraulic fracture propagation numerical model, whereupon the fracture stops propagating and the model calculation ends; the other fracture is the main fracture, which encounters the first gravel when propagating downward, turns right around the gravel, and continues to propagate to the right boundary of the model; Wherein, the second preset displacement is greater than the first preset displacement.

6. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 4, characterized in that: Under different interface tensile strength conditions, the hydraulic fracture propagation through gravel is simulated when the interface tensile strength increases to different values, including: When the interfacial tensile strength reaches the first preset strength, the hydraulic fracture starts from the left injection point along the direction of the maximum horizontal principal stress. During the expansion process, the front section expands almost horizontally between the particles. When encountering a gravel with a diameter of the first preset diameter, the fracture expands from the left side of the gravel upward around the interface between the gravel and the matrix to the right side of the gravel, stops expanding around the gravel, and continues to expand parallel to the maximum horizontal principal stress. When the interface tensile strength increases to the second preset strength, the hydraulic fracture propagates from the left side parallel to the direction of the maximum horizontal principal stress, penetrates the small-sized gravel at the second preset diameter, and continues to extend horizontally to the gravel with the first preset diameter. At this interface, the fracture turns and propagates through the gravel along the bottom of the gravel and then continues to extend horizontally. When the interfacial tensile strength continues to increase to the third preset strength, the hydraulic fracture completely penetrates the gravel and extends in a direction parallel to the direction of the maximum horizontal principal stress.

7. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 1, characterized in that: Optimize hydraulic fracturing schemes for tight conglomerate reservoirs, including: Inputting relevant formation parameters and fracturing operation parameters of the tight conglomerate reservoir into the tight conglomerate hydraulic fracture propagation numerical model to perform multi-fracture competition propagation morphology analysis of the tight conglomerate reservoir; The multi-fracture competition expansion morphology analysis includes the influence of different reservoir elastic moduli, different reservoir horizontal stress differences, different reservoir permeabilities and different reservoir construction displacements on the expansion of hydraulic fractures.

8. The method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate according to claim 1, characterized in that: The method further includes: The established tight conglomerate hydraulic fracture propagation numerical model is verified. If the model accuracy meets the preset requirements, the model verification is completed.

9. A system for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate rock, characterized in that: The system includes: An acquisition unit for acquiring a pre-built tight conglomerate physical model and a fluid-solid coupling governing equation for hydraulic fracture propagation; a numerical model building unit for establishing a numerical model of hydraulic fracture propagation in dense conglomerate based on the dense conglomerate physical model and the fluid-solid coupling governing equations of hydraulic fracture propagation, and inserting a fracture propagation unit that considers interface characteristics and a finite element criterion for hydraulic fracture initiation and propagation; a simulation analysis unit for analyzing the initiation and propagation characteristics of hydraulic fractures in the dense conglomerate taking into account interface characteristics based on the dense conglomerate hydraulic fracture propagation numerical model, and obtaining simulation analysis results; The scheme optimization unit is used to use the simulation analysis results as a theoretical basis for optimizing the hydraulic fracturing scheme of the tight conglomerate reservoir, optimize the hydraulic fracturing scheme of the tight conglomerate reservoir, and obtain an optimized hydraulic fracturing scheme of the tight conglomerate reservoir.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for simulating and optimizing the initiation and propagation of hydraulic fractures in dense conglomerate as claimed in any one of claims 1 to 8 is implemented.

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