Horizontal well fracturing perforation parameter optimization method considering non-uniform ground stress, equipment and medium

Abstract

The invention discloses a horizontal well fracturing perforation parameter optimization method and device considering non-uniform crustal stress and a medium, and relates to the field of unconventional oil and gas reservoir yield increase renovation. The method comprises the steps that a three-dimensional non-uniform crustal stress field of reservoir fracturing is constructed; the method comprises the following steps of: performing grid division on a hydraulic fracture by using a fracture unit, acting a three-dimensional non-uniform ground stress field on a divided grid, and establishing a constitutive model of reservoir rock deformation and stress in a hydraulic fracturing process; according to the constitutive model, establishing a flow model of the fracturing fluid in the horizontal shaft, the perforation hole and the hydraulic fracture; establishing an expansion criterion of the hydraulic fracture in the fracture length and fracture height directions; according to the expansion criterion and the flow model, the expansion results of the horizontal well fracturing cracks under different perforation parameters are simulated; and the horizontal well fracturing perforation parameters are optimized according to the expansion result. According to the method, the defects of a uniform crustal stress field assumption and a plane crack propagation assumption in the prior art are overcome, and the optimization of the horizontal well fracturing perforation parameters in the non-uniform crustal stress field is realized.

Description

Technical Field

[0001] The present invention relates to the field of unconventional oil and gas reservoir production enhancement and transformation, and more specifically, to a method, device and medium for optimizing horizontal well fracturing and perforation parameters taking into account non-uniform ground stress. Background Art

[0002] Horizontal well staged multi-cluster fracturing is a key technology for commercializing the exploitation of unconventional underground resources such as shale oil and gas, tight oil and gas, and geothermal resources. Accurately understanding the multi-fracture patterns of horizontal well fracturing in reservoirs is crucial for reducing costs, increasing efficiency, and improving the quality of underground resource development. Hydraulic fracture propagation is a complex multi-field coupled problem. Fracture propagation patterns and fracture geometry are influenced by geological and engineering parameters, with the distribution of geostress playing a particularly significant role in the distribution of hydraulic fractures. Most reservoirs exhibit significant heterogeneity and anisotropy, leading to significant discrepancies between the spatial distribution of horizontal well fracturing fractures in actual projects and the predictions of hydraulic fracturing numerical models assuming uniform stress distribution. Consequently, the optimized completion and operation parameters in the fracturing scheme do not accurately reflect the optimal results under actual reservoir conditions. Therefore, considering the influence of reservoir heterogeneous geostress on hydraulic fracture propagation can help optimize the operation parameters of horizontal well staged multi-cluster fracturing, which is crucial for improving reservoir stimulation and resource development efficiency.

[0003] The main purpose of optimizing fracturing and perforating parameters is to promote the balanced expansion of multiple fractures in multi-cluster fracturing in horizontal wells. Currently, horizontal well fracturing and perforating parameter optimization is primarily achieved by comparing and analyzing hydraulic fracturing fracture expansion simulation predictions under different perforating parameters. The reliability of the parameter optimization results depends on the rationality of the numerical model. However, hydraulic fracturing fracture expansion models currently established using frameworks such as the finite element method, extended finite element method, discrete element method, phase field method, and boundary element method often use uniform stress boundary conditions, failing to fully consider the effects of the initial non-uniform stress in the reservoir and the superposition of fracture-induced stress to form non-uniform geostress. This results in a large deviation between the hydraulic fracture expansion prediction results during scheme design and the hydraulic fracture expansion results in actual engineering projects, making it difficult to accurately optimize horizontal well fracturing and perforating parameters and promote the balanced expansion of multiple fractures in horizontal well fracturing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method, equipment and medium for optimizing horizontal well fracturing and perforating parameters taking into account non-uniform geostress. The present invention considers the combined influence of reservoir geological differences and fracturing engineering factors, establishes a three-dimensional non-uniform geostress field for reservoir fracturing, and carries out horizontal well segmented multi-cluster fracturing crack expansion simulation based on the three-dimensional non-uniform geostress field. The present invention overcomes the defects of the uniform geostress field assumption and the planar crack expansion assumption in the prior art, realizes the prediction of the non-planar expansion trajectory of three-dimensional hydraulic fractures in the three-dimensional non-uniform stress field and the optimization of horizontal well fracturing and perforating parameters, makes the simulation results closer to the actual engineering situation, and can provide technical support for the selection of horizontal well segmented multi-cluster fracturing and perforating parameters.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A first aspect of the present invention provides a method for optimizing horizontal well fracturing and perforating parameters taking into account non-uniform ground stress, the method comprising: Constructing a three-dimensional inhomogeneous geostress field for reservoir fracturing; The hydraulic fractures are meshed using fracture elements, and the three-dimensional non-uniform stress field is applied to the meshes to establish a constitutive model of reservoir rock deformation and stress during hydraulic fracturing. Based on the constitutive model, the flow model of fracturing fluid in horizontal wellbore, perforation holes and hydraulic fractures is established; Establish the expansion criteria of hydraulic fractures along the fracture length and fracture height; Based on the expansion criteria and flow model, the expansion results of horizontal well hydraulic fractures under different perforation parameters are simulated; Optimize horizontal well fracturing and perforating parameters based on the expansion results.

[0006] In one implementation, a three-dimensional non-uniform geostress field for reservoir fracturing is constructed as follows: Obtain the initial in-situ stress field of the reservoir before fracturing; Calculate the induced stress field in the reservoir caused by hydraulic fractures; The initial geostress field and the induced stress field are superimposed to obtain the three-dimensional heterogeneous geostress field of reservoir fracturing.

[0007] In one implementation, the constitutive model is composed of a comprehensive influence coefficient matrix, a fracture width matrix of the fracture unit, a comprehensive normal stress matrix of the fracture unit, and a fluid pressure matrix of the fracture unit.

[0008] In one implementation, the process of determining the comprehensive normal stress matrix of the crack unit is as follows: Perform spatial coordinate transformation on the three-dimensional non-uniform stress field to obtain the stress along the strike, dip and normal directions of the fracture unit under the action of the three-dimensional non-uniform stress field; The influence coefficient matrix along the strike, dip and normal directions of the fracture unit is obtained, and the comprehensive normal stress matrix of the fracture unit is calculated based on the influence coefficient matrix and stress along the strike, dip and normal directions of the fracture unit.

[0009] In one implementation, a flow model of fracturing fluid in a horizontal wellbore, perforations, and hydraulic fractures is established based on the constitutive model, specifically: Obtain hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameter information, perforation hole parameter information, and flow correction coefficient caused by perforation erosion; A flow model of fracturing fluid in hydraulic fractures is established based on the fluid pressure matrix of the fracture unit, the width of the hydraulic fracture and the viscosity of the fracturing fluid. A flow model of the fracturing fluid in the horizontal wellbore is established based on the fracturing fluid viscosity, horizontal wellbore parameter information and the preset dynamic fracturing fluid displacement; A flow model of the fracturing fluid in the perforations is established based on the fracturing fluid density, perforation hole parameter information, flow correction coefficient, and preset dynamic fracturing fluid displacement; Based on the flow models of fracturing fluid in hydraulic fractures, in horizontal wellbores, and in perforations, a pressure balance relationship between multiple perforation clusters in staged multi-cluster fracturing of horizontal wells is established, as well as a mass balance relationship between the total injection rate of staged multi-cluster fracturing of horizontal wells and the dynamic fracturing fluid displacement entering each perforation cluster during the staged multi-cluster fracturing of horizontal wells. Based on the pressure balance and mass balance relationships, combined with fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameters, perforation parameters, and flow correction coefficients caused by perforation erosion, the dynamic fracturing fluid flow rate entering each perforation cluster during staged multi-cluster fracturing of a horizontal well is iteratively solved. According to the dynamic fracturing fluid displacement, fracturing fluid viscosity and hydraulic fracture width, the flow model of fracturing fluid in hydraulic fracture is substituted to calculate the fluid pressure in hydraulic fracture, and the fluid pressure matrix of fracture unit is determined based on the fluid pressure in hydraulic fracture.

[0010] In one implementation, a hydraulic fracture expansion strategy along the fracture length and fracture height is established, specifically: Obtain Young's modulus of reservoir rock, Poisson's ratio of reservoir rock, tensile stress intensity factor of fracture tip, and shear stress intensity factor of fracture tip; The first energy release rate of the fracture tip unit when the hydraulic fracture propagates along the fracture length direction is calculated based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, the tensile stress intensity factor of the fracture tip, and the shear stress intensity factor of the fracture tip. The second energy release rate of the fracture tip unit when the hydraulic fracture propagates along the fracture height direction is calculated based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, and the tensile stress intensity factor of the fracture tip. When the first energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture length direction, and the fracture deflection angle along the fracture length direction is calculated based on the tensile stress intensity factor and the shear stress intensity factor at the fracture tip. When the second energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture height direction, and the fracture deflection angle of the hydraulic fracture along the fracture length direction is zero.

[0011] In one implementation, the expansion results of horizontal well hydraulic fractures under different perforation parameters are simulated based on the expansion criterion and flow model, specifically: Obtaining basic parameters required for reservoir horizontal well segmented multi-cluster fracturing simulation; wherein the basic parameters include geological parameters, completion parameters and construction parameters; Combining basic parameters, expansion criteria and flow models, the expansion results of horizontal well hydraulic fracturing under different perforation parameters are simulated; wherein the expansion results include the coefficient of variation of crack length, coefficient of variation of crack area and coefficient of variation of perforation cluster displacement.

[0012] In one implementation, the horizontal well fracturing and perforating parameters are optimized based on the expansion results, specifically: By weighting the coefficient of variation of fracture length, fracture area, and perforation cluster rate, the analytical index of heterogeneous expansion of multiple fractures in staged multi-cluster fracturing of horizontal wells was calculated. The corresponding perforation parameters are selected according to the analysis indicators as the optimization parameters for the design of staged multi-cluster fracturing operations in horizontal wells in a non-uniform geostress field.

[0013] A second aspect of the present invention provides an electronic device including a memory and a processor; a memory for storing a computer program, wherein the computer program includes program instructions; The processor is configured to execute the program instructions so as to enable the electronic device to perform the steps of a method for optimizing horizontal well fracturing and perforating parameters provided in the first aspect of the present invention.

[0014] According to a third aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium includes a computer program. When the computer program is executed by one or more processors, the computer program implements a method for optimizing horizontal well fracturing and perforating parameters as provided in the first aspect of the present invention.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention considers the combined influence of reservoir geological differences and fracturing engineering factors, establishes a three-dimensional non-uniform geostress field for horizontal well fracturing reservoirs, and based on this, carries out simulation of fracture expansion for staged multi-cluster fracturing of horizontal wells. The present invention overcomes the defects of the uniform geostress field assumption and the planar fracture expansion assumption in the prior art, realizes the prediction of non-planar expansion trajectory of three-dimensional hydraulic fractures in the non-uniform stress field and the optimization of horizontal well fracturing perforation parameters, making the simulation results closer to the actual engineering situation and providing technical support for the optimization of perforation parameters for staged multi-cluster fracturing of horizontal wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 A schematic flow chart of a method for optimizing horizontal well fracturing and perforating parameters provided by an embodiment of the present invention; Figure 2 A diagram showing the distribution of the maximum horizontal principal stress in the reservoir plane provided by an embodiment of the present invention; Figure 3 A diagram showing the distribution of the minimum principal stress in the reservoir plane provided by an embodiment of the present invention; Figure 4 A diagram showing the calculation results of hydraulic fracture-induced stress in a horizontal section adjacent to a target reconstruction section provided by an embodiment of the present invention; Figure 5 A diagram showing the calculation results of the maximum principal stress in the reservoir plane in a three-dimensional non-uniform stress field provided by an embodiment of the present invention; Figure 6 A diagram showing the calculation results of the minimum principal stress in the reservoir plane in a three-dimensional non-uniform stress field provided by an embodiment of the present invention; Figure 7 Schematic diagram of hydraulic fracture discretization and fracture units for staged multi-cluster fracturing of a horizontal well provided by an embodiment of the present invention; Figure 8 A diagram showing the fracture trajectory and fracture width prediction results of horizontal well hydraulic fracturing in Solution 1 provided in an embodiment of the present invention; Figure 9 A diagram showing the fracture trajectory and fracture width prediction results of horizontal well hydraulic fracturing in Solution 2 provided in an embodiment of the present invention; Figure 10 A diagram showing the fracture trajectory and fracture width prediction results of horizontal well hydraulic fracturing in Solution 3 provided in an embodiment of the present invention; Figure 11 The horizontal well hydraulic fracturing crack trajectory and fracture width prediction results in Solution 4 provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0017] 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.

[0018] It should be noted that the terms "include" or "may include" used in various embodiments of the present application indicate the presence of the claimed function, operation or element, and do not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are only intended to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0019] It should be understood that terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0020] Please refer to Figure 1 , Figure 1 A flow chart of a method for optimizing horizontal well fracturing and perforating parameters provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the method includes: S101, constructing a three-dimensional non-uniform geostress field for reservoir fracturing.

[0021] In this embodiment, a three-dimensional non-uniform geostress field of reservoir fracturing is constructed, specifically by obtaining the initial geostress field of the reservoir before fracturing; calculating the induced stress field generated in the reservoir by hydraulic fractures; and superimposing the initial geostress field and the induced stress field to obtain the three-dimensional non-uniform geostress field of the reservoir fracturing.

[0022] Specifically, through geological modeling of the target reservoir, the initial three-dimensional geostress field distribution of the reservoir before fracturing is obtained, including the horizontal maximum principal stress, the horizontal minimum principal stress, and the vertical stress gradient of the reservoir. Then, considering the stress interference effect caused by hydraulic fractures after the adjacent horizontal sections are transformed, the induced stress generated by hydraulic fractures in the reservoir is calculated, including normal stress and shear stress. Finally, based on the principle of stress superposition, the initial geostress field and the induced stress field are superimposed to obtain the three-dimensional non-uniform geostress field of the reservoir after fracturing. The calculation formula is: , where σmix It represents the non-uniform ground stress field obtained by stress superposition calculation; σ far It represents the initial in-situ stress field of the reservoir before fracturing; σ ind Represents the induced stress field generated by hydraulic fractures.

[0023] According to the construction process of the three-dimensional non-uniform geostress field described in this embodiment, the following specific implementation method is provided: based on the geological exploration data, the initial three-dimensional geostress field distribution of the target reservoir before fracturing is obtained, and the horizontal maximum principal stress distribution result in the reservoir plane is referred to Figure 2 The results of the horizontal minimum principal stress distribution in the reservoir plane refer to Figure 3 The reservoir thickness is 38.0m, the average stress difference between the upper and lower layers is 3.0MPa, and the vertical stress gradient is about 0.02MPa / m. Considering the stress interference caused by the hydraulic fractures in the adjacent fractured sections near the toe of the horizontal well, the induced stress field distribution in the target reformed layer is calculated. The Young's modulus of the reservoir is 33.5GPa, the Poisson's ratio of the reservoir is 0.22, and the induced stress calculation results refer to Figure 4 By using the stress superposition principle, a three-dimensional non-uniform stress field model of reservoir fracturing is obtained. The maximum principal stress distribution in the reservoir plane is referenced to Figure 5 , the maximum principal stress distribution in the reservoir plane is referenced Figure 6 .

[0024] S102, using fracture units to mesh the hydraulic fractures, applying the three-dimensional non-uniform stress field to the meshes, and establishing a constitutive model of reservoir rock deformation and stress during the hydraulic fracturing process.

[0025] In this embodiment, fracture unit grid division is performed, and rectangular fracture units with the same displacement value are used to discretize hydraulic fractures. The deformation and stress of the fracture units are used to characterize the deformation and stress of the reservoir rock.

[0026] Based on the three-dimensional displacement discontinuity theory, a constitutive model of reservoir rock deformation and stress during hydraulic fracturing is established. The constitutive model consists of a comprehensive influence coefficient matrix, a fracture width matrix of the fracture unit, a comprehensive normal stress matrix of the fracture unit, and a fluid pressure matrix of the fracture unit. Figure 7For multi-cluster hydraulic fractures in horizontal wells, constant displacement rectangular fracture units with equal length and width are used to discretize hydraulic fractures. The influence coefficient is calculated based on the reservoir rock attribute parameters and the fracture unit geometric parameters, and the comprehensive normal stress acting on the fracture unit is calculated through the three-dimensional non-uniform geostress field in step S101. Specifically, the comprehensive normal stress matrix of the fracture unit is determined as follows: the three-dimensional non-uniform geostress field is transposed to obtain the stress along the strike, dip and normal directions of the fracture unit under the action of the three-dimensional non-uniform geostress field; the influence coefficient matrix along the strike, dip and normal directions of the fracture unit is obtained, and the comprehensive normal stress matrix of the fracture unit is calculated based on the influence coefficient matrix and the stress along the strike, dip and normal directions of the fracture unit.

[0027] The matrix form of the constitutive model is: ; in, ; ; , where the subscripts L, H, and N represent the strike, dip, and normal directions of the fracture unit, respectively; C represents the influence coefficient matrix; Indicates the influence coefficient between normal and tangential directions; Indicates the influence coefficient between the strike and the normal direction; Indicates the influence coefficient between direction and tendency; Indicates the influence coefficient between tendency and direction; Indicates the influence coefficient between normal and inclination; It represents the influence coefficient between the inclination and the normal direction; Indicates the influence coefficient between normal and normal directions; It represents the influence coefficient between tendencies; represents the influence coefficient between strikes; w represents the fracture width matrix of the fracture unit; C M represents the comprehensive influence coefficient matrix; σ M represents the comprehensive normal stress matrix acting on the crack element; p f represents the fluid pressure matrix acting on the fracture unit; R represents the spatial coordinate transpose matrix; T represents the matrix transpose symbol; represents the strike stress matrix of the fracture unit under the action of ground stress; The dip stress matrix of the fracture unit under the action of ground stress; Represents the normal stress matrix of the fracture unit under the action of ground stress; It represents the strike stress of the fracture unit under the action of ground stress; It represents the dip stress of the fracture unit under the action of ground stress; Represents the normal stress of the crack unit under the action of ground stress.

[0028] S103: Based on the constitutive model, a flow model of the fracturing fluid in the horizontal wellbore, perforation holes and hydraulic fractures is established.

[0029] In this embodiment, a flow model of fracturing fluid in a horizontal wellbore, perforation holes, and hydraulic fractures is established based on the constitutive model, specifically: S1031, obtaining hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameter information, perforation hole parameter information, and flow correction coefficient caused by perforation erosion; S1032, establishing a flow model of the fracturing fluid in the hydraulic fracture based on the fluid pressure matrix of the fracture unit, the hydraulic fracture width, and the fracturing fluid viscosity; S1033, establishing a flow model of the fracturing fluid in the horizontal wellbore based on the fracturing fluid viscosity, horizontal wellbore parameter information, and a preset dynamic fracturing fluid displacement; S1034: Establishing a flow model of the fracturing fluid in the perforations based on the fracturing fluid density, perforation parameter information, flow correction coefficient, and a preset dynamic fracturing fluid displacement; S1035: Based on the flow model of the fracturing fluid in the hydraulic fracture, the flow model in the horizontal wellbore, and the flow model in the perforations, establish a pressure balance relationship between multiple perforation clusters in the horizontal well staged multi-cluster fracturing, and establish a mass balance relationship between the total injection rate of the horizontal well staged multi-cluster fracturing and the dynamic fracturing fluid discharge rate entering each perforation cluster during the horizontal well staged multi-cluster fracturing; S1036, based on the pressure balance relationship and the mass balance relationship, combined with the fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameter information, perforation hole parameter information, and the flow correction coefficient caused by perforation erosion, iteratively solves the dynamic fracturing fluid flow rate entering each perforation cluster during the staged multi-cluster fracturing of the horizontal well; S1037: Substitute the dynamic fracturing fluid displacement, fracturing fluid viscosity, and hydraulic fracture width into the flow model of the fracturing fluid in the hydraulic fracture to calculate the fluid pressure in the hydraulic fracture, and determine the fluid pressure matrix of the fracture unit based on the fluid pressure in the hydraulic fracture.

[0030] It should be noted that in steps S1033 and S1034, the preset dynamic fracturing fluid displacement refers to a given initial value of the fracturing fluid displacement. On the basis of this initial value and in combination with the corresponding parameter information, a flow model of the fracturing fluid in the horizontal wellbore and the perforation holes is established. Then, based on the correlation between the parameters of the three flow models, a pressure balance relationship between multiple perforation clusters in the horizontal well segmented multi-cluster fracturing is established, as well as a mass balance relationship between the total injection displacement of the horizontal well segmented multi-cluster fracturing and the dynamic fracturing fluid displacement entering each perforation cluster during the horizontal well segmented multi-cluster fracturing process. On the basis of these two balance relationships, On this basis, combined with the obtained parameter information, the final dynamic fracturing fluid displacement can be iteratively solved, and then the final dynamic fracturing fluid displacement is substituted into the flow model of the fracturing fluid in the horizontal wellbore and perforation hole, so as to simulate the dynamic displacement of the fracturing fluid in the horizontal wellbore, perforation hole and hydraulic fracture. On this basis, the dynamic fracturing fluid displacement, fracturing fluid viscosity and hydraulic fracture width are substituted into the flow model of the fracturing fluid in the hydraulic fracture to calculate the fluid pressure in the hydraulic fracture. The fluid pressure matrix of the fracture unit is composed of multiple fluid pressures. Therefore, the fluid pressure matrix can be calculated based on the fluid pressure.

[0031] Specifically, (1) the flow of fracturing fluid in a horizontal wellbore is described by a circular tube flow model, and the wellbore friction calculation formula is: , where Δ p w,i Indicates the i Flow friction pressure drop in horizontal wellbore section; μ f Indicates fracturing fluid viscosity; q w,i Indicates the i The fracturing fluid displacement of the horizontal wellbore section; L i Indicates the i The length of the horizontal wellbore section; d w Indicates the inner diameter of the horizontal wellbore.

[0032] (2) The formula for calculating the frictional pressure drop when the fracturing fluid enters the hydraulic fracture from the horizontal wellbore through the perforation hole is: , where Δ p p,i Indicates the i perforation friction pressure drop of cluster perforation cluster; ρ f Indicates the density of the fracturing fluid; q p,i Indicates entering i Fracturing fluid discharge rate of cluster perforation cluster; F p Indicates the flow correction factor caused by hole erosion;n i Indicates the i The number of holes in the cluster perforation cluster; d i Indicates the i Cluster perforation: The perforation diameter of the cluster.

[0033] (3) The laminar flow model is used to describe the flow of fracturing fluid in hydraulic fractures, and the fracturing fluid flow continuity equation is obtained according to Poiseuille's law: , that is, the flow model of fracturing fluid in hydraulic fractures. The mass conservation equation of fracturing fluid flow in hydraulic fractures is: , the control equation of fracturing fluid flow in hydraulic fractures can be obtained as follows: , where v f Indicates the flow rate of fracturing fluid; w Indicates the width of hydraulic fracture; μ f Indicates fracturing fluid viscosity; p f Indicates the fluid pressure in the hydraulic fracture; t Indicates time; q inj represents the injection rate of the hydraulic fracture; q leak Indicates the filtration rate of hydraulic fractures; represents the Laplace operator; Indicates the fracturing fluid velocity.

[0034] (4) Based on the pressure balance principle, the dynamic fracturing fluid displacement entering each perforation cluster during the horizontal well multi-cluster fracturing process is calculated, and the pressure balance relationship between multiple perforation clusters in the horizontal well multi-cluster fracturing process is established using Kirchhoff's law: , where n represents the number of perforation clusters; p in represents the fluid pressure at the entrance of the hydraulic fracture; It represents the pressure difference between the nth cluster and the n-1th cluster at the heel of the horizontal well.

[0035] Based on the mass conservation relationship, the dynamic fracturing fluid flow rate into each perforation cluster satisfies the following relationship: , where Q It represents the total injection rate of multi-cluster fracturing in horizontal wells. represents the dynamic fracturing fluid displacement of the nth perforation cluster.

[0036] Combining the pressure balance relationship with the mass conservation relationship, a nonlinear equation system is constructed, and the Newton-Raphson iteration is used to solve the dynamic fracturing fluid displacement entering each perforation cluster during the staged multi-cluster fracturing of a horizontal well: ; ; ; , where m represents the iteration step; q p represents the matrix of fracturing fluid displacement into the perforation cluster; represents the inequality residual matrix; Represents the dynamic fracturing fluid displacement matrix under the mth iteration step.

[0037] In this embodiment, the flow rate of the fracturing fluid entering each perforation cluster at the current moment is preset, and the flow control equation of the fracturing fluid in the hydraulic fracture is solved to obtain the fluid pressure distribution in the hydraulic fracture. Then, the flow rate of the fracturing fluid entering each perforation cluster is calculated based on the pressure balance relationship and mass conservation relationship between multiple perforation clusters in the horizontal well. The flow rate of the fracturing fluid entering each perforation cluster and the fluid pressure in the hydraulic fracture are obtained by cyclic iterative numerical calculation. In the execution process of this embodiment, the flow model of the fracturing fluid in the horizontal wellbore, perforation holes and hydraulic fracture is established according to steps (3), (4), (1) and (2).

[0038] S104: Establish the expansion criteria of hydraulic fractures along the fracture length and fracture height.

[0039] In this embodiment, a hydraulic fracture expansion strategy along the fracture length and fracture height is established, specifically: S1041, obtain the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, the tensile stress intensity factor of the fracture tip, and the shear stress intensity factor of the fracture tip; S1042, calculating a first energy release rate of a unit at the fracture tip when the hydraulic fracture propagates along the fracture length direction based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, the tensile stress intensity factor of the fracture tip, and the shear stress intensity factor of the fracture tip; and calculating a second energy release rate of a unit at the fracture tip when the hydraulic fracture propagates along the fracture height direction based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, and the tensile stress intensity factor of the fracture tip; S1043, when the first energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture length direction, and a fracture deflection angle of the hydraulic fracture along the fracture length direction is calculated based on the fracture tip tensile stress intensity factor and the fracture tip shear stress intensity factor; S1044, when the second energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture height direction, and the fracture deflection angle of the hydraulic fracture along the fracture length direction is zero.

[0040] Specifically, within the framework of the displacement discontinuity method, the tangential and normal displacements of the hydraulic fracture tip element can be directly calculated. Therefore, according to the maximum energy release rate criterion, the energy release rate of the available tip element can be calculated to predict whether the hydraulic fracture will propagate: Where, G tip represents the energy release rate of the hydraulic fracture tip unit; G c represents the critical energy release rate of crack expansion. G tip ≥ G c When hydraulic fractures expand.

[0041] The calculation formula for the energy release rate of the crack tip unit when the hydraulic fracture expands along the fracture length direction is: ; The calculation formula for the energy release rate of the crack tip unit when the hydraulic fracture expands along the fracture height direction is: , where E represents the Young's modulus of reservoir rock; v represents the Poisson's ratio of reservoir rock; K I represents the tensile stress intensity factor at the crack tip; K II represents the shear stress intensity factor at the crack tip.

[0042] The maximum circumferential stress criterion is used to predict the expansion direction of hydraulic fractures along the fracture length direction, that is, the expansion direction of hydraulic fractures is the same as the direction in which the circumferential tensile stress near the fracture tip takes the maximum value. K II When >0, the crack deflection angle calculation formula is: .

[0043] When the shear stress intensity factor at the crack tip K II When <0, the calculation formula of the crack deflection angle is: ; When the shear stress intensity factor at the crack tip K II =0, the calculation formula for the crack deflection angle is: Where, Δ θ It represents the deflection angle of the crack tip when the hydraulic fracture expands.

[0044] When the hydraulic fracture expands along the fracture height, the deflection of the fracture is not considered, so the deflection angle at the fracture tip is 0.

[0045] In this embodiment, according to the maximum energy release rate criterion, the normal displacement and tangential displacement of the hydraulic fracture tip crack unit are used to calculate the stress intensity factors of the tensile and shear types of the crack tip. Then, the energy release rate of the tip unit is calculated to determine the expansion along the crack length and crack height. When the hydraulic fracture tip crack unit meets the expansion conditions, the expansion direction along the crack length is calculated according to the maximum circumferential stress criterion, while the expansion direction along the crack height remains unchanged along the vertical direction. The normal displacement and tangential displacement of the newly added crack unit are set to 1.0×10 -6 m.

[0046] S105, based on the expansion criterion and the flow model, the expansion results of the horizontal well hydraulic fracture under different perforation parameters are simulated.

[0047] In this embodiment, the expansion results of horizontal well fracturing cracks under different perforation parameters are simulated based on the expansion criterion and flow model. Specifically, the basic parameters required for the simulation of multi-cluster fracturing of horizontal wells in the reservoir are obtained; wherein the basic parameters include geological parameters, completion parameters and construction parameters; and the expansion results of horizontal well fracturing cracks under different perforation parameters are simulated by combining the basic parameters, the expansion criterion and the flow model.

[0048] In this embodiment, the basic parameters required for the simulation of staged multi-cluster fracturing of horizontal wells in the target reservoir are shown in Table 1.

[0049] Table 1 Basic parameters required for staged multi-cluster fracturing simulation of horizontal wells in target reservoirs

[0050] Considering the influence of adjacent fracture sections of horizontal wells, the influence of induced stress is calculated. The results refer to Figure 4 , and combined with the initial three-dimensional stress field data to calculate the target reservoir fracture section non-uniform stress field, the results refer to Figure 5 and Figure 6 Different perforation parameter schemes are further designed. This embodiment considers different perforation densities. For details, refer to Table 2. Table 2 Perforation density plan

[0051] Based on the four perforation schemes in Table 2, the simulation results of multi-cluster hydraulic fracturing fracture extension in horizontal wells under the conditions of schemes 1 to 4 were obtained. The hydraulic fracture extension trajectory and fracture width distribution in three-dimensional space were referenced. Figure 8 、 Figure 9 、 Figure 10 and Figure 11 .

[0052] S106: Optimize horizontal well fracturing and perforating parameters based on the expansion results.

[0053] In this embodiment, the horizontal well fracturing and perforating parameters are optimized based on the expansion results, specifically: S1061, weighting the coefficient of variation of fracture length, fracture area, and perforation cluster rate to calculate analytical indicators for the non-uniform expansion of multiple fractures in staged multi-cluster fracturing of horizontal wells.

[0054] Specifically, first, it should be noted that the expansion results simulated in step S105 include the coefficient of variation of fracture length, the coefficient of variation of fracture area, and the coefficient of variation of perforation cluster displacement. Therefore, the calculation formula for the analysis index of the non-uniform expansion of multiple fractures in staged multi-cluster fracturing of horizontal wells is: , where α It represents the comprehensive evaluation index of the heterogeneous expansion of multiple cracks; C L represents the coefficient of variation of crack length; C A represents the coefficient of variation of crack area; C Q represents the coefficient of variation of perforation cluster discharge rate; β 1 represents the crack length weight coefficient; β 2 represents the crack area weight coefficient; β 3 represents the perforation cluster displacement weight coefficient. The calculation formula for the coefficient of variation of different indicators is: , where C represents the coefficient of variation; μ represents the mean; σ Represents standard deviation.

[0055] S1062: Select the corresponding perforation parameters based on the analysis indicators as the optimization parameters for the design of multi-cluster fracturing operations for horizontal wells in a non-uniform geostress field. Specifically, lower values of the analytical indicators for heterogeneous multi-fracture expansion indicate more uniform multi-fracture expansion, and the corresponding perforation parameters more accurately reflect the optimal results under real reservoir conditions. Therefore, these indicators can be used as recommended parameters for the design of staged multi-cluster fracturing operations in horizontal wells in heterogeneous geostress fields.

[0056] In this embodiment, the coefficient of variation of fracture length, the coefficient of variation of fracture area, and the coefficient of variation of perforation cluster displacement under different perforation schemes are shown in Table 3. The fracture length weight coefficient is 0.45, the fracture area weight coefficient is 0.35, and the perforation cluster displacement weight coefficient is 0.20, and the comprehensive evaluation index of non-uniform expansion of multi-cluster fracturing and multi-fractures in horizontal well segments is calculated. The results show that the comprehensive evaluation index is reduced by 0.0923 from 18 holes / m in Scheme 1 to 12 holes / m in Scheme 1, indicating that reducing the number of perforations under the uniform perforation scheme can promote the uniform expansion of multi-cluster fracturing and multi-fractures in horizontal well segments. Schemes 3 and 4 adopt non-uniform perforation parameter design to address the differences in the expansion of different perforation clusters. It can be found that under the perforation scheme of Scheme 3, the perforation density from the 1st cluster on the left to the 6th cluster on the right is 8 holes / m, 8 holes / m, 10 holes / m, 10 holes / m, 12 holes / m, and 12 holes / m, respectively, and the comprehensive evaluation index is 0.1993. The simulation results are shown in Table 3. Figure 10 This design achieves the most uniform expansion of multiple fractures in staged multi-cluster fracturing of horizontal wells among the four schemes 1 through 4. Compared to uniform perforation schemes, under non-uniform geostress conditions, non-uniform perforation cluster parameter design is required to tailor the stress profile of each perforation cluster's hydraulic fractures, optimizing perforation parameters that promote the expansion of multiple hydraulic fractures. In this example, a non-uniform perforation scheme was employed to optimize the operation parameters of staged multi-cluster fracturing of horizontal wells in a non-uniform geostress field to promote uniform expansion of multiple fractures in horizontal wells. Based on the comprehensive evaluation indicators, the recommended parameters are the perforation density parameters corresponding to Scheme 3.

[0057] Table 3 Comprehensive evaluation indicators for heterogeneous expansion of multi-cluster fracturing and multi-fractures in horizontal wells under different perforation schemes

[0058] An embodiment of the present invention further provides an electronic device. The electronic device includes a processor, a memory, a communication interface, and at least one communication bus for connecting the processor, the memory, and the communication interface. The memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (PROM), or a compact disc read-only memory (CD-ROM), and is used to store relevant instructions and data.

[0059] The communication interface is used to receive and send data. The processor can be one or more CPUs. When the processor is a CPU, the CPU can be a single-core CPU or a multi-core CPU. The processor in the electronic device is used to read one or more programs stored in the memory and perform the following operations: construct a three-dimensional non-uniform geostress field for reservoir fracturing; mesh the hydraulic fractures using fracture units, apply the three-dimensional non-uniform geostress field to the meshed grid, and establish a constitutive model of reservoir rock deformation and stress during hydraulic fracturing; establish a flow model of fracturing fluid in the horizontal wellbore, perforation holes, and hydraulic fractures based on the constitutive model; establish expansion criteria for hydraulic fractures along the fracture length and fracture height; simulate the expansion results of horizontal well fracturing fractures under different perforation parameters based on the expansion criteria and flow model; and optimize the horizontal well fracturing perforation parameters based on the expansion results.

[0060] It should be noted that the specific implementation of each operation can be as described above. Figure 1 The corresponding description of the method embodiment shown, the electronic device can be used to execute a horizontal well fracturing perforation parameter optimization method considering non-uniform ground stress in the above method embodiment of the present application, which will not be described in detail here.

[0061] An embodiment of the present invention further provides a computer-readable storage medium, which is a memory device in a computer device and is used to store programs and data. It is understood that the computer-readable storage medium herein may include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides storage space, which stores the terminal's operating system. Furthermore, this storage space stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium herein may be a high-speed RAM memory or a non-volatile memory, such as at least one disk drive. The processor may load and execute the one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the above-described embodiment of a method for optimizing horizontal well fracturing and perforating parameters considering non-uniform geostress. Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0062] Embodiments of the present invention also provide a computer program product containing program instructions. This computer program product can be software or a program product containing program instructions that can be executed on a computing device or stored on any usable medium. When executed on at least one electronic device, the computer program product causes the at least one electronic device to execute a method for optimizing horizontal well fracturing and perforating parameters that considers non-uniform geostress.

[0063] 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 optimizing horizontal well fracturing perforation parameters considering non-uniform ground stress, characterized in that: Methods include: Constructing a three-dimensional inhomogeneous geostress field for reservoir fracturing; The hydraulic fractures are meshed using fracture elements, and the three-dimensional non-uniform stress field is applied to the meshes to establish a constitutive model of reservoir rock deformation and stress during hydraulic fracturing. Based on the constitutive model, the flow model of fracturing fluid in horizontal wellbore, perforation holes and hydraulic fractures is established; Establish the expansion criteria of hydraulic fractures along the fracture length and fracture height; Based on the expansion criteria and flow model, the expansion results of horizontal well hydraulic fractures under different perforation parameters are simulated; Optimize horizontal well fracturing and perforating parameters based on the expansion results.

2. The method for optimizing horizontal well fracturing and perforating parameters considering non-uniform ground stress according to claim 1, characterized in that: Construct a three-dimensional heterogeneous geostress field for reservoir fracturing, specifically: Obtain the initial in-situ stress field of the reservoir before fracturing; Calculate the induced stress field in the reservoir caused by hydraulic fractures; The initial geostress field and the induced stress field are superimposed to obtain the three-dimensional heterogeneous geostress field of reservoir fracturing.

3. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform ground stress according to claim 1, characterized in that: The constitutive model is composed of a comprehensive influence coefficient matrix, a crack width matrix of a crack unit, a comprehensive normal stress matrix of a crack unit and a fluid pressure matrix of a crack unit.

4. The method for optimizing horizontal well fracturing and perforating parameters considering non-uniform ground stress according to claim 3, characterized in that: The process of determining the comprehensive normal stress matrix of the crack unit is as follows: Perform spatial coordinate transformation on the three-dimensional non-uniform stress field to obtain the stress along the strike, dip and normal directions of the fracture unit under the action of the three-dimensional non-uniform stress field; The influence coefficient matrix along the strike, dip and normal directions of the fracture unit is obtained, and the comprehensive normal stress matrix of the fracture unit is calculated based on the influence coefficient matrix and stress along the strike, dip and normal directions of the fracture unit.

5. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform ground stress according to claim 3, characterized in that: Based on the constitutive model, the flow model of fracturing fluid in horizontal wellbore, perforation holes and hydraulic fractures is established, specifically: Obtain hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameter information, perforation hole parameter information, and flow correction coefficient caused by perforation erosion; A flow model of fracturing fluid in hydraulic fractures is established based on the fluid pressure matrix of the fracture unit, the width of the hydraulic fracture and the viscosity of the fracturing fluid. A flow model of the fracturing fluid in the horizontal wellbore is established based on the fracturing fluid viscosity, horizontal wellbore parameter information and the preset dynamic fracturing fluid displacement; A flow model of the fracturing fluid in the perforations is established based on the fracturing fluid density, perforation hole parameter information, flow correction coefficient, and preset dynamic fracturing fluid displacement; Based on the flow models of fracturing fluid in hydraulic fractures, in horizontal wellbores, and in perforations, a pressure balance relationship between multiple perforation clusters in staged multi-cluster fracturing of horizontal wells is established, as well as a mass balance relationship between the total injection rate of staged multi-cluster fracturing of horizontal wells and the dynamic fracturing fluid displacement entering each perforation cluster during the staged multi-cluster fracturing of horizontal wells. Based on the pressure balance and mass balance relationships, combined with fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameters, perforation parameters, and flow correction coefficients caused by perforation erosion, the dynamic fracturing fluid flow rate entering each perforation cluster during staged multi-cluster fracturing of a horizontal well is iteratively solved. According to the dynamic fracturing fluid displacement, fracturing fluid viscosity and hydraulic fracture width, the flow model of fracturing fluid in hydraulic fracture is substituted to calculate the fluid pressure in hydraulic fracture, and the fluid pressure matrix of fracture unit is determined based on the fluid pressure in hydraulic fracture.

6. The method for optimizing horizontal well fracturing and perforating parameters considering non-uniform ground stress according to claim 1, characterized in that: Establish a hydraulic fracture expansion strategy along the fracture length and fracture height, specifically: Obtain Young's modulus of reservoir rock, Poisson's ratio of reservoir rock, tensile stress intensity factor of fracture tip, and shear stress intensity factor of fracture tip; The first energy release rate of the fracture tip unit when the hydraulic fracture propagates along the fracture length direction is calculated based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, the tensile stress intensity factor of the fracture tip, and the shear stress intensity factor of the fracture tip. The second energy release rate of the fracture tip unit when the hydraulic fracture propagates along the fracture height direction is calculated based on the Young's modulus of the reservoir rock, the Poisson's ratio of the reservoir rock, and the tensile stress intensity factor of the fracture tip. When the first energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture length direction, and the fracture deflection angle along the fracture length direction is calculated based on the tensile stress intensity factor and the shear stress intensity factor at the fracture tip. When the second energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture height direction, and the fracture deflection angle of the hydraulic fracture along the fracture length direction is zero.

7. The method for optimizing horizontal well fracturing and perforating parameters considering non-uniform ground stress according to claim 1, characterized in that: Based on the expansion criterion and flow model, the expansion results of horizontal well hydraulic fractures under different perforation parameters are simulated, specifically: Obtaining basic parameters required for reservoir horizontal well segmented multi-cluster fracturing simulation; wherein the basic parameters include geological parameters, completion parameters and construction parameters; Combining basic parameters, expansion criteria and flow models, the expansion results of horizontal well hydraulic fracturing under different perforation parameters are simulated; wherein the expansion results include the coefficient of variation of crack length, coefficient of variation of crack area and coefficient of variation of perforation cluster displacement.

8. The method for optimizing horizontal well fracturing and perforating parameters considering non-uniform ground stress according to claim 7, characterized in that: Optimize horizontal well fracturing and perforating parameters based on the expanded results, specifically: By weighting the coefficient of variation of fracture length, fracture area, and perforation cluster rate, the analytical index of heterogeneous expansion of multiple fractures in staged multi-cluster fracturing of horizontal wells was calculated. The corresponding perforation parameters are selected according to the analysis indicators as the optimization parameters for the design of staged multi-cluster fracturing operations in horizontal wells in a non-uniform geostress field.

9. An electronic device, characterized in that: including memory and processor; a memory for storing a computer program, wherein the computer program includes program instructions; A processor is used to execute the program instructions so that the electronic device performs the steps of the method for optimizing horizontal well fracturing perforation parameters as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a computer program, and when the computer program is executed by one or more processors, the computer program implements the method for optimizing horizontal well fracturing and perforating parameters according to any one of claims 1 to 8.

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