Consideration non-uniformly stressed horizontal well fracturing perforation parameter optimization method, equipment and medium

Abstract

This invention discloses a method, equipment, and medium for optimizing perforation parameters in horizontal well fracturing considering non-uniform geostress, relating to the field of unconventional oil and gas reservoir production enhancement. The method includes: constructing a three-dimensional non-uniform geostress field for reservoir fracturing; meshing hydraulic fractures using fracture elements, applying the three-dimensional non-uniform geostress field to the mesh, and establishing a constitutive model of reservoir rock deformation and stress during hydraulic fracturing; establishing a flow model of fracturing fluid in the horizontal wellbore, perforation hole, and hydraulic fractures based on the constitutive model; establishing propagation criteria for hydraulic fractures along fracture length and height; simulating the propagation results of horizontal well fracturing fractures under different perforation parameters based on the propagation criteria and flow model; and optimizing the horizontal well fracturing perforation parameters based on the propagation results. This invention overcomes the shortcomings of the uniform geostress field assumption and planar fracture propagation assumption in existing technologies, achieving optimization of horizontal well fracturing perforation parameters in a non-uniform geostress field.

Description

Technical Field

[0001] This invention relates to the field of unconventional oil and gas reservoir production enhancement and stimulation, and more specifically, to a method, equipment, and medium for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress. Background Technology

[0002] Horizontal well segmented multi-cluster fracturing technology is a key technology for the commercial exploitation of unconventional underground resources such as shale oil and gas, tight oil and gas, and geothermal energy. Accurately understanding the multi-fracture patterns in horizontal well fracturing within 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. The propagation law and fracture geometry are influenced by geological and engineering parameters, among which the distribution of in-situ stress has a particularly significant impact on the propagation of hydraulically fractured fractures. The significant heterogeneity and anisotropy of most reservoirs lead to substantial discrepancies between the spatial propagation of fractures in actual horizontal well fracturing and the predictions of hydraulic fracturing numerical models under the assumption of uniform stress distribution. The optimized completion and construction parameters obtained in fracturing schemes cannot accurately reflect the optimal results under real reservoir conditions. Therefore, considering the influence of non-uniform reservoir stress on hydraulic fracture propagation helps to rationally optimize the construction parameters of horizontal well segmented multi-cluster fracturing, which is of great significance for improving reservoir stimulation effects and resource development efficiency.

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

[0004] The purpose of this invention is to provide a method, equipment, and medium for optimizing perforation parameters in horizontal well fracturing that considers non-uniform geostress. This invention considers the combined influence of reservoir geological differences and fracturing engineering factors, establishing a three-dimensional non-uniform geostress field for reservoir fracturing. Based on this three-dimensional non-uniform geostress field, it conducts simulations of multi-cluster fracturing fracture propagation in horizontal wells. This invention overcomes the shortcomings of the uniform geostress field assumption and planar fracture propagation assumption in existing technologies, realizing the prediction of non-planar propagation trajectories of three-dimensional hydraulic fractures and the optimization of perforation parameters in horizontal well fracturing within a three-dimensional non-uniform stress field. This makes the simulation results closer to actual engineering conditions and provides technical support for the selection of perforation parameters in multi-cluster fracturing of horizontal wells.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A first aspect of the present invention provides a method for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress, the method comprising:

[0007] Constructing a three-dimensional non-uniform stress field for reservoir fracturing;

[0008] The hydraulic fractures are meshed using fracture elements, and a three-dimensional non-uniform stress field is applied to the mesh to establish a constitutive model of reservoir rock deformation and stress during hydraulic fracturing.

[0009] Based on the constitutive model, a flow model of fracturing fluid in horizontal wellbore, perforation hole and hydraulic fracture was established;

[0010] Establish criteria for the propagation of hydraulic fractures along the fracture length and fracture height;

[0011] Based on the propagation criteria and flow model, the propagation results of horizontal well fracturing fractures under different perforation parameters were simulated;

[0012] Optimize horizontal well fracturing perforation parameters based on the extended results.

[0013] In one implementation scheme, a three-dimensional non-uniform stress field for reservoir fracturing is constructed, specifically as follows:

[0014] Obtain the initial geostress field of the reservoir before fracturing;

[0015] Calculate the induced stress field generated by hydraulic fractures in the reservoir;

[0016] By superimposing the initial geostress field with the induced stress field, a three-dimensional non-uniform geostress field for reservoir fracturing is obtained.

[0017] In one implementation, the constitutive model consists of a comprehensive influence coefficient matrix, a fracture width matrix of the fracture element, a comprehensive normal stress matrix of the fracture element, and a fluid pressure matrix of the fracture element.

[0018] In one implementation, the process for determining the composite normal stress matrix of the crack element is as follows:

[0019] By performing spatial coordinate transformation on the three-dimensional non-uniform stress field, the stress along the strike, dip and normal directions of the crack element under the action of the three-dimensional non-uniform stress field is obtained.

[0020] Obtain the influence coefficient matrix along the strike, dip, and normal directions of the crack element. Based on the influence coefficient matrix and stress along the strike, dip, and normal directions of the crack element, calculate the comprehensive normal stress matrix of the crack element.

[0021] In one implementation scheme, a flow model of fracturing fluid in the horizontal wellbore, perforation hole, and hydraulic fracture is established based on a constitutive model, specifically as follows:

[0022] Obtain information on hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameters, perforation parameters, and flow correction coefficients caused by perforation erosion;

[0023] Based on the fluid pressure matrix of the fracture element, the hydraulic fracture width, and the fracturing fluid viscosity, a flow model of fracturing fluid in the hydraulic fracture is established.

[0024] Based on the fracturing fluid viscosity, horizontal wellbore parameters, and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the horizontal wellbore is established.

[0025] Based on the fracturing fluid density, perforation orifice parameters, flow correction coefficient, and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the perforation orifice is established.

[0026] Based on the flow models of fracturing fluid in hydraulic fractures, in horizontal wellbores, and in perforation holes, the pressure balance relationship between multiple perforation clusters in multi-cluster fracturing of horizontal wells is established, as well as the mass balance relationship between the total injection rate of multi-cluster fracturing of horizontal wells and the dynamic fracturing fluid rate entering each perforation cluster during multi-cluster fracturing of horizontal wells.

[0027] 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 coefficient caused by perforation erosion, the dynamic fracturing fluid discharge rate entering each perforation cluster during the segmented multi-cluster fracturing process of a horizontal well is iteratively solved.

[0028] Based on the dynamic fracturing fluid discharge rate, fracturing fluid viscosity, and hydraulic fracture width, the flow model of fracturing fluid in the hydraulic fracture is substituted to calculate the fluid pressure in the hydraulic fracture, and the fluid pressure matrix of the fracture element is determined based on the fluid pressure in the hydraulic fracture.

[0029] In one implementation scheme, a strategy for the propagation of hydraulic fractures along the fracture length and fracture height is established, specifically as follows:

[0030] The Young's modulus, Poisson's ratio, tensile stress intensity factor at fracture tip, and shear stress intensity factor at fracture tip of reservoir rock were obtained.

[0031] The first energy release rate of the fracture tip unit when the hydraulic fracture extends along the fracture length direction is calculated based on the Young's modulus, Poisson's ratio, tensile stress intensity factor and shear stress intensity factor of the fracture tip. The second energy release rate of the fracture tip unit when the hydraulic fracture extends along the fracture height direction is calculated based on the Young's modulus, Poisson's ratio and tensile stress intensity factor of the fracture tip.

[0032] When the first energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture length. The fracture deflection angle along the fracture length is calculated based on the tensile stress intensity factor and the shear stress intensity factor at the fracture tip.

[0033] 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 along the fracture length direction is zero.

[0034] In one implementation scheme, the propagation results of horizontal well fracturing fractures under different perforation parameters are simulated based on the propagation criterion and flow model, specifically:

[0035] The basic parameters required for simulating multi-cluster fracturing in horizontal wells of reservoirs are obtained; wherein, the basic parameters include geological parameters, completion parameters and construction parameters;

[0036] By combining basic parameters, propagation criteria, and flow models, the propagation results of horizontal well fracturing are simulated under different perforation parameters; wherein, the propagation results include the coefficient of variation of fracture length, the coefficient of variation of fracture area, and the coefficient of variation of perforation cluster discharge rate.

[0037] In one implementation scheme, the horizontal well fracturing perforation parameters are optimized based on the expansion results, specifically as follows:

[0038] The coefficient of variation of fracture length, coefficient of variation of fracture area, and coefficient of variation of perforation cluster discharge rate were weighted to calculate the analytical index of non-uniform propagation of multiple fractures in segmented multi-cluster fracturing of horizontal wells.

[0039] Based on the analysis indicators, the corresponding perforation parameters are selected as the optimization parameters for the segmented multi-cluster fracturing construction design of horizontal wells in non-uniform geostress fields.

[0040] A second aspect of the present invention provides an electronic device, including a memory and a processor;

[0041] A memory for storing computer programs, the computer programs including program instructions;

[0042] A processor is configured to execute the program instructions to cause the electronic device to perform the steps of a horizontal well fracturing perforation parameter optimization method as provided in the first aspect of the invention.

[0043] A third aspect of the present invention provides a computer-readable storage medium comprising a computer program that, when executed by one or more processors, implements a method for optimizing horizontal well fracturing perforation parameters as provided in the first aspect of the present invention.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention considers the combined effects of reservoir geological differences and fracturing engineering factors, and establishes a three-dimensional non-uniform geostress field for horizontal well fracturing reservoirs. Based on this, it conducts simulations of multi-cluster fracturing fracture propagation in horizontal wells. This invention overcomes the shortcomings of the uniform geostress field assumption and planar fracture propagation assumption in existing technologies, and realizes the prediction of non-planar propagation trajectory of three-dimensional hydraulic fractures in non-uniform stress fields and the optimization of horizontal well fracturing perforation parameters. This makes the simulation results closer to the actual engineering situation and can provide technical support for the optimization of perforation parameters in multi-cluster fracturing of horizontal wells. Attached Figure Description

[0046] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 A flowchart illustrating a method for optimizing perforation parameters in horizontal well fracturing according to an embodiment of the present invention;

[0048] Figure 2 This is a diagram showing the distribution of the maximum horizontal principal stress in the reservoir plane, provided in an embodiment of the present invention.

[0049] Figure 3 This is a diagram showing the distribution of the minimum principal stress in the reservoir plane, provided in an embodiment of the present invention.

[0050] Figure 4 This is a diagram showing the calculation results of hydraulic crack induced stress in the horizontal section adjacent to the target modification section, provided in an embodiment of the present invention.

[0051] Figure 5 The figure shows the calculation results of the maximum principal stress in the reservoir plane in a three-dimensional non-uniform stress field provided in the embodiments of the present invention.

[0052] Figure 6The figure shows the calculation results of the minimum principal stress in the reservoir plane in a three-dimensional non-uniform stress field provided by the embodiments of the present invention.

[0053] Figure 7 This is a schematic diagram of the discrete hydraulic fractures and fracture units in a horizontal well segmented multi-cluster fracturing system provided in an embodiment of the present invention.

[0054] Figure 8 This is a diagram showing the predicted fracture trajectory and width of a horizontal well in Scheme 1 provided by an embodiment of the present invention.

[0055] Figure 9 This is a diagram showing the predicted fracture trajectory and width of a horizontal well in Scheme 2 provided in this embodiment of the invention.

[0056] Figure 10 This is a diagram showing the predicted fracture trajectory and width of a horizontal well in Scheme 3 provided in this embodiment of the invention.

[0057] Figure 11 The predicted fracture trajectory and width of horizontal well fracturing in Scheme 4 provided in the embodiment of the present invention. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0059] It should be noted that the terms "comprising" or "may include" used in the various embodiments of this 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. Furthermore, as used in the various embodiments of this application, the terms "comprising," "having," and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0060] 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] Please refer to Figure 1 , Figure 1This is a flowchart illustrating a method for optimizing perforation parameters in horizontal well fracturing according to an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes:

[0062] S101, constructing a three-dimensional non-uniform stress field for reservoir fracturing.

[0063] In this embodiment, the three-dimensional non-uniform geostress field of reservoir fracturing is constructed by: obtaining the initial geostress field of the reservoir before fracturing; calculating the induced stress field generated by hydraulic fractures in the reservoir; and superimposing the initial geostress field and the induced stress field to obtain the three-dimensional non-uniform geostress field of reservoir fracturing.

[0064] Specifically, through geological modeling of the target reservoir, the initial three-dimensional geostress field distribution before fracturing is obtained, including the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress gradient of the reservoir. Then, considering the stress interference caused by hydraulic fractures after fracturing of adjacent horizontal sections, the induced stresses generated by the hydraulic fractures in the reservoir are 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, calculated as follows: In the formula, σ mix This represents a non-uniform stress field obtained from stress superposition calculations. σ far This represents the initial in-situ stress field of the reservoir before fracturing. σ ind This represents the induced stress field generated by hydraulic fractures.

[0065] The construction process of the three-dimensional non-uniform geostress field described in this embodiment is implemented as follows: Based on geological exploration data, the initial three-dimensional geostress field distribution of the target reservoir before fracturing is obtained. The distribution results of the maximum horizontal principal stress within the reservoir plane are referenced. Figure 2 The results of the horizontal minimum principal stress distribution in the reservoir plane are referenced. Figure 3 The reservoir thickness is 38.0 m, the average stress difference between the upper and lower layers is 3.0 MPa, and the vertical stress gradient is approximately 0.02 MPa / m. Considering the stress interference caused by hydraulic fractures in adjacent fracturing sections near the horizontal well toe, the induced stress field distribution in the target stimulated section is calculated. The reservoir Young's modulus is 33.5 GPa, and the reservoir Poisson's ratio is 0.22. The induced stress calculation results are referenced from... Figure 4 By applying the principle of stress superposition, a three-dimensional non-uniform stress field model for reservoir fracturing is obtained, with the maximum principal stress distribution within the reservoir plane referenced. Figure 5 The distribution of maximum principal stress in the reservoir plane is referenced. Figure 6 .

[0066] S102 uses fracture elements to mesh hydraulic fractures, applies a three-dimensional non-uniform stress field to the mesh, and establishes a constitutive model of reservoir rock deformation and stress during hydraulic fracturing.

[0067] In this embodiment, fracture element meshing is performed, and rectangular fracture elements with the same displacement value are used to discretize hydraulic fractures. The deformation and stress of reservoir rocks are characterized by the deformation and stress of fracture elements.

[0068] Based on the theory of three-dimensional displacement discontinuity, 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 for fracture elements, a comprehensive normal stress matrix for fracture elements, and a fluid pressure matrix for fracture elements. (Refer to...) Figure 7 For horizontal wells with segmented multi-cluster hydraulic fractures, constant displacement rectangular fracture elements with equal length and width are used to discretize the hydraulic fractures. Influence coefficients are calculated based on reservoir rock property parameters and fracture element geometric parameters. The comprehensive normal stress acting on the fracture element is calculated through the three-dimensional non-uniform stress field in step S101. Specifically, the process of determining the comprehensive normal stress matrix of the fracture element is as follows: the three-dimensional non-uniform stress field is transposed to obtain the stress along the strike, dip, and normal directions of the fracture element 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 element is obtained; and the comprehensive normal stress matrix of the fracture element is calculated based on the influence coefficient matrix and stress along the strike, dip, and normal directions of the fracture element.

[0069] The matrix form of the constitutive model is: ;

[0070] in, ;

[0071] ;

[0072] In the formula, the subscripts L, H, and N represent the three directions along the crack element's strike, dip, and normal, respectively; C represents the influence coefficient matrix. Indicates the influence coefficient between the normal and tangential directions; This represents the influence coefficient between the direction and the normal. This represents the influence coefficient between the direction and the tendency; Indicates the influence coefficient between tendency and trend; Indicates the influence coefficient between normal and yaw; This represents the influence coefficient between the tendency and the normal. Indicates the influence coefficient between normals; Indicates the influence coefficient between tendencies; The influence coefficient between different orientations is represented by ; w represents the crack width matrix of the crack element; C M Represents the comprehensive influence coefficient matrix; σ M p represents the combined normal stress matrix acting on the crack element. f R represents the fluid pressure matrix acting on the fracture element; T represents the transpose matrix; The stress matrix representing the orientation of a fracture element under in-situ stress. This represents the dip stress matrix of a fracture element under in-situ stress. This represents the normal stress matrix of a fracture element under in-situ stress. This represents the stress along the fracture element under in-situ stress. This represents the tendency stress of a fracture element under in-situ stress. This represents the normal stress of a fracture element under in-situ stress.

[0073] S103, a flow model of fracturing fluid in horizontal wellbore, perforation orifice and hydraulic fracture is established based on constitutive model.

[0074] In this embodiment, a flow model of fracturing fluid in the horizontal wellbore, perforation hole, and hydraulic fracture is established based on the constitutive model, specifically as follows:

[0075] S1031, obtain information on hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameters, perforation orifice parameters, and flow correction coefficient caused by orifice erosion;

[0076] S1032, Based on the fluid pressure matrix of the fracture element, the hydraulic fracture width and the fracturing fluid viscosity, a flow model of fracturing fluid in the hydraulic fracture is established.

[0077] S1033, Based on the fracturing fluid viscosity, horizontal wellbore parameter information and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the horizontal wellbore is established;

[0078] S1034. Based on the fracturing fluid density, perforation orifice parameter information, flow correction coefficient, and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the perforation orifice is established.

[0079] S1035. Based on the flow model of fracturing fluid in hydraulic fractures, the flow model in horizontal wellbore, and the flow model in perforation holes, establish the pressure balance relationship between multiple perforation clusters in segmented multi-cluster fracturing of horizontal wells, and establish the mass balance relationship between the total injection discharge of segmented multi-cluster fracturing of horizontal wells and the dynamic fracturing fluid discharge of each perforation cluster during the segmented multi-cluster fracturing process of horizontal wells.

[0080] S1036, based on the pressure balance relationship and mass balance relationship, combined with the fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameter information, perforation orifice parameter information and flow correction coefficient caused by orifice erosion, the dynamic fracturing fluid discharge rate entering each perforation cluster during the segmented multi-cluster fracturing process of horizontal well is iteratively solved.

[0081] S1037. Based on the dynamic fracturing fluid discharge rate, fracturing fluid viscosity and hydraulic fracture width, the flow model of fracturing fluid in the hydraulic fracture is substituted to calculate the fluid pressure in the hydraulic fracture, and the fluid pressure matrix of the fracture element is determined based on the fluid pressure in the hydraulic fracture.

[0082] It should be noted that in steps S1033 and S1034, the preset dynamic fracturing fluid discharge rate refers to a given initial value for the fracturing fluid discharge rate. Based on this initial value and relevant parameter information, a flow model of the fracturing fluid in the horizontal wellbore and 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, and a mass balance relationship between the total injection discharge rate of the horizontal well segmented multi-cluster fracturing and the dynamic fracturing fluid discharge rate entering each perforation cluster during the horizontal well segmented multi-cluster fracturing process are established. Based on this, and combined with the acquired parameter information, the final dynamic fracturing fluid displacement can be iteratively solved. Then, the final dynamic fracturing fluid displacement is substituted into the flow model of fracturing fluid in the horizontal wellbore and perforation orifice, thereby simulating the dynamic displacement of fracturing fluid in the horizontal wellbore, perforation orifice, 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 fracturing fluid in the hydraulic fracture to calculate the fluid pressure in the hydraulic fracture. Since the fluid pressure matrix of the fracture element is composed of multiple fluid pressures, the fluid pressure matrix can be calculated based on the fluid pressure.

[0083] Specifically, (1) the flow of fracturing fluid in a horizontal wellbore is described using a circular pipe flow model, and the formula for calculating wellbore friction is:

[0084] In the formula, Δ p w,i Indicates the first i Pressure drop due to flow friction in a horizontal wellbore section; μ f Indicates the viscosity of the fracturing fluid; q w,i Indicates the first i Fracturing fluid discharge rate in the horizontal wellbore section; L i Indicates the first i The length of the horizontal shaft section; d w Indicates the inner diameter of the horizontal wellbore.

[0085] (2) The formula for calculating the frictional pressure drop when fracturing fluid enters the hydraulic fracture through the perforation hole in the horizontal wellbore is:

[0086] In the formula, Δ p p,i Indicates the first i Perforation friction voltage drop of a cluster of perforations; ρ f This indicates the density of the fracturing fluid; q p,i Indicates entering the first i Fracturing fluid discharge rate of the cluster of perforations; F p This represents the flow correction factor caused by perforation erosion; n i Indicates the first i The number of apertures in a cluster of apertures; d i Indicates the first i The aperture diameter of the perforation of the cluster of perforations.

[0087] (3) The laminar flow model is used to describe the flow of fracturing fluid in the hydraulic fracture. Based on Poiseuille's law, the continuity equation of fracturing fluid flow is obtained: This refers to the flow model of fracturing fluid in hydraulic fractures. The mass conservation equation for fracturing fluid flow within hydraulic fractures is: After simplification, the governing equation for the flow of fracturing fluid within the hydraulic fracture is obtained as follows: In the formula, v f Indicates the flow velocity of the fracturing fluid; w Indicates the width of the hydraulic crack; μ f Indicates the viscosity of the fracturing fluid; p f This indicates the fluid pressure within the hydraulic fracture; t Indicates time; q inj Indicates the injection rate of the hydraulic fracture; q leak This indicates the filtration rate of the hydraulic fracture; Represents the Laplace operator; This indicates the fracturing fluid velocity.

[0088] (4) Calculate the dynamic fracturing fluid discharge rate into each perforation cluster during the segmented multi-cluster fracturing process of a horizontal well based on the pressure balance principle, and establish the pressure balance relationship between multiple perforation clusters in the segmented multi-cluster fracturing of a horizontal well using Kirchhoff's law:

[0089] In the formula, n Indicates the number of perforation clusters; p in This indicates the fluid pressure at the inlet of the hydraulic fracture; This represents the pressure difference between the nth cluster and the (n-1)th cluster at the horizontal wellhead.

[0090] Based on the mass conservation principle, the dynamic fracturing fluid flow rate into each perforation cluster satisfies the following relationship:

[0091] In the formula, Q This indicates the total injection displacement of a horizontal well in a multi-cluster fracturing operation. This represents the dynamic fracturing fluid discharge rate of the nth perforation cluster.

[0092] By combining the pressure balance relationship and the mass conservation relationship, a set of nonlinear equations was constructed, and the dynamic fracturing fluid discharge into each perforation cluster during the segmented multi-cluster fracturing process in a horizontal well was solved using the Newton-Raphson iteration:

[0093] ;

[0094] ;

[0095] ;

[0096] In the formula, m represents the iteration step; q p This represents the fracturing fluid displacement matrix entering the perforation cluster; Represents the inequality residual matrix; Let fracturing fluid displacement matrix be the dynamic fracturing fluid displacement matrix at the m-th iteration step.

[0097] In this embodiment, the flow rate of fracturing fluid entering each perforation cluster at the current moment is preset, and the flow control equation of fracturing fluid in the hydraulic fracture is solved to obtain the fluid pressure distribution in the hydraulic fracture. Then, the flow rate of fracturing fluid entering each perforation cluster is calculated through the pressure balance relationship and mass conservation relationship among multiple perforation clusters in the horizontal well. The flow rate of fracturing fluid entering each perforation cluster and the fluid pressure in the hydraulic fracture are obtained by iterative numerical calculation. In the execution process of this embodiment, the flow model of the horizontal wellbore, perforation holes and fracturing fluid in the hydraulic fracture is established according to steps (3), (4), (1) and (2).

[0098] S104, establish the propagation criteria of hydraulic fractures along the fracture length and fracture height.

[0099] In this embodiment, a strategy for the propagation of hydraulic fractures along the fracture length and fracture height is established, specifically as follows:

[0100] S1041, obtain Young's modulus of reservoir rock, Poisson's ratio of reservoir rock, tensile stress intensity factor at fracture tip and shear stress intensity factor at fracture tip.

[0101] S1042, based on the Young's modulus of the reservoir rock, Poisson's ratio of the reservoir rock, tensile stress intensity factor at the fracture tip, and shear stress intensity factor at the fracture tip, the first energy release rate of the fracture tip unit when the hydraulic fracture extends along the fracture length direction is calculated, and the second energy release rate of the fracture tip unit when the hydraulic fracture extends along the fracture height direction is calculated based on the Young's modulus of the reservoir rock, Poisson's ratio of the reservoir rock, and tensile stress intensity factor at the fracture tip;

[0102] S1043, when the first energy release rate is greater than the critical energy release rate, the hydraulic fracture expands along the fracture length direction. 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.

[0103] 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 along the fracture length direction is zero.

[0104] 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, based on the maximum energy release rate criterion, the propagation of the hydraulic fracture can be predicted by calculating the energy release rate of the usable tip element. In the formula, G tip This indicates the energy release rate of the hydraulic fracture tip unit; G c This represents the critical energy release rate for crack propagation, when... G tip ≥ G c The hydraulic cracks then expanded.

[0105] The formula for calculating the energy release rate of the fracture tip unit when a hydraulic fracture propagates along its length is:

[0106] ;

[0107] The formula for calculating the energy release rate of the fracture tip element when a hydraulic fracture propagates along the fracture height is:

[0108] In the formula, E Indicates the Young's modulus of the reservoir rock; v Indicates the Poisson's ratio of the reservoir rock; K I Indicates the tensile stress intensity factor at the crack tip; K II This represents the shear stress intensity factor at the crack tip.

[0109] The maximum circumferential stress criterion is used to predict the propagation direction of hydraulic fractures along their length. This means the propagation direction of the hydraulic fracture is the same as the direction in which the circumferential tensile stress near the fracture tip reaches its maximum value. This is achieved when the shear stress intensity factor at the fracture tip... K II When the angle is greater than 0, the formula for calculating the crack deflection angle is: .

[0110] When the shear stress intensity factor at the crack tip K II When the angle is less than 0, the formula for calculating the crack deflection angle is:

[0111] ;

[0112] When the shear stress intensity factor at the crack tip K II When the crack deflection angle is 0, the formula for calculating the crack deflection angle is: In the formula, Δ θ This indicates the deflection angle at the tip of the hydraulic fracture as it propagates.

[0113] When a hydraulic fracture extends along its height, the deflection of the fracture is not considered, therefore the deflection angle at the fracture tip is 0.

[0114] In this embodiment, based on the maximum energy release rate criterion, the stress intensity factors of the tensile and shear stresses at the hydraulic fracture tip are calculated using the normal displacement and tangential displacement of the fracture element at the fracture tip. Then, the energy release rate of the tip element is calculated to determine the propagation along the fracture length and height directions. When the hydraulic fracture tip element meets the propagation conditions, the propagation direction along the fracture length is calculated using the maximum circumferential stress criterion, while the propagation direction along the fracture height remains unchanged along the vertical direction. The normal and tangential displacements of newly added fracture elements are set to 1.0 × 10⁻⁶. -6 m.

[0115] S105 simulates the propagation results of horizontal well fracturing fractures under different perforation parameters based on propagation criteria and flow models.

[0116] In this embodiment, the propagation results of horizontal well fracturing fractures under different perforation parameters are simulated based on the propagation criterion and flow model. Specifically, the basic parameters required for segmented multi-cluster fracturing simulation of reservoir horizontal wells are obtained; wherein, the basic parameters include geological parameters, completion parameters and construction parameters; and the propagation results of horizontal well fracturing fractures under different perforation parameters are simulated by combining the basic parameters, propagation criterion and flow model.

[0117] In this embodiment, the basic parameters required for the segmented multi-cluster fracturing simulation of the target reservoir horizontal well are shown in Table 1.

[0118] Table 1. Basic parameters required for segmented multi-cluster fracturing simulation of horizontal wells in the target reservoir.

[0119]

[0120] Considering the influence of adjacent fracturing sections in a horizontal well, the effect of induced stress is calculated, and the results are referenced. Figure 4 The non-uniform geostress field of the target reservoir fracturing section was calculated by combining the initial three-dimensional geostress field data, and the results were referenced. Figure 5 and Figure 6 Further designs for different perforation parameter schemes were developed. This embodiment considers different perforation densities, as detailed in Table 2.

[0121] Table 2 Perforation Density Scheme

[0122]

[0123] Simulations were conducted based on the four perforation schemes in Table 2, yielding the propagation results of multi-cluster hydraulic fracturing in horizontal wells under schemes 1 to 4. The hydraulic fracture propagation trajectory and fracture width distribution in three-dimensional space were referenced. Figure 8 , Figure 9 , Figure 10 and Figure 11 .

[0124] S106, optimize horizontal well fracturing perforation parameters based on the extended results.

[0125] In this embodiment, the horizontal well fracturing perforation parameters are optimized based on the expansion results, specifically as follows:

[0126] S1061, by weighting the coefficient of variation of fracture length, coefficient of variation of fracture area, and coefficient of variation of perforation cluster discharge, calculates the analytical index of non-uniform propagation of multiple fractures in segmented multi-cluster fracturing of horizontal wells.

[0127] Specifically, firstly, it should be noted that the propagation 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 analytical indices of non-uniform propagation of multiple fractures in segmented multi-cluster fracturing in horizontal wells is as follows: In the formula, α This represents a comprehensive evaluation index for non-uniform propagation of multiple cracks. C L This represents the coefficient of variation of crack length; C A Indicates the coefficient of variation of crack area; C Q Indicates the coefficient of variation of the perforation cluster displacement; β 1 indicates the crack length weighting coefficient; β 2 represents the crack area weighting coefficient; β3 represents the perforation cluster displacement weighting coefficient. The formulas for calculating the coefficients of variation for different indicators are as follows: In the formula, C Indicates the coefficient of variation; μ This represents the mean; σ It represents the standard deviation.

[0128] S1062. Based on the analysis indicators, select the corresponding perforation parameters as optimization parameters for the segmented multi-cluster fracturing construction design of horizontal wells in a non-uniform geostress field.

[0129] Specifically, the lower the value of the analytical index for non-uniform propagation of multiple fractures, the more uniform the propagation of multiple fractures, and the more accurately the corresponding perforation parameters can reflect the optimal results under real reservoir conditions. Therefore, it can be used as a recommended parameter for the design of segmented multi-cluster fracturing operations in horizontal wells in non-uniform geostress fields.

[0130] In this embodiment, the coefficients of variation of fracture length, fracture area, and perforation cluster displacement under different perforation schemes are shown in Table 3. The weighting coefficients for fracture length, fracture area, and perforation cluster displacement are set to 0.45, 0.35, and 0.20, respectively. The comprehensive evaluation index for non-uniform expansion of multiple fractures in a horizontal well segmented multi-cluster fracturing was calculated. The results show that reducing the number of perforations from 18 perforations / m in Scheme 1 to 12 perforations / m in Scheme 4 lowers the comprehensive evaluation index by 0.0923, indicating that reducing the number of perforations under a uniform perforation scheme can promote uniform expansion of multiple fractures in a horizontal well segmented multi-cluster fracturing. Schemes 3 and 4 adopted non-uniform perforation parameter designs to address the differences in perforation cluster expansion. It can be observed that under the perforation scheme of Scheme 3, the perforation densities from the first cluster from the left to the sixth cluster from the right are 8 perforations / m, 8 perforations / m, 10 perforations / m, 10 perforations / m, 12 perforations / m, and 12 perforations / m, respectively, with a comprehensive evaluation index of 0.1993. The simulation results are referenced... Figure 10 This design represents the most uniform multi-cluster horizontal well fracturing scheme among the four schemes (Schemes 1-4). Compared to the uniform perforation scheme, under non-uniform geostress conditions, it is necessary to specifically design non-uniform perforation cluster parameters for the stress conditions of each hydraulic fracture in the perforation cluster, optimizing the perforation parameters to promote the propagation of multiple hydraulic fractures. In this embodiment, for the optimization of horizontal well multi-cluster fracturing construction parameters in a non-uniform geostress field, a non-uniform perforation scheme is adopted to promote the uniform propagation of multiple fractures in the horizontal well fracturing. Based on the comprehensive evaluation index results, the recommended parameters are the perforation density parameters corresponding to Scheme 3.

[0131] Table 3. Comprehensive evaluation index of non-uniform propagation of multiple fractures in segmented multi-cluster fracturing of horizontal wells under different perforation schemes.

[0132]

[0133] This invention also 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 portable read-only memory (CD-ROM), and is used for related instructions and data.

[0134] The communication interface is used to receive and send data. The processor can be one or more CPUs; if it is a single CPU, it can be a single-core or multi-core CPU. The processor in the electronic device is used to read one or more programs stored in memory and perform the following operations: constructing a three-dimensional non-uniform stress field for reservoir fracturing; meshing the hydraulic fractures using fracture elements, applying the three-dimensional non-uniform stress field to the mesh, and establishing a constitutive model of reservoir rock deformation and stress during hydraulic fracturing; establishing a flow model of fracturing fluid in the horizontal wellbore, perforation holes, and hydraulic fractures based on the constitutive model; establishing propagation criteria for hydraulic fractures along the fracture length and height; simulating the propagation results of horizontal well fracturing fractures under different perforation parameters based on the propagation criteria and flow model; and optimizing the horizontal well fracturing perforation parameters based on the propagation results.

[0135] It should be noted that the specific implementation of each operation can be described above. Figure 1 The corresponding description of the method embodiments shown indicates that the electronic device can be used to execute a horizontal well fracturing perforation parameter optimization method considering non-uniform geostress, as described in the above method embodiments of this application, which will not be elaborated further here.

[0136] This invention also provides a computer-readable storage medium, which is a memory device in a computer device for storing programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the operating system of the terminal. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor, which can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the method for optimizing horizontal well fracturing perforation parameters considering non-uniform stress in the above embodiments. Those skilled in the art should understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can 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 code.

[0137] This invention also provides a computer program product containing program instructions. The computer program product may be software or program products containing program instructions, capable of running on a computing device or stored on any available medium. When the computer program product is run on at least one electronic device, it causes the at least one electronic device to perform a method for optimizing horizontal well fracturing perforation parameters considering non-uniform stress.

[0138] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment 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 within the scope of protection of the present invention.

Claims

1. A method for optimizing perforation parameters in horizontal well fracturing considering non-uniform geostress, characterized in that, The methods include: Constructing a three-dimensional non-uniform stress field for reservoir fracturing; Hydraulic fractures are meshed using fracture elements, and a three-dimensional non-uniform stress field is applied to the mesh to establish a constitutive model of reservoir rock deformation and stress during hydraulic fracturing. The constitutive model consists of a comprehensive influence coefficient matrix, a fracture width matrix of the fracture elements, a comprehensive normal stress matrix of the fracture elements, and a fluid pressure matrix of the fracture elements. Based on the constitutive model, a flow model of fracturing fluid in horizontal wellbore, perforation hole and hydraulic fracture was established; Establish propagation criteria for hydraulic fractures along the fracture length and height directions. Specifically, establishing these criteria involves: obtaining the Young's modulus, Poisson's ratio, tensile stress intensity factor at the fracture tip, and shear stress intensity factor at the fracture tip of the reservoir rock; calculating the first energy release rate of the fracture tip unit during hydraulic fracture propagation along the fracture length direction based on the Young's modulus, Poisson's ratio, tensile stress intensity factor at the fracture tip, and shear stress intensity factor at the fracture tip; and calculating the first energy release rate of the fracture tip unit based on the Young's modulus, Poisson's ratio, tensile stress intensity factor at the fracture tip, and shear stress intensity factor at the fracture tip. The second energy release rate of the fracture tip unit is calculated based on the Poisson's ratio of the reservoir rock and the tensile stress intensity factor at the fracture tip when the hydraulic fracture propagates along the fracture height. When the first energy release rate is greater than the critical energy release rate, the hydraulic fracture propagates along the fracture length. The fracture deflection angle along the fracture length 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 propagates along the fracture height, and the fracture deflection angle along the fracture length is zero. Based on the propagation criteria and flow model, the propagation results of fractures in horizontal wells under different perforation parameters were simulated. Specifically, this simulation involved obtaining the basic parameters required for segmented multi-cluster fracturing simulation of a reservoir horizontal well. These basic parameters included geological parameters, completion parameters, and construction parameters. Combining these basic parameters, the propagation criteria, and the flow model, the propagation results of fractures in horizontal wells under different perforation parameters were simulated. The propagation results included the coefficient of variation of fracture length, the coefficient of variation of fracture area, and the coefficient of variation of perforation cluster displacement. Optimize horizontal well fracturing perforation parameters based on the extended results.

2. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress according to claim 1, characterized in that, The three-dimensional non-uniform geostress field of reservoir fracturing is constructed as follows: Obtain the initial geostress field of the reservoir before fracturing; Calculate the induced stress field generated by hydraulic fractures in the reservoir; By superimposing the initial geostress field with the induced stress field, a three-dimensional non-uniform geostress field for reservoir fracturing is obtained.

3. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress according to claim 1, characterized in that, The process for determining the composite normal stress matrix of the crack element is as follows: By performing spatial coordinate transformation on the three-dimensional non-uniform stress field, the stress along the strike, dip and normal directions of the crack element under the action of the three-dimensional non-uniform stress field is obtained. Obtain the influence coefficient matrix along the strike, dip, and normal directions of the crack element. Based on the influence coefficient matrix and stress along the strike, dip, and normal directions of the crack element, calculate the comprehensive normal stress matrix of the crack element.

4. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress according to claim 1, characterized in that, Based on the constitutive model, a flow model of fracturing fluid in the horizontal wellbore, perforation hole, and hydraulic fracture is established, specifically as follows: Obtain information on hydraulic fracture width, fracturing fluid viscosity, fracturing fluid density, horizontal wellbore parameters, perforation parameters, and flow correction coefficients caused by perforation erosion; Based on the fluid pressure matrix of the fracture element, the hydraulic fracture width, and the fracturing fluid viscosity, a flow model of fracturing fluid in the hydraulic fracture is established. Based on the fracturing fluid viscosity, horizontal wellbore parameters, and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the horizontal wellbore is established. Based on the fracturing fluid density, perforation orifice parameters, flow correction coefficient, and preset dynamic fracturing fluid discharge rate, a flow model of fracturing fluid in the perforation orifice is established. Based on the flow models of fracturing fluid in hydraulic fractures, in horizontal wellbores, and in perforation holes, the pressure balance relationship between multiple perforation clusters in multi-cluster fracturing of horizontal wells is established, as well as the mass balance relationship between the total injection rate of multi-cluster fracturing of horizontal wells and the dynamic fracturing fluid rate entering each perforation cluster during 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 coefficient caused by perforation erosion, the dynamic fracturing fluid discharge rate entering each perforation cluster during the segmented multi-cluster fracturing process of a horizontal well is iteratively solved. Based on the dynamic fracturing fluid discharge rate, fracturing fluid viscosity, and hydraulic fracture width, the flow model of fracturing fluid in the hydraulic fracture is substituted to calculate the fluid pressure in the hydraulic fracture, and the fluid pressure matrix of the fracture element is determined based on the fluid pressure in the hydraulic fracture.

5. The method for optimizing horizontal well fracturing perforation parameters considering non-uniform geostress according to claim 1, characterized in that, Based on the extended results, the horizontal well fracturing perforation parameters are optimized as follows: The coefficient of variation of fracture length, coefficient of variation of fracture area, and coefficient of variation of perforation cluster discharge rate were weighted to calculate the analytical index of non-uniform propagation of multiple fractures in segmented multi-cluster fracturing of horizontal wells. Based on the analysis indicators, the corresponding perforation parameters are selected as the optimization parameters for the segmented multi-cluster fracturing construction design of horizontal wells in non-uniform geostress fields.

6. An electronic device, characterized in that, Including memory and processor; A memory for storing computer programs, the computer programs including program instructions; A processor is configured to execute the program instructions to cause the electronic device to perform the steps of a horizontal well fracturing perforation parameter optimization method as described in any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a computer program that, when executed by one or more processors, implements a method for optimizing horizontal well fracturing perforation parameters as described in any one of claims 1 to 5.

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