Analysis method for multi-cluster fracturing crossing in horizontal well section of sand shale reservoir

Abstract

The invention provides an analysis method for multi-cluster fracturing crossing in a horizontal well section of a sand shale reservoir, which comprises the following steps of: based on a boundary element theory, considering three-dimensional fracture stress interference and flow distribution of each cluster, and establishing a full-three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of a tight gas horizontal well; coupling the wellbore flow model and the crack propagation numerical model through bottom hole pressure to obtain a coupling model; based on a three-dimensional boundary element theory, aiming at the coupling model, discretizing different fracture forms into rectangular units, and establishing a three-dimensional boundary element stress interference calculation model through a superposition principle; under the condition that geological factors are kept constant, the influence of different construction parameters on crack propagation and layer crossing behaviors is analyzed, a crack layer crossing main control factor is obtained, and the conditions and boundaries of segmented multi-cluster fracturing layer crossing of the sand-mud interbed horizontal well are determined. The method provides a basis for optimization of crack parameters and construction parameters.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone and mudstone reservoir, and is applied to improving the transformation effect of multi-segment and multi-cluster fracturing in a horizontal well section of a tight sandstone and mudstone reservoir. Background Art

[0002] The fracturing development of tight oil and gas horizontal wells mainly uses the multi-cluster fracturing technology in the multi-stage section of the horizontal well. The fracturing transformation effect depends to a large extent on the morphology of the formed fractures. Especially for reservoirs with interlayers of sand and mud, whether the fractures can penetrate the layers in the height direction is also an important factor affecting the production.

[0003] The height and penetration range of hydraulic fractures in sandstone-mudstone interbedded reservoirs are controlled by both geological and engineering factors. In recent years, domestic and foreign scholars have conducted theoretical research, numerical simulations, and field tests on this, and have gained a certain understanding of the factors that affect fracture height.

[0004] However, the related research in the existing technology mainly applies analytical two-dimensional or semi-analytical and semi-numerical pseudo-three-dimensional solutions to meet the requirements of rapid engineering design. A small amount of three-dimensional fracture simulation is mainly aimed at the expansion of a single fracture, and the influence of multiple fractures formed by multi-cluster fracturing in the horizontal well section on the penetration is not considered. For complex situations such as fracturing through interlayers of sandstone and mudstone, these studies are difficult to give reliable fracture penetration effects.

[0005] In view of the problems of the prior art, the present invention provides an analysis method for multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir. Summary of the invention

[0006] In order to overcome the defects of the prior art, the present invention provides a method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir, the method comprising:

[0007] Based on the boundary element theory, considering the three-dimensional fracture stress interference and flow distribution of each cluster, a full three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of tight gas horizontal wells is established;

[0008] The wellbore flow model is coupled with the fracture extension numerical model through bottom hole pressure to obtain a coupled model;

[0009] Based on the three-dimensional boundary element theory, for the coupling model, different crack shapes are discretized into rectangular units, and a three-dimensional boundary element stress interference calculation model is established through the superposition principle;

[0010] Under the condition that geological factors remain constant, the influence of different construction parameters on crack expansion and penetration behavior is analyzed, the main controlling factors of crack penetration are obtained, and the conditions and limits of multi-cluster fracturing penetration in horizontal wells with sand-mud interlayers are determined.

[0011] According to one embodiment of the present invention, the wellbore flow model is established by the following steps:

[0012] For multi-cluster fracturing horizontal well sections, a multi-fracture extension physical model that couples wellbore and perforation is constructed;

[0013] Based on the multi-fracture extension physical model, ignoring the friction resistance along the wellbore, the calculation equations for the entrance pressure of each cluster of fractures, the calculation equations for the perforation friction resistance and the total flow rate are established.

[0014] According to one embodiment of the present invention, the calculation equation for the entrance pressure of each cluster of fractures is:

[0015] p w =p p,k +p in,k ,k=1,2,...,N f

[0016] In the formula, p w is the bottom hole pressure, MPa; p p,k , k=1…N f is the perforation friction of k fracture, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa; N f is the number of cracks;

[0017] The perforation friction calculation equation is:

[0018]

[0019] In the formula, p p，k is the perforation friction of the k fracture, MPa; ρ is the liquid density, g / cm 3 ;Q in,k is the inlet flow rate of crack k, m 3 / s;n k is the number of perforations in the k fracture; d k is the perforation diameter of the k-fracture, mm; K k is the abrasion correction factor for k crack, dimensionless;

[0020] The total flow calculation equation is:

[0021]

[0022] In the formula, Q T is the total flow, m 3 / s;Q in，k is the inlet flow rate of crack k, m 3 / s.

[0023] According to one embodiment of the present invention, the crack propagation numerical model is established by the following steps:

[0024] Based on the multi-fracture extension physical model, in a two-dimensional case, a fluid flow equation in a two-dimensional fracture is established;

[0025] Based on the multi-fracture extension physical model, constructing a three-dimensional boundary element rock deformation equation in a three-dimensional case;

[0026] Based on the fluid flow equation and the rock deformation equation, the fracture extension condition is determined to obtain the fracture extension numerical model.

[0027] According to one embodiment of the present invention, the fluid flow equation is:

[0028]

[0029] Where w is the crack width, mm; μ is the fluid viscosity, Pa·s; p f is the fluid pressure, MPa; δ is the Kronecker function; (x in，k ,y in，k , z in，k ) is the position of the liquid inlet point of crack k; Q in，k is the inlet flow rate of crack k, m 3 / s; N f is the number of cracks;

[0030] The rock deformation equation is:

[0031] p f -σ0=∫ A(t) C(x-x',y-y',z-z')w(x',y',z')dA

[0032] In the formula, p f is the fluid pressure, MPa; σ0 is the far field stress, MPa; C is the Green function; t is the time, s; A(t) is the area of ​​the crack opened at time t, m 2 ; w is the crack width, m; (x', y', z') is the source point, (x, y, z) is the field point.

[0033] According to one embodiment of the present invention, the coupling equation for flow distribution of each cluster of fractures is:

[0034]

[0035] In the formula, Q in,k , k=1…N f is the inlet flow rate of crack k, m 3 / s;p w is the bottom hole pressure, MPa; Nf is the number of cracks; F is N f+1 A system of nonlinear equations, whose specific components are:

[0036]

[0037] In the formula, p p,k , k=1…N f is the perforation friction of k fracture, MPa; p c,k , k=1…N f is the friction resistance along the wellbore from the bottom of the well to the k-fracture perforation position, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa.

[0038] According to one embodiment of the present invention, the three-dimensional boundary element stress interference calculation model includes:

[0039]

[0040]

[0041]

[0042] In the formula, τ x is the stress in the x direction, MPa; τ y is the stress in the y direction, MPa; σ z is the stress in the z direction, MPa; D x is the displacement discontinuity in the x direction, mm; D y is the displacement discontinuity in the y direction, mm; D z is the displacement discontinuity in the z direction, mm; is the boundary influence coefficient.

[0043] According to one embodiment of the present invention, the conditions and limits of segmented multi-cluster fracturing penetration in sand-mud interlayer horizontal wells are determined by the following steps:

[0044] In the process of solving the coupled model of wellbore-perforation-fracture coupling, a structured grid explicit algorithm is used, and the preset step size is used to accelerate the calculation efficiency, and the fracture boundary is back-calculated through the tip asymptotic solution to improve the calculation accuracy;

[0045] The established fracture extension numerical model and the three-dimensional boundary element stress interference calculation model are used to study the influence of geological factors such as overlying interlayer thickness, interlayer stress difference, and intercluster horizontal stress distribution on fracture morphology.

[0046] According to another aspect of the present invention, a storage medium is provided, which contains a series of instructions for executing the method steps as described in any one of the above.

[0047] According to another aspect of the present invention, there is also provided a device for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir, which performs the method described in any one of the above items, and the device comprises:

[0048] The numerical model module is based on the boundary element theory, taking into account the three-dimensional fracture stress interference and flow distribution of each cluster, and establishing a full three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of tight gas horizontal wells;

[0049] A coupling model module, which is used to couple the wellbore flow model with the fracture extension numerical model through bottom hole pressure to obtain a coupling model;

[0050] A calculation model module is used to discretize different crack forms into rectangular units based on the three-dimensional boundary element theory for the coupling model, and to establish a three-dimensional boundary element stress interference calculation model through the superposition principle;

[0051] The main controlling factor module is used to analyze the influence of different construction parameters on crack expansion and penetration behavior under the condition that geological factors remain constant, obtain the main controlling factors of crack penetration, and determine the conditions and limits of multi-cluster fracturing penetration in horizontal wells with sand-mud interlayers.

[0052] The present invention provides an analysis method for multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir, which has the following advantages over the prior art:

[0053] Based on the boundary element theory, considering the 3D fracture stress interference and the flow distribution of each cluster, a boundary element full three-dimensional fracture propagation numerical model of stress interference and flow distribution of segmented multi-cluster fracturing in tight gas horizontal wells is established. Considering multiple factors such as the friction resistance between the horizontal wellbore and the perforation of multi-cluster fractures, stress interference, rock deformation, flow in fractures, fluid loss, fracture toughness, etc., the influence of geological factors such as the thickness of the overlying interlayer, the stress difference of the interlayer, and the horizontal stress distribution between clusters on the fracture morphology of multi-cluster fracturing in sand-mud interlayer horizontal wells is analyzed. Under the condition that the geological factors remain constant, different construction parameters are simulated, and the influence of construction parameters such as displacement, fracturing fluid viscosity, perforation cluster / segment, and number of perforations / cluster on the behavior of fracture propagation and penetration is analyzed. The main controlling factors of fracture penetration are obtained, and the conditions and limits of fracture penetration of segmented multi-cluster fracturing in sand-mud interlayer horizontal wells are determined. The expansion process of three-dimensional fractures under formation conditions is truly simulated, providing a basis for the optimization of fracture parameters and construction parameters.

[0054] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0056] Figure 1 A flowchart showing the steps of a method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to an embodiment of the present invention;

[0057] Figure 2 A schematic diagram of a multi-fracture propagation physical model of coupled wellbore and perforation according to an embodiment of the present invention is shown;

[0058] Figure 3 shows a flow distribution diagram of a wellbore-fracture system according to one embodiment of the present invention;

[0059] Figure 4 A schematic diagram of a discontinuous unit of multiple crack extension and displacement according to an embodiment of the present invention is shown;

[0060] Figure 5 A schematic diagram of a sand-mud interbed reservoir in a horizontal well according to an embodiment of the present invention is shown;

[0061] Figure 6 A diagram showing the influence of different reservoir layer thicknesses and stress differences on fracture penetration according to an embodiment of the present invention;

[0062] Figure 7 A graph showing the effect of the number of perforation clusters on fracture height according to one embodiment of the present invention is shown.

[0063] In the accompanying drawings, the same reference numerals are used for the same components. In addition, the accompanying drawings are not drawn according to the actual scale. DETAILED DESCRIPTION

[0064] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0065] The height and penetration range of hydraulic fractures in sandstone-mudstone interlayer reservoirs are controlled by geological factors and engineering factors. In recent years, domestic and foreign scholars have conducted theoretical research, numerical simulation, and field tests, and have a certain understanding of the factors affecting fracture height. Based on the theory of linear elastic fracture mechanics, Simonson et al. believed that geological factors such as reservoir-interlayer stress difference and elastic modulus difference have a significant impact on the height of hydraulic fractures; Biot et al. used fracture energy and shear modulus to establish a simple criterion for fractures entering the interlayer, but the distribution of in-situ stress was not considered in the model; Detournay et al. believed that fracture toughness had little effect on the morphology of large-scale hydraulic fractures in the field; Warpinski and Teufel et al., through field observations, indoor experiments, and finite element numerical calculations, showed that the stress difference between reservoir-interlayer is the most critical factor in inhibiting fractures from entering the interlayer, and gave the stress difference that satisfies the control of hydraulic fracture height under different reservoir-interlayer lithology combinations; Gu Hongren et al. showed that the difference in elastic modulus between reservoir and interlayer has a significant effect on the height of fracture. When the fracture has not entered the interlayer, the interlayer with large elastic modulus has an inhibitory effect on the extension of fracture height. When the fracture extends into the interlayer, the interlayer with small elastic modulus has a better inhibitory effect on the fracture height. Daneshy and Chuprakov et al. believed that the shear slip between the reservoir and interlayer interface blunts the end of the fracture, controls the extension of the fracture height, and forms a blunt fracture. Meng Shangzhi et al. believed that the fracture may enter the interlayer again in the later stage of fracturing. Cheng Yuanfang et al. studied the influence of fracturing construction parameters on the height of fracture through theoretical analysis and believed that reasonable construction conditions are conducive to controlling the height of fracture. Li Yang and Chen Zuorong et al. established a finite element nonlinear fluid-solid coupling hydraulic fracturing model to simulate the extension of fracture height. The calculation results were in good agreement with the field construction results, which greatly reduced the amount of calculation. Liu He et al. studied the influence of porosity and mud content on the height of hydraulic fracture. MB Smith et al. believed that the difference in elastic modulus between reservoir and interlayer alone was not enough to affect the extension of fracture height.

[0066] In general, the relevant research in the existing technology mainly applies analytical two-dimensional or semi-analytical and semi-numerical pseudo-three-dimensional solutions to meet the requirements of fast engineering design. A small amount of three-dimensional fracture simulation is mainly aimed at the expansion of a single fracture, and the influence of multiple fractures formed by multi-cluster fracturing in the horizontal well section on the penetration is not considered. For complex situations such as fracturing through interlayers of sandstone and mudstone, these studies are difficult to give reliable fracture penetration effects.

[0067] In order to solve the problems of the current prior art, the present invention establishes a fully three-dimensional fracture propagation numerical model for segmented multi-cluster fracturing in horizontal wells in sandstone-mudstone interlayers, considers the fracture morphology affected by multiple factors such as friction between the horizontal wellbore and multi-cluster fracture perforation, stress interference, rock deformation, flow in the fracture, fluid loss, fracture toughness, etc., truly simulates the expansion process of three-dimensional fractures under formation conditions, and analyzes the influence of geological and engineering factors on the penetration of multi-cluster fractures.

[0068] Figure 1 A flowchart of the steps of a method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to an embodiment of the present invention is shown.

[0069] like Figure 1 As shown, in step S101, based on the boundary element theory, a full three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of tight gas horizontal wells is established by considering the three-dimensional fracture stress interference and flow distribution of each cluster.

[0070] like Figure 1 As shown, in step S102, the wellbore flow model and the fracture extension numerical model are coupled through the bottom hole pressure to obtain a coupled model.

[0071] Specifically, based on the boundary element theory, considering the 3D fracture stress interference and the flow distribution of each cluster, a boundary element fracture extension numerical model of stress interference and flow distribution for segmented multi-cluster fracturing of tight gas horizontal wells is established, which mainly includes four physical processes: rock deformation, fluid flow in fractures, fluid loss to the formation and fracture tip rupture. For segmented multi-cluster fracturing of horizontal wells, the wellbore fluid diversion process is also included. The wellbore flow model can calculate the bottom hole pressure, which is also affected by the fracture extension model. Therefore, the wellbore flow model and the fracture extension numerical model are coupled through the bottom hole pressure. The diversion of the fracturing fluid injected into the wellbore to multiple fractures is determined by the "wellbore-fracture" system. Assuming that the fracture model calculates the inlet pressure of each cluster of fractures, the flow of each cluster of fractures can be obtained through the wellbore model.

[0072] Based on the boundary element theory, considering the 3D fracture stress interference and flow distribution of each cluster, a fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution boundary element for tight gas horizontal wells is established (for homogeneous layers).

[0073] Hydraulic fracturing is the process of high-pressure fluid driving fracture expansion, which mainly includes four physical processes: rock deformation, fluid flow in fractures, fluid loss to the formation, and fracture tip rupture. For horizontal well segmented multi-cluster fracturing, it also includes the wellbore fluid diversion process. In one embodiment, the multi-fracture expansion physical model coupled with wellbore and perforation is as follows Figure 2 shown.

[0074] In one embodiment, a wellbore flow model is established by the following steps: for multi-cluster fracturing horizontal well sections, a multi-fracture expansion physical model coupling the wellbore and perforation is constructed; based on the multi-fracture expansion physical model, the friction resistance along the wellbore is ignored, and the calculation equations for the entrance pressure of each cluster of fractures, the perforation friction resistance calculation equation, and the total flow calculation equation are established.

[0075] For multi-cluster fracturing, the injected fracturing fluid passes through the wellbore and perforations into each cluster of fractures. The amount of fluid entering each cluster is controlled by the "wellbore-perforation-fracture" system. Since the flow friction resistance of the horizontal wellbore is small, the friction resistance along the wellbore is temporarily ignored, so the calculation equation for the inlet pressure of each cluster of fractures is:

[0076] p w =p p,k +p in,k ,k=1,2,...,N f (1)

[0077] In the formula, p w is the bottom hole pressure, MPa; p p,k , k=1…N f is the perforation friction of k fracture, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa; N f is the number of cracks;

[0078] The calculation equation of perforation friction is:

[0079]

[0080] In the formula, p p，k is the perforation friction of the k fracture, MPa; ρ is the liquid density, g / cm 3 ;Q in,k is the inlet flow rate of crack k, m 3 / s;n k is the number of perforations in the k fracture; d k is the perforation diameter of the k-fracture, mm; K k is the abrasion correction factor for k crack, dimensionless;

[0081] At the same time, the flow rate of each cluster satisfies the mass conservation, that is, the total flow calculation equation is:

[0082]

[0083] In the formula, Q T is the total flow, m 3 / s;Q in，k is the inlet flow rate of crack k, m 3 / s.

[0084] In one embodiment, a numerical model of fracture extension is established by the following steps: based on a physical model of multiple fracture extension, in a two-dimensional case, a fluid flow equation in a two-dimensional fracture is established; based on a physical model of multiple fracture extension, in a three-dimensional case, a rock deformation equation of a three-dimensional boundary element is constructed; based on the fluid flow equation and the rock deformation equation, fracture extension conditions are determined to obtain a numerical model of fracture extension.

[0085] In one embodiment, it is assumed that the flow in the slot conforms to Poiseuille flow, so the constitutive equation of the fluid flow in the slot is:

[0086]

[0087] Where: q is the volume flow rate, m 3 / s; μ is the fluid viscosity, Pa·s; p f is the fluid pressure, MPa; w is the crack width, mm.

[0088] The component form of formula (4) is:

[0089]

[0090] Where: q is the volume flow rate, m 3 / s; μ is the fluid viscosity, Pa·s; p f is the fluid pressure, MPa, and w is the crack width, mm.

[0091] The continuity equation for fluid flow in a crack is:

[0092]

[0093] Where: Q in,k is the inlet flow rate of crack k, m 3 / s; q is the volume flow rate, m 3 / s; N f is the number of cracks; (x in，k ,y in，k , z in，k ) is the position of the liquid inlet point of crack k.

[0094] Substituting formula (4) into formula (6), the fluid flow equation is obtained:

[0095]

[0096] Where w is the crack width, mm; μ is the fluid viscosity, Pa·s; p f is the fluid pressure, MPa; δ is the Kronecker function; (x in，k ,y in，k , z in，k ) is the position of the liquid inlet point of crack k; Q in，k is the inlet flow rate of crack k, m 3 / s; N f is the number of cracks.

[0097] In one embodiment, a three-dimensional displacement discontinuity model is used to calculate rock deformation. The shear displacement discontinuity of the plane crack extension is zero, so the pressure in the crack and the crack width can be described by the rock deformation equation:

[0098] p f -σ0=∫ A(t) C(x-x',y-y',z-z')w(x',y',z')dA (8)

[0099] In the formula, p f is the fluid pressure, MPa; σ0 is the far field stress, MPa; C is the Green function; t is the time, s; A(t) is the area of ​​the crack opened at time t, m 2 ; w is the crack width, m; (x', y', z') is the source point, (x, y, z) is the field point.

[0100] The specific form of Green's function C is:

[0101]

[0102] Where: E is Young's modulus, MPa; v is Poisson's ratio, dimensionless.

[0103] In the crack expansion condition, the inlet flow rate of each crack satisfies:

[0104]

[0105] Where: Q in is the traffic of each cluster, m 3 / s; w is the crack width, mm; μ is the fluid viscosity, Pa·s; p is the fluid pressure, MPa.

[0106] In the crack extension condition, the flow rate at the crack boundary is zero, that is:

[0107]

[0108] Where: Q is the flow rate, m 3 / s; w is the crack width, mm; μ is the fluid viscosity, Pa·s; p is the fluid pressure, MPa.

[0109] In the crack propagation condition, when the stress intensity factor at the crack tip meets the rock fracture toughness, the crack propagates:

[0110] K tip =K Ic (12)

[0111] Where: K Ic is the rock type I fracture toughness, MPa·m 0.5 ; K tip is the stress intensity factor at the crack tip, MPa·m 0.5 .

[0112] Under the crack propagation condition, the calculation formula of the tip stress intensity factor is:

[0113]

[0114] Where: w tip is the width of the crack tip unit, m; d is the unit length, m; E is Young's modulus, GPa; v is Poisson's ratio, dimensionless.

[0115] Applicable conditions of the numerical model of fracture extension: 1) fracture extension is a quasi-static process that satisfies the linear elastic fracture criterion; 2) fracture extension is along the plane where the maximum horizontal principal stress is located, and fracture deflection is not considered; 3) the Carter filtration model is used to describe the vertical filtration of fluid in the fracture into the formation as a single-phase one-dimensional flow; 4) the fluid front coincides with the fracture tip, that is, the fluid lag problem is not considered.

[0116] In one embodiment, the fracturing fluid injected at the wellhead passes through the casing (or tubing) to the bottom of the well, and then flows in the hydraulic fracture after cluster perforation. The wellbore flow model can calculate the bottom hole pressure, and the bottom hole pressure is also affected by the fracture extension numerical model. Therefore, the wellbore flow model and the fracture extension numerical model are coupled through the bottom hole pressure. The wellhead injection pressure can be obtained according to the bottom hole pressure:

[0117] p s =p w +p c -p h (14)

[0118] Where: p s is the wellhead pressure, MPa; p h is the liquid column pressure, MPa; p c is the friction along the wellbore, MPa.

[0119] The liquid column pressure is calculated based on the liquid column height and density, that is:

[0120] p h =ρgh (15)

[0121] Where: ρ is the density of liquid or sand-carrying fluid, kg / m 3 , the density of the sand-carrying fluid is calculated based on the proppant density and volume fraction; h is the height of the liquid column, m.

[0122] The flow of fracturing fluid in the wellbore is the flow of liquid in a circular tube. The flow friction in the wellbore is p c The calculation formula is:

[0123]

[0124] Where: D w is the inner diameter of the fracturing string, m; l wis the length of the fracturing string, m; ε is the inner wall roughness of the fracturing string, m; V w is the liquid velocity in the wellbore, m / s; Re is the Reynolds number, Re = D W ρV W / μ.

[0125] From formula (16), we can know that the friction coefficient along the way is c is to calculate p c The friction coefficient along the way is affected by the Reynolds number and the roughness of the inner wall of the pipe, and the specific value can be solved through the Moody chart. The numerical calculation of the friction coefficient along the Moody chart adopts Churchill's full flow model:

[0126]

[0127] Where: The calculation formulas for Θ1 and Θ2 are:

[0128]

[0129] After the injected fracturing fluid reaches the bottom of the well, the total injection flow will be distributed to each cluster of opened fractures. The flow distribution of injection flow in the "wellbore-fracture" system is similar to the flow law of current in a circuit (such as Figure 3 ). In a liquid flow system, the liquid flow rate is similar to the current, and the liquid pressure is similar to the potential difference. F In the case of a single fracture, the total injection flow is equal to the sum of the flow rates of each branch, that is:

[0130]

[0131] The branch circuits formed by each fracture have the same pressure drop, so:

[0132] p w =p p,k +p in,k (20)

[0133] Where: p p,k is the perforation friction of k fracture, MPa; p in,k is the entrance pressure of crack k, MPa.

[0134] The calculation formula of perforation friction resistance in formula (20) is:

[0135]

[0136] Where: n k is the number of perforations in the k perforation cluster; d k is the perforation diameter of the k-perforation cluster, mm; K is the perforation abrasion correction factor, dimensionless; Q k is the flow rate of crack k, m 3 / s.

[0137] In one embodiment, the diversion of the fracturing fluid injected into the wellbore into the multiple fractures is determined by the "wellbore-fracture" system, such as Figure 3 As shown. Assuming that the fracture extension numerical model calculates the inlet pressure of each cluster of fractures, the flow rate of each cluster of fractures can be obtained through the wellbore flow model. The discrete equation for the flow distribution of each cluster of fractures, that is, the coupling equation for the flow distribution of each cluster of fractures is:

[0138]

[0139] In the formula, Q in,k , k=1…N f is the inlet flow rate of crack k, m 3 / s;p w is the bottom hole pressure, MPa; N f is the number of cracks; F is N f+1 A system of nonlinear equations, whose specific components are:

[0140]

[0141] In the formula, p p,k , k=1…N f is the perforation friction of k fracture, MPa; p c,k , k=1…N f is the friction resistance along the wellbore from the bottom of the well to the k-fracture perforation position, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa.

[0142] Substituting the fracture entrance pressure obtained from the fracture propagation numerical model into the equation (23), the flow rate and bottom hole pressure of each fracture cluster are obtained using the Newton-Raphson method.

[0143] like Figure 1 As shown, in step S103, based on the three-dimensional boundary element theory, for the coupling model, different crack morphologies are discretized into rectangular units, and a three-dimensional boundary element stress interference calculation model is established through the superposition principle.

[0144] Specifically, multi-cluster fracturing of horizontal wells involves the expansion of multiple cracks in a section, which involves the problem of stress interference. The present invention is based on the three-dimensional boundary element theory, discretizes different crack morphologies into rectangular units, and establishes a three-dimensional boundary element stress interference calculation model through the superposition principle. According to the induced stress calculation model, the stress at any point in space is obtained.

[0145] Based on the three-dimensional boundary element theory, different crack morphologies are discretized into rectangular units. Through the superposition principle, a three-dimensional boundary element stress interference calculation model is established, which is a stress interference simulation method under different process conditions.

[0146] like Figure 4 As shown, the definition of displacement discontinuity is as follows:

[0147]

[0148] Where: D x is the displacement discontinuity in the x direction, mm; D y is the displacement discontinuity in the y direction, mm; D z is the displacement discontinuity in the z direction, mm; u x (x,y,0 - ) is the displacement of the lower surface of the crack in the x direction, mm; u x (x,y,0 + ) is the displacement of the crack upper surface in the x direction, mm. u y (x,y,0 - ) is the displacement of the lower surface of the crack in the y direction, mm; u y (x,y,0 + ) is the displacement of the crack upper surface in the y direction, mm. u z (x,y,0 - ) is the displacement of the lower surface of the crack in the z direction, mm; u z (x,y,0 + ) is the displacement of the crack upper surface in the z direction, mm.

[0149] In one embodiment, the three-dimensional boundary element stress interference calculation model includes:

[0150]

[0151]

[0152]

[0153] In the formula, τ x is the stress in the x direction, MPa; τ y is the stress in the y direction, MPa; σ z is the stress in the z direction, MPa; D x is the displacement discontinuity in the x direction, mm; D y is the displacement discontinuity in the y direction, mm; D z is the displacement discontinuity in the z direction, mm; is the boundary influence coefficient.

[0154] The main calculation process of the three-dimensional boundary element stress interference calculation model includes: 1. Discrete segmentation according to the crack morphology; 2. Calculate the boundary influence coefficient matrix A; 3. Solve the linear equations to obtain the displacement discontinuity D; 4. According to the induced stress calculation model, the stress at any point in space is obtained.

[0155] like Figure 1 As shown, in step S104, under the condition that geological factors remain constant, the influence of different construction parameters on crack expansion and penetration behavior is analyzed, the main controlling factors of crack penetration are obtained, and the conditions and limits of multi-cluster fracturing penetration in sand-mud interlayer horizontal wells are determined.

[0156] Specifically, different construction parameters are simulated under the condition that geological factors remain constant, and the effects of construction parameters such as displacement, fracturing fluid viscosity, perforation cluster / segment, and number of perforations / cluster on crack expansion and penetration are analyzed. The main controlling factors of crack penetration are obtained, and the conditions and limits of multi-cluster fracturing penetration in horizontal wells with sand and mud interlayers are determined, providing a basis for the optimization of fracture parameters and construction parameters.

[0157] In one embodiment, in step S104, in the process of solving the fully coupled coupling model of "wellbore-perforation-fracture", a structured grid explicit algorithm is used, and a preset (large) step size is used to accelerate the calculation efficiency, and the fracture boundary is back-calculated through the tip asymptotic solution to improve the calculation accuracy. The established fracture propagation numerical model and three-dimensional boundary element stress interference calculation model are used to study the influence of geological factors such as the thickness of the overlying interlayer, the stress difference of the interlayer, and the horizontal stress distribution between clusters on the fracture morphology.

[0158] For horizontal well fracturing in sand-mud interlayer reservoirs, the fracturing transformation effect depends largely on whether the cracks can penetrate the reservoir barrier. Current related research is mostly based on two-dimensional models and does not consider the impact of the expansion of multiple cracks formed by multi-cluster fracturing in the horizontal well section on the penetration, and the fracturing design lacks a theoretical basis. The present invention adopts a numerical simulation method to establish a full three-dimensional fracture expansion numerical model for multi-cluster fracturing of horizontal wells in sand-mudstone interlayers, considering the fracture morphology affected by multiple factors such as the friction between the horizontal wellbore and the perforation of multiple clusters of fractures, stress interference of multiple clusters of fractures, rock deformation, flow in the fractures, fluid loss, fracture toughness, etc., truly simulating the expansion process of three-dimensional fractures under formation conditions, analyzing the impact of geological and engineering factors on the penetration of multiple clusters of fractures, and providing guidance for the optimization design of multi-cluster fracturing of horizontal wells in sand-mud interlayer reservoirs.

[0159] The method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone mudstone reservoir provided by the present invention can also be used in conjunction with a computer-readable storage medium, which stores a computer program. The computer program is executed to run the method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone mudstone reservoir.

[0160] A computer program can run computer instructions, which include computer program code. The computer program code may be in source code form, object code form, executable file, or some intermediate form.

[0161] Computer-readable storage media may include: any entity or device that can carry computer program code, recording media, USB flash drives, mobile hard disks, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0162] It should be noted that the content contained in computer-readable storage media can be appropriately increased or decreased based on the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, based on legislation and patent practices, computer-readable storage media do not include electrical carrier signals and telecommunications signals.

[0163] According to another aspect of the present invention, there is also provided an analysis device for multi-cluster fracturing penetration in a horizontal well section of a sandstone mudstone reservoir, which performs an analysis method for multi-cluster fracturing penetration in a horizontal well section of a sandstone mudstone reservoir. The device comprises: a numerical model module, a coupling model module, a computational model module, and a main control factor module.

[0164] The numerical model module is based on boundary element theory, takes into account the three-dimensional fracture stress interference and flow distribution of each cluster, and establishes a full three-dimensional fracture extension numerical model of stress interference and flow distribution of multi-cluster fracturing in tight gas horizontal wells; the coupling model module is used to couple the wellbore flow model with the fracture extension numerical model through the bottom hole pressure to obtain a coupling model; the calculation model module is used to discretize different fracture morphologies into rectangular units based on the three-dimensional boundary element theory and establish a three-dimensional boundary element stress interference calculation model through the superposition principle; the main control factor module is used to analyze the influence of different construction parameters on fracture extension and penetration behavior under the condition that the geological factors remain constant, obtain the main control factors of fracture penetration, and determine the conditions and limits of penetration of multi-cluster fracturing in horizontal wells with sand and mud interlayers.

[0165] The vertical characteristics of the Shan 2 reservoir in a horizontal well in northern Hubei are as follows Figure 5 As shown, the thickness of the upper overburden box 1-1 is 4m, the thickness of the upper interlayer is 4-16m, the thickness of the target layer mountain 2-2 is 12m, and the thickness of the lower interlayer is 20m.

[0166] Different geological parameters are input into the numerical model of fracture propagation to study the influence of geological factors such as overlying interlayer thickness, interlayer stress difference, and horizontal stress distribution between clusters on fracture morphology. Different construction parameters are simulated under the condition that the geological factors remain constant, and the influence of construction parameters such as displacement, fracturing fluid viscosity, perforation cluster / stage, and perforation number / cluster on fracture propagation, penetration and other behaviors is analyzed.

[0167] (1) Geological factors such as different reservoir thickness and stress difference

[0168] The simulation results are as follows Figure 6 As shown in the figure. The stress difference between the reservoir and the barrier makes the fracture pressure gradient of the barrier greater than the fracture pressure gradient of the reservoir. As the stress difference between the reservoir and the barrier increases, the difficulty of penetrating the layer gradually increases. The fracture morphology gradually transitions from penetrating the layer to being confined to the sandstone. The limitation in the fracture height direction forces the fracture to expand in the length direction, and the fracture length increases with the increase of the stress difference between the reservoir and the barrier.

[0169] In addition, the effect of interlayer thickness on fracture height is comprehensively considered. Interlayer thicknesses of 6m, 8m, 10m, 12m, and 14m are simulated respectively. As the thickness of the interlayer increases, the absolute value of the slope of the curve at each stage gradually decreases, that is, the thickness of the interlayer can enhance the fracture height reduction rate caused by the reservoir-interlayer stress difference. Comparing and analyzing the curves with an interlayer thickness of 6m and an interlayer thickness of 14 meters, when the stress difference increases from 5MPa to 7MPa, the reduction value of the fracture height of the former is about 5m higher than that of the latter.

[0170] Specifically, when the stress difference between the reservoir and the barrier layer is 3MPa and the thickness of the overlying barrier layer is less than 12m, the hydraulic fracture will penetrate the layer and expand into the overlying layer box 1-1; when the stress difference between the reservoir and the barrier layer is more than 5MPa and the thickness of the overlying barrier layer is 6m, the fracture height can be restricted and mainly expand in the target layer mountain 2-2; when the stress difference between the reservoir and the barrier layer is 3-5MPa, the fracture height transitions between penetrating the layer and being restricted.

[0171] (2) Effect of cluster number / segment on crack height

[0172] The number of perforation clusters contained in a single perforation section affects the amount of fluid inflow into each perforation cluster during fracturing, and thus affects the expansion and morphology of the fracture. At the same time, under the same stress difference conditions, the fracture height decreases with the increase of the barrier thickness. This method comprehensively considers the influence of barrier thickness and the number of perforation clusters on the expansion and morphology of the fracture. Simulation parameters: lower barrier thickness 20m, reservoir barrier stress difference 3MPa, displacement 10m 3 / min, liquid viscosity 10mPa·s, cluster spacing 25m. The simulation results are as follows Figure 7 As the number of clusters / segments increases, the fracture height gradually decreases, and the thicker the upper interlayer, the more significant the decrease in fracture height; when the upper interlayer is thin (6-10m) and the number of clusters / segments is greater than 4, the fracture height decreases rapidly and the penetration is limited; when the upper interlayer is thick (greater than 14m) and the number of clusters / segments is greater than 2, the fracture height is significantly limited.

[0173] The fracturing effect of horizontal well fracturing in sand-mud interlayer reservoirs depends largely on whether the fractures can penetrate the reservoir barrier. Current related research is mostly based on two-dimensional models and does not consider the impact of multiple fracture expansion formed by multi-cluster fracturing in the horizontal well section on the penetration, and the fracturing design lacks a theoretical basis.

[0174] Based on the boundary element theory, the present invention considers the 3D fracture stress interference and the flow distribution of each cluster, and establishes the boundary element fracture extension numerical model of stress interference and flow distribution of segmented multi-cluster fracturing of tight gas horizontal wells, which mainly includes 4 physical processes: rock deformation, fluid flow in the fracture, fluid loss to the formation and fracture tip rupture. For the segmented multi-cluster fracturing of horizontal wells, it also includes the wellbore liquid diversion process. The wellbore flow model can calculate the bottom hole pressure, and the bottom hole pressure is also affected by the fracture extension numerical model. Therefore, the wellbore flow model and the fracture extension numerical model are coupled through the bottom hole pressure. The diversion of the fracturing fluid injected into the wellbore to multiple fractures is determined by the "wellbore-fracture" system. Assuming that the fracture extension numerical model calculates the inlet pressure of each cluster of fractures, the flow of each cluster of fractures can be obtained through the wellbore flow model. Multi-cluster fracturing of horizontal wells involves the expansion of multiple fractures in the segment, which involves the problem of stress interference. Based on the three-dimensional boundary element theory, the present invention discretizes different fracture morphologies into rectangular units, establishes a three-dimensional boundary element stress interference calculation model through the superposition principle, and obtains the stress at any point in space according to the induced stress calculation model. In the process of solving the full coupling of "wellbore-perforation-fracture", a structured grid explicit algorithm is adopted, and a large step length is used to accelerate the calculation efficiency. The fracture boundary is back-calculated through the tip asymptotic solution to improve the calculation accuracy. The established model is used to study the influence of geological factors such as the thickness of the overlying interlayer, the stress difference of the interlayer, and the horizontal stress distribution between clusters on the fracture morphology. Under the condition that the geological factors remain constant, different construction parameters are simulated, and the influence of construction parameters such as displacement, fracturing fluid viscosity, perforation cluster / segment, and number of perforations / cluster on the behavior of fracture expansion and penetration is analyzed. The main controlling factors of fracture penetration are obtained, and the conditions and limits of multi-cluster fracturing penetration in sand-mud interlayer horizontal wells are determined, providing a basis for the optimization of fracture parameters and construction parameters.

[0175] In summary, the present invention provides an analysis method for multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir, which has the following advantages over the prior art:

[0176] Based on the boundary element theory, considering the 3D fracture stress interference and the flow distribution of each cluster, a boundary element full three-dimensional fracture propagation numerical model of stress interference and flow distribution of segmented multi-cluster fracturing in tight gas horizontal wells is established. Considering multiple factors such as the friction resistance between the horizontal wellbore and the perforation of multi-cluster fractures, stress interference, rock deformation, flow in fractures, fluid loss, fracture toughness, etc., the influence of geological factors such as the thickness of the overlying interlayer, the stress difference of the interlayer, and the horizontal stress distribution between clusters on the fracture morphology of multi-cluster fracturing in sand-mud interlayer horizontal wells is analyzed. Under the condition that the geological factors remain constant, different construction parameters are simulated, and the influence of construction parameters such as displacement, fracturing fluid viscosity, perforation cluster / segment, and number of perforations / cluster on the behavior of fracture propagation and penetration is analyzed. The main controlling factors of fracture penetration are obtained, and the conditions and limits of fracture penetration of segmented multi-cluster fracturing in sand-mud interlayer horizontal wells are determined. The expansion process of three-dimensional fractures under formation conditions is truly simulated, providing a basis for the optimization of fracture parameters and construction parameters.

[0177] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0178] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0179] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0180] Certain terms are used throughout this application document to indicate specific system components. As those skilled in the art will recognize, different names can usually be used to indicate the same components, so this application document is not intended to distinguish those components that are only different in name but not in function. In this application document, the terms "comprise", "include" and "have" are used in an open form, and therefore should be interpreted as meaning "including but not limited to...". In addition, the terms "substantially", "substantially" or "approximately" that may be used in this article relate to the tolerances of the corresponding terms accepted by the industry. The term "coupling" as may be used in this article includes direct coupling and indirect coupling via other components, elements, circuits, or modules, wherein for indirect coupling, the components, elements, circuits, or modules between them do not change the information of the signal but can adjust its current level, voltage level, and / or power level. Inferred coupling (for example, one of the elements is coupled to another element by inference) includes direct and indirect coupling between two elements in the same way as "coupling".

[0181] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0182] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0183] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir, characterized in that: The method comprises: Based on the boundary element theory, considering the three-dimensional fracture stress interference and flow distribution of each cluster, a full three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of tight gas horizontal wells is established; The wellbore flow model is coupled with the fracture extension numerical model through bottom hole pressure to obtain a coupled model; Based on the three-dimensional boundary element theory, for the coupling model, different crack shapes are discretized into rectangular units, and a three-dimensional boundary element stress interference calculation model is established through the superposition principle; Under the condition that geological factors remain constant, the influence of different construction parameters on crack expansion and penetration behavior is analyzed, the main controlling factors of crack penetration are obtained, and the conditions and limits of multi-cluster fracturing penetration in horizontal wells with sand-mud interlayers are determined.

2. The method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir according to claim 1, characterized in that: The wellbore flow model is established by the following steps: For multi-cluster fracturing horizontal well sections, a multi-fracture extension physical model that couples wellbore and perforation is constructed; Based on the multi-fracture extension physical model, ignoring the friction resistance along the wellbore, the calculation equations for the entrance pressure of each cluster of fractures, the calculation equations for the perforation friction resistance and the total flow rate are established.

3. The method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir according to claim 2, characterized in that: The calculation equation for the entrance pressure of each cluster of fractures is: p w =p p,k +p in,k ,k=1,2,...,N f In the formula, p w is the bottom hole pressure, MPa; p p,k , k=1…N f is the perforation friction of k fracture, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa; N f is the number of cracks; The perforation friction calculation equation is: In the formula, p p，k is the perforation friction of k fracture, MPa; ρ is the liquid density, g / cm 3 ;Q in,k is the inlet flow rate of crack k, m 3 / s;n k is the number of perforations in the k fracture; d k is the perforation diameter of the k-fracture, mm; K k is the abrasion correction factor for k crack, dimensionless; The total flow calculation equation is: In the formula, Q T is the total flow, m 3 / s;Q in，k is the inlet flow rate of crack k, m 3 / s.

4. A method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to any one of claims 2 to 3, characterized in that: The crack propagation numerical model is established by the following steps: Based on the multi-fracture extension physical model, in a two-dimensional case, a fluid flow equation in a two-dimensional fracture is established; Based on the multi-fracture extension physical model, constructing a three-dimensional boundary element rock deformation equation in a three-dimensional case; Based on the fluid flow equation and the rock deformation equation, the fracture extension condition is determined to obtain the fracture extension numerical model.

5. The method for analyzing multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir according to claim 4, characterized in that: The fluid flow equation is: Where w is the crack width, mm; μ is the fluid viscosity, Pa·s; p f is the fluid pressure, MPa; δ is the Kronecker function; (x in，k ,y in，k , z in，k ) is the position of the liquid inlet point of crack k; Q in，k is the inlet flow rate of crack k, m 3 / s; N f is the number of cracks; The rock deformation equation is: p f -σ0=∫ A(t) C(x-x',y-y',z-z')w(x',y',z')dA In the formula, p f is the fluid pressure, MPa; σ0 is the far field stress, MPa; C is the Green function; t is the time, s; A(t) is the area of ​​the crack opened at time t, m 2 ; w is the crack width, m; (x', y', z') is the source point, (x, y, z) is the field point.

6. A method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to any one of claims 1 to 5, characterized in that: The coupling equation for flow distribution of each cluster of fractures is: In the formula, Q in,k , k=1…N f is the inlet flow rate of crack k, m 3 / s;p w is the bottom hole pressure, MPa; N f is the number of cracks; F is N f+1 A system of nonlinear equations, whose specific components are: In the formula, p p,k , k=1…N f is the perforation friction of k fracture, MPa; p c,k , k=1…N f is the friction resistance along the wellbore from the bottom of the well to the k-fracture perforation position, MPa; p in,k , k=1…N f is the entrance pressure of crack k, MPa.

7. A method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to any one of claims 1 to 6, characterized in that: The three-dimensional boundary element stress interference calculation model comprises: In the formula, τ x is the stress in the x direction, MPa; τ y is the stress in the y direction, MPa; σ z is the stress in the z direction, MPa; D x is the displacement discontinuity in the x direction, mm; D y is the displacement discontinuity in the y direction, mm; D z is the displacement discontinuity in the z direction, mm; is the boundary influence coefficient.

8. A method for analyzing multi-cluster fracture penetration in a horizontal well section of a sandstone-mudstone reservoir according to any one of claims 1 to 7, characterized in that: The conditions and limits of multi-cluster fracturing penetration in sand-mud interlayer horizontal wells are determined by the following steps: In the process of solving the coupled model of wellbore-perforation-fracture coupling, a structured grid explicit algorithm is used, and the preset step size is used to accelerate the calculation efficiency, and the fracture boundary is back-calculated through the tip asymptotic solution to improve the calculation accuracy; The established fracture extension numerical model and the three-dimensional boundary element stress interference calculation model are used to study the influence of geological factors such as overlying interlayer thickness, interlayer stress difference, and intercluster horizontal stress distribution on fracture morphology.

9. A storage medium, characterized in that: It contains a series of instructions for executing the method steps as claimed in any one of claims 1 to 8.

10. An analysis device for multi-cluster fracturing penetration in a horizontal well section of a sandstone-mudstone reservoir, characterized in that: The method according to any one of claims 1 to 8 is performed, wherein the device comprises: The numerical model module is based on the boundary element theory, taking into account the three-dimensional fracture stress interference and flow distribution of each cluster, and establishing a full three-dimensional fracture propagation numerical model of segmented multi-cluster fracturing stress interference and flow distribution of tight gas horizontal wells; A coupling model module, which is used to couple the wellbore flow model with the fracture extension numerical model through bottom hole pressure to obtain a coupling model; A calculation model module is used to discretize different crack forms into rectangular units based on the three-dimensional boundary element theory for the coupling model, and to establish a three-dimensional boundary element stress interference calculation model through the superposition principle; The main controlling factor module is used to analyze the influence of different construction parameters on crack expansion and penetration behavior under the condition that geological factors remain constant, obtain the main controlling factors of crack penetration, and determine the conditions and limits of multi-cluster fracturing penetration in horizontal wells with sand-mud interlayers.

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