A low-permeability oil reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method

Abstract

The application discloses a low-permeability oil reservoir horizontal well fracturing reconstruction and yield prediction integrated simulation method, system, equipment and medium, relates to the technical field of reservoir yield improvement and reconstruction, and comprises the following steps: constructing a low-permeability oil reservoir geological model according to field geology and drilling data; constructing a low-permeability oil reservoir horizontal well fracturing and proppant transport coupling model; combining horizontal well fracturing simulation results and indoor conductivity capacity experiment results, predicting the global conductivity capacity of hydraulic fractures; constructing a low-permeability oil reservoir horizontal well production oil-water two-phase percolation model, predicting the oil-water distribution characteristics of the low-permeability oil reservoir after pressure and the horizontal well yield; and evaluating the low-permeability oil reservoir horizontal well fracturing reconstruction result according to the prediction result and optimizing horizontal well fracturing construction parameters. The method can realize integrated simulation of low-permeability oil reservoir horizontal well fracturing fracture creation, proppant migration and post-pressure yield prediction, can evaluate the fracturing reconstruction effect and optimize fracturing construction parameters according to the horizontal well yield prediction result, and can improve the low-permeability oil reservoir horizontal well fracturing reconstruction effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reservoir stimulation and reconstruction, and particularly relates to a low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method, system, device and medium. BACKGROUND

[0002] With the growing demand for oil and gas resource exploration and development worldwide, the importance of unconventional oil and gas resources is gradually highlighted, and a low-cost and high-efficiency development method becomes the key to commercial exploitation of low-grade resources. At present, the process system combining horizontal wells and hydraulic fracturing is still the preferred solution for the profitable exploitation of low-permeability reservoirs. By increasing the contact area between the wellbore and the reservoir through a long horizontal section, the permeability and flowability of the reservoir fluid are improved by using an artificial fracture network, the controlled reserves of a single well are enhanced, and the overall producing degree of the reservoir resources is improved. Under the existing technical framework, how to optimize the fracturing parameters and improve the reservoir reconstruction effect becomes a key concern in the development of low-permeability reservoirs.

[0003] The post-fracturing dynamic production characteristics of a low-permeability reservoir mainly depend on the spatial distribution of hydraulic fractures and the placement results of proppants in the fractures. There is a significant coupling effect between the hydraulic fracture propagation and the proppant migration, and the interaction results determine the geometry and conductivity of the hydraulic fractures, which further affect the reservoir oil-water distribution characteristics during the production process of the low-permeability reservoir. Therefore, coupling the key processes of low-permeability reservoir reconstruction and production, such as hydraulic fracture propagation, proppant migration and oil-water two-phase seepage, is the key to guiding field production and development. Due to the invisibility of the underground environment and the field scale characteristics, at present, engineers and scholars mainly use numerical simulation to study and explore the above processes. However, most of the researches are only focused on the single process of fracturing, sand placement and production, and the fracturing effect evaluation methods mainly use the parameters such as the geometry of the hydraulic fracture, the placement characteristics of the proppant and the reservoir reconstruction volume as the evaluation indexes. In the production prediction aspect, the uniform placement of the proppant in the fracture is assumed, and important influencing factors such as the coupling effect of the hydraulic fracture propagation and the proppant migration, the non-uniform distribution of the hydraulic fracture conductivity and the post-fracturing oil-water two-phase seepage characteristics are not fully considered. It is difficult to directly reflect the quantitative influence law of different fracturing parameters on the production performance, and there is a lack of an integrated simulation method for fracturing reconstruction and production prediction, which can optimize the key parameters of the low-permeability reservoir fracturing reconstruction by taking the production as the evaluation index. SUMMARY

[0004] The present application aims to provide a low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method, system, device and medium, which realizes the integrated simulation of the fracturing, proppant migration and post-fracturing production prediction of the low-permeability reservoir horizontal well, evaluates the fracturing reconstruction effect and optimizes the fracturing construction parameters according to the horizontal well production prediction results, and improves the fracturing reconstruction effect of the low-permeability reservoir horizontal well.

[0005] The application is achieved by the following technical solutions:

[0006] In a first aspect, the application provides a low-permeability oil reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method, comprising the following steps:

[0007] S1: constructing a low-permeability oil reservoir geological model according to field geology and drilling data;

[0008] S2: constructing a low-permeability oil reservoir horizontal well fracturing and proppant transport coupling model, predicting hydraulic fracture and proppant placement characteristics, and obtaining a horizontal well fracturing simulation result;

[0009] S3: combining the horizontal well fracturing simulation result and the laboratory conductivity experiment result to predict the global conductivity of the hydraulic fracture;

[0010] S4: constructing a low-permeability oil reservoir horizontal well oil-water two-phase seepage model, combining the global conductivity of the hydraulic fracture to predict the low-permeability oil reservoir post-fracturing reservoir oil-water distribution characteristics and the horizontal well production, and obtaining a prediction result;

[0011] S5: evaluating the low-permeability oil reservoir horizontal well fracturing reconstruction result according to the prediction result, and optimizing the horizontal well fracturing construction parameters.

[0012] Further, the specific method for constructing a low-permeability oil reservoir geological model according to field geology and drilling data comprises:

[0013] S11: collecting target block geology, drilling and production data, establishing a three-dimensional structure model and a sedimentary facies model, and obtaining a porosity and permeability attribute model;

[0014] S12: obtaining horizontal well staged fracturing reconstruction region reservoir basic parameters, the parameters comprising: reservoir horizontal maximum principal stress, horizontal minimum principal stress, vertical stress, barrier stress difference, stress gradient, reservoir thickness, pore pressure, Young's modulus and Poisson's ratio.

[0015] Further, the specific method for constructing a low-permeability oil reservoir horizontal well fracturing and proppant transport coupling model comprises:

[0016] S21: constructing a hydraulic fracture deformation mathematical model: discretizing a field-scale hydraulic fracture into a rectangular fracture unit based on a displacement discontinuity method, establishing a hydraulic fracture deformation model according to a stress and deformation relationship, and establishing an induced stress calculation model to describe the stress interference effect between hydraulic fractures when a horizontal well is staged and multi-cluster fractured;

[0017] S22: a fracturing fluid flow mathematical model is established, including: the fracturing fluid flow in the hydraulic fracture is described by using the Poiseuille law, the fracturing fluid seepage process in the reservoir is described by using the porous medium seepage theory, the fracturing fluid filtration is calculated according to the fluid pressure relationship between the hydraulic fracture and the reservoir matrix, the flow difference of different perforation clusters in the horizontal well staged multi-cluster fracturing process is considered, the fluid pressure equation set is established by using the Kirchhoff law, and the Newton iteration method is used for solving, and the dynamic flow distribution results of each perforation cluster of the horizontal well staged multi-cluster fracturing at different times are obtained;

[0018] S23: a hydraulic fracture propagation model is established, including: the equivalent stress intensity criterion is used as the judgment basis for the hydraulic fracture propagation, when the equivalent stress intensity factor of the fracture tip element is greater than or equal to the fracture toughness of the rock, the hydraulic fracture propagates, and a new fracture element is added at the current hydraulic fracture tip, the propagation direction of the hydraulic fracture is predicted based on the maximum circumferential stress criterion, and the deflection angle of the hydraulic fracture tip element is calculated;

[0019] S24: a proppant transport model in the hydraulic fracture is constructed, including: the density and viscosity of the mixed sand liquid formed by the mixing of the proppant and the fracturing fluid are calculated, the proppant passability in the hydraulic fracture is described by using the plugging function, the corrected proppant settling velocity is calculated, and the proppant transport mathematical model in the hydraulic fracture is established based on the Euler multiphase flow theory;

[0020] S25: a low-permeability oil reservoir horizontal well fracturing fracture and proppant transport coupling model is solved, including: based on the hydraulic fracture deformation model and the fracturing fluid flow model, the hydraulic fracture and the reservoir matrix in the horizontal well staged multi-cluster fracturing are established, the fracturing fluid seepage control equation set, the proppant transport control equation set in the hydraulic fracture, and the hydraulic fracture propagation fluid-solid coupling equation set, the hydraulic fracture and the reservoir matrix in the fracturing fluid seepage control equation set, the proppant transport control equation set in the hydraulic fracture, and the hydraulic fracture propagation fluid-solid coupling equation set are calculated at the same time step by using the sequential coupling method for iterative calculation, and the hydraulic fracture width, the fluid pressure in the fracture, the proppant concentration in the fracture, and the reservoir matrix pore pressure are calculated under the set convergence condition.

[0021] Further, the specific method for combining the horizontal well fracturing simulation results and the laboratory conductivity experiment results to predict the global conductivity of the hydraulic fracture includes:

[0022] S31: after the horizontal well fracturing simulation is completed, the proppant placement thickness is calculated according to the hydraulic fracture width and the proppant concentration in the fracture, and the hydraulic fracture elements are divided into filled elements and unfilled elements according to the filling thickness;

[0023] S32: the conductivity of the hydraulic fracture elements filled with proppant and not filled with proppant is obtained through the laboratory experiment;

[0024] S33: Calculate the closure stress according to the target low-permeability reservoir stress and the hydraulic fracture induced stress, and interpolate based on the conductivity chart to obtain the spatial distribution results of the conductivity of the filled fracture unit and the unfilled fracture unit.

[0025] Further, the specific method for constructing the oil-water two-phase percolation model of the horizontal well in the low-permeability reservoir includes:

[0026] S41: Establish an oil-water two-phase percolation mathematical model in the low-permeability reservoir matrix;

[0027] S42: Establish an oil-water two-phase percolation mathematical model in the hydraulic fracture of the low-permeability reservoir;

[0028] S43: Establish a mathematical model for calculating the yield after hydraulic fracturing of the low-permeability reservoir;

[0029] S44: Establish the flow conduction relationship between the reservoir matrix and the hydraulic fracture based on the embedded discrete fracture theory, use the finite volume method to numerically disperse the two-phase flow mathematical model in the reservoir matrix and the hydraulic fracture, and establish an oil-water two-phase flow mathematical model of the matrix-fracture-wellbore of the horizontal well in the low-permeability reservoir under the condition of constant pressure production.

[0030] Further, the specific method for predicting the oil-water distribution characteristics and the horizontal well yield of the low-permeability reservoir after pressure based on the global conductivity of the hydraulic fracture includes:

[0031] S45: Design the key construction parameters of the reservoir horizontal well fracturing based on the development needs of the low-permeability reservoir;

[0032] S46: Simulate the fracture creation and proppant transport of the horizontal well in the low-permeability reservoir to obtain the hydraulic fracture trajectory, fracture size, and proppant placement results;

[0033] S47: Calculate the global conductivity of the hydraulic fracture after the horizontal well fracturing based on the prediction results of the hydraulic fracture geometric parameters and the proppant concentration distribution;

[0034] S48: Develop the production performance simulation of the low-permeability reservoir horizontal well after pressure based on the matrix-fracture-wellbore oil-water two-phase flow mathematical model with the global conductivity of the hydraulic fracture as the input condition;

[0035] S49: Output the reservoir oil-water distribution and horizontal well yield results corresponding to different horizontal well fracturing construction schemes.

[0036] Further, the specific method for evaluating the horizontal well fracturing results in the low-permeability reservoir and optimizing the horizontal well fracturing parameters based on the prediction results includes:

[0037] According to the prediction result, the reconstruction effect of different horizontal well fracturing construction schemes is evaluated by taking the cumulative production of the horizontal well under the same production condition as the index, and the key construction parameters of the horizontal well fracturing reconstruction in the low-permeability reservoir are optimized.

[0038] In a second aspect, another embodiment of the present application provides a low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation system for implementing the low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method described in the first embodiment, comprising a first model construction module, a second model construction module, a prediction module, a third model construction module and a calculation and optimization module.

[0039] The first model construction module is used to construct a low-permeability reservoir geological model according to field geological and drilling data.

[0040] The second model construction module is used to construct a low-permeability reservoir horizontal well fracturing and proppant transport coupling model, to predict the hydraulic fracture and proppant placement characteristics, and to obtain the horizontal well fracturing simulation result.

[0041] The prediction module is used to combine the horizontal well fracturing simulation result and the laboratory conductivity experiment result to predict the global conductivity of the hydraulic fracture.

[0042] The third model construction module is used to construct a low-permeability reservoir horizontal well production oil-water two-phase percolation model, to combine the global conductivity of the hydraulic fracture to predict the low-permeability reservoir post-fracturing reservoir oil-water distribution characteristics and the horizontal well production, and to obtain the prediction result.

[0043] The calculation and optimization module is used to evaluate the low-permeability reservoir horizontal well fracturing reconstruction result according to the prediction result, and to optimize the horizontal well fracturing construction parameters.

[0044] In a third aspect, another embodiment of the present application provides an electronic device comprising a processor, an input device, an output device and a memory, which are connected to each other, the memory is used to store a computer program, the computer program comprises program instructions, the processor is configured to invoke the program instructions to execute the method described in the first embodiment.

[0045] In a fourth aspect, another embodiment of the present application provides a computer readable storage medium, which stores a computer program, the computer program comprises program instructions, the program instructions, when executed by a processor, cause the processor to execute the method described in the first embodiment.

[0046] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0047] The embodiment of the present application provides a low-permeability oil reservoir horizontal well fracturing reconstruction and yield prediction integrated simulation method, system, device and medium, which has the following advantages.

[0048] (1) The dynamic coupling simulation of hydraulic fracture propagation and proppant transport is realized through proppant accumulation bridging and rheological parameter change of sand mixing liquid, and the hydraulic fracture morphology and proppant placement result are accurately predicted;

[0049] (2) The hydraulic fracture conductivity chart under the conditions of proppant filling and non-filling is obtained through indoor experiments, and the post-fracturing hydraulic fracture global conductivity is reasonably calculated in combination with the hydraulic fracture geometric parameter and proppant concentration simulation result;

[0050] (3) The horizontal well fracturing reconstruction and yield prediction integrated simulation is realized in combination with the hydraulic fracture global conductivity and the matrix-fracture-wellbore oil-water two-phase percolation model, the fracturing reconstruction effect is evaluated and the fracturing construction parameter is optimized according to the horizontal well yield prediction result, the horizontal well fracturing reconstruction effect of the low-permeability oil reservoir is improved, and the low-permeability oil reservoir development is facilitated to reduce cost, increase benefit and improve quality. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical scheme of the exemplary embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings. In the drawings:

[0052] Figure 1 A flowchart of a low-permeability oil reservoir horizontal well fracturing reconstruction and yield prediction integrated simulation method provided by the first embodiment of the present application is shown in the figure;

[0053] Figure 2 A target low-permeability oil reservoir porosity model schematic diagram is shown in the figure;

[0054] Figure 3 A target low-permeability oil reservoir permeability model schematic diagram is shown in the figure;

[0055] Figure 4 A hydraulic fracture extension trajectory and geometric form simulation result schematic diagram under different schemes is shown in the figure;

[0056] Figure 5 A hydraulic fracture proppant concentration distribution simulation result schematic diagram under different schemes is shown in the figure;

[0057] Figure 6 A hydraulic fracture proppant filling fracture conductivity chart obtained through indoor experiments schematic diagram is shown in the figure;

[0058] Figure 7A schematic diagram of a conductivity chart of a fracture without proppant filling for indoor experiments is shown in the figure;

[0059] Figure 8 A schematic diagram of the calculation results of the global conductivity of the hydraulic fracture under different schemes is shown in the figure;

[0060] Figure 9 A schematic diagram of the relative permeability curve of the water phase and the oil phase in the reservoir matrix is shown in the figure;

[0061] Figure 10 A schematic diagram of the relative permeability curve of the water phase and the oil phase in the hydraulic fracture is shown in the figure;

[0062] Figure 11 A schematic diagram of the capillary pressure curve of the water phase and the oil phase in the reservoir matrix is shown in the figure;

[0063] Figure 12 A schematic diagram of the prediction results of the reservoir pore pressure of the horizontal well under different schemes is shown in the figure;

[0064] Figure 13 A schematic diagram of the prediction results of the reservoir water saturation of the horizontal well under different schemes is shown in the figure;

[0065] Figure 14 A schematic diagram of the cumulative production curve of the horizontal well under different schemes is shown in the figure;

[0066] Figure 15 A structural block diagram of a low-permeability oil reservoir horizontal well fracturing reconstruction and production prediction integrated simulation system provided by another embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application is further described in detail below with examples and drawings, the schematic embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0068] As Figure 1 shown, the first embodiment of the present application provides a low-permeability oil reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method, mainly including the following steps:

[0069] S1: constructing a low-permeability oil reservoir geological model according to field geology and drilling data;

[0070] S2: constructing a low-permeability oil reservoir horizontal well fracturing and proppant transport coupling model, predicting the hydraulic fracture and proppant placement characteristics, and obtaining the horizontal well fracturing simulation results;

[0071] S3: combine the horizontal well fracturing simulation results with the laboratory conductivity experiment results to predict the global conductivity of the hydraulic fracture; S4: construct a low-permeability oil reservoir horizontal well oil-water two-phase seepage flow model, combine the global conductivity of the hydraulic fracture to predict the low-permeability oil reservoir post-fracturing reservoir oil-water distribution characteristics and the horizontal well production, and obtain the prediction results;

[0072] S5: evaluate the low-permeability oil reservoir horizontal well fracturing reconstruction results according to the prediction results, and optimize the horizontal well fracturing construction parameters.

[0073] Specifically, step S1: constructing a low-permeability oil reservoir geological model according to field geology and drilling data includes:

[0074] S11: collecting target block geology, drilling and production data, establishing a three-dimensional structure model and a sedimentary facies model, and obtaining porosity and permeability attribute models;

[0075] S12: obtaining a horizontal well staged fracturing reconstruction area, and obtaining reservoir horizontal maximum principal stress, horizontal minimum principal stress, vertical stress, stress difference of the barrier layer, stress gradient, reservoir thickness, pore pressure, Young's modulus, Poisson's ratio and other parameters.

[0076] In this embodiment, by collecting and processing target low-permeability oil reservoir geology, drilling and production data, three-dimensional structure and sedimentary facies modeling is performed, porosity and permeability attribute models are obtained, and the following is referred to: Figure 2 and Figure 3 Further based on the reservoir rock mechanics properties and the oil-water distribution characteristics, the horizontal well staged fracturing reconstruction area is screened, and the basic parameters of the reservoir to be reconstructed are obtained, referring to Table 1.

[0077] Table 1 Basic parameters of the horizontal well staged fracturing reconstruction area of the embodiment

[0078]

[0079] Specifically, the method for constructing a low-permeability oil reservoir horizontal well fracturing fracture and proppant transport coupling model includes:

[0080] S21: constructing a hydraulic fracture deformation mathematical model, specifically including:

[0081] Based on the displacement discontinuity method, the field-scale hydraulic fracture is discretized into rectangular fracture elements, and a hydraulic fracture deformation model is established according to the stress and deformation relationship:

[0082] ;

[0083] A induced stress calculation model is established to describe the stress interference effect between hydraulic fractures in horizontal well staged multi-cluster fracturing:

[0084] ;

[0085] where the subscripts L, H, N represent the along strike, dip and normal directions of the hydraulic fracture, respectively; D L , D H represent the tangential displacements of the fracture element along the strike and dip directions, respectively; w represents the normal displacement of the fracture element, i.e. the fracture width; τ L , τ H , σ N represent the stresses acting on the rectangular fracture element along the strike, tangential and normal directions, respectively; A inf represents the stress boundary influence coefficient matrix, which characterizes the stress influence of the displacement of the fracture element at a certain point in space.

[0086] S22: establishing a mathematical model of fracturing fluid flow, specifically including:

[0087] The Poiseuille law is used to describe the fracturing fluid flow in the hydraulic fracture:

[0088] ;

[0089] The Darcy seepage theory of porous media is used to describe the fracturing fluid seepage process in the reservoir:

[0090] ;

[0091] The fracturing fluid filtration is calculated based on the fluid pressure relationship between the hydraulic fracture and the reservoir matrix:

[0092] ;

[0093] where t represents time; μ f represents the viscosity of the fracturing fluid; p f represents the fluid pressure in the hydraulic fracture; p m represents the reservoir pore fluid pressure; γ represents the fluid static pressure gradient; z represents the unit vector along the gravity direction; q f,inj represents the fracturing fluid injection source term; q m,inj represents the fracturing fluid injection source term in the reservoir, which is obtained by calculating the fracturing fluid filtration; q leak represents the fracturing fluid filtration term; ψ p represents the proppant volume fraction in the hydraulic fracture; represents the reservoir matrix porosity; k m represents the reservoir matrix permeability, which is calculated by fracturing fluid filtration; C leak represents the fluid flow coefficient between the hydraulic fracture and the reservoir matrix, which can be obtained by theoretical derivation or laboratory experiment.

[0094] Considering the flow difference of different perforation clusters in the process of horizontal well staged multi-cluster fracturing, the fluid pressure equation set is established by the Kirchhoff law, and the Newton iteration method is used to solve it, and the dynamic flow distribution results of each perforation cluster of horizontal well staged multi-cluster fracturing at different times are obtained.

[0095] S23: Establishing a hydraulic fracture propagation model, specifically including:

[0096] The equivalent stress intensity criterion is used as the basis for judging the hydraulic fracture propagation. When the equivalent stress intensity factor of the crack tip element is greater than or equal to the fracture toughness of the rock, the hydraulic fracture propagates, and a new crack element is added at the current hydraulic fracture tip:

[0097] ;

[0098] wherein K e represents the equivalent stress intensity factor of the hydraulic fracture tip element; K IC represents the fracture toughness of the reservoir rock, K I represents the tensile stress intensity factor; K II represents the shear stress intensity factor, and θ represents the deflection angle of the hydraulic fracture propagation.

[0099] The maximum circumferential stress criterion is used to predict the propagation direction of the hydraulic fracture, and the deflection angle calculation formula of the hydraulic fracture tip element is:

[0100]

[0101] S24: Constructing a proppant transport model in the hydraulic fracture, specifically including:

[0102] Based on the Eulerian multiphase flow theory, a mathematical model for proppant transport in the hydraulic fracture is established:

[0103] .

[0104] wherein ψp represents the proppant volume concentration; represents the dimensionless proppant concentration; ρ f represents the density of the fracturing fluid; μ s represents the viscosity of the sand slurry; v p represents the proppant transport velocity; v s represents the sand slurry flow velocity; v set represents the proppant settling velocity; represents the dimensionless proppant injection concentration.

[0105] The density and viscosity of the sand slurry formed by mixing the proppant and the fracturing fluid are calculated as follows:

[0106] .

[0107] wherein ψ p,max represents the maximum allowable proppant concentration; p s represents the density of the mixed sand fluid formed by mixing the proppant with the fracturing fluid; p p represents the proppant density; m f represents the fracturing fluid viscosity.

[0108] The proppant passability in the hydraulic fracture is described by using a plugging function:

[0109] ;

[0110] The corrected proppant settling velocity is:

[0111] ;

[0112] wherein v stokes represents the particle Stokes settling velocity; N min represents the particle concentration; N max represents the bridging coefficient; d p represents the proppant particle size; C com represents the particle settling comprehensive correction coefficient, which represents the comprehensive influence of particle inertia, particle concentration, wall roughness and other factors on particle settling, and can be obtained by indoor experiment or empirical formula.

[0113] S25: solving of the horizontal well fracturing fracture creation and proppant transport coupling model, specifically comprising:

[0114] Based on the hydraulic fracture deformation model and the fracturing fluid flow model, a horizontal well segmented multi-cluster fracturing fracture propagation fluid-solid coupling equation set is established:

[0115] ;

[0116] wherein M M represents the hydraulic fracture deformation coefficient matrix; C f represents the fracturing fluid flow coefficient matrix in the hydraulic fracture; w represents the hydraulic fracture width matrix; p f represents the fluid pressure matrix in the hydraulic fracture; p m represents the pore pressure matrix in the reservoir matrix; s M represents the stress matrix under the action of the far-field stress; q f,s represents the fracturing fluid source term matrix in the hydraulic fracture.

[0117] The fracturing fluid seepage control equation set in the reservoir matrix is:

[0118] ;

[0119] wherein, represents the fracturing fluid seepage coefficient matrix in the reservoir matrix; The matrix of the proppant source term in the reservoir matrix.

[0120] The proppant transport control equations in the hydraulic fracture are:

[0121] ;

[0122] where, represents the proppant transport coefficient matrix, represents the dimensionless proppant concentration matrix in the hydraulic fracture; q p,s represents the proppant source term matrix.

[0123] The Newton-Raphson iterative method is used to solve the fluid-solid coupling nonlinear equations, and the increments of the hydraulic fracture width and the fluid pressure in the fracture at the current iteration step are:

[0124] ,

[0125] ,

[0126] .

[0127] where, I represents the unit matrix; F1, F2 are the Newton-Raphson iteration coefficient matrices.

[0128] The stability of the solution is enhanced by the Picard iteration, and the updated hydraulic fracture width and fluid pressure in the fracture at the current iteration step are:

[0129] ;

[0130] For the seepage of the fracturing fluid in the reservoir matrix, after the fluid pressure in the hydraulic fracture is calculated, the fracturing fluid source term in the reservoir matrix is obtained through the fracturing fluid filtration relationship, and then the finite volume method is used to discretize and display the solution of the reservoir pore pressure distribution:

[0131] ;

[0132] By calculating the fluid pressure in the hydraulic fracture, the flow velocities of the sand slurry and the proppant are calculated, and then the finite volume method is used to discretize and solve the proppant transport control equations in the hydraulic fracture, and the upwind format is used to discretize the convection term to slow down the numerical oscillation to realize stable numerical solution:

[0133] ;

[0134] ;

[0135] ;

[0136] ;

[0137] .

[0138] After the proppant transport control equation set is obtained, the proppant concentration distribution in the hydraulic fracture is obtained by display calculation:

[0139] ;

[0140] In the above formula, denotes the time step, denote the length and width of the rectangular fracture element, respectively.

[0141] The hydraulic fracture and the proppant transport control equation set in the reservoir matrix and the hydraulic fracture propagation fluid-solid coupling equation set are iteratively calculated in the same time step using the sequential coupling method, and the hydraulic fracture width, fluid pressure in the fracture, proppant concentration in the fracture and reservoir matrix pore pressure can be obtained after calculation, and the convergence condition is:

[0142] ;

[0143] wherein, denotes the convergence tolerance of the fracture width and the fluid pressure in the fracture.

[0144] In this embodiment, the number of perforation clusters is taken as the construction optimization target to carry out the coupling simulation of hydraulic fracture creation and proppant transport in low permeability reservoir horizontal wells, the fine fracturing construction design is considered, a single horizontal section is taken as the reservoir reconstruction object, and the simulation design scheme is referred to Table 2. Without changing the length of the fracturing section, this embodiment simulates four schemes of 3 clusters, 4 clusters, 5 clusters and 6 clusters, and the basic simulation parameters are referred to Table 3. The proppant transport adopts the ladder sanding scheme, the pumping program of this embodiment is referred to Table 4, and the pumping program remains the same under different scheme conditions, including the preflush fracturing, sand-carrying fluid sanding and pump stopping stages. Based on the coupling model of hydraulic fracture creation and proppant transport in low permeability reservoir horizontal wells constructed in step S2, the hydraulic fracture extension trajectory and geometric form after pump stopping are shown in Figure 4 As affected by the stress interference between fractures and the proppant distribution, the hydraulic fracture length and width of the middle perforation cluster are smaller, and the hydraulic fracture presents the characteristics of staggered extension in space. Figure 5is the dimensionless proppant concentration distribution result in the hydraulic fracture at the end of pump-off time. The hydraulic fracture in the joint interference and the proppant transport together, the fracture width in space presents non-uniform distribution, the proppant is easy to accumulate in the area with extremely small fracture width in the front of the hydraulic fracture, so that the proppant concentration in this area is higher, the proppant concentration in the area with larger fracture width is smaller, and there is no proppant in the area with extremely small fracture width that does not meet the passing criterion. Due to the differences in joint interference and proppant transport under different perforation cluster numbers, the hydraulic fracture shape and proppant placement characteristics after simulation under the four schemes are significantly different. In the next step, the implementation example will evaluate the reconstruction effect of different schemes by predicting the yield, and optimize the perforation cluster number.

[0145] Table 2: Design scheme of the implementation example simulation

[0146]

[0147] Table 3: Basic parameters of the implementation example horizontal well fracturing and proppant transport coupling simulation

[0148]

[0149] Table 4: Pumping program of the implementation example horizontal well fracturing and proppant transport coupling simulation

[0150]

[0151] Specifically, step S3: combining the horizontal well fracturing simulation results and the laboratory conductivity experiment results, the global conductivity of the hydraulic fracture is predicted, including:

[0152] S31: when the horizontal well fracturing simulation is finished, the proppant placement thickness is calculated according to the hydraulic fracture width and the proppant concentration in the fracture, and the hydraulic fracture unit is divided into filled units and unfilled units according to the filling thickness:

[0153] ;

[0154] wherein, represents the proppant filling thickness; represents the hydraulic fracture width; represents the proppant volume concentration.

[0155] S32: the conductivity of the proppant filled and unfilled hydraulic fracture units is obtained through the laboratory experiment, and the specific steps include:

[0156] First, according to the laboratory conductivity experiment conditions, use the rock sample similar to the target reservoir to make a rock plate with the same geometric size as the conductivity chamber;

[0157] Hydraulic fractures are prefabricated by artificially splitting rock slabs. Closed rock slabs without proppant are considered as unfilled hydraulic fractures, while those with proppant are considered as filled hydraulic fractures.

[0158] Next, indoor flow diversion experiments were conducted. For unfilled hydraulic cracks, the change in flow diversion capacity under different closure stresses was measured. For filled hydraulic cracks, the change in flow diversion capacity and laying thickness under different filling thicknesses and closure stresses was measured.

[0159] Finally, using indoor flow capacity experimental data, flow capacity charts of proppant-filled and unpadded hydraulic fractures were plotted, and the mathematical relationship between the thickness of the proppant-filled layer and the closure stress was obtained.

[0160] S33: Calculate the closure stress based on the geostress and hydraulic fracture-induced stress of the target low-permeability reservoir, and perform interpolation based on the conductivity chart to obtain the spatial distribution of conductivity of filled and unfilled fracture units.

[0161] In this embodiment, crack elements with a filling thickness of less than 0.1 mm are considered as unfilled elements. Figure 4 and Figure 5 The spatial distribution of hydraulic fracture width and proppant concentration within the fracture is used to obtain the distribution of filled and unfilled units within the hydraulic fracture. Based on the proppant parameters used in the simulation in step S2, the conductivity of propped-filled and unfilled hydraulic fracture units is obtained through laboratory experiments. The conductivity of propped-filled fractures is referenced... Figure 6 The conductivity of the unfilled cracks is referenced. Figure 7 The closure stress of hydraulic fractures is calculated using the target reservoir in-situ stress parameters and the distribution of induced stress between fractures. Interpolation is then performed based on conductivity charts to obtain the conductivity distribution of the hydraulic fractures. The conductivity distribution results under different scenarios are obtained, and reference is made to... Figure 8 .

[0162] Specifically, step S4: Constructing a two-phase flow model for oil-water production in a horizontal well of a low-permeability reservoir, including:

[0163] S41: Establish a mathematical model for the two-phase flow of oil and water in the matrix of low-permeability oil reservoirs, specifically including:

[0164] Establish the continuity equation for the oil and water phases in porous media:

[0165] ;

[0166] in, and These represent the densities of the aqueous phase and the oil phase, respectively; and the densities of the aqueous phase and the oil phase, respectively. and These represent the saturation levels of the aqueous and oil phases in the matrix, respectively. and These represent the seepage velocities of the aqueous and oil phases in the matrix, respectively. and These represent the source terms of the aqueous and oil phases in the matrix, respectively. Indicates reservoir matrix porosity.

[0167] Based on Darcy's law, the momentum equations for the oil and water phases in porous media are established:

[0168] .

[0169] Where, k rwm With k rom These represent the relative permeabilities of the aqueous and oil phases in the matrix, respectively, and can be obtained through laboratory experiments; μ w With μ o p represents the viscosity of the aqueous phase and the oil phase, respectively; wm With p om These represent the fluid pressures of the aqueous and oil phases in the matrix, respectively.

[0170] The mathematical model for the change in matrix permeability caused by the decrease in reservoir pore pressure during the production process of low-permeability oil reservoirs is as follows:

[0171] ;

[0172] The coupling conditions for the flow of water and oil phases in the reservoir matrix are as follows:

[0173] .

[0174] In the above formula, k em Indicates the effective permeability of the reservoir matrix; k m,0 The initial permeability of the reservoir matrix is ​​represented by t; time is represented by p. mi With p m Indicates the initial and current pore pressure of the reservoir; C m p represents the reservoir matrix stress sensitivity coefficient; c This represents the capillary pressure in the reservoir matrix.

[0175] S42: Establish a mathematical model for two-phase oil-water flow in hydraulic fractures of low-permeability reservoirs, specifically including:

[0176] Establish the continuity equation for the oil and water phases in hydraulic fractures:

[0177] ;

[0178] Among them, S wf With S of These represent the saturation levels of the water and oil phases in the fracture, respectively; v wf With vof respectively represent the seepage velocities of water phase and oil phase in the fracture; and respectively represent the source terms of water phase and oil phase in the fracture; represents the fracture porosity.

[0179] Momentum equations of oil phase and water phase in the hydraulic fracture:

[0180] ;

[0181] wherein, k rwf and k rof respectively represent the relative permeabilities of water phase and oil phase in the fracture, which are linearly weighted approximations of the saturations of water phase and oil phase in the fracture; k ef represents the effective permeability of the fracture; k f,0 represents the initial permeability of the fracture.

[0182] The mathematical model of the change of the fracture permeability caused by the pressure drop in the hydraulic fracture during the production of the low-permeability reservoir is:

[0183] ;

[0184] The coupling condition of the flow of water phase and oil phase in the hydraulic fracture is:

[0185] ;

[0186] wherein, p fi and p f represent the initial and current fluid pressures in the hydraulic fracture; C f represents the stress sensitivity coefficient of the fracture.

[0187] S43: establishing a mathematical model for calculating the production of the low-permeability reservoir after hydraulic fracturing reconstruction, specifically including:

[0188] establishing a mathematical model for the conductive relationship between the horizontal wellbore and the hydraulic fracture unit:

[0189] ;

[0190] establishing a mathematical model for the source term of the hydraulic fracture:

[0191] ;

[0192] In the above formula, Γ fw represents the conductive coefficient between the hydraulic fracture and the horizontal wellbore; w f represents the fracture width of the hydraulic fracture unit; r e represents the equivalent wellbore radius, which is determined by the geometric size of the hydraulic fracture unit; r w represents the horizontal wellbore radius; p wBHP

[0193] S44: combine the flow modules of reservoir matrix, hydraulic fracture, horizontal wellbore, etc., establish the flow conduction relationship between the reservoir matrix and the hydraulic fracture based on the embedded discrete fracture theory, use the finite volume method to numerically disperse the two-phase flow mathematical model in the reservoir matrix and the hydraulic fracture, and establish an oil-water two-phase flow mathematical model of the matrix-fracture-wellbore as a whole under the condition of constant pressure production of the horizontal well in the low-permeability reservoir:

[0194] ;

[0195] Solve using the Newton-Raphson iterative method, and increase or decrease the stability of the solution by the Picard iterative method, and the convergence condition is:

[0196] ;

[0197] In the above formula, C represents the oil-water two-phase flow coefficient matrix; the subscripts m and f represent the reservoir matrix and the hydraulic fracture, respectively, and different combinations of the two represent the coupling relationship between the reservoir matrix and the hydraulic fracture; p m and p f respectively represent the reservoir matrix pore pressure matrix and the hydraulic fracture fluid pressure matrix; q m and q f respectively represent the reservoir matrix source term matrix and the hydraulic fracture source term matrix; and n represents the iteration step.

[0198] In this embodiment, based on the full-domain conductivity of the hydraulic fracture after the horizontal well reconstruction obtained in step S4, the oil-water two-phase seepage flow model of the horizontal well production is further developed to simulate the production of the horizontal well in the low-permeability reservoir after pressure. Under the condition that the hydraulic fracture is fully drained after the horizontal well fracturing reconstruction, the water saturation of the reservoir matrix is approximately equal to the initial water saturation, and the relative permeability curves of the water phase and the oil phase can be obtained by fitting the indoor experimental data, referring to Figure 9 . The permeability and porosity in the hydraulic fracture are much greater than those in the reservoir matrix, and the linear weighted method of water saturation is used to obtain the relative permeability curves of the water phase and the oil phase in the hydraulic fracture. Considering the capillary force action between the water phase and the oil phase in the reservoir matrix, the capillary force data under different water saturations are obtained through indoor experiments, referring to Figure 11 . The remaining basic parameters for simulating the production of the horizontal well in the low-permeability reservoir after pressure are referred to Table 5.

[0199] The production prediction results of scheme 1, scheme 2, scheme 3 and scheme 4 under the constant pressure production system and under the same production pressure difference and production time conditions are shown in Figure 12 and Figure 13 . Figure 12is the reservoir pore pressure distribution after the production of the horizontal well in the low permeability reservoir under different schemes. The production of crude oil and formation water in the reservoir will cause a significant drop in the pore pressure around the hydraulic fracture. Due to the differences in the hydraulic fracture trajectory and the spatial conductivity distribution under different schemes, the pore pressure distribution after the production of the horizontal well also has significant differences. Figure 13 is the pore pressure distribution characteristics after the production simulation under different schemes. The simulation results under different schemes also have significant differences.

[0200] Table 5. Basic parameters for simulation of oil-water two-phase seepage flow model of horizontal well production in low permeability reservoir of example

[0201]

[0202] Specifically, the step S4 of predicting the oil-water distribution characteristics and the horizontal well production after the pressure of the low permeability reservoir in combination with the global conductivity of the hydraulic fracture includes:

[0203] S45: Design key construction parameters for reservoir horizontal well fracturing reconstruction according to the development requirements of the low permeability reservoir;

[0204] S46: Perform hydraulic fracture creation and proppant transport simulation of the low permeability reservoir horizontal well to obtain the hydraulic fracture trajectory, fracture size and proppant placement results;

[0205] S47: Calculate the global conductivity of the hydraulic fracture after the fracturing reconstruction of the horizontal well based on the prediction results of the hydraulic fracture geometric parameters and the proppant concentration distribution;

[0206] S48: Perform production dynamic simulation of the low permeability reservoir horizontal well after the pressure based on the matrix-fracture-wellbore oil-water two-phase flow mathematical model with the global conductivity of the hydraulic fracture as the input condition;

[0207] S49: Output the reservoir oil-water distribution and the horizontal well production results corresponding to different horizontal well fracturing reconstruction construction schemes.

[0208] In this example, the number of perforation clusters is taken as the construction optimization target for simulation and optimization, and the key construction parameters for reservoir horizontal well fracturing reconstruction refer to Tables 2 and 3. The hydraulic fracture trajectory, fracture size and proppant placement results are obtained based on the hydraulic fracture creation and proppant transport coupling model, and the simulation results refer to Figure 4 and Figure 5 . Further, the global conductivity of the hydraulic fracture after the fracturing reconstruction of the horizontal well is calculated in combination with the indoor experimental and numerical simulation results, and the results refer to Figure 8 . Subsequently, the reservoir oil-water distribution and the horizontal well production results corresponding to different schemes are obtained by performing production dynamic prediction in combination with the low permeability reservoir horizontal well production oil-water two-phase flow mathematical model with the global conductivity of the hydraulic fracture as the input condition, and refer to Figure 12 , Figure 13 andFigure 14 .

[0209] Specifically, step S5: evaluating the low-permeability oil reservoir horizontal well fracturing result according to the prediction result, and optimizing the horizontal well fracturing construction parameter includes:

[0210] According to the prediction result, the reconstruction effect of different horizontal well fracturing construction schemes is evaluated by taking the cumulative production of the horizontal well under the same production condition as the measurement index, and then the key construction parameter of the low-permeability oil reservoir horizontal well fracturing reconstruction is optimized.

[0211] In this embodiment, by carrying out the horizontal well fracturing fracture creation and proppant transport coupling simulation, the hydraulic fracture whole domain conductivity calculation after the fracturing construction is completed, and the production dynamic simulation prediction after the horizontal well fracturing reconstruction, the production dynamics corresponding to different construction schemes are obtained, and the simulation results are referred to Figure 14 . Figure 4 The simulation results show that, from scheme 1 to scheme 4, with the increase of the perforation cluster number, the cluster spacing of the hydraulic fracture gradually decreases, and the interference between fractures gradually increases, so that the fractures located in the middle cluster cannot be fully extended, and the distribution of the proppant and the conductivity of the hydraulic fracture after fracturing are affected. Figure 5 The proppant concentration distribution results show that the interference between fractures will cause the difference between the fracturing fluid and the proppant amount entering the hydraulic fractures of different perforation clusters, and the uneven distribution of the fracture width will cause the phenomenon that part of the hydraulic fracture region is not filled with proppant. Combined with Figure 4 , Figure 5 , Figure 8 It can be known that the hydraulic fracture geometric parameters, the proppant concentration spatial distribution, and the hydraulic fracture conductivity are different under different schemes, and the measurement indexes such as the conventional hydraulic fracture length, the hydraulic fracture area, the proppant placement area, and the hydraulic fracture conductivity are difficult to reasonably judge the reconstruction effect of different construction schemes, and then improve the development effect of the low-permeability oil reservoir. The present application realizes the integrated simulation of the horizontal well fracturing reconstruction and the production prediction, focuses on the yield concerned by the engineering, and evaluates the good and bad of different hydraulic fracturing construction schemes by the production effect. Figure 14 For the horizontal well production dynamic prediction results of different construction schemes, under the same production system and production time conditions, with the increase of the perforation cluster number, the cumulative oil production does not show a monotonous increasing trend, and the cumulative production of scheme 3 is the highest. Therefore, under the conditions of this embodiment, the optimized parameters are 5 clusters of perforation clusters and 15 m of cluster spacing.

[0212] Compared with the prior art, the low-permeability oil reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method provided by the embodiment of the present application has the following beneficial effects:

[0213] (1) The embodiment of the present application realizes the dynamic coupling simulation of the hydraulic fracturing fracture expansion and the proppant transport by the proppant accumulation bridging and the rheological parameter change of the sand mixing liquid, accurately predicts the hydraulic fracture shape and the proppant placement result;

[0214] (2) The embodiment of the present application obtains the hydraulic fracture conductivity chart under the conditions of proppant filling and non-filling through indoor experiments, and reasonably calculates the global conductivity of the post-fracturing hydraulic fracture in combination with the simulation results of the hydraulic fracture geometric parameters and the proppant concentration;

[0215] (3) The embodiment of the present application realizes the integrated simulation of the horizontal well fracturing reconstruction and the production prediction in combination with the global conductivity of the hydraulic fracture and the oil-water two-phase seepage model of the matrix-fracture-wellbore, evaluates the fracturing reconstruction effect and optimizes the fracturing construction parameters according to the horizontal well production prediction results, improves the fracturing reconstruction effect of the horizontal well in the low-permeability reservoir, and helps the cost reduction, efficiency increase and quality improvement development of the low-permeability reservoir.

[0216] As shown in Figure 15 , another embodiment of the present application provides a low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation system for realizing the low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method described in the above embodiment, which comprises a first model construction module, a second model construction module, a prediction module, a third model construction module and a calculation and optimization module.

[0217] The first model construction module is used for constructing a low-permeability reservoir geological model according to the field geological and drilling data.

[0218] The second model construction module is used for constructing a low-permeability reservoir horizontal well fracturing and proppant transport coupling model, predicting the hydraulic fracture and proppant placement characteristics, and obtaining the horizontal well fracturing simulation results.

[0219] The prediction module is used for predicting the global conductivity of the hydraulic fracture in combination with the horizontal well fracturing simulation results and the indoor conductivity experiment results.

[0220] The third model construction module is used for constructing a low-permeability reservoir horizontal well oil-water two-phase seepage model, predicting the low-permeability reservoir post-fracturing reservoir oil-water distribution characteristics and the horizontal well production in combination with the global conductivity of the hydraulic fracture, and obtaining the prediction results.

[0221] The calculation and optimization module is used for evaluating the low-permeability reservoir horizontal well fracturing reconstruction results and optimizing the horizontal well fracturing construction parameters according to the prediction results.

[0222] The execution process of each module of the system can be executed according to the flow steps of the low-permeability reservoir horizontal well fracturing reconstruction and production prediction integrated simulation method described in the first embodiment, and will not be described one by one in this embodiment.

[0223] Another embodiment of the present application provides an electronic device, which comprises a processor, an input device, an output device and a memory, the processor, the input device, the output device and the memory are connected with each other, the memory is configured to store a computer program, the computer program comprises program instructions, the processor is configured to invoke the program instructions, and the method for integrated simulation of low-permeability reservoir horizontal well fracturing reconstruction and production prediction described in the first embodiment is executed.

[0224] It should be understood that, in the embodiments of the present application, the processor can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0225] The input device can include a touchpad, a fingerprint acquisition sensor (used to acquire fingerprint information and direction information of a fingerprint of a user), a microphone, etc., and the output device can include a display (LCD, etc.), a speaker, etc.

[0226] The memory can include read-only memory and random access memory, and provide instructions and data to the processor. A portion of the memory can also include non-volatile random access memory. For example, the memory can also store device type information.

[0227] In specific implementations, the processor, the input device and the output device described in the embodiments of the present application can execute the implementation manners of the method embodiments described in the embodiments of the present application, and can also execute the implementation manners of the system embodiments described in the embodiments of the present application, which will not be described here.

[0228] The present application also provides an embodiment of a computer readable storage medium, which stores a computer program, the computer program comprises program instructions, and the program instructions make the processor execute the method for integrated simulation of low-permeability reservoir horizontal well fracturing reconstruction and production prediction described in the first embodiment when the processor executes the program instructions.

[0229] The computer readable storage medium can be an internal storage unit of the terminal, such as a hard disk or a memory of the terminal. The computer readable storage medium can also be an external storage device of the terminal, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, or the like. Further, the computer readable storage medium can include both the internal storage unit and the external storage device of the terminal. The computer readable storage medium is used to store the computer program and other programs and data required by the terminal. The computer readable storage medium can also be used to temporarily store data that has been output or will be output.

[0230] Those skilled in the art can understand that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0231] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the terminal and the units described above can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0232] In several embodiments provided in the present application, it should be understood that the disclosed terminal and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can also be electrical, mechanical or other forms of connection.

[0233] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. An integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs, characterized in that, Includes the following steps: S1: Construct a geological model of a low-permeability reservoir based on field geological and drilling data; S2: Construct a coupled model of horizontal well fracturing and proppant transport in low-permeability reservoirs, predict the characteristics of hydraulic fractures and proppant placement, and obtain the simulation results of horizontal well fracturing. The specific methods for constructing a coupled model of horizontal well fracturing and proppant transport in low-permeability oil reservoirs include: S21: Constructing a mathematical model for hydraulic fracture deformation: Based on the displacement discontinuity method, the hydraulic fractures at the mine scale are discretized into rectangular fracture elements. A hydraulic fracture deformation model is established according to the stress-deformation relationship. An induced stress calculation model is established to describe the stress interference between hydraulic fractures during segmented multi-cluster fracturing of horizontal wells. S22: Establish a mathematical model for fracturing fluid flow, including: using Poiseuille's law to describe the fracturing fluid flow in hydraulic fractures, using porous media seepage theory to describe the fracturing fluid seepage process in the reservoir, calculating the fracturing fluid loss based on the fluid pressure relationship between the hydraulic fracture and the reservoir matrix, considering the flow rate differences of different perforation clusters during the segmented multi-cluster fracturing process in horizontal wells, establishing a set of fluid pressure equations using Kirchhoff's law, and solving them using Newton's iteration method to obtain the dynamic flow rate distribution results of each perforation cluster in the segmented multi-cluster fracturing of horizontal wells at different times; S23: Establish a hydraulic fracture propagation model, including: using the equivalent stress intensity criterion as the basis for judging hydraulic fracture propagation; when the equivalent stress intensity factor of the fracture tip element is greater than or equal to the fracture toughness of the rock, the hydraulic fracture propagates; and new fracture elements are added to the current hydraulic fracture tip; the propagation direction of the hydraulic fracture is predicted based on the maximum circumferential stress criterion; and the deflection angle of the hydraulic fracture tip element is calculated. S24: Construct a proppant transport model within hydraulic fractures, including: calculating the density and viscosity of the mixed proppant and fracturing fluid, using a clogging function to describe the proppant's permeability in hydraulic fractures, calculating the corrected proppant settling velocity, and establishing a mathematical model for proppant transport in hydraulic fractures based on Euler's multiphase flow theory. S25: Solve the coupling model of horizontal well fracturing and proppant transport in low-permeability reservoirs, including: based on the hydraulic fracture deformation model and the fracturing fluid flow model, establish the hydraulic fracture and reservoir matrix fracturing fluid seepage control equation set, the hydraulic fracture proppant transport control equation set, and the hydraulic fracture propagation fluid-structure interaction equation set for horizontal well segmented multi-cluster fracturing. Iterate the hydraulic fracture width, fluid pressure inside the fracture, proppant concentration inside the fracture, and reservoir matrix pore pressure under the same time step using a sequential coupling method. S3: Combining horizontal well fracturing simulation results with indoor conductivity experiments, predict the overall conductivity of hydraulic fractures; S4: Construct a two-phase flow model for oil and water production in horizontal wells of low-permeability reservoirs, and combine the global conductivity of the hydraulic fractures to predict the oil and water distribution characteristics of the post-compression reservoir and the production of horizontal wells in low-permeability reservoirs, and obtain the prediction results. S5: Evaluate the fracturing results of horizontal wells in low-permeability reservoirs based on the prediction results, and optimize the fracturing construction parameters of horizontal wells.

2. The integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs according to claim 1, characterized in that, The specific methods for constructing geological models of low-permeability oil reservoirs based on field geological and drilling data include: S11: Collect geological, drilling and production data of the target block, establish a three-dimensional structural model and sedimentary facies model, and obtain porosity and permeability property models; S12: Obtain basic reservoir parameters in the horizontal well segmented fracturing stimulation area. These parameters include: maximum horizontal principal stress, minimum horizontal principal stress, vertical stress, interlayer stress difference, stress gradient, reservoir thickness, pore pressure, Young's modulus, and Poisson's ratio.

3. The integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs according to claim 1, characterized in that, The specific method for predicting the overall conductivity of hydraulic fractures by combining horizontal well fracturing simulation results with indoor conductivity experiments includes: S31: After the horizontal well fracturing simulation is completed, the proppant thickness is calculated based on the hydraulic fracture width and the proppant concentration in the fracture, and the hydraulic fracture unit is divided into filled unit and unfilled unit according to the filling thickness. S32: The conductivity of proppant-filled and unpadded hydraulic fracture elements was obtained through indoor experiments; S33: Calculate the closure stress based on the geostress and hydraulic fracture-induced stress of the target low-permeability reservoir, and perform interpolation based on the conductivity chart to obtain the spatial distribution of conductivity of filled and unfilled fracture units.

4. The integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs according to claim 1, characterized in that, The specific method for constructing a two-phase flow model for oil-water production in horizontal wells of low-permeability reservoirs includes: S41: Establish a mathematical model for two-phase oil-water flow in the matrix of low-permeability oil reservoirs; S42: Establish a mathematical model for two-phase oil-water flow in hydraulic fractures of low-permeability reservoirs; S43: Establish a mathematical model for calculating production after hydraulic fracturing in low-permeability reservoirs; S44: Based on the embedded discrete fracture theory, the flow conduction relationship between the reservoir matrix and hydraulic fractures is established. The mathematical model of two-phase flow in the reservoir matrix and hydraulic fractures is numerically discretized using the finite volume method. A mathematical model of two-phase flow of matrix-fracture-wellbore oil-water under constant pressure production conditions in horizontal wells of low-permeability reservoirs is established.

5. The integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs according to claim 4, characterized in that, The specific methods for predicting the oil-water distribution characteristics of low-permeability reservoirs and the production of horizontal wells by combining the overall conductivity of the hydraulic fractures include: S45: Design key construction parameters for horizontal well fracturing stimulation of reservoirs based on the development needs of low-permeability reservoirs; S46: Simulate horizontal well fracturing and proppant transport in low-permeability reservoirs to obtain hydraulic fracture trajectory, fracture size and proppant placement results; S47: Based on the prediction results of hydraulic fracture geometry parameters and proppant concentration distribution, calculate the overall conductivity of the hydraulic fracture after horizontal well fracturing. S48: Using the full-domain conductivity of hydraulic fractures as input, dynamic simulation of production after horizontal well pressure in low-permeability reservoirs is carried out based on the mathematical model of matrix-fracture-wellbore oil-water two-phase flow. S49: Output the reservoir oil-water distribution and horizontal well production results corresponding to different horizontal well fracturing and stimulation construction schemes.

6. The integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs according to claim 5, characterized in that, The specific methods for evaluating the fracturing results of horizontal wells in low-permeability reservoirs based on prediction results and optimizing horizontal well fracturing parameters include: Based on the prediction results, the cumulative production of horizontal wells under the same production conditions is used as the metric to evaluate the stimulation effect of different horizontal well fracturing construction schemes and optimize the key construction parameters for horizontal well fracturing stimulation in low-permeability reservoirs.

7. An integrated simulation system for horizontal well fracturing and production prediction in low-permeability reservoirs, used to implement the integrated simulation method for horizontal well fracturing and production prediction in low-permeability reservoirs as described in any one of claims 1-6, characterized in that, include: The module comprises a first model building module, a second model building module, a prediction module, a third model building module, and a computation and optimization module. The first model building module is used to build a geological model of a low-permeability oil reservoir based on field geology and drilling data; The second model building module is used to construct a coupled model of horizontal well fracturing and proppant transport in low-permeability reservoirs, predict the characteristics of hydraulic fractures and proppant placement, and obtain the simulation results of horizontal well fracturing. The prediction module is used to combine the results of horizontal well fracturing simulation with the results of indoor conductivity experiments to predict the overall conductivity of hydraulic fractures. The third model construction module is used to construct a two-phase flow model for oil and water production in horizontal wells of low-permeability reservoirs. It combines the full-domain conductivity of hydraulic fractures to predict the oil and water distribution characteristics of the post-compression reservoir and the production of horizontal wells in low-permeability reservoirs, and obtain the prediction results. The calculation and optimization module is used to evaluate the fracturing results of horizontal wells in low-permeability reservoirs based on the prediction results and to optimize the fracturing construction parameters of horizontal wells.

8. An electronic device comprising a processor, an input device, an output device, and a memory, wherein the processor, input device, output device, and memory are interconnected, and the memory is used to store a computer program, the computer program comprising program instructions, characterized in that, The processor is configured to invoke the program instructions to perform the method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a processor, cause the processor to perform the method as described in any one of claims 1-6.

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