Gas-water two-phase seepage simulation method and device based on dynamic dual media

Abstract

The invention provides a gas-water two-phase seepage simulation method and device based on dynamic dual media. The method comprises the following steps: establishing a dynamic dual-medium gas phase seepage equation, a dynamic dual-medium water phase seepage equation and a fluid exchange equation between bed rock and fractures; according to the oil reservoir dual-medium simulation well location model and the fluid exchange equation between the bed rock and the fracture, performing structural grid division on a to-be-simulated area to obtain a dual-medium stratum fracture and well location distribution result; discretizing the gas-phase and water-phase seepage equations according to the double-medium formation fractures and the well location distribution result to obtain a gas-phase discrete equation and a water-phase discrete equation; a given dual-medium formation gas-water two-phase relative permeability curve is obtained, and initial conditions and boundary conditions are set; according to a given dual-medium formation gas-water two-phase permeability curve, initial conditions and boundary conditions, after a time step and convergence precision are given, iterative solution is conducted on the gas-phase discrete equation and the water-phase discrete equation, and a gas-water two-phase seepage simulation result is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas development, and in particular to a gas-water two-phase seepage simulation method and device based on dynamic dual media. Background Art

[0002] The dual medium model in the current oil and gas reservoir theory solves the calculation problem of oil and gas development with natural microcracks in oil and gas reservoirs by defining the storage volume ratio and the crossflow coefficient. Since it is impossible to understand the distribution of natural microcracks, it is impossible to draw grids for the cracks and bedrock as two systems and calculate them separately in the actual seepage calculation. The current dual medium regards the bedrock as a "source sink term" and solves the intensity of the source sink term from the bedrock to the crack by defining the crossflow coefficient, thus ensuring the mass conservation of the dual medium system. The crossflow coefficient is also expressed as the proportional relationship between the pressure difference between the bedrock and the crack, which is another simplified expression of Darcy's law, that is, the definition of the crossflow coefficient makes the dual medium satisfy the mass conservation relationship. It shows that the existing dual medium is a static problem, while the flow of actual formation fluids is a dynamic process. For example, the ability of an airplane to fly in the air is the conversion of kinetic energy and pressure energy. Therefore, there are deficiencies in solving dynamic problems with the idea of ​​static mechanics.

[0003] The crossflow coefficient simplifies the flow from the bedrock system to the fracture system as a pressure difference drive. Due to the pressure difference between the matrix and the fracture, λ(p m -p f ) represents the fluid exchange between bedrock and fractures, which is equivalent to adding a source-sink term in the fracture system equation, such as Figure 1 As shown in (a), where p m is the pressure in bedrock, p f is the pressure in the crack. Summary of the invention

[0004] In order to better realize the gas-water two-phase seepage simulation of dual media, the embodiment of the present invention proposes a gas-water two-phase seepage simulation method and device based on dynamic dual media.

[0005] To achieve the above purpose, the technical solution proposed by the present invention is as follows:

[0006] In a first aspect, an embodiment of the present invention provides a method for simulating gas-water two-phase seepage based on dynamic dual media, comprising:

[0007] The gas phase seepage equation, water phase seepage equation and fluid exchange equation between bedrock and fractures of dynamic dual media are established:

[0008]

[0009]

[0010]

[0011] Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρ g is the gas phase density; ρ scw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock;

[0012] Establish a well location model for dual-medium simulation of oil reservoirs;

[0013] According to the reservoir dual-medium simulation well location model and the fluid exchange equation between the bedrock and the fracture, the simulated area is divided into structural grids to obtain the dual-medium formation fracture and well location distribution results;

[0014] According to the dual-medium formation fracture and well location distribution results, the gas phase seepage equation and the water phase seepage equation are discretized to obtain a gas phase discrete equation and a water phase discrete equation;

[0015] Obtain the given dual-medium formation gas-water two-phase permeability curve, set initial conditions and boundary conditions;

[0016] According to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, the gas phase discrete equation and the water phase discrete equation are iteratively solved to obtain a gas-water two-phase seepage simulation result.

[0017] In one or some optional embodiments, the step of obtaining and establishing a gas phase seepage equation, a water phase seepage equation, and a fluid exchange equation between bedrock and fractures for a dynamic dual medium includes:

[0018] Establish a coordinate system along the crack, and set the spatial direction of the crack as τ f , with a width of w f The flow rate of α-phase fluid flowing from the fracture per unit length into the matrix per unit time is q fm,α , construct the mass conservation equations of the water phase fluid in the fracture and matrix and the mass conservation equations of the gas phase fluid in the fracture and matrix:

[0019]

[0020]

[0021]

[0022]

[0023] Among them, α=w,g, w is the water phase, g is the gas phase, and are the flow rates of the α-phase fluid in the fracture and matrix,

[0024] ρ α and μ α are the density and viscosity of the α phase fluid respectively; φ (β) and K (β) are the porosity and absolute permeability of the β medium (β = f,m); and are the relative permeability, pressure and saturation of the α phase fluid in the β medium respectively;

[0025] Without considering the gas-water surface tension, the water-gas two-phase seepage equation in the fracture system and the fluid exchange equation between bedrock and fractures are obtained according to formulas (5-5) to (5-8).

[0026] In one or some optional embodiments, the area to be simulated is divided into structural grids in the following manner:

[0027] Set reference pressure p R , reference water saturation S wsc , the pressure gradient along the fracture direction Assuming that the fluid flow in a certain grid along the fracture is incompressible steady-state flow, and the reservoir is mean and isotropic, the fracture and well distribution results of the dual-medium formation are constructed;

[0028] The pressure gradient along the radial flow of the fracture is:

[0029] Where Δx is the adjacent grid step size, r eq is the equivalent radius of the grid pressure, p i,j is the distance r from the center of the cell grid (i, j) eq The pressure on the circle; p s is the pressure at the adjacent grid.

[0030] In one or some optional embodiments, the gas phase seepage equation and the water phase seepage equation are discretized to obtain a gas phase discrete equation and a water phase discrete equation, including:

[0031] Determine the two-dimensional space equations of the gas phase seepage equation and the water phase seepage equation respectively:

[0032]

[0033]

[0034] Finite difference discretization is performed on the two-dimensional space equations of the gas phase seepage equation and the water phase seepage equation to obtain the gas phase discrete equation and the water phase discrete equation:

[0035]

[0036]

[0037] Where V i,j =Δx i Δy j h is the volume of the unit grid (i, j);

[0038] Pressure and water saturation correlation function

[0039] is the potential function difference between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid block in the x direction, the potential difference between the water and gas phases at the n+1th moment, and the potential difference in the y direction is

[0040] is the density of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment, and the density in the y direction is

[0041] is the conductivity of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment, and the conductivity in the y direction is

[0042] is the conductivity multiplier of the water and gas phases between the α phase (α=w,g) fluid and its adjacent grid blocks in the x direction at the n+1th moment on the unit grid (i,j). The conductivity multiplier in the y direction is TRAN i,j±1 / 2 ;

[0043] is the mobility of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment. The upstream weighted value is used, and the mobility in the y direction is

[0044] In one or some optional embodiments, before simulating the gas-water two-phase seepage process, the method further includes:

[0045] According to the predefined kinetic energy coefficient θ, the pressure and water phase saturation related function Ψ is converted:

[0046]

[0047] in,

[0048] p R is the reference pressure, S wsc is the reference water saturation.

[0049] In one or some optional embodiments, during the time stepping process, the time step is controlled according to the following formula:

[0050] Δt n+1 =min(αΔt n ,Δt max )

[0051] In the formula, Δt n+1 refers to the next time step; α refers to the time step growth coefficient; Δt n Refers to the current time step; Δt max Refers to the maximum time step.

[0052] In a second aspect, an embodiment of the present invention provides a gas-water two-phase seepage simulation device based on dynamic dual media, comprising:

[0053] Equation building module, used to establish the gas phase seepage equation, water phase seepage equation and fluid exchange equation between bedrock and fractures of dynamic dual media:

[0054]

[0055]

[0056]

[0057] Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρg is the gas phase density; ρ scw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock;

[0058] Model building module, used to build a well location model for dual-medium simulation of oil reservoirs;

[0059] A grid division module is used to divide the simulated area into structural grids according to the reservoir dual-medium simulation well location model and the fluid exchange equation between the bedrock and the fracture, so as to obtain the dual-medium formation fracture and well location distribution results;

[0060] An equation discretization module is used to discretize the gas phase seepage equation and the water phase seepage equation according to the dual medium formation fracture and well location distribution results to obtain a gas phase discrete equation and a water phase discrete equation;

[0061] A setting module is used to obtain the gas-water two-phase permeability curve of a given dual-medium formation and to set initial conditions and boundary conditions;

[0062] The simulation calculation module is used to iteratively solve the gas phase discrete equation and the water phase discrete equation according to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, to obtain the gas-water two-phase seepage simulation result.

[0063] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, in which instructions are stored. When the instructions are executed on a terminal, the terminal executes the gas-water two-phase seepage simulation method based on dynamic dual media as described above.

[0064] In a fourth aspect, an embodiment of the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the gas-water two-phase seepage simulation method based on dynamic dual media as described above is implemented.

[0065] In a fifth aspect, an embodiment of the present invention provides a computer program product comprising instructions, which, when executed on a computer device, enables the computer device to execute the above-mentioned gas-water two-phase seepage simulation method based on dynamic dual media.

[0066] In a sixth aspect, an embodiment of the present invention provides a chip, comprising a processor and a communication interface, wherein the communication interface and the processor are coupled, and the processor is used to run a computer program or instruction to implement the gas-water two-phase seepage simulation method based on dynamic dual media as described above.

[0067] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0068] The purpose of the present invention is to carry out theoretical research on the dynamic dual-medium model based on the dynamic flow law of fracture-bedrock, and to describe the macroscopic water-sealed gas effect in the gas-water two-phase seepage process by defining the kinetic energy coefficient, so as to make up for the current seepage equation based on static dual media. When dealing with the flow between fractures and bedrock, the static mechanics criterion is used for processing, that is, as long as there is a pressure difference, there is a crossflow flow, while the pressure energy loss caused by kinetic energy is ignored, and the formation of water-sealed gas in the gas-water two-phase seepage process cannot be accurately described.

[0069] Compared with the existing methods, the advantages of the method of the present invention are mainly manifested in the following two aspects:

[0070] The gas-water two-phase seepage simulation method based on dynamic dual media provided by the embodiment of the present invention proposes a dynamic dual media seepage equation of macroscopic water-sealing gas effect based on the dynamic flow law of fracture-bedrock. Through the gas-water two-phase seepage simulation of dynamic dual media, the macroscopic water-sealing gas effect in the gas-water two-phase seepage process can be accurately described. It overcomes the seepage equation based on static dual media. When dealing with the flow between fractures and bedrock, the static mechanics principle is used for processing, that is, as long as there is a pressure difference, there is a crossflow flow, while the pressure energy loss caused by kinetic energy is ignored, and the formation of water-sealing gas in the gas-water two-phase seepage process cannot be accurately described. The problem. For macroscopic high-permeability channels, when water intrusion occurs in fractures, the problem that the reservoir numerical simulation software uses a dual media model for numerical simulation cannot obtain the calculation effect of water-sealing gas.

[0071] 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 are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0072] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0074] Figure 1 A schematic diagram of a dual medium system in which cracks and bedrock coexist provided by an embodiment of the present invention;

[0075] Figure 2 A schematic flow chart of a gas-water two-phase seepage simulation method based on dynamic dual media provided in an embodiment of the present invention;

[0076] Figure 3 A schematic diagram of crack morphology and related parameters provided by an embodiment of the present invention;

[0077] Figure 4 A schematic diagram of a grid structure of a well block and adjacent grids provided in an embodiment of the present invention;

[0078] Figure 5 A dual-medium formation fracture and well location distribution diagram of a well location model provided in an embodiment of the present invention;

[0079] Figure 6 A schematic diagram of a gas-water two-phase permeability curve of a dual-medium formation provided by an embodiment of the present invention;

[0080] Figure 7 Gas saturation distribution diagram for conventional dual-medium simulation production after 230 days;

[0081] Figure 8 A gas saturation distribution diagram based on kinetic dual-medium simulation production for 230 days provided in an embodiment of the present invention;

[0082] Fig. 9 A schematic diagram of a cross crack region provided by an embodiment of the present invention;

[0083] Fig.10 A distribution diagram of water saturation of cross fractures under different dynamic parameter conditions provided by an embodiment of the present invention;

[0084] Fig.11 A schematic structural diagram of a gas-water two-phase seepage simulation device based on dynamic dual media provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0085] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0086] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0087] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0088] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0089] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0090] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0091] It should be understood that the size of the serial numbers of the steps in the following embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0092] In order to illustrate the technical solution of the present application, a specific embodiment is provided below for illustration.

[0093] The inventors found that in the dual medium system of the existing technology where fractures and bedrock coexist, the seepage equation maintains the continuity assumption because the source and sink terms are added to the fracture system, which means that as long as p m > f There is fluid entering the cracks in the bedrock. When the cracks are invaded by water, the natural gas in the bedrock can completely enter the crack system through crossflow, so it is impossible for water-sealed gas to exist. Therefore, for macroscopic high-permeability channels, when water invasion occurs in the cracks, the existing foreign reservoir numerical simulation software cannot obtain the calculation effect of water-sealed gas even if the dual medium model is used for numerical simulation. After further research and development, the inventor believes that the current dual medium seepage equation uses static mechanics principles to deal with the flow between cracks and bedrock, that is, as long as there is a pressure difference, there will be crossflow. In fact, in addition to satisfying the conservation of momentum, liquid flow also needs to satisfy the conservation of energy principle. Since there is fluid flow in the cracks, kinetic energy cannot be ignored. Based on this, the present invention is made to provide a gas-water two-phase seepage simulation method and device based on dynamic dual media, a device, equipment and medium.

[0094] The embodiment of the present invention provides a gas-water two-phase seepage simulation method based on dynamic dual media, referring to Figure 2 As shown, the method includes:

[0095] S101: Establish the gas phase seepage equation, water phase seepage equation and fluid exchange equation between bedrock and fractures in dynamic dual media:

[0096]

[0097]

[0098]

[0099] Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρ g is the gas phase density; ρscw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock;

[0100] S102: Establish a well location model for dual-medium simulation of oil reservoirs;

[0101] S103: According to the reservoir dual-medium simulation well location model and the fluid exchange equation between the bedrock and the fracture, the simulation area is divided into structural grids to obtain dual-medium formation fractures and well location distribution results;

[0102] S104: discretizing the gas phase seepage equation and the water phase seepage equation according to the dual medium formation fracture and well location distribution results to obtain a gas phase discrete equation and a water phase discrete equation;

[0103] S105: Obtaining a given dual-medium formation gas-water two-phase permeability curve, and setting initial conditions and boundary conditions;

[0104] S106: According to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, the gas phase discrete equation and the water phase discrete equation are iteratively solved to obtain a gas-water two-phase seepage simulation result.

[0105] In the embodiment of the present invention, the execution process of the above step S101 and the above step S102-step S103 can be executed in sequence or in parallel, or, first execute step S102-step S103, and then execute step S101. The reservoir dual medium simulation well location model established in the above step S102 is a model used to describe the relationship between the well and the reservoir, which includes the geometric information of the borehole and the reservoir, the wellbore parameters, the fracture morphology, etc. By establishing the well location model, the position and characteristics of the well in the simulation area can be accurately represented. The establishment process of the model can refer to the detailed description in the prior art, and will not be repeated here. In the above step S103, the structural grid division is to divide the simulation area into a number of regular rectangular or cubic units (grids) to facilitate calculation using numerical methods. When performing structural grid division, the boundary of the simulation area and the position of each grid unit will be determined according to the information of the well location model, and the grid division method and density will be determined according to the geometric shape and boundary conditions of the simulation area. The geometric information of the well location model and the parameters of interaction with the reservoir, such as the degree of development, the intersection of fractures and grid cells, etc., will affect the structural grid division. Usually, a grid division method is selected that makes the characteristic parameters in the simulation area vary evenly in each grid cell, which can ensure the rationality and accuracy of the grid division, and then support the subsequent discretization calculation of the seepage equation and the accuracy of the simulation results.

[0106] In the embodiment of the present invention, the inventors conducted a gas-water two-phase simulation calculation of dynamic dual-medium water invasion based on the fact that liquid flow needs to satisfy the energy conservation criterion in addition to the momentum conservation. Since there is fluid flow in the crack, the kinetic energy cannot be ignored. The specific process is as follows:

[0107] When there is a dual medium system of fractures and bedrock in the formation, the crossflow model is a static system model, that is, an ideal model when the formation pressure reaches a stable state. However, for a moving system, the fluid flow must satisfy the law of energy conservation. Figure 1 In (b), it is assumed that there is water intrusion in the fracture system, and gas-water two-phase flow occurs in the fracture, but gas flows in the bedrock. Since the fracture permeability is much higher than the bedrock permeability, p f smaller than p m , so that the gas in the bedrock flows to the fracture. Assuming that the gas flows from point A in the bedrock to point B in the fracture (that is, the point on the interface between the fracture and the bedrock), there is a streamline from A to B. Conventional reservoir numerical simulation software assumes that the temperature of the production layer remains unchanged, so the change in the internal energy of the fluid can be ignored. Therefore, the Bernoulli equation holds on the streamline from A to B:

[0108] (Kinetic energy + potential energy + pressure energy) A =(kinetic energy + potential energy + pressure energy) B (5-1)

[0109] Since the cracks and bedrock are adjacent and almost at the same height, the potential energy change can be ignored. Therefore, equation (5-1) can be rewritten as:

[0110]

[0111] Considering that the bedrock is very dense, there is only gas phase in the bedrock and no water phase, equation (5-2) becomes

[0112]

[0113] In the formula, ρ w ,ρ g — are the densities of water and gas, (kg / m 3 );

[0114] V fw ,V fg — are the flow velocities of water and gas in the fracture, respectively (m / s);

[0115] p f ,p m —pressure in the fracture and bedrock, respectively, (Pa);

[0116] V mg —Gas velocity from bedrock into fractures, (m / s).

[0117] Considering the gas-water two-phase flow in the fracture, and noting the relationship between the true fluid velocity and the seepage velocity, equation (5-3) expressed using the volume coefficient can be transformed into:

[0118]

[0119] In the formula, ρ scw ,ρ scg The density of water and gas under standard conditions is constant (kg / m 3 );

[0120] B w ,B g are the volume coefficients of water and gas under formation conditions, respectively;

[0121] k rw ,k rg are the relative permeabilities of water and gas, respectively;

[0122] is the fracture pressure gradient along the fracture direction, (Pa / m);

[0123] φ f is the fracture porosity.

[0124] From the above derivation, it can be seen that the pressure difference from bedrock to crack (p m -p f ) is not entirely used for crossflow from bedrock to fractures. This pressure difference must first overcome the pressure energy loss caused by the kinetic energy of the existing fluid in the fracture. The remaining part is the crossflow from bedrock to fractures. The original dual-medium crossflow model must be modified.

[0125] Based on the above derivation process, the specific process of establishing the equation in step S101 includes:

[0126] In order to fully describe the actual shape of the crack, a coordinate system can be established along the crack. Since the crack opening is very small, the flow of the fluid can be regarded as one-dimensional. Let the spatial direction of the crack be τ f , with a width of w f , and the α (α=w,g) phase fluid flow rate from the unit length fracture into the matrix per unit time is q fm,α , then the mass conservation equation of the aqueous fluid in the fracture and matrix can be written as:

[0127] The mass conservation equation for the aqueous fluid in the fracture and matrix can be written as:

[0128]

[0129]

[0130] Similarly, the mass conservation equation of the gas phase fluid in the fracture and matrix can be expressed as:

[0131]

[0132]

[0133] in and are the flow rates of the α (α=w,g) phase fluid in the fracture and matrix, respectively;

[0134] The fluid in the fracture and matrix needs to satisfy Darcy's law:

[0135]

[0136] In the above equation, ρ α and μ α are the density and viscosity of the α phase fluid respectively; φ (β) and K (β) are the porosity and absolute permeability of the β medium (β = f,m); and are the relative permeability, pressure and saturation of α phase fluid in β medium, respectively.

[0137] Since the water in the high-permeability channel comes from the surrounding water body, it can be assumed that there is only gas but no water in the bedrock. In this way, the system equation only has gas phase crossflow term but no water phase crossflow term. At the same time, the high-permeability channel is a fracture system, so the gas-water surface tension can be ignored, that is, p w =p g Therefore, formula (5-5) to formula (5-8) are simplified to:

[0138] Water-gas two-phase seepage equation in fracture system

[0139]

[0140]

[0141] The fluid exchange equation between bedrock and fractures is adopted:

[0142]

[0143] In the formula, k rw , k rg are the water phase and gas phase permeabilities, respectively;

[0144] μ w , μ g are the viscosities of the water phase and the gas phase, respectively;

[0145] ρ w , g are the densities of water phase and gas phase, respectively;

[0146] ρ scw , scg are the densities of water phase and gas phase under standard conditions, respectively;

[0147] B w , B g are the volume coefficients of water phase and gas phase, respectively;

[0148] τ f — is the spatial direction of the crack;

[0149] Subscript f refers to fractures, and subscript m refers to bedrock.

[0150] In equation (5-12), V mg is the gas velocity from bedrock into the fracture, Figure 3 The crack distribution and the meaning of crack related parameters are given. Figure 3 Select a small unit along the crack direction, whose crack length is ΔL and crack width is w f , the micro-height of the crack is Δh, the micro-unit area of ​​the contact surface between the crack and the bedrock is Δh×ΔL, and the total gas flow rate flowing into the crack through Δh×ΔL bedrock is Q g =Δh×L×V mg, this gas production is the source-sink term for the fracture, and its source-sink intensity is

[0151] q g =ρ g Q g / (h×L×w f )=ρ g V mg / w f (5-13)

[0152] According to equation (5-11), the source-sink strength in the crack equation is Taking equation (5-13) into consideration, the gas velocity of bedrock entering the fracture can be expressed as:

[0153]

[0154] Substituting equation (5-14) into equation (5-12) yields:

[0155]

[0156] Solving equation (5-15) yields the pressure difference between the bedrock and the fracture:

[0157]

[0158] Substituting equation (5-16) into equation (5-11), we can obtain the gas phase seepage equation in the fracture system:

[0159]

[0160] The water phase seepage equation in the fracture system is still expressed by equation (5-10), that is:

[0161]

[0162] Based on the above steps S101-S103, the specific process of discretizing the equation in step S103 includes:

[0163] The equations are the water phase seepage equation (5-10) and the gas phase seepage equation (5-17) in the fracture system. There are two parameters to be solved in the two equations: f and S w , taking the two-dimensional space equation as an example, since there is only the crack equation, the subscript f is omitted.

[0164] The two-dimensional spatial equation of the water phase seepage equation (5-18) is:

[0165]

[0166] After finite difference discretization of equation (5-18), the water phase discrete equation (5-19) is obtained:

[0167]

[0168] The two-dimensional space equation of the gas phase seepage equation (5-20) is

[0169]

[0170] After finite difference discretization of equation (5-20), the gas phase discrete equation (5-21) is obtained:

[0171]

[0172] Where:

[0173] V i,j =Δx i Δy j h (5-22)

[0174] is the volume of the unit grid (i, j);

[0175]

[0176] is the potential function difference between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid block in the x direction, the potential difference between the water and gas phases at the n+1th moment, and the potential difference in the y direction is The expression is similar to the potential difference in the x direction;

[0177]

[0178] is the density of the water and gas phases between the α phase (α=w,g) fluid and its adjacent grid blocks in the x direction at the n+1th moment on the unit grid (i,j), and the density in the y direction is The expression is similar to the x-direction density;

[0179]

[0180] is the conductivity of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment, and the conductivity in the y direction is The expression is similar to the conductivity in the x direction;

[0181]

[0182] is the conductivity multiplier of the water and gas phases between the α phase (α=w,g) fluid and its adjacent grid blocks in the x direction on the unit grid (i,j) at the n+1th moment. The conductivity multiplier in the y direction is TRAN i,j±1 / 2 , the expression is similar to the conductivity in the x direction;

[0183]

[0184] is the mobility of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment, using the upstream weighted value, and the mobility in the y direction The expression is similar to the conductivity in the x direction;

[0185]

[0186] It is obvious that equation (5-28) is a function related to pressure and water phase saturation, and is also a strongly nonlinear function. Equation (5-28) has many properties, such as when α D →0, according to L’Hôpital’s limit calculation rule:

[0187]

[0188] When the crossflow coefficient α D When it is 0, that is, the bedrock does not provide gas to the fracture, equation (5-17) degenerates into the conventional gas seepage equation, which is consistent with the actual situation.

[0189] In the embodiment of the present invention, in order to realize the theoretical research of the dynamic dual medium model based on the dynamic flow law of fracture-bedrock, the inventor proposes to define a kinetic energy coefficient based on the dynamic dual medium theory, and to describe the macroscopic water-sealing gas effect in the gas-water two-phase seepage process by defining the kinetic energy coefficient, thereby simplifying the gas-water two-phase seepage simulation process, specifically, including:

[0190] According to dimensional analysis is a dimensionless parameter, obtained from Darcy's law and referring to equation (5-4)

[0191]

[0192] so It should be related to the bedrock to fracture kinetic energy, that is, and Correspondingly. Since equation (5-30) is a function related to pressure and water phase saturation, it represents the kinetic energy of the fracture term. The larger the kinetic energy of the fracture term, the larger Ψ is.

[0193] In order to further study the kinetic energy effect of double-porosity media, the kinetic energy coefficient θ is defined as:

[0194]

[0195] To facilitate calculation and comparison, we define a reference pressure and reference water saturation. For example, the reference pressure can be the average reservoir pressure (or static pressure) pR , the reference water saturation can be S wsc =0.5, It represents the pressure gradient along the fracture direction and can be expressed by the Peaceman formula on each grid.

[0196] In a specific embodiment, during the structural meshing process of step S103, referring to Figure 4 As shown in Figure 2, assuming that the fluid flow in a grid along the fracture is an incompressible steady-state flow and the reservoir is mean and isotropic, it can be approximately considered that the pressures at adjacent grids (i-1, j), (i+1, j), (i, j-1), and (i, j+1) are equal and set to p s . Assume that the adjacent grid step size is Δx and the pressure at the grid (i, j) is p i,j , the well is a production well, then there is a point (at a distance of r from the center of the grid eq At, and r eq <Δx), where the pressure is p i,j .

[0197] In fact, the pressure p of the grid (i, j) i,j is some average value of the well grid pressure, and the actual pressure at the edge of the grid is greater than p i,j , there is obviously a point (assuming it is at a distance r from the well eq The pressure is p i,j Assuming that it is an isotropic incompressible steady-state flow, it can be considered that at a distance r from the center eq The pressure on the circle should be equal, that is, p i,j , then r eq is the equivalent radius of the grid pressure. For radial flow:

[0198]

[0199] According to the above method, the above parameters are calculated under reference pressure and water saturation. Equation (5-31)θ(p R ,S wsc ) becomes a reference parameter, and equation (5-28)Ψ can be modified as follows:

[0200]

[0201] θ(p R ,S wsc ) is used as the reference kinetic energy coefficient. For the convenience of description and equation simplification, θ is used instead of θ(p R ,S wsc). θ can describe the strength of the crack and the bedrock to the crack source and sink. When θ = 0, Ψ = 0; when θ increases, Ψ also increases. Therefore, when studying macroscopic water-sealed gas, we can describe it through the kinetic energy coefficient.

[0202] Considering the conservation of energy, when the kinetic energy of the crack term increases, the kinetic energy term from the bedrock to the crack must decrease, which reduces the speed of gas flowing from the bedrock into the crack, and makes it difficult for the gas in the bedrock to enter the crack, thus forming a water-sealed gas effect. Therefore, the change of Ψ in a time step will not be too large, and Ψ can be displayed on the unit grid (i, j) in actual numerical calculations.

[0203] In the embodiment of the present invention, the gas-water two-phase seepage simulation result may include the saturation and pressure of the gas-water two-phase. In the above step S105, the gas-water two-phase permeability curve of the given dual-medium formation is obtained in order to obtain the permeability of the two phases at different saturations when performing reservoir flow simulation calculations. Acquiring and setting initial conditions and boundary conditions is an important input for simulation calculations, which can be used for the initialization and constraint conditions of simulation calculations. The physical conditions at the start of the simulation are set according to the actual situation, such as initial pressure, temperature and saturation, etc., and the conditions of the oil and gas fluid on the boundary of the simulation area are set according to the boundary constraint conditions.

[0204] In the embodiment of the present invention, when executing the above step S106, the reservoir numerical simulation software used may be software in the prior art, such as Eclipse software.

[0205] In an embodiment of the present invention, in the above step S106, the process of solving the discretized equations by an iterative calculation method to obtain the numerical solution of the gas-water two-phase seepage simulation can refer to the detailed description in the prior art. For example, it can be an iterative solution method such as Jacobi iteration method, Gauss-Seidel iteration method, conjugate gradient method, or directly using a sparse matrix solver for calculation. The solution obtained by iterative calculation updates the parameters such as pressure, saturation and relative permeability of each grid unit in the simulation area. The convergence of the solution result is judged to check whether the simulation calculation meets the convergence accuracy requirements. If not, the parameters such as the iteration method and time step can be adjusted and the solution is re-solved. In the time stepping process, the boundary conditions and initial conditions of the next time step are determined according to the solution of the current time step solved, and the iterative calculation of the time step advancement is continued. Repeat the above steps until the set end condition is reached, such as the time reaches the maximum simulation time, the change of the solution is less than the set threshold, etc. In an embodiment of the present invention, the convergence accuracy characterizes the speed and degree to which the numerical solution gradually approaches the true solution as the number of iterations increases in the numerical simulation. The convergence accuracy can be set according to actual conditions on the basis of balancing the calculation accuracy and calculation efficiency, so as to obtain efficient and accurate numerical simulation results.

[0206] Among them, during the time stepping process, the time step is controlled according to the following formula:

[0207] Δt n+1 =min(αΔt n ,Δt max ) (5-34)

[0208] In the formula, Δt n+1 refers to the next time step; α refers to the time step growth coefficient; Δt n Refers to the current time step; Δt max Refers to the maximum time step.

[0209] In order to make a clearer description of the gas-water two-phase seepage simulation method based on dynamic dual media provided by the embodiment of the present invention and verify the effectiveness of the method, the following takes the implementation plan of the example reservoir, the gas-water two-phase seepage simulation using the conventional conventional dual media model and the gas-water two-phase seepage simulation using the dynamic dual media theoretical model provided by the embodiment of the present invention as examples, and introduces the embodiment of the present invention in detail as follows:

[0210] First, in order to study whether the conventional dual-medium model can achieve the water-sealed gas effect, an example reservoir is given, in which the permeabilities of the fractures and the matrix are 2000mD and 0.1mD respectively. The transverse fractures are numbered X1-X5 from bottom to top, and the longitudinal fractures are numbered Y1-Y5 from left to right. There is a gas production well and a water injection well in the formation. Figure 5 The well location model established for this well case is given, and the fracture distribution and well location distribution map obtained are given. Figure 6 It is the gas-water two-phase permeability curve of this calculation example.

[0211] Next, when using the conventional dual-medium model to simulate the gas-water two-phase seepage, the specific process of numerical simulation can refer to the detailed description of the prior art according to the relevant calculation theory and formula of the gas-water two-phase of the traditional dual-medium water invasion. Figure 7The gas saturation distribution diagram at 230 days of production is shown. It can be seen from the figure that the fluid mainly flows along the fractures in the lower right part of the reservoir, while the flow in the upper left part is significantly weaker; between the parallel fractures, the fractures in different positions have great differences in their diversion effects: the fractures closer to the well have significantly higher diversion effects than the fractures farther away. Due to the flow exchange between the fractures and the matrix, the pressure gradient of the fluid will be discontinuous and weakened when crossing the fractures along the flow direction. After crossing the fractures many times, the attenuation degree is more obvious. The reduction of the pressure gradient at the fractures makes the flow exchange rate between the fractures and the matrix weakened. Therefore, the exchange efficiency of the fractures farther from the flow field front is much lower than that of the closer fractures. In other words, the closer fractures hinder the flow exchange of the farther fractures. In this example, the pressure gradient is transmitted from the wellhead position to the middle, so the flow exchange rate between the fractures X1 and Y5 closer to the well and the matrix is ​​greater than that of the fractures in the middle. Therefore, the fluid in the flow field mainly flows along the lower fracture X1 in the horizontal direction, and flows along the right fracture Y5 in the vertical direction. That is, water flows from the injection well to the production well along the fracture, and the gas and water advance almost synchronously without water-sealing gas phenomenon.

[0212] Next, the same calculation example, fracture distribution and well location distribution map and gas-water two-phase permeability curve as the conventional dual-medium theoretical model are used, and the dynamic dual-medium theoretical model proposed in the embodiment of the present invention is used to perform gas-water two-phase seepage simulation according to the above steps S101 to S106. When performing numerical simulation, the dimensionless crossflow coefficient α is taken as D =5×10 -3 According to the simulation results of gas-water two-phase flow, Figure 8 The gas saturation distribution diagram after 230 days of continuous production (red represents gas, blue represents water) is shown. Water flows from the injection well to the production well along the cracks, resulting in a decrease in gas saturation around the production well. At the same time, as water flows along the cracks, high-concentration gas appears in the bedrock between the two cracks, especially in the "grid" part of the bedrock formed by the intersection of the cracks. That is, water only flows along the cracks and is difficult to enter the bedrock. The bedrock is mainly gas. Since the cracks have formed water flow channels, the gas in the bedrock between the cracks cannot flow out, thus forming a water-sealed gas phenomenon.

[0213] Furthermore, in order to compare the conventional dual medium with the dynamic dual medium, a two-dimensional cross-crack region is used here. Fig. 9 Given a fracture distribution diagram in a two-dimensional region, if water is injected from x = 0 and gas is extracted from x = L, the phase permeability curve still adopts Figure 6 Gas-water two-phase permeability curve. The conventional dual medium and different reference kinetic energy coefficients θ were used for simulation calculation to obtain the gas-water two-phase permeability simulation results, such as Fig.10The gas-water saturation change diagram corresponding to different reference kinetic energy coefficients θ = 0, θ = 10, θ = 40 and θ = 50 is shown. In the figure, red is the maximum water saturation and blue is the maximum gas saturation.

[0214] Depend on Fig.10 It can be seen that when θ=0, that is, conventional dual medium, water is almost uniformly advanced, and there is no phenomenon of gas being sealed in a certain bedrock block. When θ=10, gas and water are not uniformly advanced, and water displaces gas along the cracks, but there is a phenomenon that some gas in the bedrock is "sealed" by water in the cracks. When θ=40 and θ=50, the water-sealed gas phenomenon is more obvious, and the sealed gas area increases as θ increases. Due to the limitation of the bedrock area in the calculation, the gas can only be sealed in the bedrock block at most.

[0215] Embodiment 2

[0216] Based on the same inventive concept, the embodiment of the present invention also provides a gas-water two-phase seepage simulation device based on dynamic dual media, referring to Fig.11 As shown, the device comprises:

[0217] The equation building module 101 is used to build the gas phase seepage equation, the water phase seepage equation and the fluid exchange equation between the bedrock and the fracture of the dynamic dual medium:

[0218]

[0219]

[0220]

[0221] Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρ g is the gas phase density; ρ scw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock;

[0222] Model building module 102, used to build a reservoir dual medium simulation well location model;

[0223] A grid division module 103 is used to divide the simulated area into structural grids according to the fluid exchange equation between the bedrock and the fractures in the dual-medium simulation well location model of the reservoir, and obtain the dual-medium formation fracture and well location distribution results;

[0224] The equation discretization module 104 is used to discretize the gas phase seepage equation and the water phase seepage equation according to the dual medium formation fracture and well location distribution results to obtain a gas phase discrete equation and a water phase discrete equation;

[0225] The setting module 105 is used to obtain a given dual-medium formation gas-water two-phase permeability curve and set initial conditions and boundary conditions;

[0226] The simulation calculation module 106 is used to iteratively solve the gas phase discrete equation and the water phase discrete equation according to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, to obtain a gas-water two-phase seepage simulation result.

[0227] Embodiment 3

[0228] Based on the same inventive concept, an embodiment of the present invention also provides a computer-readable storage medium, in which instructions are stored. When the instructions are executed on a terminal, the terminal executes the gas-water two-phase seepage simulation method based on dynamic dual media as described in the above embodiment 1.

[0229] Embodiment 4

[0230] Based on the same inventive concept, an embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the gas-water two-phase seepage simulation method based on dynamic dual media as described in the above-mentioned embodiment 1 is implemented.

[0231] Embodiment 5

[0232] Based on the same inventive concept, an embodiment of the present invention also provides a computer program product comprising instructions. When the computer program product is run on a computer device, the computer device executes the gas-water two-phase seepage simulation method based on dynamic dual media as described in the above embodiment 1.

[0233] Embodiment 6

[0234] Based on the same inventive concept, an embodiment of the present invention also provides a chip, the chip includes a processor and a communication interface, the communication interface and the processor are coupled, and the processor is used to run a computer program or instruction to implement the gas-water two-phase seepage simulation method based on dynamic dual media as described in the above embodiment one.

[0235] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0236] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0237] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0238] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0239] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. The present invention is not limited to any single aspect, any single embodiment, or any combination and / or permutation of these aspects and / or embodiments. Each aspect and / or embodiment of the present invention can be used alone, or in combination with one or more other aspects and / or other embodiments.

[0240] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A gas-water two-phase seepage simulation method based on dynamic dual media, characterized in that: include: The gas phase seepage equation, water phase seepage equation and fluid exchange equation between bedrock and fractures of dynamic dual media are established: Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρ g is the gas phase density; ρ scw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock; Establish a well location model for dual-medium simulation of oil reservoirs; According to the reservoir dual-medium simulation well location model and the fluid exchange equation between the bedrock and the fracture, the simulated area is divided into structural grids to obtain the dual-medium formation fracture and well location distribution results; According to the dual-medium formation fracture and well location distribution results, the gas phase seepage equation and the water phase seepage equation are discretized to obtain a gas phase discrete equation and a water phase discrete equation; Obtain the given dual-medium formation gas-water two-phase permeability curve, set initial conditions and boundary conditions; According to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, the gas phase discrete equation and the water phase discrete equation are iteratively solved to obtain a gas-water two-phase seepage simulation result.

2. The gas-water two-phase seepage simulation method based on dynamic dual media according to claim 1, characterized in that: The method of obtaining and establishing a gas phase seepage equation, a water phase seepage equation, and a fluid exchange equation between bedrock and fractures for a dynamic dual medium includes: Establish a coordinate system along the crack, and set the spatial direction of the crack as τ f , with a width of w f The flow rate of α-phase fluid flowing from the fracture per unit length into the matrix per unit time is q fm,α , construct the mass conservation equations of the water phase fluid in the fracture and matrix and the mass conservation equations of the gas phase fluid in the fracture and matrix: Among them, α=w,g, w is the water phase, g is the gas phase, and are the flow rates of the α-phase fluid in the fracture and matrix, respectively, ρ α and μ α are the density and viscosity of the α phase fluid respectively; φ (β) and K (β) are the porosity and absolute permeability of the β medium (β = f,m); and are the relative permeability, pressure and saturation of the α phase fluid in the β medium respectively; Without considering the gas-water surface tension, the water-gas two-phase seepage equation in the fracture system and the fluid exchange equation between bedrock and fractures are obtained according to formulas (5-5) to (5-8).

3. The gas-water two-phase seepage simulation method based on dynamic dual media according to claim 1, characterized in that: include: Structured meshing is applied to the simulation area in the following way: Set reference pressure p R , reference water saturation S wsc , the pressure gradient along the fracture direction Assuming that the fluid flow in a certain grid along the fracture is incompressible steady-state flow, and the reservoir is mean and isotropic, the fracture and well distribution results of the dual-medium formation are constructed; The pressure gradient along the radial flow of the fracture is: Where Δx is the adjacent grid step size, r eq is the equivalent radius of the grid pressure, p i,j is the distance r from the center of the cell grid (i, j) eq The pressure on the circle; p s is the pressure at the adjacent grid.

4. The gas-water two-phase seepage simulation method based on dynamic dual media according to claim 3, characterized in that: The gas phase seepage equation and the water phase seepage equation are discretized to obtain a gas phase discrete equation and a water phase discrete equation, including: Determine the two-dimensional space equations of the gas phase seepage equation and the water phase seepage equation respectively: Finite difference discretization is performed on the two-dimensional space equations of the gas phase seepage equation and the water phase seepage equation to obtain the gas phase discrete equation and the water phase discrete equation: Where V i,j =Δx i Δy j h is the volume of the unit grid (i, j); Pressure and water saturation correlation function is the potential function difference between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid block in the x direction, the potential difference between the water and gas phases at the n+1th moment, and the potential difference in the y direction is is the density of the water and gas phases between the α phase (α=w,g) fluid and its adjacent grid blocks in the x direction at the n+1th moment on the unit grid (i,j), and the density in the y direction is is the conductivity of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment, and the conductivity in the y direction is is the conductivity multiplier of the water and gas phases between the α phase (α=w,g) fluid and its adjacent grid blocks in the x direction on the unit grid (i,j) at the n+1th moment. The conductivity multiplier in the y direction is TRAN i,j±1 / 2 ; is the mobility of the water and gas phases between the α phase (α=w,g) fluid on the unit grid (i,j) and its adjacent grid blocks in the x direction at the n+1th moment. The upstream weighted value is used, and the mobility in the y direction is 5. The gas-water two-phase seepage simulation method based on dynamic dual media according to claim 4, characterized in that: Before simulating the gas-water two-phase seepage process, it also includes: According to the predefined kinetic energy coefficient θ, the pressure and water phase saturation related function Ψ is converted: in, is the reference pressure, S wsc is the reference water saturation.

6. The gas-water two-phase seepage simulation method based on dynamic dual media according to any one of claims 1 to 5, characterized in that: During the time stepping process, the time step is controlled according to the following formula: Δt n+1 =min(αΔt n ,Δt max ) In the formula, Δt n+1 refers to the next time step; α refers to the time step growth coefficient; Δt n Refers to the current time step; Δt max Refers to the maximum time step.

7. A gas-water two-phase seepage simulation device based on dynamic dual media, characterized in that: include: Equation building module, used to establish the gas phase seepage equation, water phase seepage equation and fluid exchange equation between bedrock and fractures of dynamic dual media: Where: V mg is the gas velocity from bedrock into the fracture, α D k is the crossflow coefficient; rw is the water phase permeability; k rg is the gas phase permeability μ w is the viscosity of the water phase; μ g is the gas phase viscosity; ρ w is the water phase density; ρ g is the gas phase density; ρ scw is the density of water phase under standard conditions; ρ scg is the gas phase density under standard conditions; B w is the volume coefficient of water phase; B g is the gas phase volume coefficient; τ f — is the spatial direction of the crack; f represents the crack; m represents the bedrock; Model building module, used to build a well location model for dual-medium simulation of oil reservoirs; A grid division module is used to divide the simulated area into structural grids according to the reservoir dual-medium simulation well location model and the fluid exchange equation between the bedrock and the fracture, so as to obtain the dual-medium formation fracture and well location distribution results; An equation discretization module is used to discretize the gas phase seepage equation and the water phase seepage equation according to the dual medium formation fracture and well location distribution results to obtain a gas phase discrete equation and a water phase discrete equation; A setting module is used to obtain the gas-water two-phase permeability curve of a given dual-medium formation and to set initial conditions and boundary conditions; The simulation calculation module is used to iteratively solve the gas phase discrete equation and the water phase discrete equation according to the given dual-medium formation gas-water two-phase permeability curve, the initial conditions and the boundary conditions, after a given time step and convergence accuracy, to obtain the gas-water two-phase seepage simulation result.

8. A computer-readable storage medium storing instructions, which, when executed on a terminal, enable the terminal to execute the gas-water two-phase seepage simulation method based on dynamic dual media as described in any one of claims 1 to 6.

9. A computer device, characterized in that: It includes a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the gas-water two-phase seepage simulation method based on dynamic dual media as described in any one of claims 1 to 6 is implemented.

10. A computer program product comprising instructions, which, when executed on a computer device, enables the computer device to execute the gas-water two-phase seepage simulation method based on dynamic dual media as claimed in any one of claims 1 to 6.

11. A chip, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a computer program or instruction to implement the gas-water two-phase seepage simulation method based on dynamic dual media as described in any one of claims 1 to 6.

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