A porous media imbibition simulation method and system considering dynamic contact angle effect

Abstract

The present invention relates to the fields of porous media fluid flow and oil and gas field development, and more specifically to a method and system for simulating porous media imbibition that considers the dynamic contact angle effect. This invention considers the dynamic contact angle effect and adapts different dynamic contact angle theories to different application scenarios. By coupling the dynamic contact angle theory with a two-phase imbibition mathematical model, a method and system for simulating porous media imbibition that considers the dynamic contact angle effect is proposed. This method can effectively analyze the impact of the dynamic contact angle effect on porous media imbibition, thus improving the theory and method for simulating porous media imbibition.

Description

Technical Field

[0001] The present invention relates to the fields of porous medium fluid flow and oil and gas field development, and in particular to a porous medium imbibition simulation method and system considering dynamic contact angle effect. Background Art

[0002] Imbibition in porous media is one of the most common phenomena in nature, such as rainwater absorption in the ground, water absorption in towels, and water absorption in diapers. Imbibition in porous media also has important applications in engineering, such as the manufacture of nanoporous materials and enhanced oil and gas recovery. For example, in the context of enhanced oil and gas recovery, imbibition has been widely applied in fractured and carbonate reservoirs. Fractured and carbonate reservoirs are characterized by the development of fractures, which creates two distinct systems: the reservoir matrix and the fractures. The matrix has low permeability, while the fractures have high permeability. Under capillary pressure, the wetting phase (typically water) in the fracture system is imbibed into the matrix, displacing the non-wetting phase (typically oil or gas) from the matrix system and flowing into the fractures.

[0003] Currently, imbibition recovery is a key area of ​​research in tight oil reservoirs. Tight oil and gas reservoirs primarily have nanoscale pore throats, making capillary pressure more pronounced. Large-scale volume fracturing creates numerous artificial fractures, creating conditions for imbibition recovery. The dynamic contact angle effect refers to the change in the three-phase contact angle (solid, wetting, and non-wetting phases) with fluid velocity during flow or imbibition due to friction at the contact line. While the dynamic contact angle effect has been extensively studied and applied in single-tube or single-pore imbibition, the complex flow patterns of the wetting and non-wetting phases in porous media (such as rock) and the impact of the dynamic contact angle effect on imbibition remain unclear. Summary of the Invention

[0004] The present invention takes into account the dynamic contact angle effect and adapts different dynamic contact angle theories for different application scenarios. By coupling the dynamic contact angle theory and the two-phase imbibition mathematical model, a porous medium imbibition simulation method and system considering the dynamic contact angle effect are proposed, which can effectively analyze the influence of the dynamic contact angle effect on the imbibition of porous media.

[0005] The present invention proposes a porous media imbibition simulation method and system considering the dynamic contact angle effect, which specifically includes the following steps:

[0006] 1) Determine the basic parameters of the porous media imbibition system under study;

[0007] The basic parameters include fluid data and porous medium data;

[0008] 2) Select dynamic contact angle theory;

[0009] The dynamic contact angle theory includes: molecular dynamics theory, hydrodynamics theory, and empirical model;

[0010] 3) Establish a two-phase imbibition mathematical model;

[0011] 4) Coupling dynamic contact angle theory and two-phase imbibition mathematical model;

[0012] 5) Set the corresponding fluid pressure and boundary conditions according to the actual imbibition conditions;

[0013] 6) Simulation solution.

[0014] During the flow of porous media fluid, due to the friction of the three-phase contact line, the three-phase contact angle is not fixed, but changes with the fluid velocity.

[0015] The present invention provides three dynamic contact angle theories for application in different scenarios:

[0016] When the application scenario is a solid-liquid-liquid system at the micro-nano scale, choose molecular dynamics theory;

[0017] When the application scenario is a solid-liquid-gas system at the micro-nano scale, choose molecular dynamics theory or hydrodynamics theory;

[0018] When the application scenario is a solid-liquid-gas system at a conventional scale, choose an empirical model or hydrodynamic theory.

[0019] The micro-nano scale refers to pores less than or equal to 1 μm; the conventional scale refers to pores greater than 1 μm.

[0020] (1) Molecular dynamics theory

[0021] The relationship between the three-phase contact line velocity and the dynamic contact angle is as follows:

[0022] (1);

[0023] Where: U is the contact line velocity, m / s; γ is the interfacial tension between the two phases of fluid, N / m; is the three-phase contact line friction coefficient, Pa·s; θ st is the static contact angle, °; θ d is the dynamic contact angle, °.

[0024] For the solid-liquid-gas system, considering the viscosity of the fluid and the solid-fluid interaction, the three-phase contact line friction coefficient can be further expressed as:

[0025] (2);

[0026] Where: μis the fluid viscosity, Pa·s; V is the volume of a single fluid molecule, m 3 ; λ is the jump length of the fluid molecules, m; k B is the Boltzmann constant, 1.38×10 −23 J / K; T is the temperature, K; the subscript w indicates the wetting phase.

[0027] For a solid-liquid-liquid system, the three-phase contact line friction coefficient can be expressed as:

[0028] (3);

[0029] Where: η ing is the displacement phase viscosity, Pa·s; V ing is the molar volume of the displacing phase molecules, m 3 / mol; x ing is the displacement phase viscosity fraction; η ed is the viscosity of the displaced phase, Pa·s; V ed is the molar volume of the displaced phase molecules, m 3 / mol; x ed is the viscosity fraction of the displaced phase; A and B are the coefficients related to flow-flow interaction (viscous effect) and solid-flow interaction, respectively; A Usually it can be taken as 1, B It can be obtained by fitting experimental data; h p is Planck's constant.

[0030] The present invention utilizes molecular dynamics theory to comprehensively consider the characteristics of fluid viscosity and solid-fluid interaction, and applies it to solid-fluid systems at the micro-nano scale. More preferably, the solid-fluid system is a solid-liquid-liquid system.

[0031] (2) Hydrodynamics theory

[0032] (4);

[0033] Where: g ( θ ) is a function of ; Ca is the capillary number; χ is a constant that is related to the length of the capillary or porous medium and the strength of the solid-liquid interaction.

[0034] For a solid-liquid-gas system, the above formula can be simplified to:

[0035] (5);

[0036] Where: L is the characteristic length of the capillary; L s is the slip length.

[0037] The present invention utilizes hydrodynamic theory to emphasize the viscous dissipation in the three-phase contact zone, comprehensively considers the effects of capillary number and fluid slip, and applies it to a solid-liquid-gas system.

[0038] (3) Empirical model

[0039] The empirical model is one of formulas (6) to (8):

[0040] (6);

[0041] (7);

[0042] (8);

[0043] Where: A 0 and B 0 is an empirical constant obtained through fitting.

[0044] The present invention utilizes the characteristics of the empirical model derived from experimental data, and comprehensively considers the difficulty of conducting dynamic wetting experiments on different solid-fluid systems, and applies it to the solid-liquid-gas system; more preferably, the solid-liquid-gas system is a solid-liquid-gas system at a conventional scale.

[0045] In step 3), the method for establishing the two-phase imbibition mathematical model is as follows:

[0046] In the x-direction, the mass conservation equation is as follows:

[0047] (9);

[0048] Where: v is the Darcy speed, m / s; x is the distance, along the core axis, m; is the porosity, a decimal; S is the saturation, a decimal; t is the time, s; subscript β Indicates wetting or non-wetting phase;

[0049] In the x-direction, the flow equation is as follows:

[0050] (10);

[0051] Where: k is the permeability of the porous medium, m 2 ; k r is the relative permeability, dimensionless; P is pressure, Pa; μ is the fluid viscosity, Pa·s.

[0052] In step 4), the method for coupling the dynamic contact angle effect theory and the two-phase imbibition mathematical model is as follows:

[0053] The coupled dynamic contact angle theory and two-phase imbibition mathematical model are shown below:

[0054] (11);

[0055] Where: P cd is the dynamic capillary pressure; a and b is the coefficient in the J function that characterizes the capillary pressure and is dimensionless; S wn is the normalized water saturation and is dimensionless.

[0056] According to the definition of capillary pressure (capillary pressure is the pressure difference between the non-wetting phase and the wetting phase at the interface between the two phases), formula (11) is derived through the mass conservation equation and the flow equation.

[0057] Specifically, the molecular dynamics theory is coupled with the two-phase imbibition mathematical model, and the dynamic capillary pressure of the solid-liquid-gas system at the micro-nanoscale is:

[0058] (12);

[0059] Specifically, the molecular dynamics theory is coupled with the two-phase imbibition mathematical model, and the dynamic capillary pressure of the solid-liquid-liquid system at the micro-nanoscale is:

[0060] (13);

[0061] Specifically, the hydrodynamic theory is coupled with the two-phase imbibition mathematical model, and the dynamic capillary pressure of the solid-liquid-gas system is:

[0062] (14);

[0063] Specifically, the empirical model is coupled with the two-phase imbibition mathematical model. The dynamic capillary pressure of the solid-liquid-gas system at a conventional scale is:

[0064] (15);

[0065] (16);

[0066] (17).

[0067] When the normalized water saturation reaches 1, the dynamic capillary pressure is equal to the capillary back pressure or threshold pressure, and the fluid velocity is close to zero. The capillary back pressure can be expressed as:

[0068] (18).

[0069] In step 5), the fluid pressure includes an inlet boundary pressure and an outlet boundary pressure; wherein the difference between the inlet boundary pressure and the internal pressure of the porous medium at the initial moment is equal to the capillary back pressure, and the outlet boundary pressure is equal to the internal pressure of the porous medium.

[0070] The boundary conditions can be set to be open or closed according to requirements, that is, they can be in contact with or not in contact with the ambient fluid, thereby controlling whether the imbibition process occurs.

[0071] In step 6), the simulation method of steps 1) to 5) is solved by programming the program or embedding it into simulation software.

[0072] Preferably, the simulation software is Comsol Multiphysics software.

[0073] The porous media imbibition simulation method considering the dynamic contact angle effect provided by the present invention can accurately describe the influence of the dynamic wetting angle effect on the imbibition of porous media, and can be applied to systems with different wettability, viscosity, interfacial tension, permeability, etc., thus improving the theory and method of porous media imbibition simulation.

[0074] An embodiment of the present invention further provides a porous media imbibition simulation system that considers the dynamic contact angle effect. The system includes: an equation building module, a coupling module, and a simulation solution module.

[0075] The equation establishment module is used to select the dynamic contact angle theory and establish a two-phase imbibition mathematical model; the coupling module characterizes the J function through capillary pressure, couples the dynamic contact angle theory and the established two-phase imbibition mathematical model; the simulation solution module can perform simulation solutions based on the coupled dynamic contact angle theory and the two-phase imbibition mathematical model.

[0076] Compared with the prior art, the advantages of the present invention are:

[0077] Based on existing theories, this paper considers the influence of the dynamic contact angle effect and proposes a method for simulating porous media imbibition. This method accurately describes the impact of the dynamic contact angle effect on porous media imbibition and is applicable to various fluid and porous media imbibition systems. The present invention has broad application prospects in fluid flow, petroleum engineering, and the fabrication of nano- and micro-porous materials, particularly in oilfield development. This simulation method will further improve imbibition oil recovery methods and theories. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0079] Figure 1 This is a flowchart of the application of the simulation method in an embodiment of the present invention;

[0080] Figure 2 A cross section of a three-dimensional porous medium grid according to an embodiment of the present invention;

[0081] Figure 3 The YZ plane water saturation distribution of the porous medium at different imbibition moments in the embodiment of the present invention;

[0082] Figure 4 The oil-water streamline distribution in the XY plane of the porous medium at different imbibition moments in the embodiment of the present invention;

[0083] Figure 5 The capillary pressure distribution of the porous medium in the XY plane at different imbibition moments in the embodiment of the present invention;

[0084] Figure 6 Comparison of the imbibition amounts simulated by the method of the present invention and the traditional method in the examples of the present invention;

[0085] Figure 7 Comparison of the recovery degree simulated by the method of the present invention and the traditional method in the embodiment of the present invention;

[0086] Figure 8 is the average water saturation change calculated by the method of the present invention in the embodiments of the present invention;

[0087] Figure 9 is the average capillary pressure change calculated by the method of the present invention in the embodiment of the present invention;

[0088] Figure 10 Diagram of the porous media imbibition simulation system considering the dynamic contact angle effect;

[0089] Among them, the method of the present invention refers to a research method based on the present invention that considers the dynamic contact angle effect; the traditional method refers to a research method that does not consider the dynamic contact angle effect, that is, a research method when the three-phase contact line friction coefficient is zero. DETAILED DESCRIPTION

[0090] To make the objects, solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their descriptions are provided herein to explain the present invention but are not intended to limit the present invention. Various similar representations may be made without departing from the spirit and claims of the present invention, and such variations fall within the scope of protection of the present invention.

[0091] The main implementation steps of the present invention are as follows (see Figure 1 ):

[0092] Step 101: First, determine the basic parameters of the porous media imbibition system, including fluid data, porous media data, etc., to provide a basis for subsequent simulation solutions;

[0093] Step 102: Select an appropriate dynamic contact angle effect theory based on the content provided by the present invention and calculate relevant parameters;

[0094] Step 103: According to the present invention, a two-phase imbibition mathematical model is established;

[0095] Step 104: coupling the dynamic contact angle theory and the two-phase imbibition mathematical model according to the present invention;

[0096] Step 105: Calculate the capillary back pressure according to the present invention and set appropriate fluid initial pressure and boundary pressure;

[0097] Step 106: Perform simulation, solve, and apply.

[0098] The above method of the present invention is further described below with reference to specific embodiments.

[0099] Example

[0100] The imbibition process is influenced by a variety of factors, including fluid interfacial tension, fluid viscosity, porous medium wettability, porous medium permeability, and porous medium imbibition boundary conditions. This example simulates the dynamic contact angle effect on imbibition in a fully open porous medium boundary condition. This example can be used to simulate imbibition under other influencing factors and is also within the scope of the present invention.

[0101] in accordance with Figure 1First, the basic data of the porous media imbibition system was determined, including the fluid's viscosity, density, oil-water interfacial tension, and the porous media's porosity and permeability. The fluid properties assumed water as the wetting phase, and shale oil as the non-wetting phase. The porous medium was a rectangular parallelepiped made of quartz. The porous medium imbibition boundary condition was fully open, meaning that imbibition could occur on all ends of the porous medium. The basic parameters of the porous media imbibition system are shown in Table 1.

[0102] Table 1 Basic parameters of porous media imbibition system

[0103] parameter Parameter value Permeability / mD 0.1 Porosity / decimal 0.1 Porous medium length / cm 6 Porous medium width / cm 5 Porous medium height / cm 5 Irreducible water saturation / decimal 0.35 Residual oil saturation / decimal 0.50 Water phase viscosity / Pa·s 0.001 Oil phase viscosity / Pa·s 0.001 Oil-water interfacial tension / mN / m 48 Static contact angle / ° 30

[0104] Secondly, the main parameters are calculated according to the present invention. Based on the parameters in Table 1 and the capillary pressure formula (18), the capillary back pressure can be calculated to be 0.083 MPa.

[0105] Then, according to the present invention, the dynamic contact angle theory is preferred. The porous medium in this example is a low-permeability dense medium, belonging to the micro-nano scale, and the object is a solid-liquid-liquid system. Therefore, the dynamic contact angle effect is characterized by molecular dynamics theory. According to the three-phase contact line friction coefficient formula (3), the calculated three-phase contact line friction coefficient is 25 Pa·s, where η ing is 0.001Pa·s; V ing is 2.99×10 -29 m 3 / mol; x ing It is 0.5; η ed is 0.001 Pa·s; V ed is 3.78×10 -28 m 3 / mol; x ed It is 0.5; A is 1, B is 1; h p is 6.62607×10 -34 J.s.

[0106] If the three-phase contact line friction coefficient is zero, it means that the dynamic contact angle effect is not considered, which belongs to the static imbibition process of the traditional method; if the three-phase contact line friction coefficient is not zero, it means that the dynamic contact angle effect is considered, which belongs to the dynamic imbibition process of the method of the present invention.

[0107] Finally, by coupling the dynamic contact angle theory and the two-phase imbibition mathematical model, and performing simulation and solution using Comsol Multiphysics software, we can obtain the porous media imbibition simulation results taking into account the dynamic contact angle effect. The coupling formula of the dynamic contact angle theory and the two-phase imbibition mathematical model is:

[0108] (13).

[0109] Attachment Figure 2 The shape of the porous medium is not limited to the rectangular parallelepiped shape of this embodiment, and any shape can undergo the imbibition process.

[0110] Attachment Figure 3 Figure 2 shows the water saturation distribution of the porous medium in the YZ plane at different imbibition moments in an embodiment of the present invention. The color bars in the figure represent the water saturation level. At 1 second, imbibition begins at the periphery. The water saturation within the porous medium remains unchanged, while the water saturation at the periphery begins to change slightly. At 100 seconds, the imbibition process remains relatively small. At 1000 seconds, the imbibition process significantly expands, with the water saturation within the porous medium increasing significantly and the oil saturation decreasing significantly. At 3548.1 seconds, the imbibition process is nearing completion, and the oil within the porous medium has been expelled.

[0111] Attachment Figure 4 Figure 1 shows the distribution of oil-water streamlines in the XY plane of a porous medium at different imbibition times in an embodiment of the present invention. The color bars in the figure represent water saturation, with pink arrows representing the oil phase and green arrows representing the water phase. At 1 second, imbibition begins at the surrounding boundary, disrupting the fluid equilibrium within the porous medium and resulting in highly chaotic oil-water streamlines. At 100 seconds, these streamlines remain relatively chaotic. At 1000 seconds, imbibition has stabilized, and the streamlines are relatively uniform. At 3548.1 seconds, the imbibition process is essentially complete, the fluid has been largely redistributed, and the streamlines are more uniform and stable.

[0112] Attachment Figure 5 Figure 3 shows the capillary pressure distribution in the XY plane of the porous medium at different imbibition times in an embodiment of the present invention. The color bars in the figure represent the capillary pressure magnitude. At 1 second, imbibition begins at the surrounding boundary. At this time, the water saturation is low, the capillary pressure is maximum, and the imbibition rate is fastest. At 100 seconds, the water saturation remains low, the capillary pressure remains high, and the imbibition rate is fast. At 1000 seconds, the imbibition process has significantly expanded, the water saturation within the porous medium has increased significantly, and the capillary pressure has decreased. At 3548.1 seconds, the imbibition process has essentially concluded, the water saturation approaches maximum, and the capillary pressure moves toward minimum.

[0113] Attachment Figure 6Figure 2 compares the imbibition values ​​simulated using the inventive method and conventional methods in the examples of the present invention. As can be seen, static imbibition values ​​are greater than dynamic imbibition values ​​in the early and middle stages, indicating that conventional research methods overestimate imbibition values ​​in these early and middle stages. In the later stages, static and dynamic imbibition values ​​are equal, primarily because the initial oil-containing volumes of the porous media are the same, resulting in the same final imbibition volumes.

[0114] Attachment Figure 7 This figure compares the recovery rates simulated using the inventive method and conventional methods in the examples of the present invention. As can be seen from the figure, while the imbibition rate changes, the recovery rate simulated using the conventional method is higher than that simulated using the inventive method. This means that the recovery rate after considering the dynamic contact angle effect is lower than that without it. This is primarily because the dynamic contact angle effect acts as a resistance during the imbibition process; a larger dynamic contact angle effect is less conducive to imbibition.

[0115] Attachment Figure 8 is the average water saturation change calculated by the method of the present invention in the embodiment of the present invention. As can be seen from the figure, similar to the two-dimensional water saturation, as the imbibition time increases, the water saturation of the porous medium gradually increases, and a large amount of oil is driven out.

[0116] Attachment Figure 9 is the average capillary pressure change calculated by the method of the present invention in the embodiment of the present invention. As can be seen from the figure, as the imbibition time increases, the water saturation of the porous medium increases, and the capillary pressure between the oil-water phase gradually decreases, which is consistent with basic knowledge.

[0117] The embodiment of the present invention also provides a porous media imbibition simulation system considering the dynamic contact angle effect. Figure 10 As shown, including:

[0118] Equation establishment module 1001: Select an appropriate dynamic contact angle theory. The present invention provides three main dynamic contact angle theories. Establish a two-phase imbibition mathematical model, including the main mass conservation equation, motion equation, capillary pressure equation, etc.

[0119] Coupling module 1002: Through the capillary pressure J function, the dynamic contact angle theory and the established two-phase imbibition mathematical model are coupled to lay the foundation for subsequent solutions.

[0120] Simulation solution module 1003: Based on the coupled dynamic contact angle theory and the two-phase imbibition mathematical model, a simulation program can be compiled by the user for simulation solution or embedded in Comsol Multiphysics software for solution.

[0121] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes 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 invention.

[0122] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0123] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0124] In the embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0125] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected according to actual needs to achieve the objectives of the embodiments of the present invention.

[0126] In addition, the functional units in the embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0127] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0128] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A porous media imbibition simulation method considering the dynamic contact angle effect, characterized in that: The specific steps include: 1) Determine the basic parameters of the porous media imbibition system; The basic parameters include fluid data and porous medium data; 2) Select dynamic contact angle theory; The dynamic contact angle theory includes: molecular dynamics theory, hydrodynamics theory, and empirical model; 3) Establish a two-phase imbibition mathematical model; 4) Coupling dynamic contact angle theory and two-phase imbibition mathematical model; 5) Based on the coupling results, calculate the capillary back pressure and set the fluid pressure and boundary conditions; 6) Simulation solution; When the application scenario is a solid-liquid-liquid system at the micro-nano scale, choose molecular dynamics theory; When the application scenario is a solid-liquid-gas system at the micro-nano scale, choose molecular dynamics theory or hydrodynamics theory; When the application scenario is a solid-liquid-gas system at a conventional scale, choose an empirical model or hydrodynamic theory; The micro-nano scale refers to pores less than or equal to 1 μm; the conventional scale refers to pores greater than 1 μm.

2. The porous media imbibition simulation method considering the dynamic contact angle effect according to claim 1, characterized in that: In step 3), the method for establishing the two-phase imbibition mathematical model is as follows: In the x-direction, the mass conservation equation is: （9）； Where: v is the Darcy speed, m / s; x is the distance, along the core axis, m; is the porosity, a decimal; S is the saturation, a decimal; t is time, s; Subscript β Indicates wetting or non-wetting phase; In the x-direction, the flow equation is: （10）； Where: k is the permeability of the porous medium, m 2 ; k r is the relative permeability, dimensionless; P is pressure, Pa; μ is the fluid viscosity, Pa·s.

3. The porous media imbibition simulation method considering the dynamic contact angle effect according to claim 2, characterized in that: In step 4), the method for coupling the dynamic contact angle effect theory and the two-phase imbibition mathematical model is as follows: （11）； Where: P cd is the dynamic capillary pressure; γ is the interfacial tension between the two phases of fluid, N / m; θ d is the dynamic contact angle, °; a and b is the coefficient in the J function that characterizes the capillary pressure and is dimensionless; S wn is the normalized water saturation and is dimensionless.

4. The porous media imbibition simulation method considering the dynamic contact angle effect according to claim 3, characterized in that: In the molecular dynamics theory, the relationship between the three-phase contact line velocity and the dynamic contact angle is: （1）； Where: U is the contact line velocity, m / s; γ is the interfacial tension between the two phases of fluid, N / m; is the three-phase contact line friction coefficient, Pa·s; θ st is the static contact angle, °; θ d is the dynamic contact angle, °; For the solid-liquid-gas system, the three-phase contact line friction coefficient for: （2）； Where: μ is the fluid viscosity, Pa·s; V is the volume of a single fluid molecule, m 3 ; λ is the jump length of the fluid molecules, m; k B is the Boltzmann constant, 1.38×10 −23 J / K; T is the temperature, K; the subscript w indicates the wetting phase; For a solid-liquid-gas system, the dynamic capillary pressure is: （12）； For a solid-liquid-liquid system, the three-phase contact line friction coefficient for: （3）； Where: η ing is the displacement phase viscosity, Pa·s; V ing is the molar volume of the displacing phase molecules, m 3 / mol; x ing is the displacement phase viscosity fraction; η ed is the viscosity of the displaced phase, Pa·s; V ed is the molar volume of the displaced phase molecules, m 3 / mol; x ed is the viscosity fraction of the displaced phase; A and B are the coefficients related to flow-flow interaction and solid-flow interaction, respectively; h p is Planck's constant; For a solid-liquid-liquid system, the dynamic capillary pressure is: （13）。 5. The porous media imbibition simulation method considering the dynamic contact angle effect according to claim 3, characterized in that: In the hydrodynamic theory, （4）； Where: g ( θ ) is a function of ; Ca is the capillary number; χ is a constant related to the length of the capillary or porous medium and the strength of the solid-liquid interaction; θ st is the static contact angle, °; θ d is the dynamic contact angle, °; For the solid-liquid-gas system, formula (4) can be simplified as: （5）； Where: L is the characteristic length of the capillary; L s is the slip length; U is the contact line velocity, m / s; μ is the fluid viscosity, Pa·s; the subscript w indicates the wetting phase; γ is the interfacial tension between the two phases of fluid, N / m; For a solid-liquid-gas system, the dynamic capillary pressure is: （14）； P cd is the dynamic capillary pressure; is the porosity, a decimal; k is the permeability of the porous medium, m 2 ; a and b is the coefficient in the J function that characterizes the capillary pressure and is dimensionless; S wn is the normalized water saturation and is dimensionless.

6. The porous media imbibition simulation method considering the dynamic contact angle effect according to claim 3, characterized in that: The empirical model is one of formulas (6) to (8): （6）； （7）； （8）； Where: A 0 and B 0 is an empirical constant obtained by fitting; θ st is the static contact angle, °; θ d is the dynamic contact angle, °; Ca is the capillary number; The dynamic capillary pressure is one of the equations (15) to (17): （15）； （16）； （17）； P cd is the dynamic capillary pressure; γ is the interfacial tension between the two phases of fluid, N / m; is the porosity, a decimal; k is the permeability of the porous medium, m 2 ; a and b is the coefficient in the J function that characterizes the capillary pressure and is dimensionless; S wn is the normalized water saturation and is dimensionless.

7. The porous media imbibition simulation method considering dynamic contact angle effect according to claim 1, characterized in that: In step 5), the fluid pressure includes an inlet boundary pressure and an outlet boundary pressure; the difference between the inlet boundary pressure and the internal pressure of the porous medium at the initial moment is equal to the capillary back pressure, and the outlet boundary pressure is equal to the internal pressure of the porous medium; The boundary condition is set to open or closed.

8. The porous media imbibition simulation method considering dynamic contact angle effect according to claim 1, characterized in that: In step 6), the simulation solution method is to program the simulation method of steps 1) to 5) or embed it into simulation software for solution.

9. A porous media imbibition simulation system considering dynamic contact angle effect based on the method according to any one of claims 1 to 8, characterized in that: The system includes: an equation building module, a coupling module, and a simulation solution module; The equation building module is used to select the dynamic contact angle theory and establish a two-phase imbibition mathematical model; The coupling module characterizes the J function through capillary pressure, couples the dynamic contact angle theory and the established two-phase imbibition mathematical model; The simulation solution module performs simulation solution based on coupled dynamic contact angle theory and two-phase imbibition mathematical model.

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