Discontinuous phase drive numerical simulation characterization method

Abstract

The invention relates to a discontinuous phase displacement numerical simulation characterization method. The method comprises the following steps: constructing a physical property characterization model of an oil displacement process; based on the physical property characterization model, constructing a discontinuous phase displacement characterization method according to a multi-component chemical reaction; establishing a substance conservation equation based on the discontinuous phase displacement characterization method; solving the substance conservation equation to obtain a solving result; and displacement effect prediction is carried out through the solving result. According to the method, the efficiency, the accuracy and the adaptability of discontinuous phase drive numerical simulation are improved.

Description

Technical Field

[0001] The invention relates to the technical field of marine oil and gas field development engineering, and in particular to a discontinuous phase drive numerical simulation characterization method. Background Art

[0002] Discontinuous phase systems such as polymer microspheres have elastic characteristics and are squeezed and deformed during migration, resulting in complex mechanisms such as "migration, capture, and re-migration" and deep displacement. The complex mechanism of discontinuous phases caused by elastic characteristics is difficult to accurately consider in conventional numerical models, resulting in huge deviations in numerical simulation results. Therefore, studying the oil displacement mechanism and characterization of sandstone discontinuous phase systems has important theoretical and practical significance for the efficient development of offshore loose sandstone reservoirs.

[0003] The oil displacement mechanism of non-continuous phase systems is complex. Current prediction methods include field prediction, empirical estimation, experimental research, theoretical calculation model method and numerical simulation method, but the prediction accuracy needs to be further improved. At present, mainstream simulators cannot accurately describe the oil displacement mechanism of non-continuous phase systems, resulting in unsatisfactory results in actual application.

[0004] Therefore, it is necessary to establish a new mathematical model to describe the migration characteristics of discontinuous phases, realize the oil displacement mechanism and characterization of discontinuous phase systems in loose sandstone reservoirs, and provide an effective simulation method for discontinuous phase displacement. Summary of the invention

[0005] The present invention provides a discontinuous phase drive numerical simulation characterization method to solve the defects of the prior art.

[0006] The present invention provides a discontinuous phase drive numerical simulation characterization method, comprising:

[0007] S1: Construct a physical property characterization model for oil recovery process;

[0008] S2: Based on the physical property characterization model, a discontinuous phase drive characterization method is constructed according to multi-component chemical reactions;

[0009] S3: Based on the discontinuous phase drive characterization method, a material conservation equation is established;

[0010] S4: solving the material conservation equation to obtain a solution result;

[0011] S5: Predicting the displacement effect through the solution results to complete the numerical simulation characterization of the discontinuous phase displacement.

[0012] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the physical property characterization equation in step S1 includes:

[0013] Discontinuous phase viscosity model, adsorption retention model, water phase permeability reduction coefficient model, and start-up pressure gradient model.

[0014] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the expression of the discontinuous phase viscosity model is:

[0015]

[0016] Among them, v cp is the viscosity of the discontinuous phase, ζ is the characteristic parameter of the pore structure shape, k is the absolute permeability of the reservoir, k rw is the relative permeability of water phase, φ is the reservoir porosity, s w is the water saturation of the reservoir, R k is the universal gas constant, θ fp is the relaxation time of the polymer, n is the rheological index;

[0017] The expression of the adsorption retention model is:

[0018]

[0019] Among them, i represents the index value. represents the adsorption mass fraction of component i, γ is the shear rate, represents the saturated adsorption mass fraction of component i, b i represents the adsorption equilibrium parameter of component i, c i represents the concentration of component i;

[0020] The expression of the water phase permeability reduction coefficient model is:

[0021] R k =max(R kp ,R kd );

[0022]

[0023] Among them, R k is the water phase permeability reduction coefficient, R kp is the water phase permeability reduction coefficient of the polymer, R kdl is the water phase permeability reduction coefficient of the discontinuous phase, R ki is the permeability reduction coefficient of the water phase containing representative i, R i max is the maximum permeability reduction coefficient of the water phase when component i is dissolved;

[0024] The expression of the starting pressure gradient model is:

[0025] G=aK b ;

[0026] Wherein, G is the starting pressure gradient, K is the permeability, a is the first parameter determined by experimental data, and b is the second parameter determined by experimental data.

[0027] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the expression of the discontinuous phase drive characterization method in step S2 is:

[0028]

[0029] Among them, C p is the concentration of the precursor in the aqueous phase, C d is the concentration of the discontinuous phase in water, K is the reaction rate constant, λ is the half-life, is the minimum reaction concentration, (·) θ is the reaction rate multiplier, θ is the preset exponent, φ is the reaction porosity, and φ min Minimum reactive porosity.

[0030] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the material conservation equation in step S3 includes:

[0031] Oil phase continuity equation, gas phase continuity equation, water phase continuity equation, proagent and discontinuous phase system component continuity equation.

[0032] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the expression of the oil phase continuity equation is:

[0033]

[0034] Where k is the absolute permeability of the reservoir, k ro is the relative permeability of the oil phase, B o is the oil phase volume coefficient, μ o is the oil phase viscosity, p o is the oil phase pressure, ρ o is the oil phase density, g is the gravity acceleration, D is the formation depth at the center of the grid, q vo is the oil phase injection rate, φ is the reaction porosity, s o is the oil phase saturation, t is the simulation time;

[0035] The expression of the gas phase continuity equation is:

[0036]

[0037] Among them, k rg is the relative permeability of the gas phase, B g is the gas phase volume coefficient, μ g is the gas phase viscosity, p g is the gas phase pressure, ρg is the gas phase density, R s is the dissolved gas-oil ratio, q vg is the gas injection and production rate, s g is the gas phase saturation;

[0038] The expression of the water phase continuity equation is:

[0039]

[0040] Among them, k rw is the relative permeability of the water phase, B w is the volume coefficient of water phase, μ w is the viscosity of the water phase, p w is the water phase pressure, ρ w is the density of water phase, R k is the water phase permeability reduction coefficient, q vw is the water phase injection rate, s w is the water phase saturation.

[0041] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the continuity equation of the precursor and the discontinuous phase system components is expressed as:

[0042]

[0043] Among them, c p is the concentration of the precursor in the aqueous phase, c d is the concentration of the discontinuous phase in the aqueous phase, R rep is the reaction rate of the precursor per unit pore volume, R red is the reaction rate of the discontinuous phase per unit pore volume, p rb is the rock density, is the mass fraction of the precursor adsorbed on the rock surface, is the mass fraction of the discontinuous phase adsorbed on the rock surface.

[0044] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, step S4 further comprises:

[0045] S41: discretizing the material conservation equation by a finite volume method to obtain a discretized equation group;

[0046] S42: Solving the discretized equation group based on Newton's iteration method to obtain a solution result.

[0047] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, step S42 further comprises:

[0048] S421: Construct Jacobian matrix;

[0049] S422: Fully implicit solution of the displacement of each time step of the discontinuous phase model based on Newton iteration method;

[0050] S423: Based on the Newton iteration method, the Jacobian matrix is ​​used to update the displacement variables of each time step until convergence to obtain a solution result.

[0051] According to a discontinuous phase drive numerical simulation characterization method provided by the present invention, the solution results include time step pressure, time step displacement, oil-water saturation, and component concentration.

[0052] The present invention provides a discontinuous phase flooding numerical simulation characterization method, which can comprehensively and accurately simulate the complex physical and chemical phenomena in the discontinuous phase oil displacement process. The present invention constructs a physical property characterization model including a discontinuous phase viscosity model, an adsorption retention model, a water phase permeability reduction coefficient model and a start-up pressure gradient model, and fully considers various physical and chemical factors in the discontinuous phase oil displacement process, thereby improving the accuracy and reliability of the simulation; secondly, the discontinuous phase drive characterization method of the present invention is based on multi-component chemical reactions, which can simulate the transformation and distribution of different chemical components in the discontinuous phase, and is suitable for a variety of complex oil displacement scenarios, such as deep adjustment and flooding, plugging of high permeability layers, etc.; in addition, the present invention discretizes the material conservation equation using a finite volume method and solves it using the Newton iteration method, which has high efficiency and stability when processing nonlinear equations. At the same time, the constructed Jacobian matrix realizes the rapid update and convergence of variables, further improving the solution speed and accuracy; thirdly, the solution results of the present invention include key parameters such as time step pressure, time step displacement, oil-water saturation and component concentration, which can fully reflect the dynamic changes and distribution in the discontinuous phase oil displacement process, and provide strong support for subsequent reservoir analysis and decision-making. The discontinuous phase drive numerical simulation characterization method of the present invention not only has theoretical value, but also has broad application prospects. It can provide reservoir engineers with more accurate and reliable simulation tools to help them better understand and predict the discontinuous phase oil displacement process, thereby optimizing mining plans, improving recovery rates, and promoting the development of reservoir engineering.

[0053] In summary, the present invention provides an efficient, accurate and highly adaptable discontinuous phase drive numerical simulation characterization method, which provides strong technical support for scientific research and practical application of reservoir engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A schematic diagram of a discontinuous phase drive numerical simulation characterization method for an embodiment of the present invention

[0056] Figure 2 A schematic diagram for comparing the experimental pressure measurement points and the numerical simulation results of the discontinuous phase drive numerical simulation characterization method provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments, and they should not be understood as limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the description of the present invention, it should be understood that the terms used are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0058] like Figure 1 As shown, the present invention provides a discontinuous phase drive numerical simulation characterization method, comprising:

[0059] S1: Construct a physical property characterization model for the oil recovery process.

[0060] Wherein, the physical property characterization equation in step S1 includes:

[0061] Discontinuous phase viscosity model, adsorption retention model, water phase permeability reduction coefficient model, and start-up pressure gradient model.

[0062] The expression of the discontinuous phase viscosity model is:

[0063]

[0064] Among them, v cp is the viscosity of the discontinuous phase, ζ is the characteristic parameter of the pore structure shape, k is the absolute permeability of the reservoir, k rw is the relative permeability of water phase, φ is the reservoir porosity, s w is the water saturation of the reservoir, R k is the universal gas constant, θ fp is the relaxation time of the polymer, n is the rheological index;

[0065] Furthermore, in the above formula, the expression of the specific parameter is:

[0066]

[0067] Among them, μ pv is the shear viscosity, μ w is the viscosity of the water phase, c p is the concentration of the precursor in the aqueous phase, M p is the relative molecular mass of the polymer, T is the absolute temperature, is the viscosity of the polymer at zero shear rate, γ is the shear rate, The polymer viscosity is The corresponding shear rate, pa p is the non-Newtonian power law index of the polymer, v w is the water phase flow rate, A1 is the first coefficient, A2 is the second coefficient, A3 is the third coefficient, A4 is the fourth coefficient, is the effective salt ion concentration, t pa is the percolation time of the polymer in the porous medium.

[0068] Furthermore, the above-mentioned discontinuous phase viscosity model is a mathematical model used to describe the change law of viscosity of the discontinuous phase during the flow process. Viscosity is a physical quantity that describes the fluid resistance. For a discontinuous phase, its viscosity may be affected by many factors, such as temperature, pressure, shape and size of the discontinuous phase, etc.

[0069] In numerical simulation, the discontinuous phase viscosity model is the basis for calculating the flow behavior of the discontinuous phase, which directly affects the movement trajectory and speed of the discontinuous phase during the oil recovery process. Through this model, the viscosity change of the discontinuous phase under different conditions can be predicted, and then the oil recovery plan can be optimized and the oil recovery efficiency can be improved.

[0070] The expression of the adsorption retention model is:

[0071]

[0072] Among them, i represents the index value. represents the adsorption mass fraction of component i, γ is the shear rate, represents the saturated adsorption mass fraction of component i, b i represents the adsorption equilibrium parameter of component i, c i is the concentration of component i.

[0073] Furthermore, the adsorption retention model is a mathematical model used to describe that when certain components in the fluid pass through porous media (such as rocks), they are retained inside the porous medium due to adsorption. This retention phenomenon is particularly common in the oil recovery process because the rocks in the oil reservoir often have a porous structure and are easy to adsorb certain components in the fluid.

[0074] The adsorption retention model can help understand the distribution and migration of fluid components in the reservoir, so as to more accurately predict the oil recovery effect. Through this model, the adsorption capacity of different oil recovery agents on porous media can be evaluated, providing a basis for selecting appropriate oil recovery agents.

[0075] The expression of the water phase permeability reduction coefficient model is:

[0076] R k =max(R kp ,R kd );

[0077]

[0078] Among them, R k is the water phase permeability reduction coefficient, R kp is the water phase permeability reduction coefficient of the polymer, R kdl is the water phase permeability reduction coefficient of the discontinuous phase, R ki is the permeability reduction coefficient of the water phase containing representative i, R i max is the maximum permeability reduction coefficient of the water phase when component i is dissolved;

[0079] Furthermore, the water phase permeability reduction coefficient model is a mathematical model used to describe the decrease in water phase permeability due to the existence and migration of discontinuous phases during the oil recovery process. Permeability is a physical quantity that describes the ability of fluid to pass through porous media. The decrease in water phase permeability will directly affect the oil recovery efficiency.

[0080] The water phase permeability decline coefficient model is one of the important indicators for evaluating the oil recovery effect. It can help understand the dynamic changes of water phase permeability during the oil recovery process. Through this model, the degree of decline of water phase permeability under different oil recovery conditions can be predicted, providing a theoretical basis for optimizing the oil recovery plan.

[0081] The expression of the starting pressure gradient model is:

[0082] G=aK b ;

[0083] Wherein, G is the starting pressure gradient, K is the permeability, a is the first parameter determined by experimental data, and b is the second parameter determined by experimental data.

[0084] The starting pressure gradient refers to the minimum pressure gradient that the fluid needs to overcome to start migrating. During the oil displacement process, the size of the starting pressure gradient directly affects the flow behavior of the fluid.

[0085] S2: Based on the physical property characterization model, a discontinuous phase drive characterization method is constructed according to multi-component chemical reactions.

[0086] Furthermore, in step S2, the present invention considers the chemical reaction from the precursor to the discontinuous phase, sets a minimum reaction concentration reaction to achieve deep displacement, and sets a reaction rate multiplier reaction to achieve plugging of the high permeability layer, thereby obtaining the above-mentioned discontinuous phase drive characterization method.

[0087] Wherein, the expression of the discontinuous phase drive characterization method in step S2 is:

[0088]

[0089] Among them, C p is the concentration of the precursor in the aqueous phase, C d is the concentration of the discontinuous phase in water, K is the reaction rate constant, λ is the half-life, is the minimum reaction concentration, (·) θ is the reaction rate multiplier, θ is the preset exponent, φ is the reaction porosity, and φ min Minimum reactive porosity.

[0090] The discontinuous phase flooding characterization method provided in step S2 can predict and describe the concentration change, distribution and migration law of the discontinuous phase during the oil displacement process based on the principle of chemical reaction kinetics, which is of great significance for the subsequent understanding of the oil displacement mechanism and optimization of the oil displacement plan.

[0091] The discontinuous phase flooding characterization method can control the depth and range of the chemical reaction in the reservoir by setting the minimum reaction concentration, thereby achieving deep flooding, helping to improve the oil recovery efficiency and reduce the residual oil saturation; by setting the reaction rate multiplier, the rate of the chemical reaction can be adjusted to achieve an ideal oil recovery effect when plugging the high permeability layer, which can improve the fluid distribution in the reservoir and improve the overall oil recovery efficiency; at the same time, the method provides multiple adjustable parameters, which can be optimized and adjusted according to the actual reservoir conditions and oil recovery requirements.

[0092] S3: Based on the discontinuous phase drive characterization method, a material conservation equation is established.

[0093] Wherein, the material conservation equation in step S3 includes:

[0094] Oil phase continuity equation, gas phase continuity equation, water phase continuity equation, proagent and discontinuous phase system component continuity equation.

[0095] The expression of the oil phase continuity equation is:

[0096]

[0097] Where k is the absolute permeability of the reservoir, k ro is the relative permeability of the oil phase, B o is the oil phase volume coefficient, μo is the oil phase viscosity, p o is the oil phase pressure, ρ o is the oil phase density, g is the gravity acceleration, D is the formation depth at the center of the grid, q vo is the oil phase injection rate, φ is the reaction porosity, s o is the oil phase saturation, and t is the simulation time.

[0098] Furthermore, the oil phase continuity equation describes the flow and change of the oil phase in the reservoir. It takes into account the absolute permeability of the reservoir, the relative permeability of the oil phase (affected by factors such as fluid saturation and pressure), the volume coefficient of the oil phase (reflecting fluid compressibility), the oil phase viscosity, the oil phase pressure, the oil phase density, gravity acceleration, the grid center formation depth, the oil phase injection and production rate (including injection and production), the reactive porosity (effective porosity, affected by chemical reactions) and the oil phase saturation. The above parameters jointly determine the flow speed and direction of the oil phase in the reservoir.

[0099] The expression of the gas phase continuity equation is:

[0100]

[0101] Among them, k rg is the relative permeability of the gas phase, B g is the gas phase volume coefficient, μ g is the gas phase viscosity, p g is the gas phase pressure, ρ g is the gas phase density, R s is the dissolved gas-oil ratio, q vg is the gas injection and production rate, s g is the gas phase saturation.

[0102] Furthermore, the gas phase continuity equation is similar to the oil phase continuity equation, and mainly considers the relative permeability, volume coefficient, viscosity, pressure, density, dissolved gas-oil ratio (reflecting the amount of dissolved gas in oil), gas injection and production rate, and gas saturation of the gas phase. The parameters jointly determine the flow characteristics of the gas phase in the reservoir.

[0103] The expression of the water phase continuity equation is:

[0104]

[0105] Among them, k rw is the relative permeability of the water phase, B w is the volume coefficient of water phase, μ w is the viscosity of the water phase, p w is the water phase pressure, ρ w is the density of water phase, R k is the water phase permeability reduction coefficient, qvw is the water phase injection rate, s w is the water phase saturation.

[0106] The water phase continuity equation describes the flow of water in the reservoir. In addition to the permeability, volume coefficient, viscosity, pressure, density and other parameters related to the water phase, it also takes into account the water phase permeability decrease coefficient (due to the presence of discontinuous phases or chemical reactions that cause the water phase permeability to decrease) as well as the water phase injection rate and water phase saturation. The above parameters jointly affect the flow behavior of the water phase in the reservoir.

[0107] The expression of the continuity equation of the pro-agent and discontinuous phase system components is:

[0108]

[0109] Among them, c p is the concentration of the precursor in the aqueous phase, c d is the concentration of the discontinuous phase in the aqueous phase, R rep is the reaction rate of the precursor per unit pore volume, R red is the reaction rate of the discontinuous phase per unit pore volume, p rb is the rock density, is the mass fraction of the precursor adsorbed on the rock surface, is the mass fraction of the discontinuous phase adsorbed on the rock surface.

[0110] Furthermore, when the discontinuous phase is subjected to sufficient pressure gradient, it will begin to migrate; when the pressure gradient decreases, the discontinuous phase may be trapped in the rock pores; and when the pressure gradient increases again, the trapped discontinuous phase may migrate again. By considering the starting pressure gradient, the migration behavior of the discontinuous phase in the reservoir can be more accurately described.

[0111] Therefore, the present invention also constructs the above-mentioned continuity equations of the precursor and the components of the discontinuous phase system in step S3, and considers the existence of the starting pressure gradient in the discontinuous phase system to achieve the characterization of the "migration, capture, and re-migration" mechanism of the discontinuous phase.

[0112] The continuity equation of the components of the precursor and discontinuous phase system describes the concentration changes of the precursor and the discontinuous phase (such as oil droplets, bubbles, etc.) in the water phase, taking into account the concentration of the precursor in the water phase, the concentration of the discontinuous phase in the water phase, the reaction rate of the precursor per unit pore volume (reflecting the rate of consumption or generation of the precursor), the reaction rate of the discontinuous phase per unit pore volume, the rock density, and the mass fraction of the precursor and the discontinuous phase adsorbed on the rock surface. The above parameters jointly determine the distribution and changes of the precursor and the discontinuous phase in the reservoir.

[0113] S4: Solve the material conservation equation to obtain a solution result.

[0114] Wherein, step S4 further comprises:

[0115] S41: Discretize the material conservation equation by finite volume method to obtain a set of discretized equations.

[0116] In step S41, the continuity equation, the material conservation equation and other related physical and chemical equations are first spatially discretized, that is, the simulation area is divided into a series of small units (such as grids or control volumes), and the mass conservation and energy conservation principles are applied to each unit. Discretization methods include finite difference method, finite volume method or finite element method, etc. In the present invention, discretization is performed based on the finite volume method because the finite volume method can well maintain mass conservation when dealing with fluid flow problems.

[0117] S42: Solving the discretized equation group based on Newton's iteration method to obtain a solution result.

[0118] Wherein, step S42 further comprises:

[0119] S421: Construct Jacobian matrix.

[0120] In step S421, since the iterative implicit method is used to solve the system of equations, it is necessary to construct a Jacobian matrix. The Jacobian matrix is ​​a matrix containing all partial derivatives in the system of equations. It describes the mutual influence between the variables in the system of equations. When constructing the Jacobian matrix, the nonlinear terms and linear terms in the system of equations need to be taken into account.

[0121] S422: Fully implicitly solve the displacement of the discontinuous phase model at each time step based on the Newton iteration method.

[0122] S423: Based on the Newton iteration method, the Jacobian matrix is ​​used to update the displacement variables of each time step until convergence to obtain a solution result.

[0123] The solution results in step S423 include time step pressure, time step displacement, oil-water saturation, and component concentration.

[0124] In steps S422 to S423, the Newton iteration method is needed to solve the system of equations. The Newton iteration method is a gradient-based iterative method that approximates the solution of the system of equations by continuously updating the values ​​of variables.

[0125] Specifically, in each iteration, the Jacobian matrix is ​​used to calculate the update amount of the variable, and then the update amount is applied to the current variable value to generate a new variable value. This process is repeated until certain convergence conditions are met. The convergence conditions may include that the change in the variable is less than a preset threshold.

[0126] For each subsequent time step, the above steps need to be repeated to solve the system of equations, including updating the values ​​of the variables, constructing a new Jacobian matrix, and applying Newton's iteration method to solve. As time goes by, the fluid flow and chemical reactions in the simulation area will gradually evolve and produce results corresponding to each time step.

[0127] S5: Predicting the displacement effect through the solution results to complete the numerical simulation characterization of the discontinuous phase displacement.

[0128] Based on the solution results obtained in step S4, in step S5, the displacement effect and distribution state of the discontinuous phase (such as gas, foam, etc.) in the reservoir can be predicted by the solution results, and the feasibility of different oil recovery schemes and the optimization of oil recovery strategies can be evaluated; in addition, the solution results can also reveal the physical properties of the reservoir, such as key parameters such as permeability and porosity, which are used to understand the behavior of the reservoir and formulate development plans; secondly, according to the solution results, production parameters such as injection pressure and injection rate can be adjusted to optimize production operations, improve recovery and economic benefits; thirdly, when conducting oil recovery tests in the laboratory or on-site, the solution results can be used as a guide to help determine the test conditions, monitoring methods and data analysis methods, thereby improving the accuracy and reliability of the test. By analyzing the solution results, the risks and uncertainties in the oil recovery process, such as the uncertainty of fluid distribution and the impact of changes in production parameters, can be evaluated to provide support for decision-making. The solution results can also be used for reservoir management, including reservoir dynamic monitoring, production planning, resource assessment, etc., to provide a scientific basis for reservoir development.

[0129] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0130] like Figure 2 FIG. 1 is a comparison between the experimental pressure measurement points and the numerical simulation results performed by a discontinuous phase drive numerical simulation characterization method of the present invention. Figure 2The horizontal axis is the injection PV number, which represents the multiple of the pore volume of the injected fluid, ranging from 0 to 1.0, with an interval of 0.1. The vertical axis is the corresponding pressure value. Experimental pressure measuring point 1 is marked in orange, indicating the pressure value measured under specific conditions. Experimental pressure measuring point 2 is marked in green, indicating the pressure value measured under another set of conditions. Digital model 1 and digital model 2 are used to predict or simulate the pressure changes at the experimental pressure measuring points.

[0131] In the embodiment, as the number of injected PV increases, the pressure values ​​at the two experimental pressure measuring points show an upward trend. When the number of injected PV reaches a certain value, the pressure value begins to stabilize or slightly decreases. It can be seen from the figure that the predicted curves of digital model 1 and digital model 2 are close to the actual measured curves of the experimental pressure measuring points, indicating that the numerical simulation model of the present invention has high accuracy, the calculation results of the method of the present invention are highly consistent with the experimental results, are more in line with the seepage characteristics of the discontinuous phase, and can achieve accurate simulation of the discontinuous phase model.

[0132] The present invention discloses a method for numerical simulation characterization of discontinuous phase drive, which adopts a method for introducing a precursor to a discontinuous phase system to realize the drive reaction, and establishes a pseudo-component model of the precursor and discontinuous phase system drive, which can better describe the seepage mechanism of the discontinuous phase "migration, capture, re-migration" and deep drive adjustment, and can more accurately realize the simulation of oil displacement of the discontinuous phase system; at the same time, the present invention includes the components of oil, gas, water phase, precursor and discontinuous phase in the numerical simulation method of discontinuous phase drive, and adopts an iterative implicit method to solve, thereby accelerating the calculation speed.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for numerical simulation characterization of discontinuous phase drive, characterized in that: include: S1: Construct a physical property characterization model for oil recovery process; S2: Based on the physical property characterization model, a discontinuous phase drive characterization method is constructed according to multi-component chemical reactions; S3: Based on the discontinuous phase drive characterization method, a material conservation equation is established; S4: solving the material conservation equation to obtain a solution result; S5: Predicting the displacement effect through the solution results to complete the numerical simulation characterization of the discontinuous phase displacement.

2. A discontinuous phase drive numerical simulation characterization method according to claim 1, characterized in that: The physical property characterization equation in step S1 includes: Discontinuous phase viscosity model, adsorption retention model, water phase permeability reduction coefficient model, and start-up pressure gradient model.

3. A discontinuous phase drive numerical simulation characterization method according to claim 2, characterized in that: The expression of the discontinuous phase viscosity model is: Among them, v cp is the viscosity of the discontinuous phase, ζ is the characteristic parameter of the pore structure shape, k is the absolute permeability of the reservoir, k rw is the relative permeability of water phase, φ is the reservoir porosity, s w is the water saturation of the reservoir, R k is the universal gas constant, θ fp is the relaxation time of the polymer, n is the rheological index; The expression of the adsorption retention model is: Among them, i represents the index value. represents the adsorption mass fraction of component i, γ is the shear rate, represents the saturated adsorption mass fraction of component i, b i represents the adsorption equilibrium parameter of component i, c i represents the concentration of component i; The expression of the water phase permeability reduction coefficient model is: R k =max(R kp ,R kd ); Among them, R k is the water phase permeability reduction coefficient, R kp is the water phase permeability reduction coefficient of the polymer, R kdl is the water phase permeability reduction coefficient of the discontinuous phase, R ki is the permeability reduction coefficient of the water phase containing representative i, R imax is the maximum permeability reduction coefficient of the water phase when component i is dissolved; The expression of the startup pressure gradient model is: G=aK b ; Wherein, G is the starting pressure gradient, K is the permeability, a is the first parameter determined by experimental data, and b is the second parameter determined by experimental data.

4. A discontinuous phase drive numerical simulation characterization method according to claim 1, characterized in that: The expression of the discontinuous phase drive characterization method in step S2 is: Among them, C p is the concentration of the precursor in the aqueous phase, C d is the concentration of the discontinuous phase in water, K is the reaction rate constant, λ is the half-life, is the minimum reaction concentration, (·) θ is the reaction rate multiplier, θ is the preset exponent, φ is the reaction porosity, and φ min Minimum reactive porosity.

5. The method for numerical simulation characterization of discontinuous phase drive according to claim 1, characterized in that: The material conservation equation in step S3 includes: Oil phase continuity equation, gas phase continuity equation, water phase continuity equation, proagent and discontinuous phase system component continuity equation.

6. A discontinuous phase drive numerical simulation characterization method according to claim 5, characterized in that: The expression of the oil phase continuity equation is: Where k is the absolute permeability of the reservoir, k ro is the relative permeability of the oil phase, B o is the oil phase volume coefficient, μ o is the oil phase viscosity, p o is the oil phase pressure, ρ o is the oil phase density, g is the gravity acceleration, D is the formation depth at the center of the grid, q vo is the oil phase injection rate, φ is the reaction porosity, s o is the oil phase saturation, t is the simulation time; The expression of the gas phase continuity equation is: Among them, k rg is the relative permeability of the gas phase, B g is the gas phase volume coefficient, μ g is the gas phase viscosity, p g is the gas phase pressure, ρ g is the gas phase density, R s is the dissolved gas-oil ratio, q vg is the gas injection and production rate, s g is the gas phase saturation; The expression of the water phase continuity equation is: Among them, k rw is the relative permeability of the water phase, B w is the volume coefficient of water phase, μ w is the viscosity of the water phase, p w is the water phase pressure, ρ w is the density of water phase, R k is the water phase permeability reduction coefficient, q vw is the water phase injection rate, s w is the water phase saturation.

7. A discontinuous phase drive numerical simulation characterization method according to claim 6, characterized in that: The expression of the continuity equation of the pro-agent and discontinuous phase system components is: Among them, c p is the concentration of the precursor in the aqueous phase, c d is the concentration of the discontinuous phase in the aqueous phase, R rep is the reaction rate of the precursor per unit pore volume, R red is the reaction rate of the discontinuous phase per unit pore volume, p rb is the rock density, is the mass fraction of the precursor adsorbed on the rock surface, is the mass fraction of the discontinuous phase adsorbed on the rock surface.

8. A discontinuous phase drive numerical simulation characterization method according to claim 1, characterized in that: Step S4 further comprises: S41: discretizing the material conservation equation by a finite volume method to obtain a discretized equation group; S42: Solving the discretized equation group based on Newton's iteration method to obtain a solution result.

9. A discontinuous phase drive numerical simulation characterization method according to claim 8, characterized in that: Step S42 further includes: S421: Construct Jacobian matrix; S422: Fully implicit solution of the displacement of each time step of the discontinuous phase model based on Newton iteration method; S423: Based on the Newton iteration method, the Jacobian matrix is ​​used to update the displacement variables of each time step until convergence to obtain a solution result.

10. A discontinuous phase drive numerical simulation characterization method according to claim 9, characterized in that: The solution results include time step pressure, time step displacement, oil and water saturation, and component concentration.

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