CN-119940218-B - Method, system and medium for constructing oil-water two-phase seepage model based on critical path

CN119940218BCN 119940218 BCN119940218 BCN 119940218BCN-119940218-B

Abstract

The invention discloses an oil-water two-phase seepage model construction method, a system and a medium based on a critical path; relates to the technical field of oil and gas field development; according to the scheme, the traditional black oil model simulation technology and the critical radius technology based on the critical path seepage theory are combined, the oil-water two-phase seepage characteristic oil reservoir simulation method considering the critical path of the microscopic scale is provided on the basis of guaranteeing the scale of an oil reservoir model, microscopic features such as the hole-throat structure in the real reservoir rock are reduced to the greatest extent by utilizing the critical radius, and phenomena such as dominant channels (critical paths) of seepage of the oil-water two-phase fluid in the hole-throat and factors affecting the displacement efficiency are researched from the microscopic angle, so that an oil reservoir simulation analysis result with higher precision is obtained; the flow and pressure of each component of oil and water are calculated directly based on the critical radius and the critical path length, a static oil-water relative permeability curve is not required to be input in the simulation process, and the stress state and the change process of each part of the oil reservoir can be reflected more directly.

Inventors

YANG XIN
SUN ZHAOLEI
FU QI
MI ZHONGRONG
KANG BO
XU BING
DUAN CE
CUI LIGONG
Lv Xindong
ZHANG XIAOPING
ZHOU CHUNXIANG

Assignees

成都北方石油勘探开发技术有限公司

Dates

Publication Date: 20260512
Application Date: 20250121

Claims (9)

1. The method for constructing the oil-water two-phase seepage model based on the critical path is characterized by comprising the following steps of: establishing a critical radius model of the oil-water two-phase fluid flow process based on a nuclear magnetic logging technology and a critical path seepage theory; Based on the critical radius model, under the condition of equivalent assumption, an oil-water two-phase numerical model suitable for the single well scale of the oil reservoir is established; solving the oil-water two-phase numerical model to obtain an oil-water two-phase mutual displacement simulation result; oil-water two-phase numerical model the construction method of (1) comprises: Calculating the equivalent capillary force p cij of the oil reservoir grid caused by the oil-water interface in the critical path: Wherein r cij represents the critical radius of the critical path between grid i and grid j, gamma represents the interfacial tension of oil-water two phases, and theta represents the wetting angle; Calculating the conductivity of the oil-water two-phase fluid between any two grids based on the critical path; obtaining effective viscosity and density of oil-water two-phase fluid in a critical path between oil reservoir grids; Inputting conductivity, effective viscosity and density into a mass conservation equation based on critical radius to construct an oil-water two-phase flow and pressure diffusion differential equation; And carrying out numerical simulation on the oil-water two-phase flow and pressure diffusion differential equation to obtain an oil-water two-phase numerical model.
2. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 1, wherein the method for constructing the critical radius model of the oil-water two-phase fluid flow process comprises the following steps: constructing a well site grid model, and calculating the permeability and the porosity of each grid; Based on a critical path seepage theory, taking actual rock pore throat characteristics and seepage channel characteristics into consideration in a well position grid model, constructing a critical radius model of an oil-water two-phase fluid flow process, wherein the critical radius model comprises the following components: the critical radius r cij between grids i and j is: ; Where k ij denotes the permeability between adjacent grid i and grid j, Represents the porosity between the adjacent grid i and grid j, τ represents tortuosity, σ z represents the rock heterogeneity coefficient.
3. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 2, wherein the equivalent hypothesis condition comprises: a, in a critical radius model, a critical path is a main channel of fluid seepage, and pressure drop generated by fluid flow mainly occurs in the critical path; b, only one two-phase fluid interface exists between the oil-water two-phase fluid in the critical path; c, the two fluids flowing in the network are not miscible; d, piston displacement occurs in the critical path.
4. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 1, wherein the method for calculating the conductivity of the oil-water two-phase fluid between any two grids based on the critical path comprises the following steps: When there is coexistence of oil-water two phases in the critical path between grid i and grid j, conductivity of the oil-water two-phase fluid in the critical path The method comprises the following steps: ; The pressure difference between grid i and grid j The flow rate q ij of the following oil-water two-phase mixed fluid is as follows: ; Wherein p i =p oi +ρ ow gZ i ,p oi is the pore pressure of grid i, ρ ow is the mixed fluid density, Z i is the vertical height of grid i, g is the gravitational acceleration, 9.8m/s 2 ;p j =p oj +ρ ow gZ j ,p oj is the pore pressure of grid j, Z j is the vertical height of grid j, m, p cij is the equivalent capillary force of the reservoir grid, τ is the tortuosity, l ij is the grid side length; r cij is the critical radius; is the effective viscosity of the mixed fluid.
5. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 1, wherein the step of obtaining the effective viscosity and density of the oil-water two-phase fluid in the critical path between the oil reservoir grids comprises the following steps: Calculating effective viscosity of oil-water two-phase fluid in critical path between oil reservoir grids according to the following formula : ; Wherein B w represents the volume coefficient of water and has no dimension, B o represents the volume coefficient of oil and has no dimension, mu w represents the viscosity of water, pa.s, mu o represents the viscosity of oil, X ij represents the dimensionless number related to the position of an oil-water two-phase interface, and X ij is more than or equal to 0 and less than or equal to 1, namely the position of a concave liquid level is divided by the length of the whole critical path; The density ρ ow of the oil-water two-phase fluid in the critical path between the reservoir grids is calculated according to: ; where ρ w represents the density of water and ρ o represents the density of oil.
6. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 4, wherein the oil-water two-phase flow and pressure diffusion differential equation comprises: ; Wherein i represents an arbitrary number of 1 to N, N represents a total mesh number, Deltap ij represents the pressure difference between grid i and grid j; ; The initial porosity of the grid i is represented, V bi is represented by the volume of the grid i, deltat is the simulation time step, deltap i is represented by the change value of the pressure of the grid i in Deltat, C tow is the comprehensive compression coefficient of oil-water two phases, and the value of C tow is consistent with the compression coefficient of oil or water for simplifying calculation because the oil-water compression is approximately equal.
7. The method for constructing an oil-water two-phase seepage model based on a critical path according to claim 1, wherein the solving the oil-water two-phase numerical model to obtain an oil-water two-phase mutual displacement simulation result comprises the following steps: in combination with the oil-water displacement process, in the process of carrying out numerical simulation on the oil-water two-phase flow and pressure diffusion differential equation, updating and calculating the interface movement process and the distribution state according to the time steps, and updating the fluid conductivity of all grids; And solving the pressure and flow of different grids, and solving the result data of the global pressure field and the oil-water flow at different moments by a conjugate gradient method.
8. The oil-water two-phase seepage model construction system based on the critical path is characterized by being used for realizing the oil-water two-phase seepage model construction method based on the critical path as claimed in any one of claims 1-7, and comprises the following steps: the first building module is used for building a critical radius model of the oil-water two-phase fluid flowing process based on a nuclear magnetic logging technology and a critical path seepage theory; The second establishing module is used for establishing an oil-water two-phase numerical model suitable for the single well scale of the oil reservoir based on the critical radius model under the condition of equivalent hypothesis; and the solving module is used for solving the oil-water two-phase numerical model to obtain an oil-water two-phase mutual displacement simulation result.
9. A computer readable medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the critical path-based oil-water two-phase seepage model construction method according to any one of claims 1 to 7.

Description

Method, system and medium for constructing oil-water two-phase seepage model based on critical path Technical Field The invention relates to the technical field of oil-gas field development, in particular to an oil-water two-phase seepage model construction method, an oil-water two-phase seepage model construction system and a medium based on a critical path. Background Petroleum is an indispensable strategic resource for national survival and development, and how to convert underground energy into power for economic development to the greatest extent is important, so that the petroleum plays a very critical role in national energy planning and deployment. Through researches for many years, oil reservoir development modes tend to be mature, researchers mostly adopt a numerical simulation method to reduce development cost, and a reasonable open scheme is formulated according to simulation results and scientific guidance is provided. The oil reservoir numerical simulation method is to utilize a model to study the dynamic change rule of an oil reservoir, and comprises physical simulation and mathematical (numerical) simulation, wherein the physical simulation is the indoor study of oil reservoir development dynamics, the main principle of the oil reservoir numerical simulation method is to describe the oil reservoir exploitation state by utilizing a partial differential equation system, and the change of a development index is obtained by computer numerical solution. The numerical simulation method of the oil deposit can consider the influence of factors such as the geometric shape, the heterogeneity, the property change of rock and fluid, the well pattern mode, the yield and the like of the oil deposit on the dynamic state, is one of the most considered factors in the oil deposit dynamic state research so far, and has become one of the important means of the oil deposit development research, and the main characteristic of the numerical simulation method is that the development dynamic state is analyzed and predicted by simulating and analyzing the distribution of the fluid and the energy in the oil deposit. In the actual oil extraction process, the application of the oil-water two-phase model is important because the oil-water two-phase model can accurately describe and predict the complex flow behavior of oil-water two-phase fluid in an oil reservoir. By constructing a mathematical model and by means of a numerical simulation technology, the model can simulate dynamic changes such as water flooding process, oil-water front propulsion and the like, and provides scientific basis for formulating and optimizing an oil field development scheme, evaluating submersible pump performance, optimizing oil-water separation technology and carrying out oil reservoir dynamic monitoring and analysis, thereby effectively improving the recovery ratio and economic benefit of an oil field. The oil-water two-phase seepage model in the traditional black oil model is a simplified model for simulating the flow of oil and water in an oil reservoir. Although the model is a widely applied basic tool in oil reservoir simulation, the model has some defects in actual oil extraction process that the heterogeneity of reservoir rock is ignored, the geological heterogeneity of the oil reservoir, the existence of cracks and small-scale characteristics are generally subjected to simplification treatment in the form of grids (the side length of the grids is usually tens of meters), the actual oil reservoir condition cannot be accurately described, and the influence of microscopic factors such as rock pore throat characteristics, pore scale (micrometer and centimeter scale) dynamic multiphase fluid dynamic seepage characteristics and the like on macroscopic seepage processes cannot be directly considered. Meanwhile, due to simplification of a complex flow mechanism, the complex flow mechanism such as gravity effect in multiphase flow is roughly processed. In addition, in the multiphase seepage simulation of the traditional black oil model, a static oil-water relative permeability curve is required to be input, so that the stress states of the oil-water content, the viscous force and the capillary force of each grid point are described, and the stress states are used for calculating the grid conductivity, but the oil-water relative permeability curve in the actual seepage process is dynamic data and can dynamically move and change along with time and the position of fluid, so that the relative permeability curve input by the traditional simulation method has a certain defect. These drawbacks limit the use of conventional black oil models under complex reservoir conditions. Disclosure of Invention The invention aims to provide an oil-water two-phase seepage model construction method, a system and a medium based on a critical path, aiming at the stress states of dynamic pore fluid pressure, gravity and capillary force of each grid (space position)