Nonlinear seepage numerical simulation method

Abstract

The invention relates to a nonlinear seepage numerical simulation method. The nonlinear seepage numerical simulation method comprises the following steps: establishing a model; setting assumed conditions, on the premise that the assumed conditions are met, establishing an oil, gas and water three-phase motion equation, and obtaining a rock compression coefficient, an oil, gas and water phase compression coefficient and an oil, gas and water component continuity equation; substituting the motion equation of the oil phase, the gas phase and the water phase into a corresponding continuity equation, and converting into a volume conservation form under a ground standard condition; converting the non-Newtonian fluid motion equation into an expression consisting of apparent viscosity, apparent gradient and flow correction coefficient; and solving the established model to obtain so, sg and sw. The method better conforms to the actual condition of the heavy oil reservoir, the prediction index precision is higher, and the actual condition of the oil reservoir is better met.

Description

technical field [0001] The invention relates to a nonlinear seepage numerical simulation method. Background technique [0002] The particularity of fluid and nonlinear seepage characteristics are two factors restricting the efficient development of heavy oil reservoirs. Establishing a reservoir numerical simulation model considering nonlinear seepage characteristics has important practical significance for the development of heavy oil reservoirs. Currently, the commonly used reservoir numerical simulation methods are all based on Darcy's seepage mathematical model, which cannot accurately and effectively predict the influence of nonlinear seepage characteristics on the production performance of heavy oil reservoirs. Scholars at home and abroad have improved the numerical model to better describe the seepage law of non-Newtonian fluids, mainly including the numerical simulation method based on the pseudo-threshold pressure gradient model and the variable permeability numerica...

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Problems solved by technology

The numerical model based on the pseudo-threshold pressure gradient describes the non-Darcy characteristics of the reservoir, which makes up for the deficiency of the numerical simulation method based on Darcy flow to a certain extent; Cheng Shiqing et al. based on the pseudo-threshold pressure gradient motion equation, A mathematical model of oil-water two-phase non-Darcy flow was established; Zhao Guozhong et al. established the non-Darcy equation by assuming that the oil-water quasi-threshold pressure gradient is a function of the permeability of the medium and the water shunt coefficient, and realized the numerical value of the variable threshold pressure gradient. The simulation method can better describe the nonlinear seepage process, but it cannot solve the problems of the finite difference discretization of the permeability state equation, and it is difficult to realize the fully implicit numerical solution method

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