变温条件下弹塑性油藏中多相渗流的流固耦合数学模型与数值模拟

传统的多相渗流数学模型和数值模拟没有考虑流体渗流与岩石变形之间相互作用,然而生产实践表明,基于这种简化和近似来描述流体渗流是不准确的。为了准确模拟油气藏中流体流动,必须将经典的渗流力学、岩石力学、热力学结合起来,全面考虑流体渗流、岩石变形、温度场变化之间的耦合过程,建立耦合模型。

The coupled model and numerical simulation of multiphase flow in an elastoplastic deforming oil reservoir with transformation temperature

The mathematical mo del of multiphase flow in an elastopla stic deforming oil reservoir with the variable temperature distribution is devel oped based on the theory of fluid solid interaction mechanics and thermodynamic s . The solid skeleton of the oil reservoir is assumed to have the characteristics of deformation and the changes of the pore pressure and the temperature distrib ution result in changes of effective stresses acting in the oil reservoir and in the deformation of the solid skeleton. Conversely, deformation of the solid ske leton affects the seepage of the multiphase flow. In this paper, fully coupled s eepage equations and deformation equations are developed in consideration of tra nsformation temperature. These equations are not independent and can't be solved divisionally. The solid skeleton is assumed to have an elastoplastic behavior a nd an elastoplastic constitutive model based on yield function is utilized. The variation of the deformation of the solid skeleton and the seepage of the multip hase derived from the change of temperature distribution is fully considered in a reservoir with violent transformation temperature such as a oil reservoir in w hich hot water or steam is injected. The concept "thermal load" is added in de formation equations to describe this thermodynamic process and the solving for" thermal load"is presented. The approach of coupled numerical simulation in whic h finite difference method and finite element method are used alternately is pre sented.