The Damage Theory Model on Fluid-Solid-Heat Coupling of Reservoir under Process Injection

Abstract

Based on the study of double porous medium, the paper provides a new model of cylinder volume element plastic yielding, which assumes that the rock mass is compressible and obeys the D-P formula, and deformation, nucleation and growing of pores and fractures are induced by stress of injection pressure and temperature. The damage variable is defined by strain porosity, and then constitutional equation of double pore medium saturated liquid-solid is set up. Taking one well of Jilin Oil Field in China as a case, the damage variable, porosity and induced stress change laws of rock strain coupling with temperature-injection are studied. The results are acquired from numerical simulation of finite element software, including induced stresses of thermal field, water flood pressure, rock stress distribution rule, together with evolving regulations of stress, damage variable and strain porosity. The numerical computation results match well with the practical situation, which shows that there is obvious elastic and plastic damage characteristic during mass water flood recovery. The new model provides a new research method and theoretical base for changes of reservoir pores and fractures during water flood exploration.