| In the process of developing low permeability reservoir and that of tertiary oil recovery, physico-chemical reaction occurs in the interface region of fluid-fluid or fluid-solid as injecting chemical agents into oil layer, which destroys the stable structure of porous medium and the proportionality of fluids, as a result, reservoir performance system is more complicated than that of water flood[1]. Make a visualization study of the process of non-ionic surfactant and polymer combination system displacing waterflood retained oil. It shows that the process of activating and removing resident oil is a non-stationary and irreversible process, in which retained oil transforms into motion from stillness and motion morphology evolves continously. The displacement process refers to many interface phenomena changed with time and space, which contains fluid mass transfer, heat transfer, momentum transfer, interphase characteristics and interaction of capillary force, buoyance and viscous force. Along with displacement, porous medium structure sometimes changes obviously in the process. Been up against the evolved, diversified and unstabilized process of fluid flow form transformation, it is necessary to introduce nonequilibrium thermodynamics theory to analyze and investigate. This paper combined with thermodynamics analyzes interface phenomena occurring in the process of surfactant waterflooding. It analyzes the relationship of non-ionic surfactant structure and characteristics. In-house experiment shows the process of fluid flow form transformation in the process of non-ionic surfactant and polymer combination system displacing waterflood retained oil. Cited thermodynamics theory, it analyzes the internal cause of system occurring such change of state, which is based on many potential differences in phase interface region, contributing to spontaneous (irreversible) process, activating and transferring retained oil. The process is a process of entropy increasing. |
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