| In process of developing low permeability reservoir and that of secondary and tertiary oil recovery, physicochemical reaction occurs in the interface region of fluid-fluid or fluid-solid as injecting chemical agents into oil layer, which destroys stable structure of porous medium and proportionality of fluids, resulting in reservoir performance system is more complicated than that of water flood. Made a visualization study of process of polymer or surfactant and polymer combination slug system displacing water-flood 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 continuously. And the displacement process is a process of fluid mass and heat transfer, which refers to many interface phenomena changed with time and space. It also proves that different combination slug system has different motion morphology and makes different swept areas and displacement efficiency. Been up against diversified evolution and non-stabilized process of fluid flow form transformation, it is necessary to introduce non-equilibrium thermodynamics theory to analyze and investigate. In this paper, introduced polymer or surfactant combination slugs system is injected cyclically with method of cyclically and changeably displacing resident oil to analyze and demonstrate process of activating and removing resident oil through corresponding theory of many courses. And then combined with thermodynamics theory, interface phenomena and transport and transition of matter and energy occurring in the process of high water cut reservoir with profile modification are analyzed. Besides, the internal cause of system with such state changes based on many potential differences in interface region which leads to spontaneous (irreversible) process of activating and transferring retained oil is analyzed and demonstrated. The essential connotation of fluid flow form transformation is further analyzed, which is matter transform into exergy in the interface region as injecting agents into oil layers with pump, thus physical chemistry entropy is accreting along with potential energy dissipating. That is to say, the process of activating and removing resident oil is an inconvertible and self-organized process in which exergy dissipating result in entropy increasing. To adopt this analysis breaks through the traditional thought of macroscopic statistical analysis, and highlights transformation and interaction between fluid component and energy in the interface region, which leads research of EOR into a new field, and has great theoretical and practical significance. |
