The Interface Thermodynamics Research On Resident Oil Migration During Polymer Flooding Process

In view of the problem of fluid flowing condition evolution on the interface territory during the process of polymer flooding the resident oil after water flooding. On the basis of the viscoelasticity of polymer solution enhancing microscopic flooding oil efficiency in the mechanism foundation, the paper studies polymer solution energy transform into the water-oil interface energy, the polymer negative entropy flow pulling effect on water-oil interface, oil thread production, breaking and gathering in the visible experiment by the polymer thermodynamics, the interface thermodynamics and the modern thermodynamics theory. The research results of the paper are as follows:The visible flooding oil experiments of the glass sculpture thin slice and the visible experiment of water-oil interface distortion migration indicate that the part of resident oil breaks out, the grows and is pulled to form oil thread, the oil thread breaks and rapidly retracts to form the small oil drops. These oil drops gather step by step. This process is a non- equilibrium state irreversible process. During the whole processes each link of water-oil interface shape change is the result of interface energy conversion. The polymer solution has the net chain structure, it shows the effect of viscoelasticity in the movement which directly relates to the interface energy conversion. Under the certain condition, to enlarge the speed of the polymer fluid flow, increase polymer solution density, enhance the polymer molecular weight or reduce the water-oil interfacial tension can enlarge the water oil interface distortion degree.The process of the polymer flooding oil in the core sample is a thermodynamics opening system, the polymer activation and migration water flooding resident oil in the core sample is a imbalance flow process. The structure of polymer molecular net chain can change through the core sample causes the polymer fluid free energy change. the work that the environment does transforms into the internal friction heat and free energy change of the system. The core sample pressure drop of the polymer solution with the big molecular weight and the high density must be higher than with the small molecular weight and the low density. The increase of the polymer solution current capacity and the decrease of the core sample penetration can enlarge the deformation degree of polymer molecular net chain, increase the free energy of the polymer solution and core sample pressure drop. The polymer fluid follows the energy conservation law of thermodynamics in the process of the imbalance stationary state core sample flow, the change of the system free energy is the total of the polymer fluid pressure energy, the kinetic energy, the potential energy, the fluid alternates energy and the friction heat, and is influenced by the pore size and the distribution characteristic in the reservoir.In the polymer concentrated solution, the polymer molecular chains each other pass forming the molecular net chain structure, the free energy change of polymer solution is the direct ratio with the number of polymer networking chain in the unit volume. The polymer solution with the similar deformation degree has the bigger free energy change with higher networking chain number. The polymer molecular chain conformation change can cause the...