In order to meet the practical needs of profile control and flooding technology in Bohai reservoir, the hydration dynamic characteristics and seepage characteristics of polymer microspheres were studied in this paper. Results indicate that, with the prolonging of hydration time, the expansion ratio of polymer microspheres increases, and the final expansion ratio is about 4.5. When the hydration time is less than 50 h, the expansion velocity is faster, then the expansion velocity slows down, and finally reaches stable after 360 h. Compared with the size distribution of molecular aggregates in the polymer solution, the size distribution of the two polymer microspheres is relatively concentrated. The initial median particle size of 10 ^# microspheres is 4.36μm, and then reaches 20.00 μm after hydration for 240 h. The initial median particle size of 11 ^# microspheres is 8.45 μm, and then reaches 40.0 μm after hydration for 360 h. The expansion ratio is about 4.72. In the injection process of polymer microsphere, the adhesion between particles and the pore filtering effect can cause the retention and temporary plugging of polymer microsphere in the core end, which leads to the abnormal increase of the pressure in the injection process. The polymer microspheres can further hydration expand in the core pore, showing the seepage characteristics of “migration, trapping, re migration and re trapping......”.

This paper researches the seepage characteristics and oil displacement effect of polymer solution and weak-base ternary compound system, taking the reservoir geology and fluid from Daqing Oilfield as research object, taking injectionpressure and oil recovery as the evaluation indexes. Results show that, under the condition of the same oil displacement agent viscosity and slug size, the oil recovery increment of weak-base ASP flooding is larger than that of polymer flooding. Because there are emulsification and Jamin effect during weak-base ASP flooding, which can increase seepage resistance and injection-pressure, and its oil sweep efficiency is also higher. Compared with ternary compound system with scaleremoval water, there are carbonate micro particles in the sewage ternary compound system, which can be detained in porous media. This can increase seepage resistance and cause fluid diversion effect, which eventually leads to a large increase in oil recovery. Compared with constant-speed experiment, it is early for constantpressure experiment to adopt peak-pressure, which accelerates the forward speed of agent in the core high permeability layer and shortens the breakthrough time. As a result, the sweep efficiency and oil displacement efficiency of constantpressure experiment is lower.

In order to improve the performance of macromolecule polymer demulsifier and enlarge the range of application of nano-material, the nano-Al ₂O ₃ and macromolecule polyether demulsifier TA1031 were grafted by sol-gel method with Al ₂(SO ₄) ₃ and NH ₃·H ₂O. The Nanometer modified demulsifier was analyzed by FTIR, SEM, rotational viscometer and interfacial tensionmeter. The results show that applying nano-Al ₂O ₃ to crude oil polymer demulsifier would greatly improve the performance of the original demulsifier. When the mass ratio of aluminium oxide and TA1031 was 1∶10, the performance of the nanometer modified demulsifier is better, and the ratio of demulsification would be improved about 20%~25%. The time of demulification and dewatering would be greatly shorten, and the demusification mechanism and formation mechanisms of nanometer modified demulsifier was preliminary analysised.