Parallel-column experiments for enhancing oil recovery after polymer flooding

In order to prove the water flooding method after polymer flooding, the variations of the pressure, relative water intake, recovery efficiency of respective layers and water cut are studied in flow experiments of parallel columns simulating the real reservoir heterogeneity with high, medium and low permeability. The results show that, with polymer occupying part of the high permeability channels, direct deep profile control after polymer flooding, with the deep profile control agent of high viscosity, will do harm to the layers of low and medium permeability, then will decrease oil recovery. Injecting polymer-fixing agent after polymer flooding will cross-link and fix the high concentration polymer existing in pores of high permeability, then effectively control the water intake ability of big channels and increase the sweep efficiency of succeeding water flooding, which will make foundation for further deep profile control. Compared with the technology of injecting deep profile control agent after polymer flooding, this polymer-fixing technology is predominant in low cost, high oil recovery and utilizing extent of polymer existing in porous media as an effective treatment for improving oil recovery after polymer flooding.