Research and application of EOR technology by polymer flooding in wellblock Ji-7 of Changji Oilfield

The recovery rate of conventional water flooding in wellblock Ji-7 is 15%. The application potential of the polymer flooding technology in this block is studied by the method of physical model experiment. The experimental results show that the permeability of the reservoir in wellblock Ji-7 is very poor, but the water content and crude viscosity both can meet the conditions to carry out this process. The optimum ratio of water to oil fluidity is optimized and the effect of EOR is evaluated. The experimental results show that under the condition of three-pipe parallel core, the oil recovery of polymer flooding increases 5%-10% than that of conventional water flooding under water-oil mobility ratio of 3:1 to 1:1. The polymer flooding is carried out in 5 wells in wellblock Ji-7 of Changji Oilfield. The result of field test shows that the polymer flooding can improve the water absorption profile, and control the rising speed of water cut. Compared with conventional injection wells, the recovery factor increases 5.5%.