Study on dual-degrade workover fluid system of high permeability reservoir

Most of Bohai oilfield reservoirs are high permeability, and leakage often occurs in the process of workover. If the compatibility of workover fluid flowing into layer with reservoir is poor, and polymer in workover fluid is hard to degrade, which will cause reservoir damage and reduce the output after workover. Therefore workover fluid is required with high seal capability and easy degradability. Considering the requirement of degradation rate from workover time, and starting with thermal-degrade and bio-enzyme degrade, dual-degrade workover fluid system was developed in this paper. The indoor evaluate results indicate that this workover fluid system has strong seal capability, good thermal-degradation and bio-enzyme degradation, and the reservoir protection effect is also better.