The effects and control of viscosity loss of polymer solution compounded by produced water in oilfield development

摘要

To avoid the environment pollution and remit the pressure of produced water stored up in water stations at high-water-cut stage, a special technology of enhanced oil recovery (EOR), in which produced water is used for compounding polymer solution, has been formed in Daqing Oilfield. However, the viscosity loss is difficult to be avoided only by modifying the polymer production. Then the effects of salinity, bacteria and reducing substances of produced water on viscosity loss are analysed respectively in this paper. The results proved that biodegradation and chemical degradation are as important as mechanical degradation in polymer solution. As more complicated processes and higher cost are needed for the desalination of produced water, a sterilisation-aeration treatment technique with simple process and low cost is proposed. The application of proposed procedures indicated that, viscosity loss of polymer solution with different molecular weights and different concentrations can be reduced by 10 mPa.s, and more than 100 mg/L polymer working concentration can be saved in compounding with the same viscosity.