Successful polymer flooding and surfactant-polymer flooding projects at Shengli Oilfield from 1992 to 2012

Shengli Oilfield, located in Northeast China, is one of the largest and oldest oilfields in China. The field production peaked in 1991 and the overall water cut has reached 95 % in 2012. The decline in production and the increasing demand for fossil energy have motivated the Shengli Oilfield Company (SLOF) to seek feasible enhanced oil recovery methods. Since 1992, more than 60 units at Shengli field have received injection of polymer or a combination of polymer and low-concentration surfactants. Partially hydrolyzed polyacrylamide and petroleum sulfonate were chosen for most polymer flood projects. Field cases demonstrated that polymer flood and surfactant-polymer flood could effectively increase oil rate, decrease water cut and improve oil recovery. This paper reviews several unique field trials at Shengli Oilfield. The earlier polymer flood projects targeted relatively ideal reservoirs with low temperature and low water salinity. However the undergoing polymer flood projects and future projects have to face very challenging reservoir conditions. Loss of polymer viscosity and reservoir heterogeneity affect the success of polymer flood projects. Future research at SLOF will focus on developing more tolerant polymers and improving the flow of polymer in reservoirs.