Recent Advances of Polymer Flooding in China

Polymer flooding is one of the most promising chemical enhanced oil recovery (EOR) techniques which have both high incremental oil recovery factor (IORF), low cost and wide reservoir applicability. The first field test of polymer flooding was reported in the United States. The first commercial polymer flooding in China started in Daqing oilfield, which has been remained the largest application in the world. However, encouraged by the conventional field applications and new findings of polymer's viscoelasticity effect on residual oil saturation, some high concentration high molecular weight polymer flooding (HCHMw) field tests have been conducted and reported. Although some field tests were documented, subsequent progress was seldom reported. According to a review of latest polymer flooding projects in China, it is found that HCHMw have only very limited application in Daqing. This is not in agreement with the expectations especially that viscoelastivity of synthetic partically hydrolyzed polyacrylamide (HPAM) is drawing much attention recently. This paper explains why HCHMw is not widely used at present. Different opinions on polymer's viscoelasticity effect on ROS reduction are also critically reviewed. Other field progress of salt-tolerance polymer flooding tests and new amphiphilic polymer tests in Daqing were well Associative polymer (APs) commercial application and some new polymers used in China were also introduced. Risk of high polymer injection pressure, optimum viscosity ratio, blocking mechanism, and capillary number theory are discussed. Learning from many polymer flooding field applications has been given. In the end, quaternary recovery in post-polymer flooding reservoirs practices are compared. This paper helps to clarify some misleading ideas in polymer flooding implementations based on theory and practices of polymer flooding in China.