Review of theoretical technologies and field application of chemical flooding for enhanced oil recovery in high-temperature and high-salinity reservoirs

Chemical flooding is one of the essential means to enhance oil recovery and has played an important role in the efficient development of oilfields. Based on the current development status of chemical flooding technology in China and abroad，the theory and technology of chemical flooding for enhanced oil recovery in Shengli Oilfield were systematically summarized in response to the harsh conditions of high temperature and high salinity reservoirs. This article reviewed the theoretical and technical challenges overcome in the development of chemical flooding technology from indoor research to field application and introduced the development process of chemical flooding in high-temperature and high-salinity reservoirs of Shengli Oilfield over the past 60 years. By understanding the interaction and structure-activity relationships between oil displacement agents and between oil displacement agents and crude oil，Shengli Oilfield iteratively created the theory of “equal emphasis on viscoelasticity and expansion” for polymers in high-temperature and high-salinity reservoirs，the theory of “similar enrichment of oil agents and anionic non-ionic additive efficiency enhancement” for surfactants，and the theory of “control flooding by deformation” for viscoelastic particles. Shengli Oilfield also developed polymer flooding technology，alkali-free binary composite flooding technology，and heterogeneous composite flooding technology for high-temperature and high-salinity reservoirs with the characteristics of Shengli Oilfield and overcame the problem of significantly enhancing oil recovery in reservoirs with a temperature of 85 °C and a mineralization of 30 000 mg/L. The annual oil production of 96 chemical flooding projects implemented in the field has accounted for over 11% of the oilfield’s production for 20 consecutive years. This series of technologies has made important contributions to the stable production and sustainable development of the Shengli Oilfield.