Zhang, Fan (PetroChina) | Yang, Siyu (PetroChina) | Ma, Desheng (PetroChina) | Lv, Jianrong (PetroChina) | Zhang, Qun (PetroChina) | Luo, Wenli (PetroChina) | Zhou, Zhaohui (PetroChina) | Tian, Maozhang (PetroChina) | Cai, Hongyan (PetroChina)
Chemical flooding technique is one of effective EOR (Enhanced Oil Recovery) ways to improve the oil recovery for mature oilfield in China. It is usually applied successfully in low temperature and low salinity sandstone reservoirs, such as Daqing oilfield (45 C, 5,100 mg/L) and in Changqing oilfield (50 C, 4,700 mg/L). However, it is great challenges to develop chemical EOR formulations for the high temperature and high salinity carbonate reservoir. On the one hand, the high temperature and high salinity condition may cause decomposition of the conventional chemical agents with poor long-term stability. On the other hand, the oil types and compositions, rock surface property and pore structure are all different for sandstone and carbonate reservoirs. Therefore, it is necessary and important to development low cost and high efficiency chemical formulations for high temperature and high salinity carbonate reservoirs. In this paper, the betaine surfactant has been synthesized with cheap raw material of fatty acid, and its functional group of hydroxyl propyl sulfo hydrophilic group can improve the heat resistant and salt tolerant abilities; the star-polymer has been developed and the introduction of multi-functional monomer can inhibit the hydrolysis at high temperature and high salinity conditions. The new SP and ASP chemical formulations have been developed, and show good properties for high temperature and high salinity carbonate reservoir.