Chemical flooding methods are used to recover residual oil left after water flooding. Several chemical flooding processes has been used to improve recovery: surfactant-polymer (SP), low-tension polymer flooding (LTPF), and alkaline-surfactant-polymer flooding (ASP). When working high salinity/high hardness reservoirs each of above processes will interact differently with reservoir component and will give different recovery results.
An experimental study was conducted to examine different type of chemical flooding technologies on the oil recovery of the water flooded residual oil, formation and injectivity decline of each technology. Two Anionic, two amphoteric surfactant, two alkalis and two types of polymers were used in this work to formulate the different chemical solutions. Core flow experiments using core samples of 1.5" diameter and 20" in length prepared from Berea sandstone material. Core flooding experiments was conducted on challenging condition of elevated temperature of 95°C and high salinity environment of 172,000 ppm.
ASP formulation prepared with anionic surfactant showed the best oil recovery compared to other chemical flooding processes. Although solutions prepared with amphoteric surfactant shows the least IFT values they did not give the highest recovery. ASP solution prepared using organic alkali low surfactant concentration showed similar recovery when compared to high concentration surfactant formulation. Formulations prepared using the ASP technology showed the highest pressure drop after chemical injection which can be due to the precipitation of the inorganic alkali when mixed with residence brine before the chemical injection.