Abstract
Through rheological experiments and indoor core experiments, the rheological properties and oil displacement efficiency of Alkali-Surfactant-Polymer (ASP) system containing amphoteric surfactants is studied at ultralow interface tension (0.001mN/m). The effects of changing the concentration of polymer (0.5, 1.0 and 2.0g/L), alkali types (Sodium carbonate and sodium hydroxide) and concentration of Sodium carbonate (0.3-1.5%) on the rheological properties and oil displacement recovery is studied. The viscosity of ASP system increases with mass concentration of polymer increased, and the viscosity of ASP system decreased with mass concentration of Sodium carbonate increased. The viscosity of the system containing 0.6% Sodium hydroxide is higher than the system containing the same concentration of Sodium carbonate. Indoor man-made core displacement experiment results showed: With the mass concentration of polymer changing from 0.5g/L, 1.0g/L and 2.0g/L, the improving value of recovery rate is 25.26%, 21.05% and 22.1% respectively. After water flooding, with the changing of mass concentration of Sodium carbonate on ASP from 0.3%, 0.6%, 1.0% and 1.5%, the recovery rate of ASP systems is 25.26%, 21.42%, 23.81% and 35.35% respectively, the increment of recovery rate is all more than 20.0%, the Total recovery rate is 85.26%, 79.75%, 83.33% and 93.93% respectively. This research results in this paper has important guiding significance on production design.
