Experimental Study on Switchable Acetamidine Surfactant Flooding in Sandstone Using NMR

As a promising chemical-enhanced oil recovery method (CEOR), switchable acetamidine surfactant flooding is investigated in sandstone oil reservoirs. To describe the distributions of the injected water during the surfactant flooding, long-time and multifrequency NMR scanning was employed in combination with core displacement experiments. We found that the water saturation increased and swept volume was improved with the injection rates increasing from 0.01 to 0.5 mL/min in all pores. During water flooding, the water injection rate and distribution had a positive correlation. The water saturation increased as the surfactant concentration increased, and the water saturation and the swept volume of surfactant flooding were larger than those of the water flooding. Furthermore, the water saturation increase in migration pore (MP) was much larger than that in other pores during the switchable acetamidine surfactant flooding. As a result, the water saturation increased and the oil recovery enhanced. Our research results provided novel perspectives on switchable acetamidine surfactant flooding for enhanced oil recovery (EOR).