Mobility control ability and stability investigation of nitrogen foam under high temperature and high salinity condition

The mobility disparity between oil and water accounted for the poor water swept efficiency. Previous research has testified that nitrogen foam can increase sweep area and control water and gas mobility. However, the former studies have largely covered the mobility control ability performance in some conventional reservoir rather than that under high temperature and high salinity. This paper presents the results of a laboratory study of nitrogen foam at the experimental condition (113 °C and 21.28 × 104 mg/L) on its mobility control ability investigation, including different gas-to-liquid ratio, injection rate and core permeability; additionally, a novel method on studying the stability of mobility control ability of foam was utilized. Nitrogen foam injection was conducted in core holder to investigate the shape discrepancy of each resistance factor and residual resistance curve. The results showed that the most moderate gas-to-liquid ratio and injection rate were 2:1 and 1 mL/min, respectively; foam performed more significant mobility control ability with the increase in permeability. After 5 days’ aging, nitrogen foam still got enough mobility control ability to block water channeling. The above results demonstrate that, under high temperature and high salinity condition, nitrogen foam still can act as a promising economical method for improving the mobility difference between water and oil by applying appropriate injection parameters.