Visualized Study of a Nanoparticle-Assisted Foam System to Enhance Oil Recovery by Nuclear Magnetic Resonance Online Flooding Experiment

Abstract

To solve the problems of high water cut and low oil production in some blocks of Xinjiang Oilfield, nanoparticle-assisted foam flooding technology has been proposed recently to improve the oil recovery. In this study, the foam static evaluation experiment was first employed to study the effects of modified nano-SiO2 on foam stability and foaming performance. Then, the influences of temperature and salinity on foam stability were investigated. Finally, both the water and oil displacement performances of foam systems with and without nanoparticle assistance were studied separately by the nuclear magnetic resonance (NMR) online flooding experiment. Foam static evaluation results showed that the stability of the foam was obviously increased by modified nano-SiO2 particles. However, the foam stability slightly decreased with the increase in temperature and salinity. Moreover, the foam half-life under the reservoir conditions of 80 °C and 80,000 mg/L salinity could reach 240 min, indicating that resistance to high temperature and salinity of the nanoparticle-assisted foam system was enhanced compared to that of the conventional foam systems. Magnetic resonance imaging results demonstrated that the water displacing effect of the nanoparticle-assisted foam system was significantly increased compared with that without adding modified nano-SiO2. The core finally contained almost no original water after flooding. In addition, the nanoparticle-assisted foam system can substantially improve oil displacement efficiency and increase the oil recovery efficiency by 31.11 percentage points based on the results of water flooding.