Stability mechanism of SiO2/SDS dispersion for foam flooding in hydrocarbon reservoirs: experimental research and molecular simulation.

Abstract

The dispersion of silica dioxide (SiO2)/sodium lauryl sulfate (SDS) has been widely used in hydrocarbon reservoirs, but its instability is still a problem in practical engineering applications. The dispersion morphology of SiO2 nanoparticles before and after modification was studied by TEM, and the thermal stability of different foam dispersions was evaluated by FoamScan. In this paper, the mechanism of foam stability was investigated by combining the measurement of interfacial energy of nanoparticles at the gas-liquid interface with dynamics simulation of molecular diffusion. The results showed that SiO2/SDS dispersions had good thermal stability due to the synergistic effect of SiO2 nanoparticles and SDS. The addition of SiO2 nanoparticles improved the interfacial energy and interfacial activity at the gas-liquid interface, meanwhile limited the movement of SDS molecules and water molecules, which was beneficial for foam stability. Notably, the addition of modified SiO2 nanoparticles further enhanced the interfacial energy at the gas-liquid interface and strengthened the restriction of water/SDS molecular movement, thereby slowing down the drainage and decay of the foam dispersions. The mechanism investigation of SiO2/SDS dispersions was of benefit to foam flooding in hydrocarbon reservoirs.