Effect of Spontaneous Formation of Nanoparticle Stabilized Emulsion on the Stability of a Displacement

Abstract

Abstract Injecting nanoparticles into the subsurface can have a potential impact on altering both oil recovery and/or CO2 sequestration. In this work we conduct core floods in which a CO2-analogue fluid (n-octane) displaces brine with and without dispersed nanoparticles. We find that the floods with nanoparticles cause a greater pressure drop, and a change in flow pattern compared to the floods without. Emulsion formation is inferred by measuring the saturation distribution and pressure drop along the core. The results suggest that nanoparticle stabilized emulsion is formed during a drainage process (at low shear rate condition) which acts to reduce the mobility of the injected fluid. We also perform imbibition experiments, where the nanoparticle dispersion in brine displaces n-octane. Here we observe little difference in the flow pattern and pressure drop as a function of nanoparticle concentration. There is an observed accumulation of nanoparticles at the imbibition front, which suggests that nanoparticles may be used as a tracer of the displacement front.