Mobility control through spontaneous formation of nanoparticle stabilized emulsions

1 We report on measurements of the flow pattern and in-situ saturations whenn-octane displaces a brine in which surface treated silica nanoparticles are dispersed. The nanoparticles are known to stabilize octane-in-water emulsions. We find that the displacement front is more spatially uniform, and with a later breakthrough when compared to a control displacement with no in-situ nanoparticles. Pressure measurements during the displacement are consistent with generation of a viscous phase such as an emulsion. These observations suggest that a nanoparticle stabilized emulsion is formed during the displacement which acts to suppress the viscous instability. We argue that generation of droplets of nonwetting phase occurs at the leading edge of all drainage displacements. The droplets rejoin the bulk phase in the absence of stabilizing agents, but are preserved when nanoparticles adhere to the fluid/fluid interface.