Microemulsion phase formation at oil–cellulose microcrystal suspension interfaces

The use of cellulose microcrystal suspensions has two advantages for displacement of viscous oil from porous media—first, it viscosifies the aqueous phase thus improving the mobility ratio and second, it reduces the interfacial tension between the phases leading to improved capillary number. Here we examine oil displacement both macroscopically and microscopically to understand the interface between oil and cellulose microcrystal and in particular, the formation of stable microemulsions at the interface. The results show that microcrystal suspensions improve the displacement of oil from porous media over that of water alone and the reason for this is the formation of a viscous microcrystal microemulsion phase that forms at the interface. This high viscosity phase improves the mobility ratio of the system locally at the interface raising the efficiency of oil displacement.