Comparing the effect of nanofluids in capillary imbibition with traditional displacing fluids

The effectiveness of surfactant solutions, polymers and nanosuspensions in capillary imbibition was studied comparatively. Two series of experiments on capillary imbibition with displacing liquids from cores saturated with low-viscosity (4.2 mPa s) and high-viscosity (28.9 mPa s) oil were performed. Water, a polymer solution of polyacrylamide, surfactant solutions (AES and SDS), as well as suspensions of spherical nanoparticles were considered as displacing fluids. The mass concentration of the substances varied from 0.05 to 0.25%. The rate of change in the volume of the displaced oil for 0.1% AES solution and suspension 1030 over time was greater than for other displacing liquids. The smallest increase in the volume of displaced oil was observed for the polymer solution. The coefficient of low-viscosity oil displacement from sandstone by water as a result of capillary imbibition was found to be 58%. When using surfactant solutions and suspensions, an increase in the oil displacement coefficient was observed: the SDS solution increased the capillary imbibition rate by 4%, and the suspension of SiO₂ nanoparticles (10 nm) gave a 3% increase. The polyacrylamide solution reduced the capillary imbibition rate by 12%. In the series with higher oil viscosity, the effect of additives was more significant. The rate of capillary imbibition increased by 22% in the case of 0.1% SDS solution and by 24% for 0.1% SiO₂ suspension (10 nm). The analysis of the factors influencing the displacement coefficient during capillary imbibition with solutions of surfactants, polymers and nanosuspensions was carried out. It has been shown that nanosuspensions are not inferior to surfactant solutions and leave polymer solutions far behind in terms of their positive effect on the oil displacement coefficient.