Insights into Nanoparticles, Electrokinetics and Hybrid Techniques on Improving Oil Recovered in Carbonate Reservoirs

Use of nanoparticles as a method for enhancing oil recoveries has become an attractive prospect. Experimental evidence has shown that this technique possesses the ability to improve recoveries via wettability alteration and interfacial tension reduction amongst other strategies. In this study, we analyze the potential of nanoparticles employed in coreflood experiments. Low concentration acid was added to aid in the dispersion of the nanoparticles in the brine by protecting them from being aggregated, while enhancing the stimulation of the tight porous media. Electrokinetics was also implemented following a sequential as well as a simultaneous approach to further stimulate the fluids injected, controlling their mobility, and therefore, increasing the depth of penetration within the porous media. Several coreflood experiments were carried out on highly heterogeneous carbonate samples of Middle Eastern origin with permeabilities of around 0.1 mD. Zeta potential measurements were conducted on the inlet side of the preserved core-plugs after the conclusion of each coreflood. The findings indicated a close connection between the rate of wettability alteration observed over the duration of nano-acid fluid injection and mode of electrokinetic application. The best performing nano-acid fluids correlated with the highest shift in the magnitude of the zeta potential across all tested strategies. Results show that oil recovered via this hybrid technique was mostly 10–15% higher than that derived when only smart brine was employed.