Wettability Alteration of Oil- Wet and Water-Wet of Iranian Heavy Oil Reservoir by CuO Nanoparticles

The petroleum industry requires the best materials to reverse the rock wettability to water-wet state which give significantly improved oil recovery.Nanoparticles are suggested as enhanced oil recovery potential agents to decrease viscosity and alter the wettability of reservoir towards more water-wet. This study provides new insights into CuO nanoparticles effects on wettability alteration of different core types (sandstone and carbonate) and increases oil recovery. The first objective of this research is to determine the potential of CuO nanoparticles to imbibe through spontaneous imbibition cell and raise the oil recovery experimentally. The second goal is to prove that CuO nanoparticles have the ability to alter wettability of sandstone and carbonate cores quantitatively. Laboratory tests were conducted in two experiments on four cylindrical core samples taken from Iranian heavy oil reservoir. In the first experiment, core samples were saturated by crude oil and in the second test, nanoparticles were flooded and then saturated by crude oil, immersed in distilled water and the amount of recovery was monitored during 30 days. Experimental results show that oil recoveries for sandstone cores change from 20.74, 4.3 and 3.5% of OOIP without nanoparticles to 31.77, 17.3 and 14.42% of OOIP with CuO nanoparticles, respectively. The oil recoveries for carbonate core vary from zero without nanoparticles to 6.92% of OOIP with nanoparticles, respectively. By investigation of relative permeability curve, the crossover-point is shifted to the right by adding CuO nanoparticles which means nanoparticles succeed in altering the wettability to more water- wet for sandstone and even carbonate cores.