A novel method for application of nanoparticles as direct asphaltene inhibitors during miscible CO2 injection

Asphaltene precipitation is one of the main technical challenges during the miscible gas injection. The asphaltene may deposit on the rock surface and it may change the reservoir wettability and reduces permeability. This paper focused on the asphaltene precipitation by liquid-free asphaltene inhibitors at reservoir conditions. The Fe3O4 and Al2O3 nanoparticles were used as direct asphaltene inhibitors (DAI) during CO2 injection. The cloud point pressures were measured to ensure that the CO2/nanoparticles mixtures are in single-phase conditions. After that, the vanishing interfacial tension technique was considered to evaluate the effect of DAI on minimum miscibility pressure. Moreover, the asphaltene precipitation during CO2/nanoparticles injection was studied for both volatile and intermediate live oils at reservoir conditions for DAI concentration varied from 500 to 3000 ppm. The results showed that the DAI can reduce the amounts of asphaltene precipitation during miscible CO2/nanoparticles injection at reservoir conditions. In addition, the CO2/nanoparticles injection reduced the asphaltene precipitation in comparison to pure CO2 injection. Also, the mixtures containing Fe3O4 can provide more performance than Al2O3 solutions, so the effect of solubility is more dominant than the aggregation impact during DAI injection.