Ionic liquid in stabilizing asphaltenes during miscible CO₂ injection in high pressure oil reservoir

The potential of ionic liquids to prevent asphaltene precipitation during miscible Carbon dioxide (CO₂) flooding was investigated. Asphaltene dispersion tests were performed to compare the effectiveness of commercial inhibitors and the ionic liquids at ambient conditions. Based on the results 1-Butyl-3-methyl-imidazolium bromide [BMIM][Br], Ionic Liquid was selected and asphaltene onset pressure (AOP) was determined at high-temperature high-pressure conditions through isothermal depressurization experiments in PVT cell. The effect of CO₂, organic solvents and [BMIM][Br] on AOP were documented and correlated with nodal pressure analysis of the reservoir/wells. The results show a 21% decrease in AOP compared to the untreated oil and about 46% decrease when 35 mol% of CO₂ is solubilized in oil. [BMIM][Br] is seen to have higher activity when injected in solution with isopropanol-n-heptane compared to direct addition. The application of [BMIM][Br]in miscible CO2 flooded reservoir is found to have good potential in inhibiting asphaltene deposition within the reservoir and near wellbore nodal conditions.