Nature friendly Application of Ionic Liquids for Dissolution Enhancement of Heavy Crude Oil

Abstract

AbstractThe upstream petroleum industry faces operational and technical challenges due to the production of crude oil containing waxes, asphaltenes and aromatic compounds and also due to the formation of gas hydrates resulting in their deposition in the surface and production equipments and in offshore pipelines affecting the safer operations, in turn resulting in huge production losses, and threatening the environment. It is also estimated that, all over the globe there are more than double the times of reserves of heavy and extra-heavy crude oil than the lighter one. In spite of this, the production of heavy oil is still low. As the world’s demand for light crude oil continues to increase tremendously, the supplies of these easily extractable crude oil continues to decrease although efforts have already been made to extract the heavy and extra-heavy oil that was previously considered uneconomical to produce and process. The enhancement in the solubility of heavy crude oil in solvent and ionic liquids mixture is investigated using UV-visible, FT-IR and 13C- NMR spectroscopic techniques. Ionic liquids also aid in the reduction of surface forces between oil-water systems thereby helping for the recovery of entrapped oil from exhausted reservoirs which have failed to produce the residual oil. This work also investigates the role of ionic liquids in reducing the surface forces at the interface of crude oil-water system. Synergistic effect of ionic liquids along with brine has also been tested. It is observed that, the dissolution of heavy crude oil is more in the solution with ionic liquid than with the solvent alone. Solubility of heavy crude oil in the presence of studied ionic liquids and in the studied solvents increases about 60 %, when compared with the solutions of heavy crude oil in solvents without ionic liquids. Measured interfacial tension values between solutions of ionic liquid and crude oil reveal that these ionic liquids are successful in reducing the surface tension and interfacial tension. Improved efficiency in reducing the interfacial tension using salt and ionic liquid mixture has been observed between crude oil and the aqueous solution of ionic liquid. This method also helps in minimizing the amount of organic solvents that may be used to a considerable extent. Delayed production of crude oil due to flow- assurance issues or the loss of valuable fuel which remains unrecoverable due to the huge and cumbersome technical difficulties in the prevailing enhanced oil recovery processes could be greatly reduced by employing the use of ionic liquids.