Evaluation of Crude Oil Wax Dissolution Using a Hydrocarbon-Based Solvent in the Presence of Ionic Liquid

Abstract

The current alternative of using aromatic-based wax soak solvents has been found to be hazardous and imposes a high cost on field expenditures. These solvents are widely used in the oil and gas industry to soften up wax before the pigging process. However, their impacts on the environment are quite concerning. Plus, they also impose hazardous exposure and are found to be damaging to both plastic and rubber hoses. To replace the current alternative with other hydrocarbon-based wax soak solvents, ionic liquids were found to have the capability to increase the solvent power capabilities and the efficiency of wax soak solvent in dissolving heavy crude oil. To optimise the application of hydrocarbon solvents and ionic liquid in wax dissolution, the affinity of ionic liquids in three solvents was studied. The solvents were condensate, ethyl acetate, and xylene. It was found that from four types of ionic liquids tested, only BMIMCL and HMIMBr were miscible in all three of the solvents used. Dissolution of hard deposited paraffin wax in condensate, ethyl acetate and xylene was conducted using the spectral analysis method, and it was found that the dissolution of paraffin wax was greatest in ethyl acetate. However, enchantment on wax dissolution was also observed for gas condensate and xylene. The wax soaking time was also optimised, in which the dissolution of wax was found to reach a saturation level when the wax had been soaked for over 90 min in the solvents, especially for gas condensate. Further study on the effect of ionic liquid introduced alongside condensate, ethyl acetate and xylene, aiming to enhance the solvent power, was also conducted using the spectral analysis method. The introduction of ionic liquids to all hydrocarbon-based wax soak solvents used in this project was proven to significantly increase the UV-VIS absorbance of the extracted solvents after paraffin wax had been soaked for 30 min.