Preparation and Characterization of Petroleum Sulfonate Directly from Crude

Abstract

Sulfonate surfactants used in enhanced oil recovery (EOR) need not be very pure, such as linear alkyl benzene sulfonate, but should be similar in terms of surface activity. The possibility of preparation, isolation, and purification of petroleum sulfonate directly from crude is studied in the lab. Crudes chosen in this study are GSPC and Panna supplied by Oil and Natural Gas Corporation (ONGC), India. Crude is digested with sulfuric acid (98%) or oleum (20%) for sulfonation and then neutralized with sodium hydroxide. Finally, sulfonate surfactant is isolated and purified by a series of solvent extraction procedures using alcohols and alkanes. The sulfonate surfactant obtained is characterized with respect to EOR applicability, e.g., surface tension measurement and interfacial tension measurement against benzene. The dosing of the sulfonating agent was verified to study its effect on yield of sulfonate and surface tension value. The yield of sulfonate increases with the increase in dosing of the sulfonating agent; however, the surface activity of sulfonate decreases. Optimum yield and surface activity are obtained for sulfonate surfactants produced from GSPC crude when a crude-to-sulfonating agent volume ratio of 1:5 is used. Surface activity of sulfonate surfactant obtained from GSPC crude compares well with commercially available surfactant, TRS 10-80, used in EOR. This study also brings the possibility of an in situ generation of sulfonates in oil fields for EOR.