Removal of oil from sandstone rocks by solid-liquid extraction using oil phase-free microemulsion systems

Abstract

The impregnation of oil on solid surfaces is a major challenge currently due to the need to purify environments affected by disasters and accidents related to the oil and gas industry. In this work, microemulsion systems without oil phase were formulated containing nonionic surfactants of different degrees of ethoxylation (10, 8 and 6 ethoxylation bonds) for the solid-liquid extraction of heavy oil impregnated in sandstone rocks. A central composite design was carried out showing the total oil extraction efficiency (%EE) entre 3.680 ± 0.933 e 99.800 ± 0.266. Micellar comparison analyses showed the importance of alcohol in the process, since 20% more oil was removed in the presence of alcohol, and the use of oil-free microemulsions proved to be feasible in cross-current and counter-current processes, especially the system containing lauryl alcohol with six ethoxylation bonds (LA 6EO) that reached satisfactory oil extraction results on both processes (%EE ≥ 90%).