Effect of Liquid-Liquid Extraction Process by Using a Paraffinic Solvent in the Removal of Acidity in Colombian Heavy Crude Oil

Abstract

Abstract Processing heavy and acid crudes involves failure risks associated to sulfidation and naphthenic corrosion in refinery equipments (Troncoso, E., 2009). In addition, acid crudes show a tendency to cause fouling in transportation pipelines and processing production facilities. In Colombia, the increasing rates in heavy oil production have driven the development of technologies to remove contaminants like sulfur, metals and acids. This work present the results obtained in laboratory test for the precipitation of asphalthene aggregateds applied to three different Colombian crude oils. This method includes mixing the crude with a paraffinic solvent, and following decantation and separation by gravity using a vacuum filtration technique. The acid content in the Asphalthene Aggregate fraction (AAF), and the Aggregate Free Fraction (AFF) was quantified using KOH titration method ASTM D664. Three different solvent-crude ratios were evaluated in this study (3:1, 5:1, 7:1) and the results shown an acidity content reduction found was an average of 11%, a reduction of sulfur content, and increase of gravity API in 7 points. Additionally a decrease in asphalthene content in the treated crude (nC7 insolubles) was found in all scenarios. A methodology to simulate Liquid Liquid Extraction process (LLEX) of acid and heavy crudes by tuning the binary interaction parameters of solvent-asphaltene pairs of pseudocomponents with experimental data is used here. The model predicts the process behavior under similar conditions than experimental test, and this allow to expand this study in a theoretical basis, reducing the cost in test and laboratory analysis.