The influence of petroleum acids and solid surface energy on pipeline wettability in relation to hydrate deposition

The mechanisms by which hydrates deposit in a petroleum production-line are probably related to pipeline surface properties, e.g. pipeline material, surface energy and toughness. In this work, the wettability alteration of pipeline surfaces from contact with oil, and the adhesion energy between water and solid in the presence of oil is investigated. Contact angles for model systems are determined as a function of solid material and oil composition. Although contact angles in oil/brine/solid systems have previously been extensively reported in the literature, the variety of solids that mimic a pipeline surface is limited. In this study, we include various metal surfaces in addition to glass and epoxy coating. The results show that both the presence of petroleum acids in the oil, and low surface free energy of the pipeline material, lead to more oil-wet systems and consequently reduced adhesion energy between water and solid. (C) 2009 Elsevier Inc. All rights reserved.