Surface energy characterization of carbonate rocks

Carbonate rocks (calcite and dolomite) account for more than half of the world's hydrocarbon reserves. Despite the complexity posed by these rocks, it is important to understand the fundamental forces of adhesion responsible for the spreading and distribution of reservoir fluids, such as crude oil/brine on the reservoir rock surface. These physico-chemical interactions determine the surface energetics of a reservoir and affect their wetting characteristics. Inverse gas chromatography is introduced to characterize the surface energy of carbonates (calcite and dolomite). The behavior of the polar and non-polar interaction forces was investigated at varying water coverage and at different temperatures. The results indicated that in general as the water coverage increased, the Lifshitz-van der Waals component of surface energy decreased to nearly that of the bulk water, while the acid base component also showed a decreasing trend. The Lifshitz van der Waals component of surface energy always decreased with increase in temperature, while the acid base properties showed contrasting trends for the two minerals. (C) 2013 Elsevier B.V. All rights reserved.