Surface energy and wetting behavior of reservoir rocks

An accurate description of the surface chemistry of the reservoir rock–fluid system is essential to understand the attractive forces between the various phases (crudes, brines and the rock surface). These physico-chemical interactions determine the fundamental nature of the reservoir wettability and the wetting behavior of fluids on the reservoir rock surface. Inverse gas chromatography (IGC) is used to characterize the surface chemistry of a Saudi Arabian reservoir rock (henceforth referred to as ‘reservoir rock’) at different moisture coverage and temperatures. This information combined with the surface tension of the interacting reservoir fluids is utilized to develop a new method for quantifying wettability in terms of a wettability index. This index is based on the relative magnitude of the work of adhesion between the rock surface and the competing oleic/aqueous phase.