Determination of Dead-Oil Wetting and Adhesive Forces on Carbonate Rocks Using Colloidal-Probe Atomic Force Microscopy

Abstract

In the attempt to unveil the effects of carbonate reservoir surface interactions with crude oil on its wettability, novel in situ atomic force microscopy (AFM) experiments (force volume) were performed to map the adhesion forces between the dead crude oil and the carbonate rocks rich with the natural minerals calcite and dolomite. In this sense, carbonate samples were submerged in a fluid cell filled with deionized water to minimize the effect of the surrounding environment and to account only for the interactions involving the AFM probe functionalized with oil and the carbonate surface. The wettability alteration on carbonate was determined through contact angle (CA) measurements using both the sessile drop technique and in situ environmental scanning electron microscopy. These measurements were carried out with respect to both water and oil at various roughness induced by the sample surface modifications. Our results show that the obtained CA is sensitive to both the mineralogy and the surface roughness...