Different approaches to understand mechanism of wettability alteration of carbonate reservoirs

Wettability is a key parameter when concerned with the flow of fluids in any porous medium. This paper describes the several possible mechanisms of wettability alteration of carbonate rocks using different approaches. The most crucial parameters which have severe impact on wettability alteration such as oleic phase composition, aqueous phase pH, as well as temperature are discussed. At the oleic/aqueous interface, the interfacial tension and its variation with the structure of active surface species, partitioning of species between phases, and temperature are important signs to track the wettability alteration. The effect of the IFT on wettability alteration is revealed with the contact angle measurements on the carbonate rock surfaces. On the other hand at rock/fluids interface, the paper presents the variations in surface tension and adsorption isotherms of surface active species on the rock surfaces which imply the strength of wettability alteration. The degree of wettability alteration and its reversibility due to influence of aforementioned parameters are explained based on desorption of active species from surfaces justifying by several thermo-gravimetric measurements.