Wettability alteration in berea sandstone cores by contact angle measurements

Herein is discussed the physicochemical mechanisms occurring during wettability alteration in mixed wet rocks. Defined by the strength with which a petroleum fluid adheres to the surface of the reservoir rock formation, wettability is of a great interest for oil recovery. The present work presents thewettability alteration of light and heavy crudes in strongly wetted sandstone, by the means of contact angle measurement. The spreading was found to be not only dependent of the reservoir fluid properties but also of the saturation of core. Different multiphase flow patterns were observed from the crude oil migration through the pore throats of reservoir formation suggesting a change in the surface properties of the reservoir rock. Furthermore, reservoir water salinity and presence of meta-aqua ionswere found to promote pore blocking which further altered surface tension, thence the wettability.