Contact angle hysteresis and the stability of wetting changes induced by adsorption from crude oil

Abstract

The dynamic Wilhelmy plate technique was used to investigate contact angle hysteresis and the stability of wetting changes induced on quartz surfaces by adsorption from crude oil. Some degree of contact angle hysteresis was always observed on surfaces that were first equilibrated with brine, then exposed to crude oil at elevated temperature. The extent to which hysteresis persisted through repeated cycles of advancing and receding of the probe fluids was different for different crude oil compositions. Regardless of whether or not the surface was dried, and whether the measurements began with the surface in brine or decane, quartz surfaces aged in asphaltic crude oils having more basic than acidic character showed large and reproducible contact angle hysteresis. For quartz surfaces aged in less asphaltic crude oils that are below their wax appearance temperatures (WAT) at room conditions, receding contact angles were usually reproduced but advancing angles tended to decrease with each wetting cycle.