POINT-BY-POINT METHOD OF DETERMINING CONTACT ANGLES FROM DYNAMIC WILHELMY PLATE DATA FOR OIL BRINE SOLID SYSTEMS

The wetting behavior of crude-oil/brine/rock systems can have a domina nt effect on processes by which oil is recovered from underground rese rvoirs. A working knowledge of the crude-oil/brine/solid interactions that govern wetting behavior is needed. Application of the dynamic Wil helmy plate technique to a variety of wettability conditions induced b y adsorption from crude oil shows that the conventional method of dete rmining advancing and receding contact angles from force-distance reco rds is not always applicable. A point-by-point interpretation is prese nted and applied to a variety of situations. These include slippage of the three-phase line of contact and time-dependent wetting phenomena related to adsorption kinetics. For such complex wetting conditions, d irect observation of the behavior of the three-phase line of contact i s a necessary part of ensuring that interpretations of the force-dista nce record are reasonable. (C) 1995 Academic Press, Inc.