Imbibition is restricted to concurrent flow. Despite a marked difference in rock properties including permeability and porosity, we find similar trends in saturation profiles and weight gain versus time functions. Imbibition in diatomite is relatively rapid when initial water saturation is low due to large capillary forces. In this study, we study in more detail the properties of the rock and the effects that each of these properties have on the process of spontaneous imbibition. The saturation profile history allows direct computation of the relative permeability for both phases from a single experiment when used in combination with a previously measured capillary pressure curve.
Results are unique within experimental error.
The proposed procedure works equally well for spontaneous and forced cocurrent imbibition. Test results are described within the paper. Advantages include the incorporation of capillary forces and no requirement for steady state conditions. This method is useful to measure imbibition relative permeability curves, especially in low permeability rocks. In such systems, it is laborious to reach multiple steady states and capillary forces are significant so that classical unsteady state techniques do not apply.