Capillary and Surface Effects During the Movement of Oil, Water and Gas in a Porous Medium

Capillary effects due to the existence of menisci either promote or curtail the movement of the multiphase system through the porous medium. Surface effects exert a considerable influence on the flow of oil and water through the capillary pores. Capillary hysteresis, consisting of the existence of a metastable equilibrium of the liquid phase in capillaries of varying cross section, makes possible the existence of several equilibrium heights of capillary rise of the liquid in individual capillaries as well as in the porous medium. The capillary hysteresis of form should be considered when solving static problems on the equilibrium between oil and water in inclined layers. Capillary and surface effects play an especially important part when secondary recovery methods are used to ensure the fullest possible recovery of capillary-held and filmed oil from the layer, taking advantage of physico-chemical methods.