Effects of displacement velocity on interfacial reconstruction events during immiscible two-phase displacement

Abstract

During the two-phase fluid displacement in porous media, with the increase in capillary number Ca, different wettability effects are suppressed; however, its potential control mechanism has not been clarified. Therefore, in this study, we have analyzed the pore scale process related to interface reconfiguration events in detail and profoundly clarified the nature of a series of interface reconfiguration events being suppressed. Based on typical pore throat, we elaborated and confirmed that the development and evolution direction of fluid displacement mode always follow the principle of minimum operating power. That is to say, in order to avoid extra work, the system will compare all the potential moving meniscus at the displacement front and always choose the local path with the minimum operating power (Po=ΔpQ) of the system for displacement. Under this theory, a series of interface reconfiguration events are considered energy favorable self-regulation events derived by the system in order to avoid extra energy consumption. However, the appearance and disappearance of interface reconstruction events are considered to be the result of the mechanism of “self-regulation of surface energy change rate” and “self-regulation of viscosity dissipation rate” in order to approach the minimum operating power. This study provides us with a sufficient physical explanation to understand the nature of the wettability effect being suppressed.