Flow mechanisms, relative permeabilities, and coupling effects in steady-state two-phase flow through porous media, the case of strong wettability

The pore-scale flow mechanisms and the relative permeabilities during stead y-state two-phase flow in a glass model pore network were studied experimen tally for the case of strong wettability (theta(e) < 10 degrees). The capil lary number, the fluid flow rate ratio, and the viscosity ratio were change d systematically, while all other parameters were kept constant. The flow m echanisms at the microscopic and macroscopic scales were examined visually and videorecorded. As in the case of intermediate wettability, we observed that over a broad range of values of the system parameters the pore-scale f low mechanisms include many strongly nonlinear phenomena, specifically, bre akup, coalescence, stranding, mobilization, etc. Such microscopically irrev ersible phenomena cause macroscopic nonlinearity and irreversibility, which make an Onsager-type theory inappropriate for this class of flows. The mai n effects of strong wettability are that it changes the domains of the syst em parameter values where the various flow regimes are observed and increas es the relative permeability values, whereas the qualitative aspects of the flow remain the same. Currently, a new true-to-mechanism model is being de veloped for this class of flows.