Modeling unsteady-state gravity-driven flow in porous media

This paper presents an investigation of gravity-driven flow in porous media using angular capillary tubes. Gravity is important in many fluid transport processes, such as ground water flow, oil flow in reservoir, and water flow in subsurface in CO2 sequestration processes. In these processes, density contrast of the fluids is generally large, e.g., water vs. gas, or oil vs. gas. Gravity-driven flow of the denser fluid largely takes control in these processes. In particular, gravity-driven flow falls into two regimes in regarding to the denser fluid: the bulk flow (steady-state) and the film/corner flow (unsteady-state) that follows. The geometrically complicated flow channels in a porous medium are represented by shaped capillary tubes. As far as the author knows, this work models for the first time the unsteady-state laminar flow of Newtonian fluids in angular channels.The fluid distribution or the tail of the flow above the fluid contact (Fig. 1) is governed by the fluid dynamics. Theoretical and numerical simulations of the film/corner flow are conducted for the corner-shapes. The results of this study provide basis for more detailed network models, which describe rock-fluid systems at microscopic level with deterministic solutions. The modeling procedure and results are useful for modeling the performance of gravity dominated improved oil recovery processes, ground water filtration, and water movement in a CO2 plume in CO2 sequestration processes.