Analysis of three-phase counter-current fluid flow in porous media using a neuro-simulation approach

This work examines the physics of three-phase counter-current fluid flow driven by gravity and capillary transport mechanisms through a combination of experimental measurements and neuro-simulation modeling. There has been very little work reported in the literature addressing counter-current flow, especially under three-phase flow conditions. Counter-current flow driven by gravity and capillarity may occur in fractured reservoirs, both in the matrix and in the fractures, in solution gas drive and gas cap systems with high vertical permeability, and in some water-flooding scenarios.; Three-phase flow experiments were conducted with an ideal system and the temporal and spatial saturation distributions during counter-current flow periods were acquired using computed tomography. The experimental results were simulated using a conventional reservoir simulator. The simulation results provided the basis for training an artificial neural network that provides the best relative permeability and capillary pressure functions that match the experimental data through pattern recognition.; The convectively derived relative permeabilities do not represent well the counter-current flow processes; the counter-current relative permeabilities must be significantly lower than the standard convective ones in order to match the experimental data; the shape of the vertical saturation distribution at equilibrium is similar to the shape of the capillary curve that describes counter-current flow; the capillary pressure curve for counter-current flow does not have the shape of the standard Leverett J function curve. The neuro-simulation model used in the course of this work provides a rapid method to extract the counter-current relative permeabilities and capillary pressure from spatial-temporal experimental x-ray computed tomography (CT) data. The findings of this work may lead to new procedures for modeling systems that have combined co-current convective flow and counter-current gravity and capillary flow.