Three-Dimensional Mixed-Wet RandomPore-Scale Network Model of Two-andThree-Phase Flow in Porous Media

摘要

We present a three-dimensional network model to simulatetwo-and three-phase capillary dominated processes at the porelevel. The displacement mechanisms incorporated in the model arebased on the physics of multi-phase flow observed in micromodelexperiments. All the important features of immiscible fluid flow atthe pore-scale, such as wetting layers, spreading layers of theintermediate-wet phase, hysteresis and wettability alteration areimplemented in the model. Wettability alteration allows any valuesfor the advancing and receding oil/water, gas/water and gas/oilcontact angles to be assigned. Multiple phases can be present ineach pore or throat (element), in wetting and spreading layers, aswell as occupying the centre of the pore space. In all, some thirtydifferent generic fluid configurations for two-and three-phaseflow are analyzed. Double displacement and layer reformation areimplemented as well as direct two-phase displacement and layercollapse events. Every element has a circular, square or triangularcross-section. A random network that represents the pore space inBerea sandstone is used in this study. The model computes relativepermeabilities, saturation paths, and capillary pressures for any displacement sequence. A methodology to track a given three-phase saturation path is presented that enables us to comparepredicted and measured relative permeabilities on a point-by-point basis. A new and robust displacement based clusteringalgorithm is presented. We predict measured relativepermeabilities for two-phase flow in a water-wet system. We thensuccessfully predict the steady-state oil, water, and gas three-phase relative permeabilities measured by Oak [1]. We also studysecondary and tertiary gas injection into media of differentwettability and initial oil saturation and interpret the results interms of pore-scale displacement processes. 1.Oak, M. J., 'Three-Phase Relative Permeability of Water-Wet Berea. ' SPE 20183, proceedings of the 7 th SPE/DOEEnhanced Oil Recovery Symposium, Tulsa, Oklahoma, 22-25 April 1990.