Visualization of Pore-level Displacement Mechanisms During CO2 Injection and EOR Processes
J. Gauteplass, H.N. Follesø, A. Graue, A.R. Kovscek and M.A. Fernø
Event name: IOR 2013 - 17th European Symposium on Improved Oil Recovery
Session: Fundamental Science behind EOR II
Publication date: 16 April 2013
Info: Extended abstract, PDF ( 1.59Mb )
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Multiphase flow and fluid displacements at pore-level were visualized in two-dimensional micromodels retaining essential characteristics of porous rocks. Microvisual data during CO2 injection for enhanced oil recovery was obtained from high resolution images using UV-sensitive dye to improve contrast. The dominating mechanisms were piston-like displacement of one fluid by another, either by a stable moving interface or through Haines-like jumps. Film thickening, film drainage, snap-off mechanisms and capillary trapping of CO2 were also observed. Both stable and unstable flow regimes were identified as the front advanced through the network during two-phase flow. In the latter regime, instabilities in the displacements were manifested by capillary fingering perpendicular to the main flow direction. Oil was found to be spreading in the water-oil-gas system at the experimental conditions. This led to an efficient oil production at pore-level from CO2 gas injection, even at high water saturation. The injected gaseous CO2 contacted only oil in three-phase systems, and led to direct oil displacement, whereas water was displaced through double or multiple displacement events.