The Vapour Extraction Process (VAPEX) for heavy oil recovery is targeted for reservoirs having oil viscosity greater than 10 Pa.s. The pore scale events of heavy oil recovery using the VAPEX process are not yet well developed to the extent of incorporating pore level physics into mathematical models to the point that the observed phenomena can be described mathematically. The primary objective of this paper is to elucidate the pore scale events of gas absorption type of mass transfer during the gravity drainage of live oil in heavy oil reservoirs when employing the VAPEX process by way of documenting pore scale events seen in micromodels of porous media. VAPEX experiments were carried out in micromodels of capillary networks etched on glass saturated with heavy oil, as well as in thin slabs of porous media consisting of glass beads sintered between glass plates and were vapour extracted using butane. The observed phenomena of vapour extraction at the pore scale demonstrate that gravity drainage of heavy oil from a vertically standing heavy oil/VAPEX interface occur in a very thin layer comprised of a monolayer of pores in the direction perpendicular to the interface.
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