Effect of Capillarity and Surface Tension on the performance of VAPEX Process

Abstract

Vapour Extraction process is one of the newest emerging technology for heavy oil reservoirs which is based on the injection of hydrocarbon solvents into viscous oil. Despite the fact that no promising field results have been reported so far about the successfulness of VAPEX process, talking about the application of this method in low permeable rocks seems to be controversial. Although the potential of this process has long been practiced by previous researchers, their predictions are just based on their high permeable systems and there is no attempt to apply this process for so-called tight reservoirs.The scope of this study is to do a profound investigation for finding and understanding the interplay of the involved capillary, gravitational and viscous forces for fluid flow in low permeable systems. A simulation study was carried out with different models of varying capillary pressures. Effect of solvent concentration on gas-oil surface tension and subsequently on residual oil saturation was investigated. Capillary hold-up phenomenon as a problematic issue was studied through block height and capillary number alteration.The results showed that in higher capillary pressure values, the shape of vapor chamber differs from conventional model and it is more piston-like. Residual oil saturation declines as a result of gas-oil interfacial tension reduction by means of solvent concentration alteration. Diluted oil may not be totally produced as a result of capillary hold up. Reservoir height and solvent injection velocity are the key factors which are contributing to this deficiency. Capillary hold up level decreases as the block height and capillary number increase.

Numerical Study of Single Well Vapor Extraction Process

“…The single horizontal well is simulated using discretized wellbore model [40] (released with CMG version 98.01) that accurately represents fluid and heat transfer in the well. The well is divided into two parts whose lengths are equal, and they coincide end to end.…”

Study of Asphaltene and Metal Upgrading in the Vapor Extraction (VAPEX) Process

“…In thermal methods [cyclic steam stimulation (CSS), in situ combustion (ISC), steam-assisted gravity drainage (SAGD)], the viscosity is reduced by heating the reservoir and their problems are the heated loss to adjacent formations. Therefore, non-thermal methods, including vapor extraction (VAPEX) and gas-assisted gravity drainage (GAGD), are preferred …”