Use of Air with Methane in Cyclic Solvent Injection Applications for Improved Foam Stability and Cost Effective Heavy Oil Recovery

Abstract

The cornerstone of foamy oil behavior during cyclic solvent injection (CSI) is its stability, of which depends on parameters such as oil viscosity, temperature, dissolved gas ratio, pressure decline rate, and dissolved gas (solvent) composition. Although the process has been investigated and analyzed for different parameters in the literature, the optimal conditions for an effective and more economical process (mainly foamy oil stability) has not been thoroughly understood, especially for secondary recovery conditions. In this study, air has been used as an ameliorative to improve foamy oil stability during CSI. Four pressure-depletion tests were performed, each of them consisting of five consecutive cycles. It was observed that increasing pressure-depletion rates increased the formation of foamy oil; however, when pressure-depletion rates were too high, it may have caused a negative effect in the final oil recovery factor by CSI. Injecting air into the sandpack caused an increase in the viscosity of heavy oil, and the subsequent injection of methane as a solvent became more effective in generating a more stable foamy oil, which resulted in obtaining a higher oil recovery factor.

Effects of Pressure and Depressurization Rate of Dissolved CO2 on the Foaming Characteristics of Crude Oil

“…This can prevent the coalescence of microbubbles and enhance their splitting possibility. Basilio and Babadagli 18 conducted four pressure depletion rate experiments to investigate the foam properties. The generation of foamy oil was seen to increase with elevating pressure decline rate, while excessive pressure decline rates may have a damaging effect.…”

An experimental investigation to consider thermal methods efficiency on oil recovery enhancement

“…Regarding the lack of new exploration wells and their high drilling expenditures, to provide sufficient demand, improving the oil recovery percentage is considered an efficient way. It implies that heavy oil reservoirs are considered as significant reservoirs regarding the high potential volumes of oil which are trapped in the cracks and fractures 4‐7 …”

“…significant reservoirs regarding the high potential volumes of oil which are trapped in the cracks and fractures. [4][5][6][7] Approximately most of the volume of 1012 m 3 of the remaining crude oil (especially heavy oil) would be extracted via enhanced oil recovery (EOR) or improved oil recovery (IOR) techniques. The selection of recovery methods would be dependent on the reservoir and rock characteristics, economical and technical aspects of the proposed methods, corrosion issues, etc, which should be taken into consideration before operational performances to virtually eliminate the extra expenses of production operations.…”