Effects of temperature on foamy oil flow in solution gas-drive in cold lake field

The roles of foamy oil flow in cold production of heavy oils under solution gas-drive have been extensively studied in recent years. However, the mechanisms of foamy oil flow in porous media are still not fully understood. The viscosities of heavy oils and bitumen are often so high that the solution gas drive should yield very little oil production. However, several heavy oil reservoirs in Canada and Venezuela have displayed very high solution gas drive recovery factors and foamy oil flow is believed to be the cause. The recovery factor projected for steam stimulation operation in Cold Lake is also very high, up to 30% of OOIP. Since the primary drive energy in Cold Lake comes from solution gas drive, it has been suggested that foamy oil flow may be responsible for this high recovery factor. The objective of this work was to examine the effects of temperature on foamy oil flow in a clean sand with Cold Lake oil and methane gas. Solution gas drive experiments were carried out in a sand-pack at several different temperatures and depletion rates. The results show that in isothermal depletion tests, the highest recovery factor does not occur at the highest temperature used. Instead, a much lower optimum temperature exists which provides the highest recovery. The reasons for this appear to be the diminished gas solubility and reduced foamy behaviour at higher temperatures, which counteract the positive influence of reduced viscosity.