Laboratory experiments have been conducted to investigate the use of propane as a steam additive to enhance production of 13.5°API oil from Morichal field, Venezuela. The main component of the apparatus is an injection cell into which is tamped a sand mix consisting of sand, water, and oil. Thermocouples placed in the cell enable tracking of the steam front. The cell pressure is set at 50 psig, while superheated steam at 160°C is injected at 5 ml/min cold-water equivalent at the top of the cell. Produced liquid is collected from the bottom of the cell, and after emulsion-breaking treatment, oil and water volumes are measured.

Experimental runs have been conducted in which the propane:steam mass ratio is varied from 0:100 (steam only) to 5:100. A run using 5:100 nitrogen:steam mass ratio has also been made to evaluate the contribution of convective heat to oil production. The main findings of this research (derived from four runs with consistent operating conditions) are as follows. First, the propane:steam mass ratio of 5:100 accelerates the start and peak of oil production by 20 % and 13 % pore volume steam injected (cold-water equivalent), compared to steam injection alone. In the field, this could translate into significant gain in discounted revenue and reduction in steam injection costs. Second, oil recoveries appear to be similar in all cases, 63 % - 70 % OOIP. Third, the start of production is practically the same for 0:100 and 1:100 propane:steam ratio and for 5:100 nitrogen:steam ratio, indicating probably a minimum propane:steam ratio requirement. Fourth, oil production acceleration in the 5:100 propane:steam case is probably caused by 'dry distillation'. Last, convective heat transfer at any of these low (5:100) ratios appears to be of secondary importance. Research continues to better understand the mechanism and thereafter model the production of oil under steam-propane injection.

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