Experimental Study of Morichal Heavy Oil Recovery Using Combined Steam and Propane Injection

摘要

Laboratory experiments have been conducted to investigaternthe use of propane as a steam additive to enhance productionrnof 13.5°API oil from Morichal field, Venezuela. The mainrncomponent of the apparatus is an injection cell into which isrntamped a sand mix consisting of sand, water, and oil.rnThermocouples placed in the cell enable tracking of the steamrnfront. The cell pressure is set at 50 psig, while superheatedrnsteam at 160℃ is injected at 5 ml/min cold-water equivalentrnat the top of the cell. Produced liquid is collected from thernbottom of the cell, and after emulsion-breaking treatment, oilrnand water volumes are measured.rnExperimental runs have been conducted in which thernpropane:steam mass ratio is varied from 0:100 (steam only) torn5:100. A run using 5:100 nitrogen:steam mass ratio has alsornbeen made to evaluate the contribution of convective heat tornoil production. The main findings of this research (derivedrnfrom four runs with consistent operating conditions) are asrnfollows. First, the propane:steam mass ratio of 5:100rnaccelerates the start and peak of oil production by 20 % and 13rn% pore volume steam injected (cold-water equivalent),rncompared to steam injection alone. In the field, this couldrntranslate into significant gain in discounted revenue andrnreduction in steam injection costs. Second, oil recoveriesrnappear to be similar in all cases, 63 % - 70 % OOIP. Third,rnthe start of production is practically the same for 0:100 andrn1:100 propane:steam ratio and for 5:100 nitrogen:steam ratio,rnindicating probably a minimum propane:steam ratiornrequirement. Fourth, oil production acceleration in the 5:100rnpropane:steam case is probably caused by ‘dry distillation’.rnLast, convective heat transfer at any of these low (5:100)rnratios appears to be of secondary importance. Researchrncontinues to better understand the mechanism and thereafterrnmodel the production of oil under steam-propane injection.