Experimental studies of steam-propane injection for the Duri intermediate crude oil

Abstract

Laboratory experimental studies were carried out to better understand production mechanisms involved in steam-propane injection and to investigate effects of expected field pressure and temperature conditions on steam-propane injection for the intermediate Duri crude oil. The experiments involved injecting steam or a mixture of steam and propane into a cell in which was tamped a mixture of sand, oil and water. The cell was placed inside a vacuum jacket set at a reservoir temperature of 100⁰F. Superheated steam at 500⁰F was injected at 5.5 ml/min (cold-water equivalent) while the cell outlet pressure was maintained at 500 psig. Five propane:steam mass ratios were used, namely, 0:100 (pure steam), 1.25:100, 2.5:100, 3.75:100, and 5:100. Produced liquids were collected from the bottom of the cell and analyzed to determined oil and water volume as well as density and viscosity after being treated to break the emulsion. The main results of the study are as follows. First, with steam-propane injection, oil production accelerated by 30% in the best case compared to that with pure steam injection. In the field, this translates into early revenue and shorter injection periods and thus lower injection cost. Second, steam injectivity with steam-propane injection was up to three times higher than that with pure steam injection, and the improvement in oil acceleration and injectivity was observed even with propane:steam mass ratio as low as 1.25:100.