Experimental study of Morichal heavy oil recovery using combined steam and propane injection

Abstract

Considerable research and testing have been conducted for the improvement of basic thermal recovery processes and for the development and application of other methods of reservoir heating. Effects of various additives injected simultaneously with steam (for the purpose of increasing steam recovery efficiency) are being evaluated. An experimental study has been performed to investigate the effect of combined steam and propane injection on recovery of heavy oil from the Morichal field, Venezuela. The experiments were conducted using an injection cell packed with sandmix containing a mixture of sand, water, and Morichal oil. Experimental runs involved injection of steam, or propane, or a mixture of steam and propane into the cell at constant rate, temperature, and pressure. The injection was kept constant at 5 g/min for all runs. Five experiments were performed, namely, run 1 (50 wt.% steam and 50 wt.% propane), run 2 (100 wt.% steam), run 3 (75 wt.% steam and 25 wt.% propane), run 4 (100 wt.% propane), and run 5 (95 wt.% steam and 5 wt.% propane). Main findings for this study are as follows. First, it appears possible to accelerate recovery of Morichal oil using combined steam and propane injection. Oil recovery at 61% OOIP may be up to 0.23 pore volume faster than using steam injection alone, with gain in ultimate recovery of up to 5% OOIP. Second, with only propane injection, at temperature and pressure conditions tested, practically no oil is recovered. Steam is necessary to reduce interfacial tension and the oil viscosity, thus allowing propane to permeate through the oil. This increases propane miscibility with oil, further reducing the residual oil saturation, and enhances the displacement efficiency. It is recommended that further research be conducted to confirm the technical and economic feasibility of steam-propane injection, particularly for other crude oil types, and at pressure and temperature conditions encountered in the field.