Simulation studies of steam-propane injection for the Hamaca heavy oil field

Abstract

Simulation studies were performed to evaluate a novel technology, steam-propane injection, for the heavy Hamaca crude oil. The oil has a gravity of 9.3⁰API and a viscosity of 25,000 cp at 50⁰C. Two types of simulation studies were performed: a simulation study to history-match laboratory experimental results, and a reservoir simulation study of steam-propane injection in a 5-spot pattern. A 1D 48 grid-cell model was used to describe the sand mix in the injection cell. A ten pseudo-component oil model for the Hamaca oil was developed based on composition up to C₇₊. The ten pseudo-component model used gave a satisfactory history match of the experimental results. Components in the C₇ - C₁₀ range appear to play a significant role during steam-propane injection and therefore need to be described in greater detail. The pseudo-component oil model, developed from history-matching the experimental results, was subsequently used in the reservoir model. The reservoir model represented a symmetry volume that is one-eighth of a 10-acre 5-spot pattern. A 9 x 5 x 10 3D Cartesian model was used to describe the symmetry volume, with one axis (x-axis) oriented parallel to the injector-producer direction. Results of the reservoir simulation study may be summarized as follows. First, oil acceleration of 2 months with a PSR of 0.05 was observed compared to pure steam injection. A substantial gain in discounted revenue and savings in steam injection cost would be realized. Second, unlike the experimental results, the oil production rate peak with steam-propane injection (1100 STB/D) is significantly higher than that with pure steam injection (690 STB/D). Third, oil production acceleration increases with increasing propane content. However, oil recovery at the end of the five-year forecast period increases with PSR up to a PSR of about 0.05 then declines with increasing PSR up to 0.09. More important, oil recovery at the end of the forecast period with PSR of 0.05 is 6.7% OOIP compared to 2.3% OOIP with pure steam injection. Both experimental and simulation studies indicate that steam-propane injection is a very promising technology. Further researches followed by field tests are recommended to better understand and verify the process under actual field conditions.