Efficient oil displacement near the chamber edge in ES-SAGD

In this paper, we conduct a detailed investigation on oil displacement mechanisms and the placement of solvent near the chamber edge using fine-scale reservoir simulation. The importance of properly considering both phase behavior and flow to design ES-SAGD is demonstrated. Results show that ES-SAGD can achieve a higher displacement efficiency than SAGD. Oil production rate in ES-SAGD can be two times higher than that in SAGD. As a result, the ultimate oil recovery of ES-SAGD is enhanced by almost 20%, compared to SAGD in this research. The oil saturation reduction results from condensed solvent bank and phase transition near the chamber edge. The condensed solvent bank lowers the oil-component concentrations there. The diluted oil with solvent is then redistributed in the gaseous and oleic phases in the presence of the water phase on the phase transition at the chamber edge. The resulting amount of the oleic phase can be significantly small, yielding lowered oil saturations in the ES-SAGD chamber.