Numerical simulation study on gas miscibility of anoil field located in Afghanistan

In this study, a reservoir modeling approach was used to evaluate the miscibility conditionsfor an Afghan oil reservoir. A model of slim-tube apparatus was built for compositional simulation in CMG-GEM. Minimum miscibility pressure/enrichment(MMP/MME) ofcrude oil-gas (carbon dioxide, methane and nitrogen) systemswere determined by slim-tube simulation. To study the reservoir performance undereach injection gasprocess, we built a quarter of five spot pattern model. The model was assumed to represent a homogeneous section of the reservoir. Simulation resultsof slim-tube testsuggest that, to be miscible with reservoir oil, carbon dioxide requires less addition of enriched gas comparing to nitrogen ormethane. But,the reservoirsection modelshowed thata miscible nitrogeninjectionis better, with higher oil recovery factor than that of miscible carbon dioxide ormethane.