A compositional modeling study is conducted to compare huff-n-puff solvent injection with gas injection in improving oil recovery from shale gas-condensate reservoirs. The solvents used are methanol and isopropanol, and gases are methane and ethane. The model represents a simple 8″X1″ lab scale core model based on a published experimental work. The phase behavior data and relative permeability data are tuned to match the published lab data. Simulation results are analyzed to compare the performance of four injection fluids – methane, ethane, methanol and isopropanol (IPA) based on the recovery of fluids in place in terms of barrel of oil equivalent within the same operation time. Comparisons were made for two reservoir fluids, Fluid A and Fluid B, with the latter having a higher liquid dropout. Recovery mechanisms are also studied for gases and solvents. Ethane injection is a novel idea in this paper and proved to be the best injection fluid on accounts of higher as well as much faster recovery as compared to methane, methanol or isopropanol. This is attributed to ethane being a lighter fluid and aiding in revaporizing the condensate. While this is also true for methane, the most significant difference between the two is that ethane is also able to reduce overall dew point pressure of the mixture, ensuring lower injection volume and time for the same recovery factor.
- Shale condensate reservoir