The Optimal Conditions for the Immiscible Gas Injection Process: A Simulation Study

Abstract

Recycle-gas injection scheme is a promising recovery process to improve oil and gas production. This method uses continues injection of the produced gas at economical rates to keep the reservoir energy up and using viscous force as driving force. There are numerous studies in the availabale literatures done on recycle-gas injection in conventional reservoirs; however, little is known about implementation of this method in fractured reservoirs. The authors investigate the immiscible recycle-gas injection process in one of the Iranian carbonate naturally fractured reservoirs on a field scale. The real heterogeneous model was constructed and simulated by Eclipse-100 module as a dual porosity/dual permeability model. The effects of operational parameters, such as number and location of injection/production wells, production/injection rate, and completion interva,l on immiscible gas injection performance were evaluated and the result were compared with natural depletion method. It was found that in sensitivity with number of the wells, one injection-two production wells were the most efficient case. Also, oil well production rate of 200 SM3/day and well bottom-hole pressure of 75 bar provided higher oil recovery. Completing the production wells in matrix and injection wells in fracture has a better field oil efficiency in comparison to the other cases. The results showed that the substantial secondary oil recovery can be achieved using optimum conditions for immiscible recycle-gas injection in this reservoir.