Evaluation of Miscible and Immiscible Gas Injection in One of the Iranian Oilfields

A compositional reservoir simulator has been used to determine the reservoir management and production strategies to optimize the oil recovery from an offshore low porosity, low permeability carbonate reservoir with permeability of 1-3 md and porosity of 5-20%. This reservoir is a candidate for an EOR process, because the reservoir production rate has been declined rapidly to about half of the initial production rate within four years. The injection techniques that were used in this study include gas injection with different fluid that it causes miscible and immiscible process. Specific strategy that was used includes the use of injectors and producers. This well configuration has been shown to yield the best oil recovery compared to other well configurations. Simulation results show that the most economical method to produce this reservoir is miscible gas injection. This production strategy has resulted in better efficiency and therefore higher oil recovery and good economics.