Comparison of Miscible and Immiscible Gas Injection in Respect of Formation Damage and Displacement Characteristics in Porous Media

This study investigates asphaltene precipitation and deposition due to miscible/immiscible gas injection as well as its impact on rock properties and gas injectivity in one of Iranian southwestern oilfields. Displacement characteristics like GOR, breakthrough time and oil recovery are also studied.According to experiments, induced miscible/ immiscible gas injection permeability impairments are negligible. Therefore, gas injection has no negative impact on the formation regarding asphaltene precipitation and deposition. Ultimate oil recoveries are about 73% and 66% for miscible and immiscible gas injections respectively. These approximate oil recoveries are obtained in laboratory core scale representing microscopic sweep efficiencies then to convert it to field recoveries it should be multiplied by macroscopic ones to be experienced in the field application.