Simulation and Study of Various Water Alternating Gas Injection Methods in One of the Fractured Reservoirs in the West of Iran

In the ordinary methods of enhanced oil recovery (EOR), high and inappropriate mobility ratio between the displacing and displacement fluid leads to early gas fingering and reduction of its contact with the reservoir, which in turn may lead to lowered microscopic efficiency. In order to improve and increase contact surface of fluid with reservoir and prevent from gas fingering, water and gas slugs are alternatively injected into reservoir in a method called water alternating gas (WAG) injection. WAG injection is a modern method of EOR, improves and increases sweep efficiency of gas injection by helping to control and decrease the mobility ratio and stability of gas mobility front, through water injection (because a three-phase region). WAG injection in five methods, immiscible, miscible, hybrid, simultaneous and selective simultaneous. In this article, we design injection scenarios and to simulate and study various WAG injection method in a fractured reservoir using GeoQuest commercial software package and ECLIPSE100 module on one I.C.O.F.C. oil reservoir. Then efficiency coefficient, residual oil saturation, daily and total oil production are evaluated to find the optimal injection method in each of the above scenarios. Finally the gas oil ratio (GOR) and water cut by each of injection methods are compared. The results show enhancement of efficiency and production and reduction of residual oil saturation in the method of selective simultaneous WAG injection.