Koupal oil field is located 60Km in the east of the Ahwaz city. This oil field has two reservoirs known as Asmari and Bangestan. Asmari is shallower than Bangestan and consist of calcite, dolomite, shale and sand. On the other hand, Bangestan is composed of pure calcite with negligible traces of shale in the Ilam formation. Both of the reservoirs have almost around 6 billion oil in place, however their low recovery factor cast doubt on the amount of reserve. Approximate recovery factors are around 10 and 30 percent, respectively for Bangestan and Asmari reservoirs. About 58 wells has been drilled in this field and currently the total production is around 80 MSTB.