Dual-porosity fractured Miocene syn-rift dolomite reservoir in the Issaran Field (Gulf of Suez, Egypt): a case history of the zonal isolation of highly fractured water carrier bed

Abstract

Abstract We describe a fractured dolomite reservoir in the Miocene syn-rift succession of the Gulf of Suez, and the impact of fractures on the increase in the water cut during production from this reservoir and the measures taken to overcome this problem. The Issaran Field includes two dolomite reservoirs (the Upper and Lower Dolomite). The Lower Dolomite reservoir has a highly fractured zone (HFZ) corresponding to a brittle layer that extends down-dip below the highest know water level, allowing the flow of water from the water-wet area to other parts of the reservoir and, thus, causing an increase in the water cut in the wells. Setting an inflatable packer above the HFZ in open holes, perforation above its level in cased holes and reaching total depth of new wells above the HFZ are recommended to decrease the water cut. Accidental hydraulic fractures might develop by steam injection at pressures exceeding rock fracture pressure. These fractures and critically stressed natural fractures allow injected steam to pass laterally through the reservoir along interconnected natural fractures.