Key challenges to realizing full potential in an emerging giant gas province: Nile Delta/Mediterranean offshore, deep water, Egypt

Abstract

The Nile Delta is an emerging giant gas province with proven reserves of approximately 42 × 10 12 SCF. This resource has more than doubled in the last three years, largely from successful deep water exploration for Pliocene slope-channel systems. Proven reservoirs vary in age from Oligocene through Pleistocene. Source rocks include Jurassic coals and shales and the Lower Miocene condensed Qantara Formation shales. Additional source rocks may be present in condensed intervals of Cretaceous, Oligocene and Eocene age. Following Tethyan rifting and opening of the Mediterranean in the Jurassic, prominent Cretaceous mixed clastic and carbonate shelf edges aggraded vertically along a steep fault-bounded shelf-slope break (the ‘hingeline’) in northern Egypt, which exerts the fundamental control on reservoir distribution in Tertiary age strata. In late Eocene time, northern Egypt was tilted toward the Mediterranean during regional uplift associated with the opening of the Gulf of Suez and Red Sea rifts. Drainage systems shed reservoir quality sediments northward in a series of forced regressions. These regressions culminated in be-heading of the youngest deltas by subaerial erosion during the Messinian salinity crisis. Early Pliocene transgressions laid a thick sealing interval over the low-stand Messinian valley networks. Renewed deltaic deposition began at approximately 3.8Ma. The steep structural hingeline and faulted continental shelf created a large amount of accommodation space with relatively minor progradation of depositional systems. As a result, the primary play consists of slope-channel fairways in all levels. The Pliocene systems are the shallowest targets in the basin and future large reserve growth will come from the pre-Messinian strata. Nile Delta gas resources lie close to emerging and established markets in the Mediterranean. Challenges to capturing the deeper pre-Messinian prize include: establishing favourable economic terms for export and domestic markets; reducing drilling costs and optimization of wellbore patterns to develop multiple stacked objectives; working in deep water and high pressure environments; developing predictive models for pressure regressions in overpressured reservoir fairways; recognizing and exploiting thin bedded low resistivity pay.