Key Challenges to Realizing Full Potentialin an Emerging Giant Gas Province:Nile Delta/Mediterranean Offshore, Deep water, Egypt
A paper given at the HGS International Explorationists Dinner Meeting on 20 September, 2004.
Authors: Paul J. Boucher, John C. Dolson, Philip D. Heppard, BP Houston and Jerry Siok, BP-Egypt.Abstract: The Nile Delta is an emerging giant gas province with proven reserves of approximately 42 TCF with approximately 50 TCF yet to find.. 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/Early Miocene through Pleistocene. Proven 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. This "hingeline" in northern Egypt 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 sealevel lowstand associated with the Messinian salinity crisis. Early Pliocene transgressions deposited a thick sealing interval over the low-stand Messinian valley networks. Renewed deltaic deposition began at approximately 3.8 MA. 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 Plio-Pleistocene systems are the shallowest targets in the basin that hold the majority of proven reserves. Future large reserve growth will come from the pre-Messinian strata.
BP, with partner RWE-DEA recently completed a test of the pre-Messinian slope channel play. The Raven-1 wildcat well was drilled to test an early Miocene slope channel system in the western Nile Delta. The well was drilled in 650 meters of water to a TD 4976 meters TVD. The well tested at a rate of approximately 37.4 million standard cubic feet per day and 740 barrels of condensate per day from lower Miocene channel sands.. The Raven-1 well is being followed by tests of Miocene age strata in the Polaris-1 well.
Nile Delta gas resources lie close to emerging and established markets in the Mediterranean. Challenges to capturing the deeper pre-Messinian prize include:
Establishing favorable 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.
Biographies:
Paul J. Boucher received a B.S. in Geology in 1990 from Salem State College in Salem, Massachusetts and an M.S. in Geophysics from Texas A&M University in1994. At that time Paul joined Amoco in Houston and began working on various projects in support of their operations in Egypt. He moved to Cairo, Egypt in 1998 to work on regional and prospect level mapping projects in the Nile Delta. He joined the BP western Nile Delta team in 2000 and was involved in the discovery of numerous large gas and gas condensate fields on the offshore Nile Delta. His main interests are exploring for hydrocarbons through integrated seismic sequence stratigraphy and petroleum systems analysis. He is currently working in the BP Brazil Deep Water Performance Unit as a senior explorer in the Foz do Amazonas area.
Philip D. Heppard is a geologist with BP in Houston, Texas. Philip received his B.S. in geology from Juniata College, Pennsylvania, in 1977 and his M.S. in geology from the University of Akron, Ohio, in 1984. He joined Amoco in 1979 and has worked as a development geologist in the Permian Basin and Trinidad, West Indies. Since 1988 Philip has been a pore pressure expert supporting BP?s worldwide exploration and development efforts, most recently within their Exploration and Production Technology Group. His interest has been the integration of well and seismic data to predict overpressure in the subsurface for well planning and evaluation of seal quality.