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The U.S. Geological Survey estimated means of 1.8 billion barrels of recoverable oil, 223 trillion cubic feet of recoverable gas, and 6 billion barrels of natural gas liquids in the Nile Delta Basin Province using a geology-based assessment methodology.
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Introduction
The U.S. Geological Survey (USGS) estimated the
undiscovered oil and gas resources of the Nile Delta Basin
Province as part of a program aimed at estimating the
recoverable oil and gas resources of priority basins around
the world. The province encompasses approximately
250,000 square kilometers of the eastern Mediterranean
area (fig. 1). It is bounded to the west by the approximate
edge of the Nile Cone, to the north by the Strabo, Pytheus,
and Cyprus Trenches, to the east by the Levant Basin Province
boundary, and to the south by the approximate edge of
compressional structures in northern Egypt (Robertson, 1998;
Roberts and Peace, 2007), which also corresponds to the
general updip limit of Neogene deltaic strata in Egypt. This
assessment was based on published geologic information
and on commercial data from oil and gas wells, fields, and
field production. The USGS approach is to define petroleum
systems and geologic assessment units and assess the potential
for undiscovered oil and gas resources.
Composite Petroleum System & Assessment Unit
The Mesozoic-Cenozoic Composite Petroleum System
was defined to include the possibility of viable source rocks
of Jurassic, Cretaceous, Oligocene, Miocene, Pliocene,
and Pleistocene ages (Abdel Aal and others, 2000, 2001;
Dolson and others, 2001a, b; Vandre and others, 2007). Four
assessment units (AU) were defined geologically within
the composite petroleum system. Two of the assessment
units-Eratosthenes Seamount AU and Mediterranean Ridge
AU-were defined northward of the Nile Cone but were not
quantitatively assessed. The two assessed areas are the Nile
Cone AU and Nile Margin Reservoirs AU (figs. 1 and 2).
Oil and Gas Source Rocks
Oil and gas were generated from multiple Mesozoic and
Cenozoic sources including: (1) hypothesized Jurassic marine
and terrigenous shale; (2) Cretaceous argillaceous shales
and limestones; (3) Oligocene and Miocene terrigenous
source rocks; and (4) possibly biogenic sources (Vandre and
others, 2007). Source rocks are thermally mature in deeper
parts of the province (Abu El-Ella, 1990; Shaaban and
others 2006).
Oil and Gas Reservoirs
Petroleum charge is confirmed by more than
100 producing fields, numerous oil seeps, mud volcanoes,
and gas chimneys imaged on seismic profiles (Loncke and
others, 2004). Reservoirs are Mesozoic to Paleogene carbonate
and clastic reservoirs and Neogene-Quaternary deltaic,
nearshore marine, deep-water slope channel, and sheet and
fan sandstones (Cross and others, 2009; Samuel and others,
2003) and Messinian-age (latest Miocene) incised-valley-fill
deposits (Dolson and others, 2001a). Traps are structural and
stratigraphic with numerous modifications because of inversion,
salt removal, normal faults, growth faults, and mass
transport (Loncke and others, 2006). Migration was enhanced
by major intersecting fault systems. Lithologic and diagenetic
seals were effective in creating pressure compartments
(Nashaat, 1998).
The Nile Margin Reservoirs AU is assumed to be
sourced from deeper thermally mature source rocks, but
currently only one oil field of minimum size is present in the
AU. The Nile Cone AU is thought to be sourced mainly from
thermally mature Neogene deltaic source rocks, but also there
might be a significant biogenic gas component (Vandre and
others, 2007). The Nile Cone AU contains two oil fields and
126 gas fields.
Geologic Model - Nile Delta Basin
The geologic model used in the assessment of the
Nile Delta Basin was derived from comparison of geologic
analogs, oil and gas production data, proved reserves, and
potential oil and gas resources for the maturely explored
Niger Delta Province (Brownfield and others, 2010). The
USGS used a minimum undiscovered field size of 5 million
barrels of oil equivalent (MMBOE).
Assessment Results
Estimates of volumes of undiscovered technically
recoverable oil and gas resources are shown in table 1.
The mean of the distribution for undiscovered oil is about
1,763 million barrels of oil (MMBO), with a range from
491 MMBO to 4,266 MMBO. For undiscovered gas, the
total mean volume is 223,242 billion cubic feet of gas
(BCFG), with a range from 92,614 to 425,935 BCFG. For
natural gas liquids, the total mean volume is 5,974 million
barrels of natural gas liquids (MMBNGL), with a range of
2,451 to 11,464 MMBNGL. By far the largest resource is
estimated to be in the Nile Cone AU, with a mean volume of
217,313 BCFG and 5,789 MMBNGL. These estimates represent
technically recoverable oil and gas resources; no attempt
was made to estimate economically recoverable resources.
References Cited
Abu El-Ella, Ramadan, 1990, Maturation history of Neogene-
Quaternary sediments, Nile Delta Basin, Egypt: American
Association of Petroleum Geologists Bulletin, v. 74, no. 1,
p. 77-84.
Abdel Aal, A., El Barkooy, A., Gerrits, M., Meyer, H.,
Schwander, M., and Zaki, H., 2000, Tectonic evolution of
the eastern Mediterranean Basin and its significance for the
hydrocarbon prospectively in the ultra-deepwater of the Nile
Delta: The Leading Edge, October 2000, p. 1086-1102.
Abdel Aal, Ahmed, El Barkooky, Ahmed, Gerrits, Marc, Meyer,
Hans-Jurg, Schwander, Marcus, and Zaki, Hala, 2001,
Tectonic evolution of the eastern Mediterranean Basin and
its significance for the hydrocarbon prospectively of the Nile
Delta deepwater area: GeoArabia, v. 6, no. 3, p. 363-384.
Barber, P.M., 1981, Messinian subaerial erosion of the proto-
Nile Delta: Marine Geology, v. 44, p. 253-272.
Brownfield, M.E, Charpentier, R.R., Cook, T.A., Klett, T.R., Pitman,
J.K., Pollastro, R.M., Schenk, C.J., and Tennyson, M.E., 2010,
Assessment of undiscovered oil and gas resources of four West Africa
geologic provinces: U.S. Geological Survey Fact Sheet 2010-3006, 2 p.
Cross, N.E., Cummingham Alan, Cook, R.J., Taha, Amal, Esmaie, Eslam,
and El Swidan, Nasar, 2009, Three-dimensional seismic geomorphology
of a deep-water slope-channel system: The Sequoia field, offshore west
Nile Delta, Egypt: American Association of Petroleum Geologists, v. 93,
no. 8, p. 1063-1086.
Dolson, J.C., Shann, M.V., Matbouly, Sayed, Harwood, Colin, Rashed,
Rashed, and Hammouda, Hussein, 2001a, in Downey, M.W., Threet, J.C.,
and Morgan, W.A., eds., The petroleum potential of Egypt: Petroleum
provinces of the twenty-first century: American Association of Petroleum
Geologists Memoir No. 74, p. 453-482.
Dolson, J.C., Shann, M.V., Matbouly, S.I., Hammouda, Hussein, and Rashed,
R.M., 2001b, Egypt in the twenty-first century: petroleum potential in
offshore trends: GeoArabia, v. 6, no. 2, p. 211-230.
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| Figure 1. Location of four assessment units in the Nile Delta Basin Province in the eastern Mediterranean. (Map not definitive for political
boundaries.) USGS image. Enlarge Map |
| Figure 2. Schematic geologic cross section of the Nile Delta Basin Province illustrating the geologic definition of three of the four assessment units (AU) in this study (dotted red lines): Nile Margin Reservoir AU, Nile Cone AU, and Eratosthenes Seamount AU. The fourth AU, Mediterranean Ridge, is out of the plane of the cross section. Modified from Barber (1981) and Abdel Aal and others (2000). Location of projected section shown in figure 1. 1, Miocene (post-Messinian) and Pliocene-Quaternary; 2, Messinian Salt; 3, Miocene (pre-Messinian); 4, Paleogene-Cretaceous; 5, hypothesized pre-Cretaceous; 6, Eratosthenes Seamount. USGS image. Enlarge Image |
| Table 1. Nile Delta Basin Province assessment results. [MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For gas accumulations, all liquids are included as NGL (natural gas liquids). Undiscovered gas resources are the sum of nonassociated and associated gas. F95 represents a 95 percent chance of at least the amount tabulated; other fractiles are defined similarly. Largest expected oil field in MMBO; largest expected gas field in BCFG. TPS, total petroleum system; AU, assessment unit. Gray shading indicates not applicable]. Enlarge Table |
For Further Information
A publication detailing the geology and the methodology for the Nile
Basin Province assessment is in progress. Assessment results are
available at the USGS Energy Program website, http://energy.cr.usgs.gov/oilgas/
Nile Delta Basin Province Assessment Team
Mark A. Kirschbaum (mkirsch@usgs.gov), Christopher J. Schenk, Ronald
R. Charpentier, Timothy R. Klett, Michael E. Brownfield, Janet K.
Pitman, Troy A. Cook, and Marilyn E. Tennyson.
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