U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
The Red Sea Basin Province: Sudr-Nubia(!) and Maqna(!) Petroleum Systems¹
Sandra J. Lindquist, Consultant to
U.S. Geological Survey, Denver, CO
World Energy Project
USGS Open-File Report 99-50-A
The Sudr-Nubia(!) oil-prone total petroleum system dominates the densely explored Gulf of Suez part of the rifted Red Sea Basin Province. Upper Cretaceous to Eocene source rocks, primarily the Senonian Sudr Formation, are organic-rich, areally uniform marine carbonates that have generated known ultimate recoverable reserves exceeding 11 BBOE. The name Nubia is used for sandstone reservoirs with a wide range of poorly constrained, pre-rift geologic ages ranging from Early Paleozoic to Early Cretaceous. Syn- and post-rift Tertiary reservoirs, especially the Kareem Formation, also contain significant reserves.
Partly overlapping Sudr-Nubia(!) is the areally larger and geochemically distinct, oil-and-gas-prone Maqna(!) total petroleum system within the southern Gulf of Suez basin and the sparsely explored remaining Red Sea basin. Known ultimate recoverable reserves are 50-100 MMBOE and more than 900 MMBOE, respectively, in those areas. Both the source and reservoir rocks in this petroleum system are Tertiary, dominantly Miocene, in age. Maqna(!) has the greater potential for future resource development.
As defined for this assessment, the Red Sea Basin Province geographically includes the rifted sedimentary basins under several bodies of water, plus their tectonically related adjacent coastal regions. In this report, the phrases "Gulf of Suez" and "Gulf of Aqaba" refer to the sedimentary basins at the northern end of the province underlying the bodies of water of the same names, plus the appropriate adjacent coastal areas. Similarly, "Red Sea" (without the word "Province") refers to the sedimentary basin beneath the Red Sea water column and its coastal region, exclusive of the Gulf of Suez and Gulf of Aqaba.
The 600,000-sq-km Red Sea Basin Province has two total petroleum systems, Sudr-Nubia(!) (Egyptian nomenclature) and Maqna(!) (Saudi Arabian nomenclature), with 18,000 sq km of overlap along a 300-km distance in the southern Gulf of Suez and adjacent Red Sea (Figure 1 and Figure 2, stratigraphy; Figure 3a, Figure 3b and Figure 3c, maps). Sudr-Nubia(!) is densely explored, but Maqna(!) is not. Tertiary rifting and sea-floor spreading have resulted in sub-basins, with floors of tilted fault blocks, containing temporally and regionally variable thermal gradients. Areas of active source rock are discontinuous and are located within grabens or on horsts that have high thermal gradients. Oil migrated along dip slopes and faults within the last several to ten million years in both petroleum systems. In the Red Sea Basin Province, 95% of all wells drilled and discoveries made are within the 25,000-sq-km Gulf of Suez.
Sudr-Nubia(!) has an approximate 31,000-sq-km area, 73% offshore, covering the Gulf of Suez and extending another 100 km southeast into the northwestern Red Sea. Source rocks are Upper Cretaceous to Eocene marine carbonates that produce a gammacerane-rich oil trapped in reservoir rocks ranging in age from Paleozoic to Tertiary. Maqna(!) is over 400,000 sq km in area. Middle Miocene shale source rocks produce oleanane-rich oils and wet gases trapped primarily in Miocene reservoirs. Eighty-nine percent of Maqna(!) is offshore. Not included within the assessed part of Maqna(!) is the Red Sea axial spreading center, which is less than 5 m.y. old and has an average width ranging from 45 to 75 km and a length of 1880 km. Other potential source rocks exist in Jurassic marine rocks of the northernmost Gulf of Suez and the southernmost Red Sea.
The Red Sea area has significant representation in international scientific literature, with volumes of study, often resulting from regional symposia, periodically published. Primary sources of published information include private and nationalized industry, academia, regional governmental agencies, the Deep Sea Drilling Project and the United Nations Development Program / World Bank. References listed in this report include a limited selection of those most recent and most pertinent to this document. Not all are specifically cited in the text. Petroconsultants (1996), a global data base of exploration and production, forms the basis for most quantitative discussion. The stratigraphic equivalents charts are composited from many references to approximately equate the range of stratigraphic nomenclature in use. They are not intended to be precise with respect to absolute geologic age.
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U.S. Geological Survey Open-File Report 99-50-A