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Petroleum geology of the Persian Gulf basin Behrooz Esrafili-Dizaji
MAPSA Co. Petroleum Engineering Department
Embayment (Sepehr et al., 2006). Most of the gas is found in the Permo-Triassic carbonate sequence of the Dehram Group, an equivalent of the Khuff Formation of Arabia situated in the right part of Kazerun fault (Alsharhan and Nairn, 1997). Statistical reviews show that more than 90% of the huge Iranian gas reserves are contained in Permo-Triassic carbonates. Dezful Embayment in the left part of the fault, which is one of the world’s richest oil provinces, containing some 8% of global oil reserves in an area of only 60,000 sq. km (Bordnave and Hegre, 2005).
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The Persian Gulf Basin is an elongate, margin sag-interior sag, sedimentary basin spanning the last 650 Ma along the northeastern subducting margin of the Arabian Plate and is the largest basin with active salt tectonism in the world. This basin is asymmetrical in NE-SW cross section with sediments thickening from 4,500 m near the Arabian Shield to 18,000 m beside the Main Zagros Reverse Fault. In fact, this basin is situated in the offshore of Zagros Fold Belt (Edgell, 1996). The Persian Gulf Basin is the richest region of the World in terms of hydrocarbon resources. According to different estimates, the basin contains 55–68% of recoverable oil reserves and more than 40% of gas reserves (Konyuhov and Maleki, 2006). The Permo-Triassic Khuff gas and Jurassic Arab oil reservoirs are well known in this area.
Three types of reservoir-related positive elements were dominant in this area: (1) broad regional paleohighs (such as Qatar Arch), (2) horsts and tilted fault blocks trending NNE-SSW, and (3) salt domes (sach as Kangan Field structure) (Murris, 1980; Alsharhan and Nairn, 1997). Some 60% of the ultimate recoverable oil reserves of the Persian Gulf Basin originate from salt tectonism, and 40% of the known world oil reserves are, thus, due to salt diapirism in this basin (Edgell, 1996). Two petroleum systems are recognized, sourced by rocks of Silurian and Jurassic-Cretaceous Jurassic-Cretaceous age.
The Qatar Arch (or Kazerun-Qatar Fault) had main effect on depositional and tectonic history, and petroleum systems formation in the Persian Gulf basin. In the most of geological time, this basin separated by Kazerun fault in to major Southern (right part or Fars province) and Northern (West part or Dezful province and its offshore) Persian Gulf Basin. At the base of the sedimentary succession in the Fars region a 1–2 km thick Cambrian salt (the (t he Hormuz Formation) overlies the Precambrian metamorphic basement and acts as the main detachment in this region. It has allowed the deformation to migrate rapidly away from the collision zone resulting in the formation of the t he broad Fars fold belt. In contrast, to the west of the Kazerun Fault Zone the Hormuz salt is absent and the deformation has moved much less rapidly resulting in the formation of the Dezful
1) Lower Total Petroleum System (Sarchahan, Zakeen, Faraghan, Dalan and Kangan and Dashtak Formations): Mostly in right part of basin with gas reserves. 2) Upper Total Petroleum System (Surmeh (Arab), Hith, Fahliyan, Gadvan, Dariyan, Kazhdumi, Sarvak (Mishrif), Ilam, Jahrum, Ghar , Asmari, Pabdeh, Gurpi, Kazhdumi, Garau, Sargelu, Gachsaran Formation): most of oil field in the Northern Persian Gulf basin
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Edgell H.S., 1996. Salt tectonism in the Persian Gulf Basin, Geological Society, London, Special Publications; 1996; v. 100; p. 129-151;
References
Alsharhan, A.S., Naim, A.E.M., 1997. Sedimentary Basins and Petroleum Geology of the Middle East. Elsevier, Netherlands. 843 pp.
Konyuhov, A. I., Maleki, B., 2006. The Persian Gulf Basin: Geological History, Sedimentary Formations, and Petroleum Potential. Lithology and Mineral Resources. 41, 344–361.
Bordenave, M. L., , Hegre, J. A., 2005. The influence of tectonics on the entrapment of oil in the Dezful embayment, Zagros Fold belt, Iran. Journal of Petroleum Geology, Vol. 28(4), October, pp 339 - 368
Murris, R.J., 1980. Middle East: Stratigraphic evolution and oil habitat. American Association of Petroleum Geologists Bulletin 64, 597–618.
Fig. 1) Persian Gulf basin and it's oil and gasfields.
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