Assessment of undiscovered conventional oil and gas resources in the eastern Mediterranean area, 2020

Abstract

The U.S. Geological Survey (USGS) quantitatively assessed the potential for undiscovered, technically recoverable conventional oil and gas resources in total petroleum systems and assessment units of the eastern Mediterranean area (fig. 1). The assessment encompasses the geographic areas of the Levantine Basin, Eratosthenes Platform, Nile Delta Basin, Herodotus Basin, and the Mediterranean Ridge. The eastern Mediterranean area developed through a complex tectonic evolution and is the subject of ongoing research (Abdel Aal and others, 2000; Netzeband and others, 2006; Segev and others, 2011; Robertson and others, 2012, Cowie and Kusznir, 2013; Sagy and others, 2015; Granot, 2016; Inati and others, 2016; Segev and others, 2018; Steinberg and others, 2018). The tectonic evolution of the eastern Mediterranean began in the Triassic with rifting of the African-Arabian plate from Eurasia. Rifting continued through the Jurassic, resulting in highly extended continental crust across much of the Levantine Basin and the Nile Delta Basin. Oceanic crust formed in the Herodotus Basin and Mediterranean Ridge as the Tethys Ocean opened. Major sequences of petroleum source rocks were deposited across the continental margins during the Late Jurassic. The Cretaceous was characterized by passive-margin conditions, with carbonate platform development along the extended continental margins, and progradation of clastic sequences across the structurally complex, extended continental crust. The Eratosthenes Platform was one of the continental fragments separated from the African-Arabian plate and moved north as oceanic crust subducted beneath the southern margin of Eurasia, forming the Mediterranean Ridge accretionary complex. Carbonate platforms ranging in age from Cretaceous to Neogene formed along the margins of the Eratosthenes Platform. Repeated sea level changes during this time span led to the development of stacked carbonate platforms. Marine source rocks were deposited during the Cretaceous and Paleogene. Northward movement of the African-Arabian plate in the Paleogene signaled the beginning of closure of the Tethys Ocean. In the Oligocene and early Miocene, the ancestral Nile drainage was established, leading to northdirected clastic deposition in the Levantine Basin, Nile Delta Basin, and Herodotus Basin. The Eratosthenes Platform collided with the Cyprus arc in the Miocene, causing uplift with subsequent subaerial exposure and karst development across the extensive carbonate platforms. In the late Miocene, the northward movement of Africa resulted in closure of the Tethys seaway at Gibraltar and in the complete evaporation of Mediterranean seawater, leading to the deposition of hundreds of meters of late Miocene Messinian evaporites. Evaporites, being impervious to fluids, form important seals, as well as providing traps marginal to the salt structures, and, where salt has moved, provide pathways for fluids to migrate into post-salt reservoirs and traps (Al-Balushi and others, 2016). Neogene development of the Nile Delta depositional system resulted in further progradation of clastic sequences into the eastern Mediterranean area. Total Petroleum Systems and Assessment Units