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The eight conventional assessment units of the eastern Mediterranean. U.S. Geological Survey.
The estimate
Using a geology-based method, the U.S. Geological Survey (USGS) estimates mean undiscovered, technically recoverable resources of 879 million barrels of conventional oil and 286.2 trillion cubic feet of conventional gas in the eastern Mediterranean. The assessment covers the Levantine Basin, the Eratosthenes Platform, the Nile Delta Basin, the Herodotus Basin and the Mediterranean Ridge.
How the region formed
The eastern Mediterranean's complex history is still being studied.
- Triassic–Jurassic: the African-Arabian plate rifted from Eurasia, stretching continental crust under the Levantine and Nile Delta Basins; oceanic crust formed in the Herodotus Basin and Mediterranean Ridge as the Tethys Ocean opened. Major source rocks were laid down on the margins in the Late Jurassic.
- Cretaceous: a passive margin, with carbonate platforms and sand and mud building out over the stretched crust. The Eratosthenes Platform, a fragment split from Africa-Arabia, moved north as oceanic crust sank beneath Eurasia, forming the Mediterranean Ridge accretionary complex. Changing sea levels stacked carbonate platforms on its margins, and marine source rocks formed in the Cretaceous and Paleogene.
- Paleogene–Miocene: Africa-Arabia's northward drift began closing the Tethys. From the Oligocene and early Miocene, the ancestral Nile poured sediment north into the basins. In the Miocene, Eratosthenes collided with the Cyprus arc and was lifted, exposed and eroded into karst.
- Late Miocene: the Tethys seaway closed at Gibraltar, and the Mediterranean dried up, leaving hundreds of meters of Messinian salt. Salt seals reservoirs, forms traps beside salt structures, and, where it moved, opens paths for fluids into post-salt reservoirs.
- Neogene: the growing Nile Delta kept building out into the basin.
Systems and units
USGS defined three total petroleum systems (TPS) with eight assessment units (AUs):
| Petroleum system | Assessment units | Geologic model |
|---|---|---|
| Mesozoic–Cenozoic Composite (Levantine Basin) | Mesozoic Reservoirs; Sub-Salt Cenozoic Reservoirs; Post-Salt Cenozoic Reservoirs | oil and gas in sandstone and carbonate traps, oil toward the east; sub-salt oil and gas; gas migrating up faults past the salt, or biogenic gas above it |
| Mesozoic–Cenozoic Composite (Nile Delta Basin) | Mesozoic–Paleogene Reservoirs; Neogene Reservoirs; Eratosthenes Platform Reservoirs | oil and gas in rift-age carbonate and sandstone; gas and minor oil in deltaic, slope-channel, fan and Messinian valley sands; gas in karst and reefs on the platform's edges |
| Cenozoic (Mediterranean Basin) | Herodotus Basin Reservoirs; Mediterranean Ridge Reservoirs | biogenic gas in distal Herodotus sands and in faulted Mediterranean Ridge sands — where possibly poor seals added geologic risk |
Results
Fully risked estimates, with the range from a 95% chance (F95) to a 5% chance (F5):
| Resource | Mean | F95–F5 |
|---|---|---|
| Oil | 879 million barrels | 449–1,472 million |
| Gas | 286,174 billion cubic feet (286.2 trillion) | 138,273–494,133 billion |
| Natural gas liquids | 2,207 million barrels (2.2 billion) | 1,247–3,449 million |
Mean gas by unit (billion cubic feet): Nile Delta Basin Neogene 102,792 (plus 336 with its oil); Levantine Basin Sub-Salt Cenozoic 52,222; Eratosthenes Platform 46,181; Nile Delta Basin Mesozoic–Paleogene 33,262 (plus 526); Herodotus Basin 19,352; Levantine Basin Post-Salt Cenozoic 15,059 (plus 27); Levantine Basin Mesozoic 13,817 (plus 157); Mediterranean Ridge 2,443, the one unit rated at a 0.9 probability.
Mean oil by unit (million barrels): Nile Delta Basin Mesozoic–Paleogene 438; Levantine Basin Mesozoic 261; Nile Delta Basin Neogene 135; Levantine Basin Post-Salt Cenozoic 45.
Sources
Based on Assessment of Undiscovered Conventional Oil and Gas Resources in the Eastern Mediterranean Area, 2020, U.S. Geological Survey Fact Sheet 2021–3032, by the USGS Eastern Mediterranean Assessment Team, USGS Publications Warehouse; a work of the United States government in the public domain. The map and the results table were recovered from the fact sheet's PDF; the imported text had lost them.
Licens: CC0 1.0 (allmän egendom) · Bearbetat efter pubs.usgs.gov
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