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Hydrocarbon in Caspian Sea

Caspian Sea is divided into three regions in terms of oil and gas reserves: Northern, Middle and Southern Caspian.

The Northern-Middle boundary is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle-Southern boundary is the Apsheron Threshold, a sill of tectonic origin between the Eurasian continent and an oceanic remnant that runs through Zhiloi Island and Cape Kuuli. The Garabogazköl Bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus that cuts it off from the Caspian.

The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5-6 meters (16-20 ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 meters (620 ft). The Southern Caspian is the deepest, with oceanic depths of over 1,000 meters (3,300 ft). The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in the winter and in the coldest winters ice forms in the south, as well.

Based on the geologic reach of the Caspian basins, this report considers the North Caucasus oblast (province) to be the only part of Russia in the Caspian region. Although Iran abuts the Caspian Sea and is one of the Caspian's coastal countries, this report will focus mainly on offshore Iranian assets, since geologically the Caspian ends at the northern tip of Iran. Iran's main centers of oil and natural gas production are far removed from both the Caspian basins and the regional energy infrastructure network.