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GEOLOGICAL REGULARITIES OF OIL FIELDS LOCATION

World oil reserves according to the age of oil-bearing rocks are distributed as follows:

Upper Paleozoic rocks – about 20%,

Mesozoic rocks – about 60%,

Cenozoic rocks – about 20%.

Deposits of Paleozoic strata. Oil-bearing basins, the deposits of which are concentrated in Paleozoic sediments, are located mainly in the sedimentary cover of ancient platforms with a Precambrian foundation, more often on their margins, bordering Phanerozoic accretionary-fold systems.

On the American continent, about half of the oil reserves of the United States and Canada are concentrated in sedimentary rocks of the Upper Paleozoic (Devonian, Carboniferous, Permian). In the United States, the largest are the Permian (Texas, New Mexico, Oklahoma) and Western Interior (Oklahoma, Texas, Kansas, Iowa, Nebraska, Missouri) oil and gas basins. In the Permian Basin, the main oil reserves are confined to Permian pre-salt sediments, and in the Western Interior - to terrigenous-carbonate rocks of Carboniferous and Permian age. In Canada, the largest is the Western Canadian oil and gas basin, where more than half of the reserves are confined to Devonian reef rocks.

Large oil fields in Devonian and Carboniferous sandstones are located in northern Africa, Algeria and Libya (Sahara-East Mediterranean megabasin).

The largest Tengiz field in Kazakhstan (Caspian basin, Guryev region) is confined to the Lower-Middle Carboniferous reef massif with an area of ​​400 km 2. The height of the deposit is more than 1140 m.

In Russia, oil deposits in Paleozoic rocks are common in the European part, where the fields of the Volga-Ural (Romashkinskoye, Tuymazinskoye, Bavlinskoye, Osinskoye, etc.) and Timan-Pechora (Ukhtinskoye, Yaregskoye, etc.) oil-bearing basins are located. The largest deposits are confined to the Devonian strata and, more often, to their Pashian terrigenous layers. Some of the deposits are localized in rocks of Carboniferous age, mainly in the Tula and Bobrikov layers, as well as in rocks of Permian age.

Deposits of Mesozoic strata. Oil basins, the deposits of which are concentrated in rocks of Mesozoic age, are usually located in the sedimentary cover of young epi-Hercynian platforms, also called plates (Gulf of Mexico, West Siberian basins), as well as on the margins of platforms adjacent to Alpine folded systems (Persian Gulf basin) .

The oil and gas basin of the Gulf of Mexico is located in the depression of the gulf of the same name in the United States, Mexico, Cuba, Guatemala and Belize.

The Persian Gulf basin is confined to the eastern margin of the Arabian Plate in the territory of Iraq and Kuwait Saudi Arabia, UAE, Iran, Syria, Qatar and other countries. The largest deposits of the basin lie predominantly among strata of organogenic limestones and sands of the Upper Jurassic and are distinguished by large reserves and high well production rates. Thus, the most famous gas-oil field of Saudi Arabia, Ghawar, is confined to a swell-like uplift 230 km long and 16–25 km wide and is located in the depth range of 2042–2576 m. The thickness of the productive horizon is 40–45 m. All wells of the field are flowing, the initial flow rate of the wells ranged from 750 to 1500 tons of oil per day, the initial recoverable oil reserves of the field were estimated at 10 billion tons, and gas at 1 trillion. m 3.

Large oil fields are located in the Ural-Emba region of Kazakhstan (Caspian basin) among terrigenous Meso-Cenozoic deposits of salt dome structures.

In Russia, the largest deposits of the West Siberian basin are concentrated in Mesozoic deposits, incl. Samotlor, confined to six local uplifts in the southern part of the Tarkhov swell of the Nizhnevartovsk arch. The thickness of the sedimentary cover in the area of ​​the field is 2700 - 2900 m. Seven oil deposits are located in the depth range of 1610 - 2230 m. They are confined to sandy reservoirs of the pore type of Lower Cretaceous deposits. The deposits of the Tersko-Caspian (Tersko-Dagestan) basin in the region of ᴦ are also associated with Meso-Cenozoic deposits. Grozny.

Deposits of Cenozoic strata. Oil deposits concentrated in Cenozoic sediments gravitate towards areas of Alpine folding. First of all, these are the largest fields of Iran and Iraq in the Mesopotamian Basin (Persian Gulf basin), the United States in the Mexican Basin (Gulf of Mexico basin), as well as the fields of Venezuela (Maracaiba Basin).

Large oil fields are located in Azerbaijan, for example Bibi Heybat (South Caspian basin).

Russian deposits in Cenozoic sediments are known in the North Caucasus (Tersk-Caspian basin), in the Ciscaucasia (North Black Sea basin), on Sakhalin Island and in its waters (Sakhalin-Okhotsk basin).

GEOLOGICAL REGULARITIES OF OIL FIELDS LOCATION - concept and types. Classification and features of the category "GEOLOGICAL REGULARITIES OF OIL FIELDS LOCATION" 2017, 2018.