Timan-Pechora Oil-Gas Basin

a region in the Komi ASSR and the Nenets Autonomous Okrug (formerly Nenets National Okrug), Arkhangel’sk Oblast. Total area, 376,000 sq km. The Timan-Pechora oil-gas basin borders on the Volga-Ural oilgas region to the south; to the east, the Urals separate it from the northern part of Tiumen’ Oblast, where extremely rich deposits of natural gas are known. The area has natural-gas, gas-condensate, petroleum, and mixed deposits.

The Timan-Pechora oil-gas basin has 48 oil and natural-gas deposits, of which 41 have been explored and 24 are being worked. Exploration of the region began in 1918 on the initiative of V. I. Lenin. Regular planned investigations were begun in 1928, and in 1930 they bore fruit in the form of an industrial flow of light crude from Devonian deposits (analogous to the Pashiia horizon) in the Chib”iu sector; this was the beginning of the petroleum-refining industry in Ukhta. The Iarega heavy petroleum deposit was discovered in 1932, and in 1937 the first oil well in the USSR was drilled there. In 1935 the Sed”in natural-gas deposit was discovered; natural gas from this deposit and from the Voivozh deposit, discovered in 1943, was shipped through the world’s first suspended gas pipeline, constructed in 1948. In 1959 the Zapadnyi Tebuk petroleum deposit was discovered in the southern part of the Izhma-Pechora depression. Between 1959 and 1974, 26 deposits were discovered in the Timan-Pechora oil-gas basin, of which the Vuktyl and Usinsk deposits have been explored.

The Timan-Pechora oil-gas basin occupies the northeastern section of the Eastern European platform. Its geological structure includes deposits of the Riphean period in the foundation and deposits of all divisions of the Paleozoic and Mesozoic in the sedimentary cover. The structural elements of the sedimentary cover include large arched uplifts (elevations) extending to the north and west—the Timan Ridge and the Pechora-Kozhva, Kolva, and Varandei-Adz’va elevations—and also the Izhma-Pechora, Denisovka, and Khoreiver depressions, which separate the elevations. To the east, the Timan-Pechora oil-gas basin is bordered by the northern part of the Cis-Ural depression.

The oil and gas deposits are associated with seven oil- and gas-bearing complexes: (1) the pre-Middle Devonian (Lower Devonian, Silurian, and Ordovician) complex, with primarily carbonaceous deposits, (2) the Middle Devonian-Lower Frasnian complex, with terrigenous deposits, (3) the Upper Devonian complex, with carbonaceous deposits, (4) the Tournai complex, with terrigenous and carbonaceous deposits, (5) the Visé complex, with terrigenous and carbonate deposits, (6) the Middle Carboniferous-Lower Permian complex, with carbonaceous and terrigenous deposits, (7) the Upper Permian-Triassic complex, with terrigenous deposits. The deposits are mainly of the massive and sheet types. Sheet deposits in the terrigenous deposits are often found in combination with zones of lithologic-stratigraphic wedging-out of productive layers. There are also oil-bearing reefs from the Upper Devonian period. The crests of anticlinal uplifts are usually oil traps.

The petroleums of the region are usually of good quality, with a density of 0.825–0.885 g/cm³, low and medium content of sulfur and paraffin (0.4–6.6 percent), low resin content (rarely high resin content), and a large yield of light fractions. There are two deposits, at Iarega and Usinsk, that contain heavy, viscous petroleum, with a density of 0.936–0.962 g/cm³. The gas deposits contain mostly methane (more than 80 percent) and are rich in heavy hydrocarbons (10–17 percent) and have a high condensate content. The gas-condensate deposits yield 50–500 cu cm of stable condensate per cu m. As of 1975, the yield of the Timan-Pechora oil-gas basin was more than 25 million conventional tons, as opposed to 1.8 million tons in 1958. During this period the Severnoe Siianie (Northern Lights) gas pipeline from Ukhta to Torzhok and an oil pipeline from Usinsk to Yaroslavl were constructed.