West Siberian petroleum basin
The West Siberian petroleum basin (also known as the West Siberian hydrocarbon province or Western Siberian oil basin) is the largest hydrocarbon (petroleum and natural gas) basin in the world covering an area of about 2.2 million km2, and is also the largest oil and gas producing region in Russia.[1]
Geographically it corresponds to the
Beneath lie remnants of the
History
Gas was discovered in 1953 in
Since the early 2010s Russia's state-owned energy company Gazprom has been developing Yamal project in the Yamal Peninsula area. As of 2020, Yamal produces over 20% of Russia's gas, which is expected to increase to 40% by 2030. The shortest pipeline routes from Yamal to the northern EU countries are the Yamal–Europe pipeline through Poland and Nord Stream 1 to Germany.[5] The proposed gas route from Western Siberia to China is known as Power of Siberia 2 pipeline.[6]
Description
Geography
The basin occupies a swampy plain between the Ural Mountains and the
Geology
The basin is a relatively undeformed Mesozoic sag that overlies the Hercynian accreted terrane and the Early Triassic rift system. The basement is composed of foldbelts that were deformed in Late Carboniferous–Permian time during collision of the Siberian and Kazakhstan continents with the Russian craton. The basement also includes several microcontinental blocks with a relatively undeformed Paleozoic sedimentary sequence.
The sedimentary succession of the basin is composed of
Oil and gas reserves
The Western Siberian oil basin is the largest oil and gas producing region in Russia. The oil extracted in this territory accounts 70% of the oil produced in the country.[1]
Three total petroleum systems are identified in the West Siberian basin. Volumes of discovered hydrocarbons in these systems are 144 billion barrels of oil and more than 1,300 trillion cubic feet of gas. The assessed mean undiscovered resources are 55.2 billion barrels of oil, 642.9 trillion cubic feet of gas, and 20.5 billion barrels of
The largest known oil reserves are in the Bazhenov-Neocomian Total Petroleum System that includes Upper Jurassic and younger rocks of the central and southern parts of the basin. Oil reservoirs are mainly in Neocomian and Upper Jurassic clastic strata. Source rocks are organic-rich siliceous shales of the Bazhenov Formation. Most discovered reserves are in structural traps, but stratigraphic traps in the Neocomian clinoform sequence are productive and are expected to contain much of the undiscovered resources. Two assessment units are identified in this total petroleum system. The first assessment unit includes all conventional reservoirs in the stratigraphic interval from the Upper Jurassic to the Cenomanian. The second unit includes unconventional (or continuous), self-sourced, fractured reservoirs in the Bazhenov Formation. This unit was not assessed quantitatively.
The Togur-Tyumen Total Petroleum System covers the same geographic area as the Bazhenov-Neocomian system, but it includes older, Lower–Middle Jurassic strata and weathered rocks at the top of the pre-Jurassic sequence. A Callovian regional shale seal of the Abalak and lower Vasyugan Formations separates the two systems. The Togur-Tyumen system is oil-prone; gas reserves are insignificant. The principal oil reserves are in sandstone reservoirs at the top and bottom of the Lower–Middle Jurassic Tyumen Formation; comparatively small reserves are in pre-Jurassic carbonate and clastic rocks. The principal source rocks are lacustrine to marine shales of the Toarcian Togur Bed. Traps are structural, stratigraphic, or a combination of the two. The total petroleum system was assessed as a single assessment unit. Most of the undiscovered resources are expected in stratigraphic and combination traps.
The northern onshore and offshore parts of the basin are included in the Northern West Siberian Mesozoic Composite Total Petroleum System that encompasses the entire sedimentary cover. The system is strongly gas-prone; it contains giant gas reserves and comparatively small oil reserves. The major part of hydrocarbon reserves is dry gas in the upper Aptian–Cenomanian sandstones (Pokur Formation and equivalents). Smaller reserves of wet gas and some oil are in Jurassic and Neocomian sandstones. Source rocks for the dry gas in the Pokur Formation that constitutes more than 80 percent of the hydrocarbon reserves are unknown. Wet Neocomian gas and oil were generated from Jurassic source rocks, including the Bazhenov Formation.
Almost all discovered reserves are in structural traps; however, stratigraphic traps in the Neocomian interval probably contain large undiscovered gas resources. The onshore and offshore parts of the total petroleum system were assessed as separate units because of different exploration maturity and different infrastructure requirements. The onshore area is substantially explored, especially in the shallow Aptian–Cenomanian sequence, whereas only three exploratory wells have been drilled offshore. Undiscovered gas potential of both assessment units is very high.
See also
- Kara Sea
- Priobskoye field
- Salym Petroleum Development
- Samotlor Field
- Tunguska Basin
- Yamburg gas field
References
- ^ a b Ulmishek, Gregory F. "West Siberian Oil Basin". PetroNeft Resources Plc. Retrieved 22 August 2021.
- ^ "The Siberian Traps - Introduction". University of Leicester.
- ^ "New evidence that Siberian volcanic eruptions caused extinction 250 million yrs ago". Phys.org. 2017.
- ^ a b Ulmishek, G. F., 2003, Petroleum Geology and Resources of the West Siberian Basin, Russia. U.S. Geological Survey Bulletin 2201-G, 49 pp.
- ^ Yermakov, Vitaly (September 2021). Big Bounce: Russian gas amid market tightness (PDF) (Report). Oxford Institute for Energy Studies. Retrieved 1 November 2021.
- ^ "'Power of Siberia 2' Pipeline Could See Europe, China Compete for Russian Gas". VOA News. 18 January 2022.