The West Siberian artesian basin (also the West Siberian artesian region ) is the largest in the world (“unnaturally large” [1] ) artesian basin with an area of 3 million square kilometers, located on the territory of the West Siberian Plain . The basin includes two hydrogeological floors, separated by a thickness (in places more than 800 m) of clay sediments that fell to the seabed in the Upper Cretaceous - Eocene . The vast oil and gas reserves of Western Siberia are directly related to the aquifers of the lower floor of the basin.
Content
- 1 Geology
- 1.1 Upper floor
- 1.2 Lower floor
- 2 Study
- 3 Resources
- 4 notes
- 5 Literature
Geology
The aquifers of the basin are formed by sedimentary sediments of the Meso- and Cenozoic and rocks of the folded basement of the West Siberian Plate . Meso-Cenozoic aquifers sink and thicken towards the central part of the basin with a decrease in filtration properties.
Upper floor
The aquifers of the upper floor are formed by sediments of the Oligocene , Neogene (in the southern part of the basin) and anthropogen . Groundwater on this floor is supported by active water exchange associated with climate and a hydrographic network on the surface. The central and northern parts of the floor contain mostly fresh water suitable for water supply with a salinity of up to 1.0 g / l (mainly HCO 3 —Ca, HCO 3 —NaCa); continental salinization results in salinity up to 10—5 ° south of 55 ° north latitude. 15 g / l and more diverse chemical composition.
Ground floor
The aquifers of the lower floor are formed by deposits of the Cretaceous and Jurassic periods, as well as the subsurface part of the basement. Groundwater of the second floor comes to the surface only at the edges of the basin, in particular, in the Ob-Yenisei interfluve - it is from here that groundwater reserves are replenished. Fresh water suitable for water supply extends to a depth of several hundred meters (in the Tomsk Region up to 1200 m). Water exchange conditions are deteriorating and mineralization is increasing towards the center of the basin due to the immersion of the layers and an increase in their clay content.
Inside the pool, the waters of the lower floor lie at a depth of more than a kilometer, and can self-flow and gush when opening the aquifers with wells. These regions are characterized by high mineralization of Cl — Na, Cl — Ca — Na, reaching 20-30 g / l, and in the Jurassic deposits and slab base in the northwest of Tomsk and up to 80 g / l (at a depth of 2.5 kilometers ) Highly mineralized waters in the regions of Tobolsk and Surgut often also contain up to 30–40 mg / l of iodine and up to 150–200 mg / l of bromine (and more); the temperature in Maly Atlym and Tobolsk at a depth of 2500–3000 m reaches 100–150 ° С .
Learning
Research on the basin began at the end of the 19th century in connection with the laying of the Siberian Railway and the activities of the Resettlement Department . A detailed study took place in the second half of the 20th century in the process of exploring oil and gas fields and developing virgin lands .
Resources
The pool water resources are:
- natural: about 4800 m³ / s ;
- operating resources (located south of 60 ° north latitude): 1200 m³ / s.
In the center and in the north of the West Siberian artesian region, the West Siberian oil and gas basin is located . The reservoir and fractured waters of the oil and gas basin are under high pressure - from less than 20 to more than 40-45 MPa .
Notes
- ↑ Krotova V. A. Some features of similarities and differences between artesian basins and industrial oil and gas potential . // Soviet geology , No. 7, 1973. P. 74-82.
Literature
- V.A. Vsevolozhsky. West Siberian artesian basin // Great Soviet Encyclopedia : [30 t.] / Ch. ed. A.M. Prokhorov . - 3rd ed. - M .: Soviet Encyclopedia, 1969-1978.
- V.A. Vsevolozhsky. West Siberian artesian region . // BDT
From TSB :
- Mavritsky B.F., West Siberian artesian basin (Hydrogeology, geothermy and paleohydrogeology), Moscow, 1962 (Trud. Laboratory of Hydrogeological Problems named after F.P. Savarensky, vol. 39).
- Geology of the USSR , vol. 44, part 2, M., 1964.
- Hydrogeology of the USSR , t. 16 - West Siberian Plain, M., 1970.