Kola Superdeep Borehole

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Kola Superdeep Borehole
Кольская сверхглубокая скважина crop.jpg
Superstructure of the Kola Superdeep Borehole, 2007
Kola Superdeep Borehole is located in Russia
Kola Superdeep Borehole
Kola Superdeep Borehole
Location of the borehole in Murmansk Oblast, Russia
Kola Superdeep Borehole is located in Murmansk Oblast
Kola Superdeep Borehole
Kola Superdeep Borehole
Kola Superdeep Borehole (Murmansk Oblast)
LocationPechengsky District
ProvinceMurmansk Oblast
Coordinates69°23′47″N 30°36′36″E / 69.3965°N 30.6100°E / 69.3965; 30.6100Coordinates: 69°23′47″N 30°36′36″E / 69.3965°N 30.6100°E / 69.3965; 30.6100
TypeScientific borehole
Greatest depth12,262 metres (40,230 ft; 7.619 mi)
  • 1970–1983
  • 1984
  • 1985–1992

The Kola Superdeep Borehole (Russian: Кольская сверхглубокая скважина, romanizedKol'skaya sverkhglubokaya skvazhina) is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, near the Russian border with Norway, on the Kola Peninsula. The project attempted to drill as deep as possible into the Earth's crust.

Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig, and it became the deepest man-made hole in history in 1979. The 23-centimetre (9 in) diameter boreholes were drilled by branching from a central hole.[1] The deepest, SG-3, reached 12,262 metres (40,230 ft; 7.619 mi) in 1989, the deepest artificial point on Earth.

In terms of true vertical depth, it is the deepest borehole in the world. For two decades it was also the world's longest borehole in terms of measured depth along the well bore, until it was surpassed in 2008 by the 12,289-metre-long (40,318 ft) (7.636 mi) Al Shaheen oil well in Qatar.[2]


Kola Superdeep Borehole, commemorated on a 1987 USSR stamp

The main target depth was set at 15,000 m (49,000 ft). On 6 June 1979, the world depth record held by the Bertha Rogers hole in Washita County, Oklahoma, United States, at 9,583 m (31,440 ft)[3] was broken. In 1983, the drill passed 12,000 m (39,000 ft), and drilling was stopped for about a year for numerous scientific and celebratory visits to the site.[4]

This idle period may have contributed to a breakdown after drilling resumed; on 27 September 1984, after drilling to 12,066 m (39,587 ft), a 5,000 m (16,000 ft) section of the drill string twisted off and was left in the hole. Drilling was later restarted from 7,000 m (23,000 ft).[4]

The hole reached 12,262 m (40,230 ft) in 1989. In that year, the hole depth was expected to reach 13,500 m (44,300 ft) by the end of 1990 and 15,000 m (49,000 ft) by 1993.[5][6] Because of higher-than-expected temperatures at this depth and location, 180 °C (356 °F) instead of the expected 100 °C (212 °F), drilling deeper was deemed unfeasible. The unexpected decrease in density, the greater porosity, and the unexpectedly high temperatures caused the rock to behave somewhat like a plastic, making drilling nearly impossible.[7] Drilling was terminated in 1992.[4]


The Kola Superdeep Borehole penetrated about a third of the way through the Baltic Shield continental crust, estimated to be around 35 kilometres (22 mi) deep, reaching Archean rocks at the bottom.[8] The project has been a site of extensive geophysical examinations. The stated areas of study were the deep structure of the Baltic Shield, seismic discontinuities and the thermal regime in the Earth's crust, the physical and chemical composition of the deep crust and the transition from upper to lower crust, lithospheric geophysics, and to create and develop technologies for deep geophysical study.

To scientists, one of the more fascinating findings to emerge from this well is that no transition from granite to basalt was found at the depth of about 7 km (4.3 mi), where the velocity of seismic waves has a discontinuity. Instead the change in the seismic wave velocity is caused by a metamorphic transition in the granite rock. In addition, the rock at that depth had been thoroughly fractured and was saturated with water, which was surprising. This water, unlike surface water, must have come from deep-crust minerals and had been unable to reach the surface because of a layer of impermeable rock.[9]

Microscopic plankton fossils were found 6 kilometers (4 mi) below the surface.[1]

Another unexpected discovery was a large quantity of hydrogen gas. The drilling mud that flowed out of the hole was described as "boiling" with hydrogen.[10]

In 1992 an international geophysical experiment obtained a reflection seismic crustal cross-section through the well. The Kola-92 working group consisted of researchers from the Universities of Glasgow and Edinburgh in Scotland, the University of Wyoming in the United States and the University of Bergen in Norway as well as several Russian earth science research institutions.[11] The experiment was documented in a video recorded by Professor David Smythe,[12] which shows the drilling deck in action during an attempt to recover a tool dropped down the hole.


The borehole in 2012
The borehole (welded shut), August 2012

The project was officially terminated in 1995, due to the dissolution of the Soviet Union, and the site has since been abandoned.[13] In 2008 the Russian InfoCentre announced that the borehole was to be destroyed.[14] The site is still visited by curious sightseers, who have reported that the structure over the borehole has been partially destroyed or removed.[7]

Similar projects[edit]


The Kola Superdeep Borehole was the longest and deepest borehole in the world from 1989 to 2008.

In May 2008, the Kola Superdeep Borehole's record length (but not record depth) was surpassed by a curved borehole of the extended reach drilling well BD-04A in the Al Shaheen Oil Field in Qatar, with a total length of 12,289 m (40,318 ft) and a horizontal reach of 10,902 m (35,768 ft).[16][17]

In terms of depth below the surface, the Kola Superdeep Borehole SG-3 retains the world record at 12,262 metres (40,230 ft) reached in 1989, and is still the deepest artificial point on Earth.[18]

See also[edit]


  1. ^ a b "Ask Smithsonian: What's the Deepest Hole Ever Dug?", smithsonian.com, 19 February 2015
  2. ^ Sakhalin-1 Project Drills World's Longest Extended-Reach Well Archived 31 January 2011 at the Wayback Machine
  3. ^ "The KTB Borehole—Germany's Superdeep Telescope into the Earth's Crust" (PDF). Oilfield Review. Archived from the original (PDF) on 19 December 2008. Retrieved 8 April 2009.
  4. ^ a b c A. Osadchy (2002). "Legendary Kola Superdeep". Наука и жизнь (Journal of Science and Life) (in Russian). Retrieved 8 May 2009.
  5. ^ Kola Superdeep is in the Guinness Book of World Records, Zemlya i Vselennaya, 1989, no. 3, p.9 (in Russian)
  6. ^ Cassino, Adam (2003). "Depth of the Deepest Drilling". The Physics Factbook.
  7. ^ a b [1] Kola Superdeep Borehole, Murmansk, Russia (Atlas Obscura, accessed 14 August 2020)
  8. ^ Ramberg, I.B.; Bryhni I. & Nøttvedt A. (2008). The making of a land: geology of Norway. Geological Society. p. 624. ISBN 978-82-92394-42-7. Retrieved 27 January 2010.
  9. ^ Alan Bellows (5 March 2007). "The Deepest Hole". Damn Interesting. Retrieved 27 December 2014.
  10. ^ G. J. MacDonald (1988). "Major Questions About Deep Continental Structures". In A. Bodén and K. G. Eriksson (ed.). Deep drilling in crystalline bedrock, v. 1. Berlin: Springer-Verlag. pp. 28–48. ISBN 978-3-540-18995-4.
  11. ^ Smythe, D. K.; Smithson, S. B.; Humphreys, C.; Gillen, C.; Kristoffersen, Y.; Karaev, N. A.; Garipov, V. Z.; Pavlenkova, N. I. (1994). "Project images crust, collects seismic data in world's largest borehole" (PDF). Eos, Transactions American Geophysical Union. 75 (41): 473–476. doi:10.1029/94EO01089. ISSN 2324-9250.
  12. ^ [2] Smythe, D. K. (1992). Crustal seismic reflection profiling through the Kola superdeep well, Russia.
  13. ^ Galina Khokhlova (15 October 2008). "Гордость пойдет в утиль: Кольская сверхглубокая скважина будет ликвидирована (Pride goes to waste: Kola superdeep borehole to be scrapped)" (in Russian). Российская Газета (Rossiyskaya Gazeta). Retrieved 9 July 2010.
  14. ^ Kola Superdeep Borehole Will Be Destroyed (10 March 2008)
  15. ^ Emmermann, Rolf; Lauterjung, Jörn (1997). "The German Continental Deep Drilling Program KTB: Overview and major results" (PDF). Journal of Geophysical Research: Solid Earth. 102 (B8): 18179–18201. Bibcode:1997JGR...10218179E. doi:10.1029/96JB03945. ISSN 2156-2202. Archived from the original (PDF) on 30 October 2012.
  16. ^ "Transocean GSF Rig 127 Drills Deepest Extended-Reach Well" (Press release). Transocean Ltd. 21 May 2008. Archived from the original on 12 November 2010. Retrieved 15 November 2010.
  17. ^ "Maersk Oil finished Drilling (BD-04A) well at Al-Shaheen field, Qatar". Gulf Oil & Gas Marketplace. 23 May 2008. Retrieved 15 November 2010.
  18. ^ "Kola Superdeep Borehole (KSDB)". ICDP. Archived from the original on 7 May 2014. Retrieved 21 July 2017.

Further reading[edit]

External links[edit]