Kola Superdeep Borehole

The Kola Superdeep Borehole SG-3 (Template:Langx) is the deepest human-made hole on Earth (since 1979), which attained maximum true vertical depth of Template:Convert in 1989.<ref name=SmithMag-2015-02-19>Template:Cite magazine</ref> It is the result of a scientific drilling effort to penetrate as deeply as possible into the Earth's crust conducted by the Soviet Union in the Pechengsky District of the Kola Peninsula, near the Russian border with Norway.

SG (СГ) is a Russian designation for a set of superdeep (Template:Langx) boreholes conceived as part of a Soviet scientific research programme of the 1960s, 1970s and 1980s. Aralsor SG-1 (in the Pre-Caspian Basin of west Kazakhstan) and Biyikzhal SG-2 (in Krasnodar Krai), both less than Template:Convert deep, preceded Kola SG-3, which was originally intended to reach Template:Convert deep.<ref name="Alekseyev_et_al_1972">Template:Cite journal</ref> Drilling at Kola SG-3 began in 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A total of five Template:Convert boreholes were drilled, two branching from a central shaft and two from one of those branches.

In addition to being the deepest human-made hole on Earth, Kola Superdeep Borehole SG-3 was, for almost three decades, the world's longest borehole in measured depth along its bore, until surpassed in 2008 by a hydrocarbon extraction borehole at the Al Shaheen Oil Field in Qatar.<ref>Template:Cite news</ref>

Drilling

Kola Superdeep Borehole, commemorated on a 1987 USSR stamp

Drilling at Kola SG-3 began on 24 May 1970 using the Uralmash-4E, a serial drilling rig used for drilling oil wells. The rig was slightly modified to be able to reach a Template:Convert depth. In 1974, the new purpose-built Uralmash-15000 drilling rig was installed onsite, named after the new target depth, set at Template:Convert.<ref name=Королев-2016-08-06>Template:Cite web</ref>

On 6 June 1979, Kola SG-3 broke the world depth record<ref name="Lobanov_etal_2021">Template:Cite journal</ref> then held by the Bertha Rogers hole in Washita County, Oklahoma, United States, at Template:Convert.<ref>Template:Cite news</ref> In October 1982, Kola SG-3's first hole reached Template:Convert.<ref name=Яковлев-Скуфьин-Чвыков-2014>Template:Cite periodical</ref>

The second hole was started in January 1983 from a Template:Convert depth of the first hole.<ref name=Королев-2016-08-06/> In 1983, the drill passed Template:Convert in the second hole, and drilling was stopped for about a year for numerous scientific and celebratory visits to the site.<ref name="NiZ" /> This idle period may have contributed to a breakdown after drilling resumed; on 27 September 1984, after drilling to Template:Convert, a Template:Convert section of the drill string twisted off and was left in the hole. Drilling was restarted in September 1986, Template:Convert from the first hole.<ref name="NiZ">Template:Cite web</ref><ref name=Яковлев-Скуфьин-Чвыков-2014/>

The third hole reached Template:Convert in 1989.<ref>Template:Cite magazine</ref> In that year, the hole depth was expected to reach Template:Convert by the end of 1990 and Template:Convert by 1993.<ref>Template:Cite news</ref><ref>Template:Cite web</ref>Template:Failed verification In June 1990, a breakdown occurred in the third hole at Template:Convert of depth.

The drilling of the fourth hole was started in January 1991 from Template:Convert of depth of third hole. The drilling of the fourth hole was stopped in April 1992 at Template:Convert of depth.

Drilling of the fifth hole started in April 1994 from Template:Convert of depth of the third hole. Drilling was stopped in August 1994 at Template:Convert of depth due to lack of funds, and the well itself was mothballed.<ref name=Яковлев-Скуфьин-Чвыков-2014/><ref name=Khokhlova-2008-10-15/>

Research

The stated areas of study of the Kola Superdeep Borehole 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. Drilling penetrated about a third of the way through the Baltic Shield of the continental crust, estimated to be around Template:Convert deep, reaching Archean rocks at the bottom.<ref>Template:Cite book</ref> Numerous unexpected geophysical discoveries were made:

• During the drilling process, the expected basaltic layers at Template:Convert down were never found, nor were basaltic layers at any depth.<ref name="Andrei">Template:Cite web</ref> There were instead more granites, deeper than predicted. The prediction of a transition at 7 kilometres was based on seismic waves indicating discontinuity, which could have been caused by a transition between rocks, or a metamorphic transition in the granite itself.<ref name="Andrei"/>
• Water pooled Template:Convert below the surface,<ref name="Andrei"/><ref name="95/01953">Template:Cite journal</ref> having percolated up through the granite until it reached a layer of impermeable rock.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> This water did not naturally vaporize at any depth in the borehole.<ref name="95/01953" />
• The drilling mud that flowed out of the hole was described as "boiling" with an unexpected level of hydrogen gas.<ref>Template:Cite book</ref>
• Microscopic plankton fossils were found Template:Convert below the surface.<ref name=SmithMag-2015-02-19/>

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 the United Kingdom, the University of Wyoming in the United States, and the University of Bergen in Norway, as well as several Russian earth science research institutions.<ref> Template:Cite journal </ref> The experiment was documented in a video recorded by Professor David Smythe,<ref> Template:Cite AV media </ref> which shows the drilling deck in action during an attempt to recover a tool dropped down the hole.

Status

Template:Multiple image The drilling ended in 1995 due to a lack of funding.<ref name="Khokhlova-2008-10-15">Template:Cite web</ref> The scientific team was transferred to the federal state unitary subsidiary enterprise "Kola Superdeep," downsized, and given the new task of thoroughly studying the exposed section.<ref name=Яковлев-Скуфьин-Чвыков-2014/> In 2007, the scientific team was dissolved and the equipment was transferred to a private company and partially liquidated.<ref name=Яковлев-Скуфьин-Чвыков-2014/>

In 2008, the company was liquidated due to unprofitability,<ref>Template:Cite news</ref> and the site was abandoned. It is still visited by sightseers, who report that the structure over the borehole has been partially destroyed or removed.<ref name="AO">Template:Cite web</ref>

Similar projects

• The United States had embarked on a similar project in 1957, dubbed Project Mohole, which was intended to penetrate the shallow crust under the Pacific Ocean off Mexico. After initial drilling, the project was abandoned in 1966 when funding was cut off. This program inspired the Ocean Drilling Program, Integrated Ocean Drilling Program, and the present International Ocean Discovery Program.
• The KTB superdeep borehole (German Continental Deep Drilling Programme, 1987–1995) at Windischeschenbach in northern Bavaria was drilled to a depth of Template:Convert, reaching temperatures of more than Template:Convert. Its ambitious measuring program used high-temperature logging tools that were upgraded specifically for KTB.<ref>

Template:Cite journal</ref>

• In 2023, China embarked on a Template:Convert super-deep borehole in the Tarim Basin in the Xinjiang region for scientific, oil and gas exploration.<ref name="Cheung2023">Template:Cite web</ref><ref name="Sharma2023">Template:Cite web</ref><ref name="SkyNews2023">Template:Cite web</ref> In March 2024, drilling of the borehole, which is known as Shendi Take 1, reached a depth of 10,000 metres.<ref>Template:Cite web</ref>

Records

The Template:Convert deep Kola Superdeep Borehole has been the world's deepest borehole since 1979.<ref name=SmithMag-2015-02-19/><ref> Template:Cite web </ref> It was also the longest borehole in the world from 1979 to 2008. Its record length was surpassed in May 2008 by the curved extended reach drilling bore of well BD-04A in the Al Shaheen Oil Field in Qatar, which attained a total length of Template:Convert but depth of just Template:Convert.<ref> Template:Cite press release </ref><ref> Template:Cite news </ref>

See also

• Template:Annotated link, based on true events at Kola Borehole
• Template:Annotated link, deep oceanic drilling ship, which achieved a subsea drilling record in 2012
• Template:Annotated link, covers the lowest point on land
• Template:Annotated link
• Template:Annotated link
• Template:Annotated link
• Template:Annotated link
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• Vertical seismic profile — relevant seismic measurements
• Template:Annotated link

Further reading

• Template:Cite book
• Template:Cite book

External links

• Official Kola Superdeep Borehole website Template:In lang
• The World's Deepest Hole – Alaska Science Forum – July 1985
• The Deepest Hole 20 June 2006
• Kola Superdeep – Scientific research results and experiences by PhD A. Osadchikh 1984 Template:In lang
• Photo report on a trip to the Kola superdeep well in 2017. Many photos of the current state. Template:In lang