Kola Superdeep Borehole
Encyclopedia
The Kola Superdeep Borehole is the result of a scientific drilling
project of the Soviet Union
in 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. A number of borehole
s were drilled by branching from a central hole. The deepest, SG-3, reached 12262 metres (40,230 ft) in 1989, and is the deepest hole ever drilled, and the deepest artificial point on earth. For two decades it was also the world's longest borehole, in terms of measured depth
along the well bore, until surpassed in 2008 by 12289 m (40,318.2 ft) long Al Shaheen oil well
in Qatar
, and in 2011 by 12,345 metres (40,502 ft) long Sakhalin-I
Odoptu OP-11 Well (offshore the Russia
n island Sakhalin
).
hole in Washita County, Oklahoma
, at 9583 m (31,440.3 ft) was broken. In 1983, the drill passed 12000 m (39,370.1 ft), and drilling was stopped for about a year to celebrate the event. This idle period may have contributed to a break-down on 27 September 1984: after drilling to 12066 m (39,586.6 ft), a 5000 m (16,404.2 ft) section of the drill string twisted off and was left in the hole. Drilling was later restarted from 7000 m (22,965.9 ft). The hole reached 12262 m (40,229.7 ft) in 1989. In that year the hole depth was expected to reach 13500 m (44,291.3 ft) by the end of 1990 and 15000 m (49,212.6 ft) by 1993. However, due to higher than expected temperatures at this depth and location, 180 °C (356 °F) instead of expected 100 °C (212 °F), drilling deeper was deemed unfeasible and the drilling was stopped in 1992. With the expected further increase in temperature with increasing depth, drilling to 15000 m (49,212.6 ft) would have meant working at a projected 300 °C (572 °F), at which the drill bit
would no longer work.
, estimated to be around 35 kilometres (22 mi) deep, reaching rocks of Archaean age (greater than 2.5 billion years old) at the bottom. The project has been a site of extensive geophysical
studies. 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 the change in seismic velocities was not found at a boundary marking Harold Jeffreys
's hypothetical transition from granite
to basalt
; it was at the bottom of a layer of metamorphic rock
that extended from about 5 to 10 kilometers beneath the surface. The rock there 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.
Another unexpected discovery was the large quantity of hydrogen
gas, with the mud flowing out of the hole described as "boiling" with hydrogen.
The project was closed down in late 2005 due to lack of funding. All the drilling and research equipment was scrapped and the site has been abandoned since 2008.
, which was intended to penetrate the shallow crust under the Pacific Ocean
off Mexico
. However, after some initial drilling, the project was abandoned in 1966 due to lack of funding. This failure inspired great successes of the Deep Sea Drilling Project, Ocean Drilling Program
, and the present Integrated Ocean Drilling Program
. The KTB superdeep borehole (German Continental Deep Drilling Program, 1990–1994) was drilled down to a depth of 9101 m (29,859 ft) reaching temperatures of more than 260° Celsius. The ambitious measuring program had to develop high temperature tools like a magnetometer tool.
The Kola Superdeep Borehole was the deepest and longest borehole in the world for nearly 20 years. However, in May 2008, a new record for borehole length was established by the extended-reach drilling (ERD)
well BD-04A, which was drilled by Transocean
for Maersk Oil
in the Al Shaheen oil field
in Qatar
. It was drilled to 12289 m (40,318.2 ft), with a record horizontal reach of 10902 m (35,767.7 ft), in only 36 days.
On January 28, 2011, Exxon Neftegas Ltd., operator of the Sakhalin-I
project, drilled the world’s longest extended-reach well offshore on the Russia
n island of Sakhalin
. It has surpassed the length of both the Al Shaheen well and the Kola borehole. The Odoptu OP-11 well reached a measured total depth of 12345 m (40,502 ft) and a horizontal displacement of 11475 m (37,647.6 ft). Exxon Neftegas completed the well in 60 days.
However, in terms of depth below the surface, the Kola Superdeep Borehole still retains the world record as of 2011.
Scientific drilling
Scientific drilling is a way to probe down into the Earth, allowing scientists and students to obtain samples of sediments, crust, and upper mantle. In addition to rock samples, drilling technology allows humans to obtain samples of connate fluids and of the subsurface biosphere, mostly microbial...
project of the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
in Kola Peninsula
Kola Peninsula
The Kola Peninsula is a peninsula in the far northwest of Russia. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely to the north of the Arctic Circle and is washed by the Barents Sea in the north and the White Sea in the east and southeast...
. The project attempted to drill as deep as possible into the Earth's crust
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
. Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A number of borehole
Borehole
A borehole is the generalized term for any narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid or gases , as part of a geotechnical investigation, environmental site...
s were drilled by branching from a central hole. The deepest, SG-3, reached 12262 metres (40,230 ft) in 1989, and is the deepest hole ever drilled, and the deepest artificial point on earth. For two decades it was also the world's longest borehole, in terms of measured depth
Measured depth
In the oil industry measured depth , is the length of the borehole, line in the image, and is measured in feet or metres...
along the well bore, until surpassed in 2008 by 12289 m (40,318.2 ft) long Al Shaheen oil well
Al Shaheen oil field
The Al Shaheen Oil Field is a production oil and gas field off the north east of coast of Qatar in the Persian Gulf, north of Doha. The oil field lies over the North Gas Field, the largest gas field in the world...
in Qatar
Qatar
Qatar , also known as the State of Qatar or locally Dawlat Qaṭar, is a sovereign Arab state, located in the Middle East, occupying the small Qatar Peninsula on the northeasterly coast of the much larger Arabian Peninsula. Its sole land border is with Saudi Arabia to the south, with the rest of its...
, and in 2011 by 12,345 metres (40,502 ft) long Sakhalin-I
Sakhalin-I
The Sakhalin-I project, a sister project to Sakhalin-II, is a consortium to locate and produce oil and gas on Sakhalin Island and immediately offshore, in the Okhotsk Sea, from three fields: Chayvo, Odoptu, and Arkutun-Dagi....
Odoptu OP-11 Well (offshore the Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n island Sakhalin
Sakhalin
Sakhalin or Saghalien, is a large island in the North Pacific, lying between 45°50' and 54°24' N.It is part of Russia, and is Russia's largest island, and is administered as part of Sakhalin Oblast...
).
Drilling
The initial target depth was set at 15000 m (49,212.6 ft). On 6 June 1979, the world depth record held by the Bertha RogersBertha Rogers
The GHK Co. 1–27 Bertha Rogers hole or well was an oil-exploratory hole drilled in Washita County, Oklahoma in 1974, and was formerly the world's deepest hole until surpassed by the Kola Superdeep Borehole, dug by the former USSR....
hole in Washita County, Oklahoma
Washita County, Oklahoma
Washita County is a county located in the U.S. state of Oklahoma. As of 2000, the population was 11,508. Its county seat is New Cordell. It was formerly located in Cloud Chief, Oklahoma....
, at 9583 m (31,440.3 ft) was broken. In 1983, the drill passed 12000 m (39,370.1 ft), and drilling was stopped for about a year to celebrate the event. This idle period may have contributed to a break-down on 27 September 1984: after drilling to 12066 m (39,586.6 ft), a 5000 m (16,404.2 ft) section of the drill string twisted off and was left in the hole. Drilling was later restarted from 7000 m (22,965.9 ft). The hole reached 12262 m (40,229.7 ft) in 1989. In that year the hole depth was expected to reach 13500 m (44,291.3 ft) by the end of 1990 and 15000 m (49,212.6 ft) by 1993. However, due to higher than expected temperatures at this depth and location, 180 °C (356 °F) instead of expected 100 °C (212 °F), drilling deeper was deemed unfeasible and the drilling was stopped in 1992. With the expected further increase in temperature with increasing depth, drilling to 15000 m (49,212.6 ft) would have meant working at a projected 300 °C (572 °F), at which the drill bit
Drill bit
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
would no longer work.
Research
The Kola borehole penetrated about a third of the way through the Baltic continental crustContinental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
, estimated to be around 35 kilometres (22 mi) deep, reaching rocks of Archaean age (greater than 2.5 billion years old) at the bottom. The project has been a site of extensive geophysical
Geophysics
Geophysics is the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and...
studies. The stated areas of study were the deep structure of the Baltic Shield
Baltic Shield
The Baltic Shield is located in Fennoscandia , northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton...
; 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
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
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 the change in seismic velocities was not found at a boundary marking Harold Jeffreys
Harold Jeffreys
Sir Harold Jeffreys, FRS was a mathematician, statistician, geophysicist, and astronomer. His seminal book Theory of Probability, which first appeared in 1939, played an important role in the revival of the Bayesian view of probability.-Biography:Jeffreys was born in Fatfield, Washington, County...
's hypothetical transition from granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
to basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
; it was at the bottom of a layer of metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
that extended from about 5 to 10 kilometers beneath the surface. The rock there 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
Permeability (fluid)
Permeability in fluid mechanics and the earth sciences is a measure of the ability of a porous material to allow fluids to pass through it.- Units :...
rock.
Another unexpected discovery was the large quantity of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas, with the mud flowing out of the hole described as "boiling" with hydrogen.
Status
The site is controlled by the State Scientific Enterprise on Superdeep Drilling and Complex Investigations in the Earth's Interior (GNPP Nedra) as the Deep Geolaboratory. , the deepest active bore, SG-5, is 8578 m (28,143 ft) and with a 214 mm (8.4 in) diameter.The project was closed down in late 2005 due to lack of funding. All the drilling and research equipment was scrapped and the site has been abandoned since 2008.
Similar projects
The United States had embarked on a similar project in 1957, dubbed Project MoholeProject Mohole
Project Mohole was an ambitious attempt to drill through the Earth's crust into the Mohorovičić discontinuity, and to provide an Earth science complement to the high profile Space Race. The project was initially led by the American Miscellaneous Society with funding from the National Science...
, which was intended to penetrate the shallow crust under the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
off Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. However, after some initial drilling, the project was abandoned in 1966 due to lack of funding. This failure inspired great successes of the Deep Sea Drilling Project, Ocean Drilling Program
Ocean Drilling Program
The Ocean Drilling Program was an international cooperative effort to explore and study the composition and structure of the Earth's ocean basins. ODP, which began in 1985, was the direct successor to the highly successful Deep Sea Drilling Project initiated in 1968 by the United States...
, and the present Integrated Ocean Drilling Program
Integrated Ocean Drilling Program
The Integrated Ocean Drilling Program is an international marine research program. The program uses heavy drilling equipment mounted aboard ships to monitor and sample sub-seafloor environments...
. The KTB superdeep borehole (German Continental Deep Drilling Program, 1990–1994) was drilled down to a depth of 9101 m (29,859 ft) reaching temperatures of more than 260° Celsius. The ambitious measuring program had to develop high temperature tools like a magnetometer tool.
Longest borehole record
The deep core-drilled Kola borehole cannot be directly compared with any other borehole in the world. In a deep core borehole, a section of the rock drilled through is recovered from within the hole. It is this recovered drill core, and the information it represents about the rock that it was retrieved from, that is the most important feature of the borehole.The Kola Superdeep Borehole was the deepest and longest borehole in the world for nearly 20 years. However, in May 2008, a new record for borehole length was established by the extended-reach drilling (ERD)
Extended Reach Drilling
Extended Reach Drilling is directional drilling of very long horizontal wells. The aims of ERD are:# to reach a larger area from one surface drilling location, and...
well BD-04A, which was drilled by Transocean
Transocean
Transocean Ltd. is one of the world's largest offshore drilling contractors. The company rents floating mobile drill rigs, along with the equipment and personnel for operations, to oil and gas companies at an average daily rate of US$282,700...
for Maersk Oil
Maersk Oil
Maersk Oil is a Danish oil and gas company owned by the A. P. Moller-Maersk Group. The company was established in 1962 when Maersk Group was awarded a concession for oil and gas exploration and production in the Danish sector of the North Sea...
in the Al Shaheen oil field
Al Shaheen oil field
The Al Shaheen Oil Field is a production oil and gas field off the north east of coast of Qatar in the Persian Gulf, north of Doha. The oil field lies over the North Gas Field, the largest gas field in the world...
in Qatar
Qatar
Qatar , also known as the State of Qatar or locally Dawlat Qaṭar, is a sovereign Arab state, located in the Middle East, occupying the small Qatar Peninsula on the northeasterly coast of the much larger Arabian Peninsula. Its sole land border is with Saudi Arabia to the south, with the rest of its...
. It was drilled to 12289 m (40,318.2 ft), with a record horizontal reach of 10902 m (35,767.7 ft), in only 36 days.
On January 28, 2011, Exxon Neftegas Ltd., operator of the Sakhalin-I
Sakhalin-I
The Sakhalin-I project, a sister project to Sakhalin-II, is a consortium to locate and produce oil and gas on Sakhalin Island and immediately offshore, in the Okhotsk Sea, from three fields: Chayvo, Odoptu, and Arkutun-Dagi....
project, drilled the world’s longest extended-reach well offshore on the Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n island of Sakhalin
Sakhalin
Sakhalin or Saghalien, is a large island in the North Pacific, lying between 45°50' and 54°24' N.It is part of Russia, and is Russia's largest island, and is administered as part of Sakhalin Oblast...
. It has surpassed the length of both the Al Shaheen well and the Kola borehole. The Odoptu OP-11 well reached a measured total depth of 12345 m (40,502 ft) and a horizontal displacement of 11475 m (37,647.6 ft). Exxon Neftegas completed the well in 60 days.
However, in terms of depth below the surface, the Kola Superdeep Borehole still retains the world record as of 2011.
See also
- Chikyū, deep oceanic drilling program
- EarthscopeEarthscopeEarthScope is an earth science program using geological and geophysical techniques to explore the structure and evolution of the North American continent and to understand the processes controlling earthquakes and volcanoes. Thousands of geophysical instruments will comprise a dense grid covering...
- Extreme points of Earth
- Mohorovičić discontinuityMohorovičić discontinuityThe Mohorovičić discontinuity , usually referred to as the Moho, is the boundary between the Earth's crust and the mantle. Named after the pioneering Croatian seismologist Andrija Mohorovičić, the Moho separates both the oceanic crust and continental crust from underlying mantle...
- San Andreas Fault Observatory at DepthSan Andreas Fault Observatory at DepthThe San Andreas Fault Observatory at Depth is one of three components of the Earthscope Project, funded by the National Science Foundation in conjunction with the USGS and NASA. The SAFOD site is located just north of the town of Parkfield, California...
- USARRAYUSARRAYUSArray is one of the three components of the Earthscope project, funded by the National Science Foundation and being constructed, operated, and maintained as a collaborative effort with UNAVCO Inc., the Incorporated Research Institutions for Seismology, and Stanford University, with contributions...
- Well to Hell hoaxWell to hell hoaxThe "Well to Hell" is a putative borehole in Russia which was purportedly drilled so deep that it broke through to hell. This urban legend has been circulating on the Internet since at least 1997...