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Kola Superdeep Borehole

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The Kola Superdeep Borehole is the deepest drilled hole ever to be produced by man. Located on the Kola Peninsula in Russia, its drilling began in 1970. Construction and preparation for the project was led by the USSR’s Interdepartmental Scientific Council for the Study of the Earth’s Interior and Superdeep Drilling (ISCSEIS). The hole, which reached a depth of 7.7 miles (12.262 km), came to a halt in 1994 when it became evident that further drilling techniques and research were needed.

Contents

[edit] Construction History

[edit] Preparing to Drill

The idea to drill a hole into the Kola Peninsula in Russia derives from a scientific longing to understand more about the Earth’s crust and seismic activity. The ISCSEIS began researching for the project in 1962. Years were spent locating a site suitable for such in-depth drilling. Surveying the Kola site was completed in 1965. Another five years were spent preparing a construction plan and drilling equipment unique to the project. Drilling the borehole would require a machine never previously produced. By 1970, all plans were in place and the drilling began.

[edit] Specialized Equipment and Techniques

A special drilling machine was constructed. Even the largest drilling machines were not capable of delving into the depths the project was attempting. New techniques also had to be devised. Russian researchers developed a machine that would rotate only at the drill bit. In normal drilling projects, implements would be added as the hole grew deeper. Since this was not possible for the SG-3 hole, lubricant would be inserted into the drill bit to keep it spinning.

[edit] Interesting Discoveries

Researchers intended to observe and investigate as the drilling commenced. Samples from the Earth were provided from the drill shaft. One scientist said of the project at the time: “Every time we drill a hole we find the unexpected. That’s exciting, but disturbing.”[1]

At the 1.9- to 3.7-mile (3- to 6-km) point, researchers had expected to find granite rock under the Earth’s crust. Instead, they found metamorphic rock, a plasticity in rock that occurs when it undergoes intense pressure and heat. The rocks were saturated with water—another surprising find.

During the drilling process, scientists also found archaeological fossils. As far down as 4.2 miles (6.7 km), as much as 24 species of plankton microfossils were found. Unique about this find was that rather than being glazed in limestone or silica, as is usual, they were cased in carbon and nitrogen.

[edit] Extreme Heat

One of the obstacles scientists faced in drilling to such depths was the increasing temperature. Scientists attempted to counter this by freezing drilling mud and pumping it down the hole. When the mud reached 7.5 miles (12 km), the drilling machine had reached the height of its heat tolerance. Scientists had estimated that rocks at that depth would be 100 degrees Celsius, but turned out to be 180 degrees Celsius. Rocks were comparable to plastic and the hole glazed over when the drill was removed. Scientists predicted that had they reached their 9.3-mile (15 km) goal, temperatures could have risen as high as 300 degrees Celsius.[2]

The hole reached its deepest point, 7.7 miles (12.3 km) into the Earth, in 1994, 1.7 miles (2.7 km) short of their original goal. Although the boring has come to a stop, research is still being conducted.[3]

[edit] Equipment Used

A drilling machine was created for the project. Typically, deep-drilling requires a rotating shaft that bores into the ground and implements are added throughout to continue drilling at such high depths, but normal drilling techniques were no match for the depth to be accomplished. New methods were sought out for this. Russian researchers invented a drilling device that rotated only at the drill bit end of the shaft. Special drilling mud acting as a lubricant was inserted into the drill bit to aid this process.[4]

Super deep drilling rigs, such as the one produced for the Kola Superdeep project can be manufactured by Uralmash-Burovoye Oborudovanie. Similarly, drilling techniques can be sought at the All-Russian Institute of Drilling Equipment.

[edit] References

  1. Elert, Glenn; ed. Depth of the Deepest Drilling. Hypertextbook.com, 2008-09-25.
  2. The Deepest Hole. Unexplained Mysteries, February, 2007. (accessed: 2008-09-25)
  3. Bellows, Alan. The Deepest Hole. Damn Interesting, March, 2007. (accessed: 2008-09-25)
  4. Elert, Glenn; ed. Depth of the Deepest Drilling. Hypertextbook.com, 2008-09-25.