What did the Soviets find in the ground? Kola ultra-deep drilling-the deepest hole in the world

By yqqlm yqqlm

US-Soviet”drilling competition”

Some people say that humans know more about some distant galaxies than the land under their feet. It took 26 years for the famous &34; Voyager 1&34; satellite to leave the solar system (transmitting measurement results from 16.5 billion kilometers away to the earth). However, it took so long for humans to penetrate the earth’s surface only 12 kilometers.

During the space race, while the United States and the Soviet Union are vying for supremacy in space exploration , An unknown contest also took place between the greatest drillers of the two countries. In the late 1950s and early 1960s, the Americans and Soviets planned to drill as deep as possible into the earth’s crust—opening a rock crust 6,730 kilometers from the core of the earth, which is 30-50 kilometers thick.

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Earth structure

stationed The US”Mohor Project” on the Pacific coast of Mexico was interrupted in 1966 due to lack of funds, but it set an important precedent for future offshore drilling programs. The Soviets achieved greater success thanks to the planning of the Scientific Committee of the Earth’s Interior and Ultra-Deep Drilling Research Department. From 1970 to 1994, they set a record that shocked the earth at the time on the Kola Peninsula:the deepest hole in the world.

Kola ultra-deep borehole-the deepest hole in the world

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Kola ultra-deep drilling

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The Kola ultra-deep borehole is located 10 kilometers north of Zapolyarny, Pechengsky District, Murmansk Region, Russia.

In fact, the Kola ultra-deep hole consists of several holes branched from a central hole. The deepest hole is called &34;SG-3&34;, although it is only 22.86 cm in diameter, it extends down an astonishing 12.07 kilometers. It is about one-third the thickness of the continental crust of the Baltic Sea.

In order to achieve scientific goals and to observe the contours of the earth’s crust almost continuously, The Soviets even developed instruments for direct physical measurement at the bottom of the borehole. This measurement method can make the results more accurate, because when the rock sample is brought to the surface, it will deform under its incredible internal pressure. Needless to say, the project produced a large amount of geological data, most of which clarify how much we know about the earth.

Discovery 1:&34;Kangra German discontinuity&34; does not exist

to the earth Research is usually limited to surface observation and seismic research, but the Kola borehole allows us to directly observe the structure of the earth’s crust and test geologists’ theories. One of the most surprising findings is that there is no evidence of the transition from granite to basalt, and scientists have long believed that basalt exists Between three and six kilometers below the surface, geologists call it”Conrad discontinuity”. This type of rock transition has been inferred to exist, and this inference is only based on the results of seismic reflection measurements.

Although this discontinuity has been detected under all continents, Drilling in Kola never encountered the proposed basalt formation. On the contrary, the granite rock extends 12 kilometers away. This makes scientists realize that the seismic reflection results are due to the metamorphic changes of the rock (that is, due to intense heat and pressure), rather than the rock type changes they had previously expected.

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Discovery 2:There are traces of biological activity in rocks more than 2 billion years ago

But the most interesting discovery of the Kola Drilling researchers is undoubtedly the discovery of biological activity in rocks more than 2 billion years ago. The clearest evidence of life is in the form of microscopic fossils encapsulated in organic compounds. Despite the extreme pressure and abnormally high temperature of the surrounding rocks, these fossils remain intact unexpectedly.


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Although the data generated by the Kola drilling project is still being analyzed, the In the early 1990s, due to unexpected high temperatures, drilling itself was forced to stop. Although the temperature gradient was still in line with the prediction at a depth of about 254 meters, the temperature rose at a higher rate thereafter until the bottom of the cave reached an astonishing 180°C, which was nearly double the expected 100°C. Also unexpectedly, after the first 376 meters, the density of the rock has decreased. Below this depth, the rock’s porosity and permeability, coupled with the high temperature, cause the rock to behave more like a plastic rather than a solid, making drilling tasks almost impossible.

In the later stages, drilling operations have become more difficult and expensive. Every time the drill bit needs to be replaced, more than 600 drill rods need to be connected in series and pulled out, which is very time-consuming. When the drilling depth reaches 12 kilometers and the diameter is only 23 cm, it is difficult to keep the drilling as straight as possible. The high temperature of the rock makes it difficult for the drilling fluid to function and reduces the strength of the drill bit and drill pipe. At the same time, due to the excessive weight of the drill rod, a large taper must be used for drilling.

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In short, a borehole reaches a depth of 12 kilometers, Pushing drilling technology to the limit. In 1995, the project was officially terminated due to the collapse of the Soviet Union, and the site was abandoned since then. In 2008, the Russian Information Center announced that the wellhead would be destroyed.

Nickel about 10 kilometers south of the Kola ultra-deep borehole In the mining town of Zapolyarny, you can find many storage places for core samples. Due to its ambitious mission and its contribution to geology and biology, the Kola ultra-deep borehole remains one of the most important relics of science during the Soviet era.


With its strong national strength, the Soviet Union has written a remarkable record in the history of geological drilling. Pen, but at the same time it also makes human beings feel their insignificance in the face of natural forces. Although the Kola ultra-deep drilling was terminated, it does not mean that this is the end of a great project, but the beginning of more great projects.

With the advancement of science and technology, mankind is bound to restart the core drilling Project, because there are still many unsolved mysteries waiting for us to explore underground. The Soviet Union was already a giant of the previous era. I hope that China, as a giant of this era, can take over the banner of the predecessors and move on!