Since the end of the 19th century, it was believed that the Earth consists of crust, mantle and core. At the same time, no one could really say where one layer ends and the next begins. Scientists did not even know what, in fact, these layers are composed of. Even some 30 years ago, researchers were sure that the granite layer begins at a depth of 50 meters and continues up to three kilometers, and then there are basalts. The mantle was supposed to be at a depth of 15-18 kilometers. Ultradeep well, which began drilling in the USSR on the Kola Peninsula, showed that scientists were wrong …
Immersion for three billion years
Projects of travel deep into the Earth appeared in the early 1960s in several countries at once. The Americans were the first to start drilling ultra-deep wells, and they tried to do it in places where, according to seismic studies, the earth's crust should have been thinner. These places, according to calculations, were at the bottom of the oceans, and the most promising area was considered the area near the island of Maui from the Hawaiian group, where ancient rocks lie under the ocean floor itself and the earth's mantle is located about five kilometers under a four-kilometer water column. Alas, both attempts to break through the earth's crust in this place ended in failure at a depth of three kilometers.
The first domestic projects also involved underwater drilling - in the Caspian Sea or on Lake Baikal. But in 1963, drilling scientist Nikolai Timofeev convinced the State Committee for Science and Technology of the USSR that it was necessary to create a well on the continent. Although the drilling would take incomparably longer, he believed, the well would be much more valuable from a scientific point of view. The drilling site was chosen on the Kola Peninsula, which is located on the so-called Baltic shield, which consists of the most ancient earth rocks known to mankind. A multi-kilometer cut of the shield layers was supposed, according to scientists, to show a picture of the history of the planet over the past three billion years.
Deeper and deeper and deeper …
The start of work after almost five years of preparation was timed to coincide with the 100th anniversary of the birth of V. I. Lenin in 1970. The project was started thoroughly. The well had 16 research laboratories, each the size of an average plant; the project was personally supervised by the Minister of Geology of the USSR. Ordinary employees received triple salaries. Everyone was guaranteed an apartment in Moscow or Leningrad. It is not surprising that getting to the Kola Superdeep was much more difficult than joining the cosmonaut corps.
The appearance of the well was capable of disappointing an outside observer. No elevators and spiral staircases leading into the depths of the Earth. Only a drill with a diameter of a little more than 20 centimeters went underground. In general, the Kola superdeep can be imagined as a thin needle piercing the earth's thickness. The drill at the end of this needle with numerous sensors, after several hours of operation, was lifted for almost a whole day for inspection, reading and repair, and then it was lowered for a day. It couldn't be faster: the strongest composite cable (drill string) could break off under its own weight.
What happened at a depth at the time of drilling was not known for certain. Ambient temperature, noise and other parameters were transmitted upstairs with a one-minute delay. Nevertheless, the drillers said that even such contact with the dungeon was sometimes frightening in earnest. The sounds coming from below were like screams and howls. To this can be added a long list of accidents that followed the Kola Superdeep, when it reached a depth of 10 kilometers. Twice the drill was taken out melted, although the temperatures from which it could take this form are comparable to the temperature of the surface of the Sun. Once the cable seemed to be pulled from below - and cut off. Subsequently, when drilled in the same place, no remnants of the cable were found. What caused these and many other accidents is still a mystery. However,they were not at all the reason for stopping the drilling of the bowels of the Baltic shield.
In 1983, when the depth of the well reached 12,066 meters, the work was temporarily stopped: it was decided to prepare materials on superdeep drilling for the International Geological Congress, which was planned to be held in 1984 in Moscow. On it, foreign scientists first learned about the very existence of the Kola superdeep, all information about which had been classified until that time. Work resumed on September 27, 1984. However, at the very first launch of the drill, an accident occurred - the drill string broke off again. Drilling had to continue from a depth of 7,000 meters, creating a new borehole, and by 1990 this new branch reached 12,262 meters, which was an absolute record for ultra-deep wells, broken only in 2008. Drilling was stopped in 1992, this time, as it turned out, forever. There were no funds for further work.
Discoveries and Finds The
discoveries made on the Kola superdeep have made a real revolution in our knowledge of the structure of the earth's crust. Theorists have promised that the temperature of the Baltic Shield will remain relatively low down to a depth of at least 15 kilometers. This means that a well can be drilled almost up to 20 kilometers, just to the mantle. On the fifth kilometer, the temperature exceeded 700 ° C, on the seventh - over 1200 ° C, and at a depth of twelve it was more than 2200 ° C.
Kola drillers questioned the theory of the layer-by-layer structure of the earth's crust - at least in the interval up to 12,262 meters. It was believed that there is a surface layer (young rocks), then granites, basalts, mantle and core should go. But the granites turned out to be three kilometers lower than expected. The basalts that were supposed to lie under them were not found at all. An incredible surprise for scientists was the abundance of cracks and voids at a depth of over 10 kilometers. In these voids, the drill swung like a pendulum, which led to serious difficulties in work due to its deviation from the vertical axis. In the voids, the presence of water vapor was recorded, which moved there at a high speed, as if carried by some unknown pump. These vapors created the very sounds that awe the drillers.
Quite unexpectedly for everyone, the hypothesis of the writer Alexei Tolstoy about the olivine belt, expressed in the novel "The Hyperboloid of Engineer Garin", was confirmed. At a depth of over 9.5 kilometers, a real mine of all kinds of minerals was discovered, in particular gold, which turned out to be 78 grams per ton. By the way, commercial production is carried out at a concentration of 34 grams per ton.
Another surprise: life on Earth appeared, it turns out, one and a half billion years earlier than expected. At depths where, as it was believed, there could be no organic matter, 14 species of fossilized microorganisms were found (the age of these layers exceeded 2.8 billion years). At even greater depths, where there are no longer any sedimentary rocks, methane appeared in high concentrations, which finally disproved the theory of the biological origin of hydrocarbons such as oil and gas.
It is impossible not to mention the discovery made when comparing the lunar soil delivered by the Soviet space station in the late 70s from the surface of the Moon, and samples taken at the Kola well from a depth of 3 kilometers. It turned out that these samples are as similar as two drops of water. Some astronomers saw this as evidence that the Moon once broke away from the Earth as a result of a cataclysm (possibly a collision of a planet with a large asteroid). However, according to others, this similarity only testifies to the fact that the Moon was formed from the same gas and dust cloud as the Earth, and at the initial geological stages they "developed" in the same way.
The Kola Superdeep was ahead of its time
The Kola well has shown that it is possible to go into the depths of the Earth for 14 or even 15 kilometers. However, one such well is unlikely to provide fundamentally new knowledge about the earth's
crust. This requires a whole network of wells drilled at different points on the earth's surface. But the days when super-deep wells were drilled for purely scientific purposes seem to be over. This pleasure is too expensive. Today's ultra-deep drilling programs are no longer as ambitious as they used to be and have practical goals.
This is mainly the discovery and extraction of minerals. In the United States, oil and gas production from depths of 6-7 kilometers is already becoming commonplace. In the future, Russia will also start pumping hydrocarbons from such levels.
However, even those deep wells that are being drilled now bring a lot of valuable information that geologists are trying to generalize to obtain a holistic picture of at least the surface layers of the earth's crust. But what lies below will remain a mystery for a long time. Only scientists working in superdeep wells like the Kola Peninsula can reveal it with the help of the most modern scientific equipment. Such wells in the future will become for mankind a kind of telescopes into the mysterious underground world of the planet, about which we know no more than about distant galaxies.