Kola superdeep. Superdeep well on the Kola Peninsula: history and secrets

The Kola super-deep well is the deepest borehole in the world (from 1979 to 2008). It is located in the Murmansk region, 10 kilometers west of the city of Zapolyarny, on the territory of the geological Baltic Shield. Its depth is 12,262 meters. Unlike other ultra-deep wells that were made for oil production or exploration, SG-3 was drilled exclusively for the study of the lithosphere in the place where the Mohorovichic boundary is. (abbreviated Moho boundary) - the lower boundary of the earth's crust, on which there is an abrupt increase in the velocities of longitudinal seismic waves.

The Kola superdeep well was laid in honor of the 100th anniversary of the birth of Lenin, in 1970. The strata of sedimentary rocks by that time were well studied during oil production. It was more interesting to drill where volcanic rocks about 3 billion years old (for comparison: the age of the Earth is estimated at 4.5 billion years) come to the surface. For mining, such rocks are rarely drilled deeper than 1–2 km. It was assumed that already at a depth of 5 km, the granite layer would be replaced by basalt. On June 6, 1979, the well broke the record of 9583 meters, previously owned by the Bert-Rogers well (oil well in Oklahoma). In the best years, 16 research laboratories worked at the Kola superdeep well, they were personally supervised by the Minister of Geology of the USSR.

Although it was expected that a pronounced boundary between granites and basalts would be found, only granites were found in the core throughout the depth. However, due to the high pressure, the pressed granites greatly changed their physical and acoustic properties. As a rule, the raised core fell apart from active gas release into sludge, as it could not withstand a sharp change in pressure. It was possible to extract a solid piece of core only with a very slow rise of the drill string, when the “excess” gas, while still in a state of high pressure, had time to leave the rock. The density of cracks at great depths, contrary to expectations, increased. At depth, water was also present, filling the cracks.

Interestingly, when the International Geological Congress was held in Moscow in 1984, at which the first results of the well research were presented, many scientists jokingly suggested that it be immediately buried, since it destroys all ideas about the structure of the earth's crust. Indeed, oddities began even at the first stages of penetration. So, for example, theorists even before the start of drilling promised that the temperature of the Baltic Shield would remain relatively low to a depth of at least 5 kilometers, the ambient temperature exceeded 70 degrees Celsius, at seven - over 120 degrees, and at a depth of 12 it was frying stronger than 220 degrees - 100 degrees higher than predicted. The Kola drillers questioned the theory of the layered structure of the earth's crust - at least in the range up to 12,262 meters.

“We have the deepest hole in the world - this is how you should use it!” - bitterly exclaims the permanent director of the research and production center "Kola Superdeep" David Guberman. In the first 30 years of the existence of the Kola Superdeep, Soviet and then Russian scientists broke through to a depth of 12,262 meters. But since 1995, drilling has been stopped: there was no one to finance the project. What is allocated within the framework of UNESCO's scientific programs is only enough to maintain the drilling station in working order and study previously extracted rock samples.

Another surprise: life on planet Earth arose, it turns out, 1.5 billion years earlier than expected. At depths where it was believed that there was no organic matter, 14 types of fossilized microorganisms were found - the age of the deep layers exceeded 2.8 billion years. At even greater depths, where there are no longer sedimentary rocks, methane appeared in huge concentrations. This completely and completely destroyed the theory of the biological origin of hydrocarbons such as oil and gas. There were also almost fantastic sensations. When, in the late 70s, the Soviet automatic space station brought 124 grams of lunar soil to Earth, the researchers of the Kola Science Center found that it was like two drops of water similar to samples from a depth of 3 kilometers. And a hypothesis arose: the moon broke away from the Kola Peninsula. Now they are looking for exactly where. By the way, the Americans, who brought half a ton of soil from the moon, did nothing sensible with it. Placed in sealed containers and left for research to future generations.

Quite unexpectedly for everyone, the predictions of Alexei Tolstoy from the novel "The Hyperboloid of Engineer Garin" were confirmed. At a depth of more than 9.5 kilometers, they discovered a real storehouse of all kinds of minerals, in particular gold. A real olivine layer, brilliantly predicted by the writer. Gold in it is 78 grams per ton. By the way, industrial production is possible at a concentration of 34 grams per ton. But, most surprisingly, at even greater depths, where there are no sedimentary rocks, natural gas methane was found in huge concentrations. This completely and completely destroyed the theory of the biological origin of hydrocarbons such as oil and gas.

Not only scientific sensations were also associated with the Kola well, but also mysterious legends, most of which turned out to be fiction of journalists during verification. According to one of them, the original source of information (1989) was the American television company Trinity Broadcasting Network, which, in turn, took the story from a Finnish newspaper report. Allegedly, while drilling a well, at a depth of 12 thousand meters, the microphones of scientists recorded screams and groans.). Journalists, without even thinking that it was simply impossible to stick a microphone to such a depth (what sound recording device can work at temperatures above two hundred degrees?) wrote about the fact that the drillers heard a "voice from the underworld."

After these publications, the Kola super-deep well began to be called the "road to hell", arguing that each new kilometer drilled brought misfortune to the country. They said that when the drillers were drilling the thirteenth thousand meters, the USSR collapsed. Well, when the well was drilled to a depth of 14.5 km (which actually did not happen), they suddenly stumbled upon unusual voids. Intrigued by this unexpected discovery, the drillers lowered a microphone capable of operating at extremely high temperatures and other sensors into it. The temperature inside allegedly reached 1,100 ° C - there was the heat of the fiery chambers, in which, allegedly, human screams could be heard.

This legend still roams the vast expanses of the Internet, having survived the very culprit of these gossip - the Kola well. Work on it was stopped back in 1992 due to lack of funding. Until 2008, it was in a mothballed state. And a year later, the final decision was made to abandon the continuation of research and dismantle the entire research complex, and "bury" the well. The final abandonment of the well took place in the summer of 2011.
So, as you can see, this time the scientists were not able to get to the mantle and explore it. However, this does not mean that the Kola well did not give anything to science - on the contrary, it turned all their ideas about the structure of the earth's crust upside down.

RESULTS

The tasks set in the ultra-deep drilling project have been fulfilled. Special equipment and technology for ultra-deep drilling, as well as for the study of wells drilled to a great depth, have been developed and created. We received information, one might say, "first-hand" about the physical state, properties and composition of rocks in their natural occurrence and from core samples to a depth of 12,262 m. 8 kilometers. Industrial copper-nickel ores were discovered there - a new ore horizon was discovered. And very handy, because the local nickel plant is already running out of ore.

As noted above, the geological forecast of the well section did not come true. The picture that was expected during the first 5 km in the well stretched for 7 km, and then completely unexpected rocks appeared. The basalts predicted at a depth of 7 km were not found, even when they dropped to 12 km. It was expected that the boundary that gives the most reflection in seismic sounding is the level where the granites pass into a more durable basalt layer. In reality, it turned out that less durable and less dense fractured rocks - Archean gneisses - are located there. This was not expected at all. And this is a fundamentally new geological and geophysical information that allows you to interpret the data of deep geophysical surveys in a different way.

The data on the process of ore formation in the deep layers of the earth's crust also turned out to be unexpected and fundamentally new. So, at depths of 9-12 km, highly porous fractured rocks saturated with underground highly mineralized waters were encountered. These waters are one of the sources of ore formation. Previously, it was believed that this was possible only at much shallower depths. It was in this interval that an increased gold content was found in the core - up to 1 g per 1 ton of rock (a concentration that is considered suitable for industrial development). But will it ever be profitable to mine gold from such a depth?

The ideas about the thermal regime of the earth's interior, about the deep distribution of temperatures in the areas of basalt shields, have also changed. At a depth of more than 6 km, a temperature gradient of 20°C per 1 km was obtained instead of the expected (as in the upper part) 16°C per 1 km. It was revealed that half of the heat flux is of radiogenic origin.

The bowels of the earth contain as many mysteries as the vast expanses of the universe. This is exactly what some scientists think, and they are partly right, because people still do not know exactly what exactly is under our feet deep underground. For the entire time of the existence of earthly civilization, we have been able to go deep into the planet a little more than 10 kilometers. This record was set back in 1990 and lasted until 2008, after which it was updated several times. In 2008, a deviated oil well, Maersk Oil BD-04A, with a length of 12,290 meters, was drilled (Al-Shaheen oil basin in Qatar). In January 2011, an inclined oil well was drilled at the Odoptu-more field (Sakhalin-1 project) with a depth of 12,345 meters. The record for drilling depth currently belongs to the Z-42 well of the Chayvinskoye field, the depth of which is 12,700 meters.

What prevents you from drilling a well to the center of the Earth and finding out what is there? We know much more about the structure of the cosmos than about how the globe works. Although attempts to penetrate deep into the Earth have been made more than once. The first two ultra-deep wells were drilled in Louisiana in North America. The project managers equipped the well with meter-diameter casing pipes going to a depth of 1 km, with three powerful automatic emergency gates. A special concrete plant was located next to the drilling rig, which, in the event of an accident, would supply a quick-hardening mortar into the casing pipe. To a depth of 9 km, the drilling proceeded as usual. But deeper they encountered increasing internal pressure, hydrogen sulfide began to be released from the well. The drillers joked that they drilled to the underworld. From a depth of 9.6 km, molten sulfur came out of the well, and the miners began to lose consciousness. The emergency gates are closed. And the concrete plant ensured the supply of special mortar to o! casing pipe, and the well was shut down.

In the USSR, they also tried to drill several ultra-deep wells, but domestic drillers suffered the same sad fate. During the drilling of the Kumzha-9 well on the Pechora River in the Arkhangelsk Region, a powerful fountain of gas, oil and drilling fluid unexpectedly hit from a depth of 7 km. Yes, so much so that the drill simply "flew" into the zone of abnormally high reservoir pressure. The pipes from the drilling rig shattered like pasta from a pot. Immediately hit a torch 150 meters high. They tried to extinguish the torch with tanks - unsuccessfully. The fountain hummed like a jet engine. As a result, it was possible to extinguish it only with the help of underground nuclear explosions. For this, an inclined well was drilled towards the emergency shaft. They brought a nuclear mine along it and blew it up at a depth of 1.5 km. An underground chamber was formed and the lateral pressure zone blocked the wellbore.

The deepest well - SGS-3 with a depth of 12.3 km - was drilled on the Kola Peninsula near the village of Nikel. The work was carried out by a special institute of geophysics with a total number of employees of 5,000 people, and 520 people worked at the mine itself in the Soviet years. The estimated drilling depth was set at 30 km. Up to 7 km, drilling proceeded as usual. Surprises began at a depth of 7.5 km, the temperature where the drill was in direct contact with basalt rose to 100°C, and the density of the samples brought to the surface decreased by 20%. Geochemists discovered various gases in the rock - hydrogen and helium, and biologists - unknown bacteria. These bacteria, extracted into an oxygen atmosphere, died, and therefore they were called aerophobic (afraid of air). Suddenly, the drill jammed tightly, then they started driving the second shaft. At a depth of 8 km, the temperature rose to 120°C, and the cores became porous, and the number of bacteria increased. Ordinary steel pipes have been replaced by! new, made of high-strength steel, the drill was made of molybdenum, diamond grains were replaced with artificial material elbor, which surpassed diamond in fire resistance, strength and hardness. Finally, the wellbore reached a depth of 12240 m. The drill jammed again, the machine fell silent.

A little about the characteristics of the drilling rig ("Uralmash-15000"). The drill string below 2000 meters was assembled with pipes made of light aluminum alloys (steel would simply break from its weight). The weight of the column is about 200 tons.

Turbodrill - a turbine 46 meters long, acting on the pressure of the drilling fluid, rotates the drill bit (bit).

Core receiver - a removable pipe inside the turbodrill, which serves to take rock samples (core).

Conventional carbide drill bits were used. One crown lasts approximately 4 hours, during which time it is possible to drill 7-10 meters. The descent and ascent of the column takes up to 18 hours. In this case, the column is disassembled into sections of several pipes.

The first 7 kilometers are composed of volcanic and sedimentary rocks: tuffs, basalts, breccias, sandstones, dolomites. Deeper lies the so-called Conrad section, after which the speed of seismic waves in the rocks increases sharply, which was previously interpreted as the boundary between granites and basalts. This section on the Kola well was passed long ago, but the basalts of the lower layer of the earth's crust did not appear anywhere. On the contrary, granites and gneisses began.

The section of the Kola well refuted the two-layer model of the earth's crust, according to which, under the granitoid crust of the continents, there should be a basalt crust, in which the continents, according to the theory of plate tectonics, move along the surface of the planet. Seismic sections in the bowels of the planet turned out to be not the boundaries of layers of rocks of different composition. Rather, they indicate a change in the properties of the stone with depth. The sample raised to the surface from a depth of 12 kilometers turned out to be not basalt, as expected by theory, but granite.

Previously, it was thought that with increasing distance from the earth's surface and an increase in pressure, the rocks become more monolithic, the number of cracks in them decreases. But the well showed the opposite - starting from 9 km, the strata turned out to be very porous and literally crammed with cracks through which aqueous solutions circulated. At depth, the temperature turned out to be higher than expected: +80°C. At the mark of 7 km, the temperature in the face was 120°C, and at 12 km - +230°C. In the samples of the Kola well, scientists discovered gold mineralization. The inclusions of the precious metal were found in ancient rocks at a depth of 9.5–10.5 km (an average of 37.7 mg of gold per ton of rock).

How many scientific discoveries have taken place on the Kola Superdeep! Literally every meter was a revelation. The well showed that almost all of our previous knowledge about the structure of the earth's crust is incorrect. It turned out that the Earth is not at all like a layer cake. Up to 4 kilometers everything went according to theory, and then the doomsday began - theorists promised that the temperature of the Baltic Shield would remain relatively low to a depth of at least 15 kilometers. Accordingly, it will be possible to dig a well up to almost 20 kilometers, just up to the mantle. But already at 5 kilometers, the ambient temperature exceeded 70 ° C, at seven - over 120, and at a depth of 12 km it was hotter than 220 ° C, which is 100 ° higher than predicted by theorists! The results called into question the theory of the layered structure of the earth's crust - at least up to 12,262 meters.

We were taught at school: there are young rocks, granites, basalts, a mantle and a core. But the granites turned out to be 3 kilometers lower than expected. Basalts were not found at all. All drilling took place in the granite layer. But all our ideas about the origin and distribution of minerals are connected with the theory of the layered structure of the Earth. At depths where it was believed that there was no organic matter, 14 types of microorganisms were found - the age of the deep layers exceeded 2.8 billion years. At even greater depths, where there are no longer sedimentary rocks, methane appeared in huge concentrations. This completely destroyed the theory of the biological origin of hydrocarbons such as oil and gas.

Problems in a German ultra-deep well in the southeast of Bavaria, laid on the remains of an ancient mountain range 300 million years old, began after reaching a depth of 7 km: at the end of the work, the bottom deviated from the vertical by 300 m. drill new holes. The temperature in the well at a depth was 270°C, and this forced the work to be stopped without reaching the cherished goal. At the maximum depth for drilling, mainly amphibolites and gneisses, ancient metamorphic rocks, occurred. The zones of transition of the granitoid crust into the gneiss one were also not found here.

The United States continues deep drilling of the ocean floor in the zones of volcanic and tectonic activity of the earth's crust. So, in the Hawaiian Islands, researchers hoped to study the underground life of the volcano and get closer to the mantle tongue - the plume, which is believed to have given rise to these islands. The well at the foot of the Mauna Kea volcano was planned to be drilled to a depth of 4.5 km, but due to the enormous temperatures, only 3 km could be mastered. Another project is a deep observatory on the San Andreas Fault. Drilling of a well through this fault in the North American continent began in June 2004 and completed 2 out of 3 planned kilometers. Already, oil and gas production in the United States from depths of 6–7 km has become commonplace. The Tyumen superdeep well showed that 7 kilometers from the surface there are rock strata that are promising for gas fields.

One of the most amazing discoveries made with the help of drilling is the existence of life deep underground. And although this life is represented only by bacteria, its limits extend to incredible depths. Bacteria are ubiquitous. They mastered the underworld, it would seem, completely unsuitable for existence. Huge pressures, high temperatures, lack of oxygen and living space - nothing could become an obstacle to the spread of life in the bowels of the lithosphere. According to some estimates, the mass of microorganisms living underground may even exceed the mass of all living creatures that inhabit the surface of our planet.

As early as the beginning of the 20th century, the American scientist Edson Bastin discovered bacteria in water from an oil-bearing horizon from a depth of several hundred meters. The microorganisms living there did not need oxygen and sunlight, they fed on organic compounds of oil. Bastin suggested that these bacteria have been living in isolation from the surface for 300 million years - since the oil field was formed. But his bold hypothesis then remained unclaimed - they simply did not believe in it. Then it was believed that life is just a thin film on the surface of the planet.

In 1980, the US Department of Energy was looking for safe methods to dispose of radioactive waste. For these purposes, it was supposed to use mines in impenetrable rocks, where bacteria that feed on radionuclides live. In 1987, deep drilling of several wells began in South Carolina. Samples were taken from a depth of half a kilometer and further inland, while observing all possible precautions so as not to bring bacteria and air from the surface of the Earth. The samples were studied by several independent laboratories, their results showed that anaerobic bacteria lived in deep layers, which do not need oxygen.

The bacteria were also found in the rocks of a gold mine in South Africa at a depth of 2.8 km, where the temperature was 60°C. They also live deep under the bottom of the oceans at temperatures above 100 °. As the Kola super-deep well showed, there are conditions for the habitation of microorganisms even at a depth of more than 12 km, since the rocks at great depths turned out to be porous, saturated with aqueous solutions.

Microbiologists also found colonies of bacteria in an ultra-deep well that opened the Siljan Ring crater in Sweden. It is curious that microorganisms lived in ancient granites. Although these were very dense, under high pressure rocks, underground, apparently juvenile waters circulated in them through a system of micropores and cracks. The American geologist Thomas Gold believes that magnetite-oil paste at a depth of 4-5 km is nothing more than a product of the vital activity of bacteria that feed on methane coming from the mantle.

The limits of endurance of lithospheric bacteria are amazing, but it seems that the temperature of the bowels still sets the lower limit of their habitat. They can multiply at 110°C and withstand, albeit for a short time, temperatures of 140°C. Under the ocean floor, the temperature rises not so fast, and the lower limit of life there can lie at a depth of 7 km. This means that the Earth's biosphere cannot be completely destroyed even in the event of the most serious cataclysms, and on planets devoid of an atmosphere and hydrosphere, microorganisms may well exist in the depths.

Katrina Edwards and her colleagues found that 3 to 4 times more bacteria live on exposed hard rocks at the bottom of deep ocean trenches than in the water layers of the ocean. Life can exist in cold, dark and rocky environments, Santelli said: "However, we did not expect to find such an abundance of microbial life at great depths." Struck by the presence of a huge variety of microorganisms, the researchers concluded that a rich microbial life is present on the entire surface of the ocean floor. The discovery supports the theory that bacteria survive on endogenous energy from deep within the Earth, "a process that will greatly add to our knowledge of the deep carbon cycle and the development of life on earth," says Katrina Edwards.

To date, there are several dozen ultra-deep wells in the world. Here are the most famous of them: Bert-Rogers, USA - 9,583 m. Beiden Unit, USA - 9,159 m. KTV Hauptbohrung, Germany - 9,100 m. 553 m. Bighorn, USA, Wyoming - 7,583 m. Siljan Ring, Sweden - 6,800 m. Deeper than the Kola (and even then not by much) is only the well in Odoptu, drilled by Exxon Neftegas Limited (ENL) in late 2010 - early 2011 (depth 12,345 m) and a well drilled by Transocean for Maersk Oil in 2008 in Qatar, in the Al Shaheen oil basin, at a depth of 12,289 meters.

Ultra-deep drilling made it possible to look into the bowels and understand how rocks behave at high pressures and temperatures. The idea that rocks become denser with depth and their porosity decreases turned out to be wrong, as well as the point of view about dry bowels. This was first discovered while drilling the Kola super-deep well. Other wells in ancient crystalline strata confirmed the fact that at a depth of many kilometers the rocks are broken by cracks and penetrated by numerous pores, and aqueous solutions (called supercritical fluids in science) move quite freely under a pressure of several hundred atmospheres. Given the information on the state of the subsoil obtained during ultra-deep drilling, projects to create radioactive waste repositories in deep ocean trenches now look very risky. According to the theory of tectonic plates, in the place of these trenches, the oceanic plate "slips" under the mainland, and pom! radioactive waste placed in such a trough in containers would also have to be “slid” under the continental plate and thus buried at a considerable depth. But it turned out that in fact, no plates in the gutters slip under each other.

"Dr. Huberman, what the hell did you dig down there?" - a remark from the audience interrupted the report of the Russian scientist at the UNESCO meeting in Australia. A couple of weeks earlier, in April 1995, a wave of reports swept the world about a mysterious accident at the Kola superdeep well.

Allegedly, on the approach to the 13th kilometer, the instruments recorded a strange noise coming from the bowels of the planet - the yellow newspapers unanimously assured that only the cries of sinners from the underworld could sound like this. A few seconds after the appearance of a terrible sound, an explosion thundered ...

Space under your feet

In the late 70s and early 80s, getting a job at the Kola Superdeep, as the inhabitants of the village of Zapolyarny in the Murmansk region call the well familiarly, was more difficult than getting into the cosmonaut corps. From hundreds of applicants, one or two were selected. Together with the order for employment, the lucky ones received a separate apartment and a salary equal to double or triple the salary of Moscow professors. There were 16 research laboratories working at the well at the same time, each the size of an average plant. Only the Germans dug the earth with such persistence, but, as the Guinness Book of Records testifies, the deepest German well is almost half as long as ours.

Distant galaxies have been studied by mankind much better than what is under the earth's crust a few kilometers from us. The Kola Superdeep is a kind of telescope into the mysterious inner world of the planet.

Since the beginning of the 20th century, it has been believed that the Earth consists of a crust, a mantle, and a core. At the same time, no one really could tell where one layer ends and the next one begins. Scientists did not even know what, in fact, these layers consist of. Some 40 years ago, they were sure that the layer of granites starts at a depth of 50 meters and continues up to 3 kilometers, and then basalts come. It was expected to meet the mantle at a depth of 15–18 kilometers. In reality, everything turned out to be completely different. And although school textbooks still write that the Earth consists of three layers, scientists from the Kola Superdeep proved that this is not so.

Baltic shield

Projects for traveling deep into the Earth appeared in the early 60s in several countries at once. They tried to drill wells in those places where the crust should have been thinner - the goal was to reach the mantle. For example, the Americans drilled in the area of the island of Maui, Hawaii, where, according to seismic studies, ancient rocks go under the ocean floor and the mantle is located at a depth of about 5 kilometers under a four-kilometer water column. Alas, not a single ocean drilling rig has penetrated deeper than 3 kilometers. In general, almost all ultra-deep well projects mysteriously ended at a depth of three kilometers. It was at this moment that something strange began to happen to the Boers: either they fell into unexpected super-hot areas, or they seemed to be bitten off by some unprecedented monster. Deeper than 3 kilometers, only 5 wells broke through, 4 of them were Soviet. And only the Kola Superdeep was destined to overcome the mark of 7 kilometers.

Initial domestic projects also involved underwater drilling - in the Caspian Sea or on Baikal. But in 1963, drilling scientist Nikolai Timofeev convinced the State Committee for Science and Technology of the USSR that a well should be created on the continent. Although drilling would take incomparably longer, he believed, the well would be much more valuable from a scientific point of view, because it was in the thickness of the continental plates in prehistoric times that the most significant movements of terrestrial rocks took place. The drilling point was chosen on the Kola Peninsula not by chance. The peninsula is located on the so-called Baltic Shield, which is composed of the most ancient rocks known to mankind.

A multi-kilometer section of the Baltic Shield layers is a clear history of the planet over the past 3 billion years.

Conqueror of the Deep

The appearance of the Kola drilling rig is capable of disappointing the layman. The well does not look like a mine that our imagination draws for us. There are no descents underground, only a drill with a diameter of a little more than 20 centimeters goes into the thickness. An imaginary section of the Kola super-deep well looks like a thin needle that has pierced the earth's thickness. A drill with numerous sensors, located at the end of the needle, is raised and lowered over several days. Faster is impossible: the strongest composite cable can break under its own weight.

What happens in the depths is not known for certain. Ambient temperature, noise and other parameters are transmitted upward with a minute delay. However, drillers say that even such contact with the dungeon can be seriously frightening. The sounds coming from below are indeed like screams and howls. To this we can add a long list of accidents that haunted the Kola superdeep when it reached a depth of 10 kilometers. Twice the drill was taken out melted, although the temperatures from which it can melt 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 drilling 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.

12,000 meters of discovery and some hell

Huberman recalls with regret how many scientific discoveries took place at the Kola Superdeep. Literally every meter was a revelation. The well showed that almost all of our previous knowledge about the structure of the earth's crust is incorrect. It turned out that the Earth is not at all like a layer cake. “Up to 4 kilometers, everything went according to theory, and then the doomsday began,” says Guberman. Theorists have promised that the temperature of the Baltic Shield will remain relatively low to a depth of at least 15 kilometers. Accordingly, it will be possible to dig a well up to almost 20 kilometers, just up to the mantle. But already at 5 kilometers, the ambient temperature exceeded 700C, at seven - over 1200C, and at a depth of 12 it was roasting more than 2200C - 1000C higher than predicted. The Kola drillers questioned the theory of the layered structure of the earth's crust - at least in the range up to 12,262 meters. We were taught at school: there are young rocks, granites, basalts, a mantle and a core. But the granites turned out to be 3 kilometers lower than expected. Next were the basalts. They weren't found at all. All drilling took place in the granite layer. This is an extremely important discovery, because all our ideas about the origin and distribution of minerals are connected with the theory of the layered structure of the Earth.

There were also almost fantastic sensations. When, in the late 70s, the Soviet automatic space station brought 124 grams of lunar soil to Earth, the researchers of the Kola Science Center found that it was like two drops of water similar to samples from a depth of 3 kilometers. And a hypothesis arose: the moon broke away from the Kola Peninsula. Now they are looking for exactly where.

In the history of the Kola Superdeep, it was not without mysticism. Officially, as already mentioned, the well stopped due to lack of funds. Coincidence or not - but it was in that 1995 that a powerful explosion of an unknown nature was heard in the depths of the mine. The journalists of a Finnish newspaper broke through to the inhabitants of Zapolyarny - and the world was shocked by the story of a demon flying out of the bowels of the planet.

“When I was asked about this mysterious story at UNESCO, I did not know what to answer. On the one hand, it's bullshit. On the other hand, I, as an honest scientist, could not say that I know what exactly happened here. A very strange noise was recorded, then there was an explosion ... A few days later, nothing of the kind was found at the same depth, ”recalls Academician David Huberman.

Quite unexpectedly for everyone, the predictions of Alexei Tolstoy from the novel "The Hyperboloid of Engineer Garin" were confirmed. At a depth of over 9.5 kilometers, they discovered a real storehouse of all kinds of minerals, in particular gold. A real olivine belt, brilliantly predicted by the writer. Gold in it is 78 grams per ton. By the way, industrial production is possible at a concentration of 34 grams per ton. Perhaps in the near future humanity will be able to take advantage of this wealth.

Today, the scientific research of mankind has reached the boundaries of the solar system: we landed spacecraft on the planets, their satellites, asteroids, comets, sent missions to the Kuiper belt and crossed the border of the heliopause. With the help of telescopes, we see events that took place 13 billion years ago - when the universe was only a few hundred million years old. Against this background, it is interesting to assess how well we know our Earth. The best way to find out its internal structure is to drill a well: the deeper, the better. The deepest well on Earth is the Kola Superdeep, or SG-3. In 1990, its depth reached 12 kilometers 262 meters. If we compare this figure with the radius of our planet, it turns out that this is only 0.2 percent of the way to the center of the Earth. But even this turned out to be enough to turn the ideas about the structure of the earth's crust.

If you imagine a well as a shaft through which you can go down by elevator into the very bowels of the earth, or at least a couple of kilometers, then this is not at all the case. The diameter of the drilling tool with which the engineers created the well was only 21.4 centimeters. The upper two-kilometer section of the well is a little wider - it was expanded to 39.4 centimeters, but still there is no way for a person to get there. To imagine the proportions of the well, the best analogy would be a 57-meter sewing needle with a diameter of 1 millimeter, slightly thicker at one end.

Well layout

But this presentation will be simplified. During drilling, several accidents occurred at the well - part of the drill string ended up underground without the possibility of extracting it. Therefore, several times the well was started anew, from the marks of seven and nine kilometers. There are four major branches and about a dozen smaller ones. The main branches have different maximum depths: two of them cross the mark of 12 kilometers, two more do not reach it by only 200-400 meters. Note that the depth of the Mariana Trench is one kilometer less - 10,994 meters relative to sea level.

Horizontal (left) and vertical projections of SG-3 trajectories

Yu.N. Yakovlev et al. / Bulletin of the Kola Scientific Center of the Russian Academy of Sciences, 2014

Moreover, it would be a mistake to perceive the well as a plumb line. Due to the fact that at different depths the rocks have different mechanical properties, the drill during the work deviated to less dense areas. Therefore, on a large scale, the profile of the Kola Superdeep looks like a slightly curved wire with several branches.

Approaching the well today, we will see only the upper part - a metal hatch screwed to the mouth with twelve massive bolts. The inscription on it was made with a mistake, the correct depth is 12,262 meters.

How was a deep well drilled?

To begin with, it should be noted that the SG-3 was originally conceived specifically for scientific purposes. The researchers chose to drill a place where ancient rocks came to the surface of the earth - up to three billion years old. One of the arguments in the exploration was that the young sedimentary rocks were well studied during oil production, and no one had yet drilled deep into the ancient layers. In addition, there were also large copper-nickel deposits, the exploration of which would be a useful addition to the scientific mission of the well.

Drilling began in 1970. The first part of the well was drilled with a Uralmash-4E serial rig - it was usually used for drilling oil wells. The modification of the installation made it possible to reach a depth of 7 kilometers 263 meters. It took four years. Then the installation was changed to "Uralmash-15000", named after the planned depth of the well - 15 kilometers. The new drilling rig was designed specifically for the Kola Superdeep: drilling at such great depths required a serious refinement of equipment and materials. For example, the weight of the drill string alone at a 15-kilometer depth reached 200 tons. The installation itself could lift loads up to 400 tons.

The drill string consists of pipes connected to each other. With its help, engineers lower the drilling tool to the bottom of the well, and it also ensures its operation. At the end of the column, special 46-meter turbodrills were installed, driven by a stream of water from the surface. They made it possible to rotate the rock crushing tool separately from the entire column.

The bits with which the drill string cut into the granite evoke associations with futuristic details from the robot - several spinning spiked disks connected to the turbine from above. One such bit was enough for only four hours of work - this roughly corresponds to a passage of 7-10 meters, after which the entire drill string must be raised, disassembled and then lowered again. Constant descents and ascents themselves took up to 8 hours.

Even the pipes for the column in the Kola Superdeep had to use unusual ones. At depth, temperature and pressure gradually increase, and, as engineers say, at temperatures above 150-160 degrees, the steel of serial pipes softens and holds multi-ton loads worse - because of this, the likelihood of dangerous deformations and breakage of the column increases. Therefore, the developers chose lighter and heat-resistant aluminum alloys. Each of the pipes had a length of about 33 meters and a diameter of about 20 centimeters - a little narrower than the well itself.

However, even specially designed materials could not withstand drilling conditions. After the first seven-kilometer section, it took almost ten years and more than 50 kilometers of pipes to further drill to the mark of 12,000 meters. Engineers were faced with the fact that below seven kilometers the rocks became less dense and fractured - viscous for the drill. In addition, the wellbore itself distorted its shape and became elliptical. As a result, the string broke several times, and, unable to lift it back, the engineers were forced to concrete the well branch and go through the wellbore again, wasting years of work.

One of these major accidents forced drillers in 1984 to concrete a well branch that reached a depth of 12,066 meters. Drilling had to be restarted from the 7-kilometer mark. This was preceded by a pause in work with the well - at that moment the existence of SG-3 was declassified, and the international geological congress Geoexpo was held in Moscow, the delegates of which visited the object.

According to eyewitnesses of the accident, after the resumption of work, the column drilled a well nine meters down. After four hours of drilling, the workers prepared to lift the column back, but it "did not go." The drillers decided that the pipe somewhere "stuck" to the walls of the well, and increased the lifting power. The workload has been drastically reduced. Gradually disassembling the string into 33-meter candles, the workers reached the next segment, ending with an uneven lower edge: the turbodrill and another five kilometers of pipes remained in the well, they could not be lifted.

The drillers managed to reach the 12-kilometer mark again only by 1990, at the same time the dive record was set - 12,262 meters. Then there was a new accident, and since 1994, work on the well was stopped.

The scientific mission of the ultra-deep

Pattern of seismic tests on SG-3

"Kola superdeep" Ministry of Geology of the USSR, publishing house "Nedra", 1984

The well was investigated by a whole range of geological and geophysical methods, ranging from core collection (a column of rocks corresponding to given depths) and ending with radiation and seismological measurements. For example, the core was taken using core receivers with special drills - they look like pipes with jagged edges. In the center of these pipes there are 6-7 centimeter holes where the rock enters.

But even with this seemingly simple (except for the need to lift this core from many kilometers deep) technique, difficulties arose. Due to the drilling fluid - the same one that set the drill in motion - the core was saturated with liquid and changed its properties. In addition, conditions in depth and on the surface of the earth are very different - the samples cracked from the pressure difference.

At different depths, the core yield was very different. If at five kilometers from a 100-meter segment it was possible to count on 30 centimeters of core, then at depths of more than nine kilometers, instead of a column of rocks, geologists received a set of washers from dense rock.

Micrograph of rocks raised from a depth of 8028 meters

"Kola superdeep" Ministry of Geology of the USSR, publishing house "Nedra", 1984

Studies of the material lifted from the well led to several important conclusions. First, the structure of the earth's crust cannot be simplified to a composition of several layers. This was previously indicated by seismological data - geophysicists saw waves that seemed to be reflected from a smooth boundary. Studies at SG-3 have shown that such visibility can also occur with a complex distribution of rocks.

This assumption affected the design of the well - scientists expected that at a depth of seven kilometers the shaft would enter basalt rocks, but they did not meet at the 12-kilometer mark either. But instead of basalt, geologists discovered rocks that had a large number of cracks and low density, which could not be expected at all from many kilometers of depth. Moreover, traces of groundwater were found in the cracks - it was even suggested that they were formed by a direct reaction of oxygen and hydrogen in the thickness of the Earth.

Among the scientific results, there were also applied ones - for example, at shallow depths, geologists found a horizon of copper-nickel ores suitable for mining. And at a depth of 9.5 kilometers, a layer of a geochemical anomaly of gold was discovered - micrometer grains of native gold were present in the rock. Concentrations reached gram per ton of rock. However, it is unlikely that mining from such a depth will ever be profitable. But the very existence and properties of the gold-bearing layer made it possible to clarify the models of the evolution of minerals - petrogenesis.

Separately, it is necessary to talk about the studies of temperature gradients and radiation. For such experiments, downhole instruments are used, which are lowered on wire-cables. The big problem was to ensure their synchronization with ground equipment, as well as to ensure operation at great depths. For example, difficulties arose with the fact that the cables, with a length of 12 kilometers, were stretched by about 20 meters, which could greatly reduce the accuracy of the data. To avoid this, geophysicists had to create new methods for marking distances.

Most of the commercial tools were not designed to work in the harsh conditions of the lower tiers of the well. Therefore, for research at great depths, scientists used equipment designed specifically for the Kola Superdeep.

The most important result of geothermal research is much higher temperature gradients than expected to be seen. Near the surface, the rate of temperature increase was 11 degrees per kilometer, to a depth of two kilometers - 14 degrees per kilometer. In the interval from 2.2 to 7.5 kilometers, the temperature rose at a rate approaching 24 degrees per kilometer, although existing models predicted a value one and a half times less. As a result, already at a five-kilometer depth, the instruments recorded a temperature of 70 degrees Celsius, and by 12 kilometers this value reached 220 degrees Celsius.

The Kola super-deep well turned out to be unlike other wells - for example, when analyzing the heat release of the rocks of the Ukrainian crystalline shield and Sierra Nevada batholiths, geologists showed that heat release decreases with depth. In SG-3, on the contrary, it grew. Moreover, measurements have shown that the main source of heat, providing 45-55 percent of the heat flow, is the decay of radioactive elements.

Despite the fact that the depth of the well seems colossal, it does not reach even a third of the thickness of the earth's crust in the Baltic Shield. Geologists estimate that the base of the earth's crust in this area runs about 40 kilometers underground. Therefore, even if SG-3 had reached the planned 15-kilometer cutoff, we still would not have reached the mantle.

Such an ambitious task was set by American scientists when developing the Mohol project. Geologists planned to reach the border of Mohorovichich - an underground area where there is a sharp change in the speed of propagation of sound waves. It is believed to be related to the boundary between the crust and the mantle. It is worth noting that the drillers chose the bottom of the ocean near the island of Guadalupe as a place for the well - the distance to the border was only a few kilometers. However, the depth of the ocean itself reached 3.5 kilometers here, which significantly complicated drilling work. The first tests in the 1960s allowed geologists to drill holes only 183 meters.

Plans were recently made to revive the deep ocean drilling project with the help of the exploration drilling vessel JOIDES Resolution. As a new goal, geologists have chosen a point in the Indian Ocean, not far from Africa. The depth of the Mohorovichic border there is only about 2.5 kilometers. In December 2015 - January 2016, geologists managed to drill a well with a depth of 789 meters - the fifth largest in the world of underwater wells. But this value is only half of what was required at the first stage. However, the team plans to return and complete what they started.

***

0.2 percent of the path to the center of the Earth is not such an impressive figure compared to the scale of space travel. However, it should be borne in mind that the boundary of the solar system does not pass along the orbit of Neptune (or even the Kuiper belt). The gravity of the Sun prevails over the stellar one up to distances of two light years from the star. So if you carefully calculate everything, it turns out that Voyager 2 also flew only a tenth of a percent of the path to the outskirts of our system.

Therefore, do not be upset by how little we know the "insides" of our own planet. Geologists have their own telescopes - seismic research - and their own ambitious plans to conquer the bowels. And if astronomers have already managed to touch a solid part of the celestial bodies in the solar system, then geologists have all the most interesting things yet to come.

Vladimir Korolev

Many scientific and industrial works are connected with drilling of underground wells. The total number of such facilities in Russia alone is hardly calculable. But legendary Kola Superdeep since the 1990s, it has remained unsurpassed, going into the thickness of the Earth for more than 12 kilometers! It was drilled not for economic benefit, but out of purely scientific interest - to find out what processes are taking place inside the planet.

Kola superdeep well. Drilling rig of the first stage (depth 7600 m), 1974

50 candidates per seat

The most amazing well in the world is located in the Murmansk region, 10 kilometers west of the city of Zapolyarny. Its depth is 12,262 meters, the diameter of the upper part is 92 centimeters, and the diameter of the lower part is 21.5 centimeters.

The well was laid in 1970 in honor of the 100th anniversary of the birth of V.I. Lenin. The choice of place was not accidental - it is here, on the territory of the Baltic Shield, that the most ancient rocks, whose age is three billion years old, come to the surface.

Since the end of the 19th century, the theory has been known that our planet consists of a crust, mantle and core. But where exactly one layer ends and the next begins, scientists could only guess. According to the most common version, granites go down to three kilometers, then basalts, and at a depth of 15-18 kilometers the mantle begins. All this had to be tested in practice.

Underground research in the 1960s was like a space race - the leading countries tried to get ahead of each other. The opinion was expressed that the richest deposits of minerals, including gold, are located at great depths.

The Americans were the first to drill super-deep wells. In the early 1960s, their scientists figured out that the Earth's crust is much thinner under the oceans. Therefore, the area near the island of Maui (one of the Hawaiian Islands) was chosen as the most promising place for work, where the earth's mantle is located at a depth of about five kilometers (plus a 4-kilometer water column). But both attempts by researchers from the United States ended in failure.

The Soviet Union had to adequately respond. Our researchers proposed to create a well on the continent - despite the fact that it took longer to drill, the result promised to be successful.

The project became one of the largest in the USSR. 16 research laboratories worked at the well. Getting a job here was no less difficult than getting into the cosmonaut corps. Ordinary employees received a triple salary and an apartment in Moscow or Leningrad. Not surprisingly, there was no staff turnover at all, and at least 50 candidates applied for each position.

space sensation

Down to a depth of 7263 meters, the drilling was carried out using a conventional serial installation, which at that time was used in the extraction of oil or gas. This phase took four years. Then there was a one-year break for the construction of a new tower and the installation of a more powerful Uralmash-15000 installation, created in Sverdlovsk and called Severyanka. In her work, the turbine principle was used - when not the entire string rotates, but only the drill head.

With each meter passed, it became more difficult to drive. Previously, it was believed that the temperature of the rock, even at a depth of 15 kilometers, would not exceed 150 °C. But it turned out that at a depth of eight kilometers it reached 169 ° C, and at a depth of 12 kilometers it was 220 ° C at all!

The equipment quickly broke down. But the work continued without stopping. The task of being the first in the world to reach the 12-kilometer mark was politically important. It was solved in 1983, just in time for the beginning of the International Geological Congress in Moscow.

Congress delegates were shown soil samples taken from a record depth of 12 kilometers, and a trip to the well was organized for them. Photos and articles about the Kola Superdeep were published in all the world's leading newspapers and magazines, and postage stamps were issued in several countries in her honor.

But the main thing is that a real sensation was prepared especially for the congress. It turned out that rock samples taken at a 3-kilometer depth of the Kola well are completely identical to the lunar soil (it was first brought to Earth by the Soviet automatic space station Luna-16 in 1970).

Scientists have long assumed that the Moon was once part of the Earth and broke away from it as a result of a cosmic catastrophe. Now it was possible to say that the breakaway part of our planet billions of years ago was in contact with the region of the present Kola Peninsula.

The ultra-deep well became a real triumph for Soviet science. Researchers, designers, even ordinary workers were honored and awarded for almost a whole year.

Kola superdeep well, 2007

Gold in the Deep

At this time, work on the Kola Superdeep was suspended. They were resumed only in September 1984. And the first launch led to the biggest accident. Employees seem to have forgotten that changes are constantly taking place inside the underground passage. The well does not forgive stopping work - and forces you to start all over again.

As a result, the drill string broke, leaving five kilometers of pipes in the depth. They tried to get them, but after a few months it became clear that this would not be possible.

Drilling work began again from the 7-kilometer mark. The depth of 12 kilometers was reached for the second time only six years later. In 1990, the maximum was reached - 12,262 meters.

And then the work of the well was affected by both failures of a local scale and events taking place in the country. The possibilities of the available equipment were exhausted, state funding decreased sharply. After several serious accidents, drilling was stopped in 1992.

The scientific significance of the Kola Superdeep is difficult to overestimate. First of all, work on it confirmed the conjecture about the rich deposits of minerals at great depths. Of course, precious metals in their pure form were not found there. But at the mark of nine kilometers, layers were discovered with a gold content of 78 grams per ton (active industrial mining is carried out when this content is 34 grams per ton).

In addition, the analysis of ancient deep rocks made it possible to clarify the age of the Earth - it turned out that it is one and a half billion years older than it was commonly thought.

It was believed that there is no and cannot be organic life at the superdeep, but in soil samples raised to the surface, whose age was three billion years, 14 previously unknown species of fossilized microorganisms were discovered.

Shortly before closing, in 1989, the Kola Superdeep was again in the center of international attention. The director of the well, Academician David Huberman, suddenly received calls and letters from all over the world. Scientists, journalists, just inquisitive citizens were interested in the question: is it true that the super-deep well has become a "well to hell"?

It turned out that representatives of the Finnish press were talking to some employees of the Kola Superdeep. And they admitted: when the drill crossed the mark of 12 kilometers, strange noises began to be heard from the depths of the well. Instead of a drill head, the workers lowered a heat-resistant microphone - and with its help recorded sounds reminiscent of human screams. One of the employees put forward a version that this the screams of sinners in hell.

How true are these stories? It is technically difficult to place a microphone instead of a drill, but it is possible. True, work on its descent can take several weeks. And it would hardly have been possible to carry it out at a sensitive facility instead of drilling. But, on the other hand, many employees of the well really heard strange sounds that regularly came from the depths. And what it could be, no one knew for sure.

At the suggestion of Finnish journalists, the world press published a number of articles claiming that the Kola Superdeep is a "road to hell." Mystical significance was also attributed to the fact that the USSR collapsed when the drillers were sinking the "unfortunate" thirteenth thousand meters.

In 1995, when the station had already been mothballed, an incomprehensible explosion occurred in the depths of the mine - if only for the reason that there was nothing to explode there. Foreign newspapers reported that a demon flew out of the bowels of the Earth through a man-made passage to the surface (the publications were full of headlines like "Satan escaped from hell").

The director of the well, David Guberman, honestly admitted in his interview: he does not believe in hell and demons, but an incomprehensible explosion really took place, as well as strange noises resembling voices. Moreover, a survey conducted after the explosion showed that all the equipment was in perfect order.

Kola superdeep well, 2012

The well itself (welded), August 2012

Museum for 100 million

For a long time, the well was considered mothballed, about 20 employees worked on it (in the 1980s, their number exceeded 500). In 2008, the facility was completely closed and part of the equipment was dismantled. The ground part of the well is a building the size of a 12-storey building, now it is abandoned and is gradually being destroyed. Sometimes tourists come here, attracted by legends about voices from hell.

According to employees of the Geological Institute of the Kola Scientific Center of the Russian Academy of Sciences, which previously managed the well, its restoration would cost 100 million rubles.

But we are no longer talking about scientific work at depth: on the basis of this object, you can only open an institute or another enterprise for training offshore drilling specialists. Or create a museum - after all, the Kola well continues to be the deepest in the world.

Anastasia BABANOVSKAYA, magazine "Secrets of the XX century" No. 5 2017

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