Current state of the Kola superdeep well. Kola superdeep well
"Dr. Huberman, what the hell did you dig up down there?" - a remark from the audience interrupted the report of a Russian scientist at a UNESCO meeting in Australia. A couple of weeks earlier, in April 1995, a wave of reports about a mysterious accident at the Kola superdeep well swept across the world.
Allegedly, on approaching 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 that. A few seconds after the terrible sound appeared, an explosion occurred...
Space under your feet
In the late 70s - early 80s, get a job at the Kola Superdeep Well, as residents of the village of Zapolyarny affectionately call the well Murmansk region, it was more difficult than getting into the cosmonaut corps. Out of hundreds of applicants, one or two were chosen. Along with the employment order, 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 operating at the well simultaneously, each the size of an average factory. Only the Germans dug the earth with such tenacity, 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 humanity much better than what is located under the earth’s crust a few kilometers away from us. Kola Superdeep - a kind of telescope in the mysterious inner world planets.
Since the beginning of the 20th century, it was believed that the Earth consists of a 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 these layers actually consist of. Some 40 years ago they were sure that the granite layer begins at a depth of 50 meters and continues up to 3 kilometers, and then there are basalts. The mantle was expected to be encountered at a depth of 15–18 kilometers. In reality, everything turned out completely different. And although school textbooks still write that the Earth consists of three layers, scientists from the Kola Superdeep Site have proven 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 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 emerge under the ocean floor and the mantle is located at a depth of approximately 5 kilometers under a four-kilometer layer of water. Alas, not a single ocean drilling site has penetrated deeper than 3 kilometers.
In general, almost all projects of ultra-deep wells mysteriously ended at a depth of three kilometers. It was at this moment that something strange began to happen to the drills: either they found themselves in unexpected super-hot areas, or as if they were being bitten off by some unprecedented monster. Only 5 wells broke through deeper than 3 kilometers, 4 of which were Soviet. And only the Kola Superdeep was destined to overcome the 7-kilometer mark.
Initial domestic projects also involved underwater drilling - in the Caspian Sea or on Lake Baikal. But in 1963, drilling scientist Nikolai Timofeev convinced the USSR State Committee for Science and Technology that it was necessary to create a well on the continent. Although it would take much longer to drill, he believed, the well would be much more valuable with scientific point sight, because it is in the thickness of the continental plates in prehistoric times the most significant movements of earth rocks occurred. The drilling point was not chosen on the Kola Peninsula 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 layers of the Baltic Shield is a visual history of the planet over the past 3 billion years.
Conqueror of the Depths
The appearance of the Kola drilling rig can disappoint the average person. The well is not like the mine that our imagination pictures. There are no descents underground, only a drill with a diameter of a little more than 20 centimeters goes into the thickness. The imaginary section of the Kola superdeep well looks like a tiny needle piercing the earth's thickness. A drill with numerous sensors, located at the end of a needle, is raised and lowered over several days. You can’t go faster: the strongest composite cable can break under its own weight.
What happens in the depths is not known for certain. Temperature environment, noise and other parameters are transmitted upward with a minute delay. However, drillers say that even such contact with the underground can be seriously frightening. The sounds coming from below really look like screams and howls. To this we can add a long list of accidents that plagued the Kola Superdeep when it reached a depth of 10 kilometers. Twice the drill was taken out melted, although the temperatures at which it can melt are comparable to the temperature of the surface of the Sun. One day, it was as if the cable had been pulled from below and was torn off. Subsequently, when they drilled in the same place, no remains of the cable were found. What caused these and many other accidents still remains a mystery. However, they were not the reason for stopping drilling in the Baltic Shield.
12,226 meters of discoveries and a little devilry
“We have the deepest hole in the world - so we must use it!” - David Guberman, the permanent director of the Kola Superdeep Research and Production Center, exclaims bitterly. In the first 30 years of the Kola Superdeep, Soviet and then Russian scientists broke through to a depth of 12,226 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 condition and study previously extracted rock samples.
Huberman recalls with regret how many scientific discoveries took place on the Kola Superdeep. Literally every meter was a revelation. The well showed that almost all our previous knowledge about the structure earth's crust are incorrect. It turned out that the Earth is not at all like layered cake. “Up to 4 kilometers everything went according to theory, and then the end of the world began,” says Huberman. 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 ºC, at seven - over 120 ºC, and at a depth of 12 it was hotter than 220 ºC - 100 ºC higher than predicted. Kola drillers questioned the theory of the layered structure of the earth's crust - at least in the interval up to 12,262 meters.
At school we were taught: there are young rocks, granites, basalts, mantle and core. But the granites turned out to be 3 kilometers lower than expected. Next there should have been basalts. They weren't found at all. All drilling took place in the granite layer. This is a very 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.
Another surprise: life on planet Earth turns out to have arisen 1.5 billion years earlier than expected. At depths where it was believed that there was no organic matter, 14 species of fossilized microorganisms were discovered - the age of the deep layers exceeded 2.8 billion years. At even greater depths, where there is 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
Demons
There were almost fantastic sensations. When in the late 70s the Soviet automatic space station brought 124 grams of lunar soil to Earth, Kola researchers scientific center They found that it is exactly like samples from a depth of 3 kilometers. And a hypothesis arose: the Moon broke away from Kola Peninsula. Now they are looking for where exactly.
The history of the Kola Superdeep is not without mysticism. Officially, as already mentioned, the well stopped due to lack of funds. Coincidence or not, it was in 1995 that a powerful explosion of unknown origin was heard in the depths of the mine. Journalists from a Finnish newspaper broke through to the residents of Zapolyarny - and the world was shocked by the story of a demon flying out of the bowels of the planet.
"When I talk about this mysterious story They started asking questions at UNESCO, I didn’t 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 to us. A very strange noise was recorded, then there was an explosion... A few days later, nothing like that was found at the same depth,” recalls academician David Guberman.
Quite unexpectedly for everyone, Alexei Tolstoy’s predictions from the novel “Engineer Garin’s Hyperboloid” were confirmed. At a depth of over 9.5 kilometers, a real treasure trove of all kinds of minerals, in particular gold, was discovered. A real olivine belt, brilliantly predicted by the writer. It contains 78 grams of gold 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.
In 1970, right on Lenin’s 100th birthday, Soviet scientists began one of the most ambitious projects of our time. On the Kola Peninsula, ten kilometers from the village of Zapolyarny, drilling of a well began, which as a result turned out to be the deepest in the world and entered the Guinness Book of Records.
Grandiose science project walked for more than twenty years. It brought a lot of interesting discoveries, went down in the history of science, and in the end acquired so many legends, rumors and gossip that it would be enough for more than one horror film.
THE USSR. Kola Peninsula. October 1, 1980. Advanced well drillers that reached a record depth of 10,500 meters
Entrance to hell
During its heyday, the drilling site on the Kola Peninsula was a cyclopean structure the height of a 20-story building. Up to three thousand people worked here per shift. The team was led by the country's leading geologists. The drilling rig was built in the tundra ten kilometers from the village of Zapolyarny, and in polar night it shone with lights like a spaceship.
When all this splendor suddenly closed and the lights went out, rumors immediately began to spread. By any measure, the drilling was extraordinarily successful. No one in the world has ever managed to reach such a depth - Soviet geologists lowered the drill more than 12 kilometers.
Sudden end successful project It looked as absurd as the fact that the Americans had closed the program of flights to the Moon. Aliens were blamed for the collapse of the lunar project. There are devils and demons in the problems of the Kola Superdeep.
A popular legend says that the drill was repeatedly pulled out from great depths melted. None physical reasons this was not the case - the temperature underground did not exceed 200 degrees Celsius, and the drill was designed for a thousand degrees. Then the audio sensors allegedly began to pick up some moans, screams and sighs. Dispatchers monitoring instrument readings complained of sensations panic fear and anxiety.
According to legend, it turned out that geologists had drilled to hell. The groans of sinners, extremely high temperatures, the atmosphere of horror at the drilling rig - all this explained why all work on the Kola superdeep was suddenly curtailed.
Many were skeptical about these rumors. However, in 1995, after work had stopped, a thunderclap thundered at the drilling rig. powerful explosion. No one understood what could explode there, not even the leader of the entire project, the prominent geologist David Guberman.
Today they take excursions to the abandoned drilling rig and tell tourists a fascinating story about how scientists drilled a hole in underground kingdom dead. It’s as if moaning ghosts roam around the installation, and in the evening demons crawl to the surface and strive to whisk the unwary extreme sportsman into the abyss.
Underground Moon
In fact, the whole “well to hell” story was invented by Finnish journalists by April 1st. Their joke article was republished American newspapers, and the duck flew to the masses. The long-term drilling of the Kola superdeep reservoir proceeded without any mysticism. But what happened there in reality was more interesting than any legends.
To begin with, ultra-deep drilling was doomed to numerous accidents. Under the yoke of enormous pressure (up to 1000 atmospheres) and high temperatures, the drills could not withstand, the well became clogged, and the pipes used to strengthen the vent broke. Countless times the narrow well was bent so that more and more branches had to be drilled.
The worst accident occurred shortly after the main triumph of geologists. In 1982, they were able to overcome the 12 kilometer mark. These results were solemnly announced in Moscow at the International Geological Congress. Geologists from all over the world were brought to the Kola Peninsula, they were shown a drilling rig and rock samples mined at fantastic depths that humanity had never reached before.
After the celebration, drilling continued. However, the break in work turned out to be fatal. In 1984, the worst drilling accident occurred. As many as five kilometers of pipes came loose and clogged the well. It was impossible to continue drilling. Five years of work were lost overnight.
We had to resume drilling from the 7-kilometer mark. Only in 1990 did geologists again manage to cross 12 kilometers. 12,262 meters - this is the final depth Kola well.
But parallel to the terrible accidents, there were also incredible discoveries. Deep drilling is like a time machine. On the Kola Peninsula they approach the surface ancient breeds, whose age exceeds 3 billion years. By going deeper, scientists have gained a clear understanding of what happened on our planet during its youth.
First of all, it turned out that the traditional diagram of the geological section compiled by scientists does not correspond to reality. “Up to 4 kilometers everything went according to theory, and then the end of the world began,” Huberman later said
According to calculations, by drilling through a layer of granite, it was supposed to get to even harder, basaltic rocks. But there was no basalt. After the granite came loose layered rocks, which constantly crumbled and made it difficult to move deeper.
But among rocks 2.8 billion years old, fossilized microorganisms were found. This made it possible to clarify the time of the origin of life on Earth. At even greater depths, huge deposits of methane were found. This clarified the issue of the emergence of hydrocarbons - oil and gas.
And at a depth of over 9 kilometers, scientists discovered a gold-bearing olivine layer, so vividly described by Alexei Tolstoy in “The Hyperboloid of Engineer Garin.”
But the most fantastic discovery occurred in the late 1970s, when the Soviet lunar station brought samples of lunar soil. Geologists were amazed to see that its composition completely coincided with the composition of the rocks they mined at a depth of 3 kilometers. How was this possible?
The fact is that one of the hypotheses for the origin of the Moon suggests that several billion years ago the Earth collided with some kind of celestial body. As a result of the collision, a piece broke off from our planet and turned into a satellite. Perhaps this piece came off in the area of the current Kola Peninsula.
The final
So why did they close the Kola superdeep pipeline?
Firstly, the main objectives of the scientific expedition were completed. It was created in extreme conditions unique equipment for drilling at great depths has been tested and significantly improved. The collected rock samples were examined and described in detail. The Kola well helped to better understand the structure of the earth's crust and the history of our planet.
Secondly, time itself was not conducive to such ambitious projects. In 1992, funding for the scientific expedition was cut off. The employees quit and went home. But even today the grandiose building of the drilling rig and the mysterious well are impressive in their scale.
Sometimes it seems that the Kola Superdeep has not yet exhausted the entire supply of its wonders. The head of the famous project was also sure of this. “We have the deepest hole in the world - so we must use it!” - exclaimed David Huberman.
Vladimir Khomutko
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Where is the deepest oil well?
Man has long dreamed of not only flying into space, but also penetrating deep into home planet. For a long time, this dream remained unrealizable, since existing technologies did not allow us to go any significantly deeper into the earth’s crust.
In the thirteenth century, the depth of the wells that the Chinese dug reached a fantastic 1,200 meters for that time, and starting in the thirties of the last century, with the advent of drilling rigs, people in Europe began to drill three-kilometer-long pits. However, all this, so to speak, was only shallow scratches on the earth's surface.
The idea to drill through the upper shell of the earth into a global project took shape in the 60s of the twentieth century. Previously, all assumptions about the structure of the earth's mantle were based on data from seismic activity and other indirect factors. However, the only way to look into the bowels of the Earth in the literal sense of the word was to drill deep wells.
Hundreds of wells drilled for these purposes, both on land and in the ocean, have provided numerous data that help answer a lot of questions about the structure of our planet. However, now ultra-deep workings pursue not only scientific, but also purely practical goals. Next, we look at the deepest wells ever drilled in the world.
This well, 8,553 meters deep, was drilled in 1977 in the area where the Vienna oil and gas province is located. Small oil deposits were discovered in it, and the idea arose to look deeper. At a depth of 7,544 meters, experts found unrecoverable gas reserves, after which the well suddenly collapsed. The OMV company decided to drill a second one, but despite its great depth, the miners were unable to find any minerals.
Austrian well Zistersdorf
Federal Republic of Germany – Hauptbohrung
To organize this deep mining German specialists inspired by the famous Kola superdeep well. In those days, many countries in Europe and the world began to develop their own deep drilling projects. Among them, the Hauptborung project stood out, which was implemented over four years - from 1990 to 1994 in Germany. Despite its relatively small depth (compared to the wells described below) - 9,101 meters, this project has become widely known worldwide thanks to open access to the obtained geological and drilling data.
United States of America – Baden Unit
The well, 9,159 meters deep, was drilled by the American company Lone Star in the vicinity of the town of Anadarko (USA). Development began in 1970 and continued for 545 days. The cost of its construction was six million dollars, and in terms of materials, 150 diamond bits and 1,700 tons of cement were used.
USA – Bertha Rogers
This mine was also created in the state of Oklahoma in the area of the Anadarko oil and gas province in Oklahoma. Work began in 1974 and lasted 502 days. The drilling was also carried out by the same company as in the previous example. Having passed 9,583 meters, the miners came across a deposit of molten sulfur and were forced to stop work.
This well in the Guinness Book of Records is called “the deepest intrusion into the Earth’s crust made by man.” In May 1970, in the vicinity of the lake with the hair-raising name Vilgiskoddeoaivinjärvi, the construction of this grandiose mine began. Initially we wanted to walk 15 kilometers, but due to too high temperatures we stopped at 12,262 meters. Currently, the Kola Superdeep Pipeline is mothballed.
Qatar – BD-04A
Drilled in an oil field called Al-Shaheen for the purpose of geological exploration.
The total depth was 12,289 meters, and the 12-kilometer mark was passed in just 36 days! It was seven years ago.
Russian Federation – OP-11
Since 2003, a whole series of ultra-deep drilling works began as part of the Sakhalin-1 project.
In 2011, Exxon Neftegas drilled the deepest oil well in the world - 12,245 meters - in just 60 days.
It happened at a field called Odoptu.
However, the records didn't end there.
O-14 is a production well in the world that has no analogues in terms of the total length of the trunk - 13,500 meters, as well as the longest horizontal well - 12,033 meters.
It was developed by Russian company NK Rosneft, part of the consortium of the Sakhalin-1 project. This well was developed in a field called Chayvo. The state-of-the-art Orlan drilling platform was used to drill it.
We also note the depth along the shaft of the well constructed in 2013 as part of the same project under number Z-43, the value of which reached 12,450 meters. In the same year, this record was broken at the Chayvinskoye field - the length of the Z-42 shaft reached 12,700 meters, and the length of the horizontal section - 11,739 meters.
In 2014, the excavation of the Z-40 well (offshore Chayvo field) was completed, which until O-14 was the longest well in the world - 13,000 meters, and also had the longest horizontal section - 12,130 m.
In other words, to date, 8 of the 10 longest wells in the world are located in the fields of the Sakhalin-1 project.
Kola superdeep well
The field, called Chayvo, is one of three being developed by the consortium on Sakhalin. It is located in the northeast of the coast of Sakhalin Island. The depth of the seabed in this area varies from 14 to 30 m. The field was put into operation back in 2005.
In general, the international shelf project Sakhalin-1 unites the interests of several large global corporations. It includes three fields located on the offshore shelf Odoptu, Chayvo and Arkutun-Dagi. According to experts, the total available hydrocarbon reserves here are about 236 million tons of oil and almost 487 billion cubic meters natural gas. The Chayvo field was put into operation (as we said above) in 2005, the Odoptu field in 2010, and at the very beginning of 2015 the development of the Arkutun-Dagi field began.
Over the entire existence of the project, it was possible to produce about 70 million tons of oil and 16 billion cubic meters of natural gas. Currently, the project has encountered some difficulties associated with fluctuations in oil prices, but members of the consortium have confirmed their interest in further work.
The deepest wells in the world March 18th, 2015
The dream of penetrating into the depths of our planet, along with plans to send a person into space, seemed absolutely impossible for many centuries. In the 13th century, the Chinese were already digging wells up to 1,200 meters deep, and with the advent of drilling rigs in the 1930s, Europeans managed to penetrate to a depth of three kilometers, but these were only scratches on the body of the planet.
As a global project, the idea to drill into the upper shell of the Earth appeared in the 1960s. Hypotheses about the structure of the mantle were based on indirect data, such as seismic activity. AND the only way literally looking into the bowels of the earth involved drilling ultra-deep wells. Hundreds of wells on the surface and in the depths of the ocean have provided answers to some of the scientists' questions, but the times when they were used to test the most different hypotheses, are long gone.
Let's remember the list of the deepest wells on earth...
Siljan Ring (Sweden, 6800 m)
At the end of the 80s in Sweden, a well of the same name was drilled in the Siljan Ring crater. According to the scientists’ hypothesis, it was in that place that natural gas deposits of non-biological origin were expected to be found. The drilling result disappointed both investors and scientists. Hydrocarbons in industrial scale were not found.
Zistersdorf UT2A (Austria, 8553 m)
In 1977, in the Vienna area oil and gas basin, where several small oil deposits were hidden, the Zistersdorf UT1A well was drilled. When unrecoverable gas reserves were discovered at a depth of 7,544 m, the first well suddenly collapsed, forcing OMV to drill a second. However, this time the miners did not find deep hydrocarbon resources.
Hauptbohrung (Germany, 9101 m)
The famous Kola well made an indelible impression on the European public. Many countries have begun to prepare their ultra-deep well projects, but the Hauptborung well, developed from 1990 to 1994 in Germany, is especially noteworthy. Reaching only 9 km, it has become one of the most famous ultra-deep wells thanks to the openness of drilling and scientific data.
Baden Unit (USA, 9159 m)
A well drilled by Lone Star near the city of Anadarko. Its development began in 1970 and lasted for 545 days. In total, this well required 1,700 tons of cement and 150 diamond bits. And its total cost cost the company $6 million.
Bertha Rogers (USA, 9583 m)
Another ultra-deep well created in the Anadarko oil and gas basin in Oklahoma in 1974. The entire drilling process took Lone Star workers 502 days. Work had to be stopped when miners stumbled upon a molten sulfur deposit at a depth of 9.5 kilometers.
Kola superdeep (USSR, 12,262 m)
Listed in the Guinness Book of Records as "the deepest human invasion of the earth's crust." When drilling began in May 1970 near the lake with the unpronounceable name Vilgiskoddeoaivinjärvi, it was assumed that the well would reach a depth of 15 kilometers. But due to high temperatures (up to 230°C), the work had to be curtailed. On this moment The Kola well is mothballed.
I already told you about the history of this well -
BD-04A (Qatar, 12,289 m)
7 years ago, exploration well BD-04A was drilled in the Al-Shaheen oil field in Qatar. It is noteworthy that the Maersk drilling platform was able to reach 12 kilometers in a record 36 days!
OP-11 (Russia, 12,345 m)
January 2011 was marked by a message from Exxon Neftegas that drilling of the longest extended reach well was close to completion. OR-11, located at the Odoptu field, also set a record for the length of a horizontal wellbore - 11,475 meters. The miners were able to complete the work in just 60 days.
The total length of the OP-11 well at the Odoptu field was 12,345 meters (7.67 miles), thereby setting a new world record for drilling extended reach wells (ERR). OR-11 also ranked first in the world in terms of the horizontal distance between the bottom and the drilling point - 11,475 meters (7.13 miles). ENL completed the drilling of a record well in just 60 days, using high-speed drilling and comprehensive drilling quality control technologies developed by ExxonMobil, achieving highest performance in drilling every foot of the OR-11 well.
“The Sakhalin-1 project continues to contribute to Russia's leadership in the global oil and gas industry,” said James Taylor, ENL President. — To date, 6 of the 10 longest EDS wells, including the OP-11 well, have been drilled as part of the Sakhalin-1 project using drilling technologies from ExxonMobil Corporation. The specially designed Yastreb drilling rig was used throughout the project, setting numerous industry records for hole length, drilling speed and directional drilling performance. We also set a new record while maintaining excellent safety, health and environmental performance.”
The Odoptu field, one of three fields of the Sakhalin-1 project, is located on the shelf, at a distance of 5-7 miles (8-11 km) from the north-eastern coast of Sakhalin Island. BOV technology makes it possible to successfully drill wells from the shore under the seabed to reach offshore oil and gas deposits, without violating the principles of safety and environmental protection, in one of the most difficult subarctic regions of the world to develop.
P.S. And here's what they write in the comments: tim_o_fay: let's separate the flies from the cutlets :) Long well ≠ deep. The same BD-04A, of its 12,289 m, has 10,902 m of horizontal trunk. http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x150185 Accordingly, the vertical there is a kilometer or so in total. What does it mean? This means low (comparatively) pressure and temperature at the bottom, soft rocks (with a good penetration rate), etc. and so on. OP-11 from the same opera. I won’t say that drilling horizontals is easy (I’ve been doing this for eight years), but it’s still much easier than drilling super-deep ones. Bertha Rogers, SG-3 (Kola), Baden Unit and others with great true vertical depth (literal translation from English True Vertical Depth, TVD) - this is truly something transcendental. In 1985, former graduates from all over the Union came to the fiftieth anniversary of SOGRT with stories and gifts for the technical school museum. Then I was honored to touch a piece of granite gneiss from a depth of more than 11.5 km :)
Despite the fact that it is the 21st century, internal structure Very little has been studied of our planet. We know quite well what is going on in deep space, but at the same time, the degree of penetration into the secrets of the Earth can be compared to a light pinprick into the surface of the rind of a watermelon.
In the mid-1950s, when drillers learned to make wells more than 7 km deep, humanity came closer to achieving a very ambitious task - to go through the earth's crust and see what lies beneath it. Our compatriots came closest to this goal when they drilled the Kola superdeep well.
The Earth's solid shell is surprisingly thin relative to its size - the thickness of the crust varies between 20-65 km on land and 3-8 km under the ocean, occupying less than 1% of the planet's volume. Behind it is a vast layer - the mantle - which accounts for the bulk of the Earth's volume. Even lower is the dense core, consisting primarily of iron, but also nickel, lead, uranium and other metals. Between the crust and the mantle there is a boundary zone, named after the Yugoslav scientist who discovered it, the Mohorovic surface (border), or Moho for short. In this zone, the speed of propagation of seismic waves increases sharply. There are a number of hypotheses designed to explain this phenomenon, but in general it remains unsolved.
The most important goal of the most serious deep drilling projects launched in the second half of the 20th century was precisely this mysterious layer. Researchers were never able to reach it, but the data on the structure of the earth’s crust obtained during the drilling of ultra-deep wells turned out to be so unexpected that the Mohorovic boundary seemed to fade into the background. First it was necessary to explain the mysteries discovered in higher layers.
The Americans were the first to begin deep drilling of the earth's crust for scientific purposes. In the 1960s, they launched the Mohole scientific project, which involved the creation of underwater ones using special drilling ships. Over the next thirty years, more than 800 wells appeared in the seas and oceans, many of which are located at depths of more than 4 km. The longest well was able to go only 800 m into the seabed, and yet the data obtained were of enormous importance for geology. In particular, they served as significant confirmation of the so-called. tectonic theory, according to which the continents are based on solid lithospheric plates, slowly floating, immersed in a liquid mantle.
Of course, the USSR could not lag behind its overseas competitor, so in the mid-1960s, we launched numerous projects to study the earth’s crust. Soviet scientists took a slightly different path, deciding to drill wells not in the sea, but on land. The most famous and successful project of this kind is the Kola superdeep well - the deepest “hole in the ground” ever made by man. The well is located at the northern tip of the Kola Peninsula. This place was not chosen by chance - over hundreds of millions of years, natural erosion destroyed the surface of the Kola crystalline shield, stripping off the upper layers of the rock. As a result, ancient Archean layers appeared on the surface, corresponding to depths of 5-10 km for the average section of the continental-type earth's crust. The 15-kilometer design depth of the well allowed scientists to hope to reach the mysterious Mohorovic surface.
Drilling of the Kola well began in 1970, and it ended more than 20 years later - in 1994. At first, the drillers worked using completely traditional methods: a column of light-alloy pipes was lowered into the well, at the end of which a cylindrical metal drill with diamond teeth and sensors was attached. The column was rotated by an engine located on the surface. As the depth of the well increased, new sections were added to the pipes. Periodically, the entire column had to be lifted to the surface to remove the cut rock core and replace the dull crown. Unfortunately, this proven technology becomes ineffective when the well depth exceeds a certain mark: the friction of the pipes against the walls of the well becomes too great for this entire huge shaft to be rotated. To overcome this difficulty, engineers developed a design in which only the drill head rotated. Turbines were installed at the end of the column, through which drilling fluid was passed - a special liquid that acts as a lubricant and circulates through the pipes. These turbines made the drill rotate.
The samples brought to the surface during the drilling process made a real revolution in geology. Existing ideas about the structure of the earth's crust turned out to be far from reality. The first surprise was the absence of a transition from granite to basalt, which scientists expected to see at a depth of about 6 km. Seismological studies indicate that in this area the speed of propagation of acoustic waves changes sharply, which has been interpreted as the beginning of a basaltic foundation of the earth's crust. However, even after the transition zone, granites and gneisses continued to rise to the surface. From this point on, it became clear that the prevailing model of a two-layer earth's crust was incorrect. Now the presence of a seismic transition is explained by a change in the properties of the rock under conditions of increased pressure and temperature.
An even more surprising discovery was the fact that rocks located at depths of more than 9 km turned out to be extremely porous. Before this, it was believed that as depth and pressure increase, they, on the contrary, should become increasingly dense. The miniature cracks were filled with an aqueous solution whose origin for a long time remained completely unclear. Later, a theory was put forward according to which the discovered water is formed from hydrogen and oxygen atoms, which are “squeezed out” from the surrounding rock under the influence of colossal pressures.
Another surprise: life on planet Earth turns out to have arisen 1.5 billion years earlier than expected. At a depth of 6.7 km, where it was believed that there was no organic matter, 14 species of fossilized microorganisms were discovered. They were found in extremely uncharacteristic carbon-nitrogen deposits (instead of the usual limestone or silica) that were over 2.8 billion years old. At even greater depths, where there are no longer sediments, methane appeared in huge concentrations. This completely and utterly destroyed the theory of the biological origin of hydrocarbons such as oil and gas.
Scientists were also extremely surprised by the speed with which the temperature increased as the well deepened. At the 7 km mark it reached 120 °C, and at a depth of 12 km it was already 230 °C, which was a third higher than the planned value: the temperature gradient of the crust was almost 20 degrees per 1 km, instead of the expected 16. It was also found that half of the heat flow is of radiogenic origin. The high temperature negatively affected the operation of the bit, so the drilling fluid began to be cooled before pumping it into the well. This measure turned out to be quite effective, however, after passing the 12 km mark, it was no longer able to provide sufficient heat removal. In addition, the compressed and heated rock acquired some properties of a liquid, as a result of which the well began to float the next time the drill string was removed. Further progress turned out to be impossible without new technological solutions and significant financial costs, so in 1994 drilling was suspended. By that time, the well had deepened to 12,262 m.