Kola ultra-deep well- the deepest borehole in the world (from 1979 to 2008) 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 geological exploration, SG-3 was drilled solely to study the lithosphere in the place where the Mohorovicic boundary is. (abbreviated Moho limit) - lower limit earth's crust, at 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 Lenin’s birth, in 1970. Sedimentary rock strata by that time had been 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. To extract minerals, 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 a basalt one. On June 6, 1979, the well broke the record of 9583 meters, previously held by the Bertha-Rogers well (an oil well in Oklahoma). IN 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 clear boundary between granites and basalts would be discovered, only granites were found in the core throughout the depth. However, due to high pressure compressed granites greatly changed their physical and acoustic properties. As a rule, the lifted core crumbled from active gas release into slurry, since it could not withstand a sharp change in pressure. It was possible to remove a strong piece of core only with a very slow lifting of the drill, when the “excess” gas, still pressed to high pressure, managed to escape from the rock. The density of cracks at great depths, contrary to expectations, increased. There was also water at depth that filled the cracks.
It is interesting that when the International Geological Congress was held in Moscow in 1984, at which the first results of research on the well were presented, many scientists jokingly proposed to immediately bury it, since it destroys all ideas about the structure of the earth’s crust. Indeed, strange things began even in the first stages of penetration. For example, even before drilling began, theorists promised that the temperature of the Baltic shield would remain relatively low to a depth of at least,at 5 kilometers ambient temperature exceeded 70 degrees Celsius, at seven - over 120 degrees, and at a depth of 12 it was hotter than 220 degrees - 100 degrees 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.
“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 12,262 meters. But since 1995, drilling has been stopped: there was no one to finance the project. What stands out within scientific programs UNESCO 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 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.
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 are no longer sediments, methane appeared in huge concentrations. This completely and utterly destroyed the theory. biological origin hydrocarbons such as oil and gas. There were almost fantastic sensations. When in the late 70s the Soviet automatic space station brought 124 grams of lunar soil to Earth, researchers from the Kola Science Center found that it was like two peas in a pod 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 where exactly. By the way, the Americans, who brought half a ton of soil from the Moon, did nothing meaningful with it. They were placed in airtight containers and left for research by future generations.
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 layer, 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. But, what is most surprising, at even greater depths, where there are no longer sedimentary rocks, natural methane gas 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, but also mysterious legends were also associated with the Kola well. most of of which, when tested, turned out to be fabrications of journalists. According to one of them, the primary source of information (1989) was the American television company Trinity Broadcasting Network, which, in turn, took the story from a report by a Finnish newspaper. Allegedly, when drilling a well, at a depth of 12 thousand meters, the scientists' microphones recorded screams and moans.) Journalists, without even thinking that it was simply impossible to insert a microphone to such a depth (what kind of sound recording device can work at temperatures above two hundred degrees?) wrote that the drillers heard a “voice from the underworld.”
After these publications, the Kola superdeep well began to be called “the road to hell,” claiming that every 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 came across unusual voids. Intrigued by this unexpected discovery, the drillers lowered down a microphone capable of operating at extremely high temperatures. high temperatures, and other sensors. The temperature inside allegedly reached 1,100 °C - there was the heat of fiery chambers, in which human screams could allegedly be heard.
This legend still roams the vast expanses of the Internet, having outlived the very culprit of these gossips - the Kola well. Work on it was stopped back in 1992 due to lack of funding. Until 2008, it was in a mothballed state. A year later, the final decision was made to abandon the continuation of research and to dismantle the entire research complex and “bury” the well. The final abandonment of the well occurred in the summer of 2011.
So, as you can see, this time scientists were not able to get to the mantle and examine 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 objectives set in the ultra-deep drilling project have been completed. Special equipment and technology for ultra-deep drilling, as well as for studying wells drilled to great depths, have been developed and created. We received information, one might say, “first hand” about physical condition, properties and composition of rocks in their natural occurrence and from core to a depth of 12,262 m. The well gave an excellent gift to the homeland at shallow depths - in the range of 1.6-1.8 km. Industrial copper-nickel ores were opened there - a new ore horizon was discovered. And it comes in handy, because the local nickel plant is already running short 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 extended 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 greatest reflection during seismic sounding is the level where the granites transform into a more durable basalt layer. In reality, it turned out that less strong and less dense fractured rocks are located there - Archean gneisses. This was never expected. And this is fundamentally new geological and geophysical information, which allows us to interpret the data of deep geophysical research differently.
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. Thus, at depths of 9-12 km, highly porous fractured rocks were encountered, saturated with highly mineralized underground waters. 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 the core was found increased content gold - 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 depths?
Ideas about thermal conditions have also changed earth's bowels, about the deep distribution of temperatures in areas of basalt shields. 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 flow is of radiogenic origin.
The depths 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 don’t know exactly what is under our feet, deep underground. Over the entire existence of earthly civilization, we have been able to go deeper 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, Maersk Oil BD-04A, a 12,290 meter long inclined oil well, was drilled (Al Shaheen oil basin in Qatar). In January 2011, an inclined oil well with a depth of 12,345 meters was drilled at the Odoptu-Sea field (Sakhalin-1 project). Drilling depth record for this moment belongs to the Z-42 well of the Chayvinskoye field, the depth of which is 12,700 meters.
Hundreds of thousands of wells were drilled into the earth's crust over the last decades of the last century. And this is not surprising, because the search and extraction of minerals in our time inevitably involves deep drilling. But among all these wells there is only one on the planet - the legendary Kola Superdeep (SG), the depth of which still remains unsurpassed - more than twelve kilometers. In addition, SG is one of the few that was drilled not for the sake of exploration or mining, but for purely scientific purposes: to study the most ancient rocks of our planet and learn the secrets of the processes taking place in them.
Today there is no drilling on the Kola superdeep; it was stopped in 1992. SG was not the first and not the only one in the program for studying the deep structure of the Earth. Three of the foreign wells reached a depth of 9.1 to 9.6 km. It was planned that one of them (in Germany) would surpass the Kola one. However, drilling at all three, as well as at SG, was stopped due to accidents and technical reasons cannot be continued yet.
Apparently, it is not for nothing that the complexity of drilling ultra-deep wells is compared with a flight into space, with a long space expedition to another planet. Rock samples extracted from the earth's interior are no less interesting than samples of lunar soil. The soil delivered by the Soviet lunar rover was studied at various institutes, including Kola scientific center. It turned out that the composition of the lunar soil almost completely corresponds to the rocks extracted from the Kola well from a depth of about 3 km.
SITE SELECTION AND FORECAST
A special geological exploration expedition (Kola Geological Exploration Expedition) was created to drill the SG. The drilling location was also, of course, not chosen by chance - the Baltic Shield in the Kola Peninsula area. Here, the oldest igneous rocks about 3 billion years old (and the Earth is only 4.5 billion years old) come to the surface. It was interesting to drill in the oldest igneous rocks, because sedimentary rocks down to a depth of 8 km have already been well studied for oil production. And during mining, they usually only penetrate 1-2 km into igneous rocks. The choice of location for the SG was also facilitated by the fact that the Pecheneg trough is located here - a huge bowl-like structure, as if pressed into ancient rocks. Its origin is associated with a deep fault. And this is where large copper-nickel deposits are located. And the tasks assigned to the Kola Geological Expedition included identifying a number of features of geological processes and phenomena, including ore formation, determining the nature of the boundaries separating layers in the continental crust, and collecting data on the material composition and physical state of rocks.
Before drilling began, a section of the earth's crust was constructed based on seismological data. It served as a forecast for the appearance of those earth layers that the well intersected. It was assumed that a granite strata extends to a depth of 5 km, after which stronger and more ancient basalt rocks were expected.
So, the drilling site was chosen in the north-west of the Kola Peninsula, 10 km from the city of Zapolyarny, not far from our border with Norway. Zapolyarny is a small town that grew up in the fifties next to a nickel plant. Among the hilly tundra on a hillock, blown by all the winds and snowstorms, there is a “square”, each side of which is formed from seven five-story buildings. Inside there are two streets, at their intersection there is a square where the House of Culture and the hotel stand. A kilometer from the town, behind a ravine, the buildings and tall chimneys of a nickel plant are visible; behind it, along the mountainside, are dark dumps of waste rock from a nearby quarry. Near the town there is a highway to the city of Nikel and to a small lake, on the other side of which is Norway.
The soil of those places contains traces in abundance past war. When you take a bus from Murmansk to Zapolyarny, about halfway along the way you cross the small river Zapadnaya Litsa, on its bank there is a memorial obelisk. This is the only place in all of Russia where the front stood motionless during the war from 1941 to 1944, facing the Barents Sea. Although there were fierce battles all the time and losses on both sides were huge. The Germans unsuccessfully tried to break through to Murmansk - the only ice-free port in our North. Winter 1944 Soviet troops managed to break through the front.
The pipe string was lowered and raised on this hook. On the left - in the basket - there are 33-meter pipes - "candles" - prepared for descent.
Kola superdeep well. In the figure on the right: A. Forecast of the geological section. B. Geological section constructed on the basis of SG drilling data (arrows from column A to column B indicate at what depth the predicted rocks were encountered). On this section top part(up to 7 km) - Proterozoic strata with layers of volcanic (diabase) and sedimentary rocks (sandstones, dolomites). Below 7 km there is an Archean sequence with repeating units of rocks (mainly gneisses and amphibolites). Its age is 2.86 billion years. B. A well bore with many drilled and lost boreholes (below 7 km) is shaped like the branched roots of a giant plant. The well seems to be twisting because the drill is constantly deviating towards less durable rocks.
From Zapolyarny to Superglubokaya - 10 km. The road goes past the plant, then along the edge of the quarry and then climbs up the mountain. From the pass a small basin opens, in which the drilling rig is installed. Its height is as high as a twenty-story building. “Shift workers” came here from Zapolyarny for each shift. In total, about 3,000 people worked on the expedition; they lived in the city in two houses. The grumbling of some mechanisms could be heard from the drilling rig around the clock. The silence meant that for some reason there was a break in the drilling. In winter, during the long polar night - and it lasts there from November 23 to January 23 - the entire drilling rig glowed with lights. Often the light of the aurora was added to them.
A little about the staff. The Kola geological exploration expedition, created for drilling, brought together a good, highly qualified team of workers. The head of the GRE, a talented leader who selected the team, was almost always D. Guberman. Chief engineer I. Vasilchenko was responsible for drilling. The drilling rig was commanded by A. Batishchev, whom everyone simply called Lekha. Geology was in charge of V. Laney, and geophysics was in charge of Yu. Kuznetsov. A huge amount of work on processing the core and creating a core storage facility was carried out by geologist Yu. Smirnov - the same one who had the “treasured cabinet”, which we will tell you about later. More than 10 research institutes took part in conducting research on SG. The team also had its own “Kulibins” and “left-handers” (S. Tserikovsky was especially distinguished), who invented and manufactured various devices that sometimes made it possible to get out of the most difficult, seemingly hopeless situations. They themselves created many of the necessary mechanisms here in well-equipped workshops.
DRILLING HISTORY
Well drilling began in 1970. Drilling to a depth of 7263 m took 4 years. It was carried out using a serial installation, which is usually used in oil and gas production. Due to constant winds and cold, the entire tower had to be covered to the top with wooden panels. Otherwise, it is simply impossible for someone who must stand at the top while lifting a pipe string to work.
Then there was a year-long break associated with the construction of a new tower and the installation of a specially designed drilling rig - Uralmash-15000. It was with its help that all further ultra-deep drilling was carried out. IN new installation- more powerful automated equipment. Turbine drilling was used - this is when not the entire column rotates, but only the drilling head. Drilling fluid was fed through the column under pressure, rotating a multi-stage turbine located below. Its total length is 46 m. The turbine ends with a drill head with a diameter of 214 mm (it is often called a crown), which has a ring shape, so an undrilled column of rock remains in the middle - a core with a diameter of 60 mm. A pipe passes through all sections of the turbine - a core receiver, where columns of mined rock are collected. The crushed rock along with the drilling fluid is carried down the well to the surface.
On the core samples on the right, oblique stripes are clearly visible, meaning that here the well passed through obliquely located formations.
The mass of the column immersed in a well with drilling fluid is about 200 tons. This is despite the fact that specially designed light alloy pipes were used. If a column is made from ordinary steel pipes, it will burst from its own weight.
Many difficulties, sometimes completely unexpected, arise in the process of drilling at great depths and with core sampling.
The penetration in one trip, determined by the wear of the drill head, is usually 7-10 m. (A trip, or cycle, is the lowering of the string with the turbine and drilling tool, the actual drilling and the complete lifting of the string.) Drilling itself takes 4 hours. And the descent and ascent of the 12-kilometer column takes 18 hours. When lifted, the column is automatically disassembled into sections (candles) 33 m long. On average, 60 m were drilled per month. 50 km of pipes were used to drill the last 5 km of the well. This is the extent of their wear.
To a depth of approximately 7 km, the well intersected strong, relatively homogeneous rocks, and therefore the borehole was smooth, almost corresponding to the diameter of the drill bit. The work progressed, one might say, calmly. However, at a depth of 7 km, less durable fractured rocks appeared, interbedded with small very hard layers - gneisses, amphibolites. Drilling became more difficult. The trunk took on an oval shape, and many cavities appeared. Accidents have become more frequent.
The figure shows the initial forecast of the geological section and the one compiled on the basis of drilling data. It is interesting to note (column B) that the inclination angle of the formations along the well is about 50 degrees. Thus, it is clear that the rocks intersected by the well come to the surface. This is where we can remember the already mentioned “cherished cabinet” of geologist Yu. Smirnov. There, on one side, he had samples obtained from the well, and on the other, samples taken on the surface at the distance from the drilling site where the corresponding formation comes up. The match between the breeds is almost complete.
The year 1983 was marked by a hitherto unsurpassed record: the drilling depth exceeded 12 km. Work was suspended.
The International Geological Congress was approaching, which, according to plan, was held in Moscow. The Geoexpo exhibition was being prepared for it. It was decided not only to read reports on the results achieved at the SG, but also to show the participants of the congress the work in situ and the extracted rock samples. The monograph “Kola Superdeep” was published for the congress.
At the Geoexpo exhibition there was a large stand dedicated to the work of the SG and the most important thing - achieving record depth. There were impressive graphs telling about drilling techniques and technology, extracted rock samples, photographs of equipment and staff at work. But the greatest attention of the participants and guests of the congress was attracted by one detail that was unconventional for an exhibition display: the most ordinary and already slightly rusty drill head with worn-out carbide teeth. The label stated that it was exactly what was used when drilling at a depth of more than 12 km. This drill head amazed even specialists. Probably, everyone involuntarily expected to see some kind of miracle of technology, maybe with diamond equipment... And they still did not know that at the SG next to the drilling rig there was a large pile of exactly the same already rusted drill heads: after all, they had to be replaced with new ones approximately every drilled 7-8 m.
Many congress delegates wanted to see with their own eyes the unique drilling rig on the Kola Peninsula and make sure that a record drilling depth had actually been achieved in the Union. Such a departure took place. A section of the congress held a meeting there on site. The delegates were shown the drilling rig, where they lifted the column from the well, disconnecting 33-meter sections from it. Photos and articles about SG circulated in newspapers and magazines in almost all countries of the world. A postage stamp was issued and special cancellation of envelopes was organized. I will not list the names of laureates of various prizes and those awarded for their work...
But the holidays were over, it was necessary to continue drilling. And it started with biggest accident on the first flight on September 27, 1984 - a “black date” in the history of SG. The well does not forgive when it is left without attention for a long time. During the time that drilling was not carried out, changes inevitably occurred in its walls, those that were not secured with a cemented steel pipe.
At first everything went casually. The drillers carried out their usual operations: one by one they lowered sections of the drill string, connected the drilling fluid supply pipe to the last, upper one, and turned on the pumps. We started drilling. The instruments on the console in front of the operator showed the normal operating mode (number of revolutions of the drill head, its pressure on the rock, fluid flow to rotate the turbine, etc.).
Having drilled another 9-meter section at a depth of more than 12 km, which took 4 hours, we reached a depth of 12.066 km. We got ready to lift the column. We tried it. Doesn't work. “Sticking” has been observed more than once at such depths. This is when some section of the column seems to stick to the walls (maybe something fell off from above and it jammed a little). To move a column, a force exceeding its weight (about 200 tons) is required. They did the same this time, but the column did not move. We increased the force a little, and the instrument needle sharply decreased the readings. The column became much lighter; such weight loss could not have happened during the normal course of the operation. We started lifting: we unscrewed the sections one by one. During the last lift, a shortened piece of pipe with an uneven bottom edge was hanging on a hook. This meant that not only the turbo drill remained in the well, but also 5 km of drill pipes...
They tried to get them for seven months. After all, they lost not just 5 km of pipes, but the results of five years of work.
Then all attempts to recover what was lost were stopped and drilling began again from a depth of 7 km. It must be said that it is after the seventh kilometer that the geological conditions here are especially difficult for work. The drilling technology of each step is worked out by trial and error. And starting from a depth of about 10 km it is even more difficult. Drilling, operation of equipment and equipment are carried out at maximum speed.
Therefore, accidents can be expected here at any moment. They are preparing for them. Methods and means of their elimination are thought out in advance. A typical complex accident is the breakage of the drilling assembly along with part of the drill pipe string. The main method of eliminating it is to create a bench just above the lost part and from this place drill a new bypass shaft. A total of 12 such bypass trunks were drilled in the well. Four of them range from 2200 to 5000 m in length. The main cost of such accidents is years of lost labor.
Only in everyday life is a well a vertical “hole” from the surface of the earth to the bottom. In reality this is far from the case. Especially if the well is super-deep and intersects inclined formations of varying densities. Then it seems to squirm, because the drill constantly deviates towards less durable rocks. After each measurement showing that the well’s inclination exceeds the permissible one, an attempt must be made to “put it back in place.” To do this, special “deflectors” are lowered along with the drilling tool, which help reduce the inclination angle of the well during drilling. Accidents often occur with the loss of drilling tools and parts of pipes. After this, the new trunk has to be made, as we have already said, by stepping aside. So imagine what a well looks like in the ground: something like the roots of a giant plant branching at depth.
This is the reason for the special duration of the last drilling phase.
After the largest accident - the "black date" of 1984 - they again approached a depth of 12 km only after 6 years. In 1990, the maximum was reached - 12,262 km. After several more accidents, we became convinced that we couldn’t get any deeper. All possibilities modern technology exhausted. It seemed as if the Earth no longer wanted to reveal its secrets. Drilling stopped in 1992.
RESEARCH WORK. OBJECTIVES AND METHODS
One of the very important goals of drilling was to obtain a core column of rock samples along the entire length of the well. And this task is completed. The longest core in the world was marked like a ruler into meters and placed in the appropriate order in boxes. The box number and sample numbers are indicated at the top. There are almost 900 such boxes in stock.
Now all that remains is to study the core, which is truly indispensable in determining the structure of the rock, its composition, properties, and age.
But a rock sample raised to the surface has different properties than in the massif. Here, at the top, he is freed from the enormous mechanical stresses that exist at depth. During drilling, it cracked and became saturated with drilling fluid. Even if you recreate deep conditions in a special chamber, the parameters measured on the sample still differ from those in the array. And one more small “hiccup”: for every 100 m of a drilled well, 100 m of core is not obtained. In the SG, from depths of more than 5 km, the average core yield was only about 30%, and from depths of more than 9 km, these were sometimes only individual plaques 2-3 cm thick, corresponding to the most durable layers.
So, the core lifted from the well using SG does not give complete information about deep rocks.
The wells were drilled for scientific purposes, so the entire complex was used modern methods research. In addition to core extraction, studies of the properties of rocks in their natural occurrence were necessarily carried out. The technical condition of the well was constantly monitored. We measured the temperature along the entire wellbore, natural radioactivity - gamma radiation, induced radioactivity after pulsed neutron irradiation, electrical and magnetic properties of rocks, the speed of propagation of elastic waves, and studied the composition of gases in the well fluid.
Up to a depth of 7 km, serial devices were used. Working at greater depths and at higher temperatures required the creation of special heat- and pressure-resistant devices. Particular difficulties arose in last stage drilling; when the temperature in the well approached 200°C and the pressure exceeded 1000 atmospheres, serial devices could no longer work. Geophysical design bureaus and specialized laboratories of several research institutes came to the rescue, producing single copies of heat- and pressure-resistant instruments. Thus, all the time we worked only on domestic equipment.
In short, the well was explored in sufficient detail to its entire depth. Research was carried out in stages, approximately once a year, after deepening the well by 1 km. Each time after this, an assessment was made of the reliability of the materials received. The corresponding calculations made it possible to determine the parameters of a particular breed. They discovered a certain alternation of layers and already knew what rocks the caverns were associated with and the partial loss of information associated with them. We learned to literally identify rocks from “crumbs” and on this basis to recreate a complete picture of what the well “hidden.” In short, it was possible to construct a detailed lithological column - to show the alternation of rocks and their properties.
FROM OWN EXPERIENCE
About once a year, when the next stage of drilling was completed - deepening the well by 1 km, I also went to the SG to take measurements that were entrusted to me. At this time, the well was usually washed out and made available for research for a month. The time of the planned stop was always known in advance. The telegram calling for the work also arrived in advance. The equipment has been checked and packaged. Formalities related to closed work in the border zone have been completed. Finally everything is settled. Let's go.
Our group is a small, friendly team: a borehole tool developer, a developer of new ground-based equipment, and I, a methodologist. We arrive 10 days before measurements. We get acquainted with the data on the technical condition of the well. We draw up and approve a detailed measurement program. We assemble and calibrate the equipment. We are waiting for a call - a call from the well. It’s our turn to “dive” third, but if our predecessors refuse, the well will be provided to us. This time everything is fine with them, they say that they will finish by tomorrow morning. With us in the same team are geophysicists - operators who record signals received from equipment in the well and command all operations for lowering and raising downhole equipment, as well as mechanics on the hoist, they control the unwinding of those same 12 km of cable from the drum and onto it. , on which the device is lowered into the well. Drillers are also on duty.
Work has begun. The device is lowered into the well several meters. Last check. Go. The descent is slow - about 1 km/h, with continuous monitoring of the signal coming from below. So far so good. But at the eighth kilometer the signal twitched and disappeared. This means something is wrong. Full lift. (Just in case, we have prepared a second set of equipment.) We begin checking all the details. This time the cable turned out to be faulty. He is being replaced. This takes more than a day. The new descent took 10 hours. Finally, the person observing the signal said: “We have arrived at the eleventh kilometer.” Command to operators: “Start recording.” What and how is planned in advance according to the program. Now you need to lower and raise the downhole tool several times at a given interval to take measurements. This time the equipment worked fine. Now it's a full rise. They raised it to 3 km, and suddenly the winchman called (he is a man with humor): “The rope is over.” How?! What?! Alas, the cable broke... The downhole tool and 8 km of cable remained lying at the bottom... Fortunately, a day later the drillers were able to pick it all up, using methods and devices developed by local craftsmen to eliminate such emergencies.
RESULTS
The objectives set in the ultra-deep drilling project have been completed. Special equipment and technology for ultra-deep drilling, as well as for studying wells drilled to great depths, 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.
The well gave an excellent gift to the homeland at shallow depths - in the range of 1.6-1.8 km. Industrial copper-nickel ores were opened there - a new ore horizon was discovered. And it comes in handy, because the local nickel plant is already running short of ore.
As noted above, the geological forecast of the well section did not come true (see figure on page 39.). The picture that was expected during the first 5 km in the well extended 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 greatest reflection during seismic sounding is the level where the granites transform into a more durable basalt layer. In reality, it turned out that less strong and less dense fractured rocks are located there - Archean gneisses. This was never expected. And this is fundamentally new geological and geophysical information, which allows us to interpret the data of deep geophysical research differently.
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. Thus, at depths of 9-12 km, highly porous fractured rocks were encountered, saturated with highly mineralized underground waters. 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 considered suitable for industrial development). But will it ever be profitable to mine gold from such depths?
Ideas about the thermal regime of the earth's interior and the deep distribution of temperatures in 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 flow is of radiogenic origin.
Having drilled the unique Kola superdeep well, we learned a lot and at the same time realized how little we still know about the structure of our planet.
Candidate technical sciences A. OSADCHY.
LITERATURE
Kola superdeep. M.: Nedra, 1984.
Kola superdeep. Scientific results and research experiences. M., 1998.
Kozlovsky E. A. World Forum of Geologists. "Science and Life" No. 10, 1984.
Kozlovsky E. A. Kola superdeep. "Science and Life" No. 11, 1985.
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In the 50-70s of the last century, the world changed at incredible speed. Things have appeared that are difficult to imagine today’s world without: the Internet, computers, cellular communications, the conquest of space and the depths of the sea. Man was rapidly expanding the spheres of his presence in the Universe, but he still had rather rough ideas about the structure of his “home” - planet Earth. Although even then the idea of ultra-deep drilling was not new: back in 1958, the Americans launched the Mohole project. Its name is formed from two words:
Moho- a surface named after Andrija Mohorovicic, a Croatian geophysicist and seismologist who in 1909 identified the lower boundary of the earth’s crust, on which there is an abrupt increase in the speed of seismic waves;
Hole- well, hole, opening. Based on assumptions that the thickness of the earth's crust under the oceans is much less than on land, 5 wells were drilled near the island of Guadelupe with a depth of about 180 meters (with an ocean depth of up to 3.5 km). Over five years, researchers drilled five wells, collected many samples from the basalt layer, but did not reach the mantle. As a result, the project was declared a failure and the work was stopped.
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 projects on deep drilling launched in the second half of the 20th century, it 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 science project“Mohole”, which provided for the creation of underwater with the help of 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 quite well 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. Miniature cracks filled water solution, whose origins remained completely unclear for a long time. 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.
At a depth of 410-660 kilometers below the surface of the Earth, there is an ocean of the Archean period. Such discoveries would not have been possible without the ultra-deep drilling methods developed and used in the Soviet Union. One of the artifacts of those times is the Kola superdeep well (SG-3), which, even 24 years after the cessation of drilling, remains the deepest in the world. Why it was drilled and what discoveries it helped make, says Lenta.ru.
The Americans were the pioneers of ultra-deep drilling. True, in the vastness of the ocean: in the pilot project they used the Glomar Challenger vessel, designed precisely for these purposes. Meanwhile, the Soviet Union was actively developing an appropriate theoretical framework.
In May 1970, in the north of the Murmansk region, 10 kilometers from the city of Zapolyarny, drilling of the Kola superdeep well began. As expected, this was timed to coincide with the centenary of Lenin’s birth. Unlike other ultra-deep wells, SG-3 was drilled exclusively for scientific purposes and even organized a special geological exploration expedition.
The drilling location chosen was unique: it is on the Baltic Shield in the Kola Peninsula area that ancient rocks come to the surface. The age of many of them reaches three billion years (our planet itself is 4.5 billion years old). In addition, there is the Pechenga-Imandra-Varzuga rift trough - a cup-like structure pressed into ancient rocks, the origin of which is explained by a deep fault.
It took scientists four years to drill a well to a depth of 7263 meters. So far, nothing unusual has been done: the same installation was used as for oil and gas production. Then the well stood idle for a whole year: the installation was modified for turbine drilling. After the upgrade, it was possible to drill approximately 60 meters per month.
The depth of seven kilometers brought surprises: alternation of hard and not very dense rocks. Accidents became more frequent, and many cavities appeared in the wellbore. Drilling continued until 1983, when the depth of SG-3 reached 12 kilometers. After this, the scientists gathered a large conference and talked about their successes.
However, due to careless handling of the drill, a five-kilometer-long section remained in the mine. They tried to get her for several months, but were unsuccessful. It was decided to start drilling again from a depth of seven kilometers. Due to the complexity of the operation, not only the main trunk was drilled, but also four additional ones. It took six years to restore the lost meters: in 1990, the well reached a depth of 12,262 meters, becoming the deepest in the world.
Two years later, drilling was stopped, the well was subsequently mothballed, and in fact abandoned.
Nevertheless, many discoveries were made at the Kola superdeep well. Engineers have created an entire system of ultra-deep drilling. The difficulty lay not only in the depth, but also in the high temperatures (up to 200 degrees Celsius) due to the intensity of the drills.
Scientists not only moved deeper into the Earth, but also lifted rock samples and cores for analysis. By the way, it was they who studied the lunar soil and found that its composition almost completely corresponds to the rocks extracted from the Kola well from a depth of about three kilometers.
At a depth of over nine kilometers they came across deposits of minerals, including gold: in the olivine layer there is as much as 78 grams per ton. And this is not so little - gold mining is considered possible at 34 grams per ton. A pleasant surprise for scientists, as well as for the nearby plant, was the discovery of a new ore horizon of copper-nickel ores.
Among other things, the researchers learned that granites do not transform into a super-strong basalt layer: in fact, behind it were Archean gneisses, which are traditionally classified as fractured rocks. This produced a kind of revolution in geological and geophysical science and completely changed traditional ideas about the interior of the Earth.
Another a pleasant surprise- discovery at a depth of 9-12 kilometers of highly porous fractured rocks saturated with highly mineralized waters. According to scientists, they are responsible for the formation of ores, but previously it was believed that this occurs only at much shallower depths.
Among other things, it turned out that the temperature of the subsoil was slightly higher than expected: at a depth of six kilometers, a temperature gradient of 20 degrees Celsius per kilometer was obtained instead of the 16 expected. The radiogenic origin of the heat flow was established, which also did not agree with previous hypotheses.
In deep layers more than 2.8 billion years old, scientists have found 14 species of fossilized microorganisms. This made it possible to shift the time of the emergence of life on the planet one and a half billion years ago. The researchers also found that at depths there are no sedimentary rocks and there is methane, forever burying the theory of the biological origin of hydrocarbons.
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