The USSR is a country that astonished the world with many projects, grandiose in both scale and cost. One such project was called «Kola Superdeep Borehole (SG-3). Its implementation began in the Murmansk region, 10 km west of the city of Zapolyarny.
Scientists wanted to learn more about the Earth's interior and "wipe the nose" of American scientists who abandoned their Mohole project due to lack of funds. When asked about, What is the deepest well in the world?, Soviet geologists dreamed of proudly answering: ours!
In this article, we will discuss in detail whether this ambitious plan was successful and what fate awaited the Kola borehole.
Journey to the Center of the Earth
As recently as the 1950s, most of the material on the Earth's structure was theoretical. Everything changed in the early 1960s and 1970s, when the United States and the Soviet Union launched a new version of the "space race"—a race to the center of the Earth, so to speak.
The Kola Superdeep Borehole was a unique project financed by the USSR, and then Russia, from 1970 to 1995. It was drilled not for the extraction of "black gold" or "blue fuel," but purely for scientific research purposes.
- First of all, Soviet scientists were interested in whether the assumption about the structure of the lower (granite and basalt) layers of the earth's crust would be confirmed.
- They also wanted to find and explore the boundaries between these layers and the mantle, one of the «engines» that ensures the constant evolution of the planet.
- At that time, geologists and geophysicists had only indirect evidence of what was happening in the Earth's crust, and an ultradeep borehole was needed to better understand the processes underlying geology. The most reliable method was direct observation.
The drilling site was chosen in the northeastern part of the Baltic Shield. Little-studied igneous rocks, believed to be three billion years old, lie there. The bowl-shaped Pechenga structure, also located on the Kola Peninsula, contains copper and nickel deposits. One of the scientists' goals was to study the ore formation process.
Even to this day, the information collected through this project is still being analyzed and interpreted.
How the super-deep well was drilled
For the first four years, while drilling to a depth of 7,263 meters, a standard drilling rig called the Uralmash-4E was used. But then its capabilities became insufficient.
Therefore, the researchers decided to use a powerful Uralmash-15000 rig with a 46-meter turbodrill, which was rotated by the pressure of the drilling fluid.
The Uralmash-15000 rig was designed to collect samples of extracted rock in a core barrel—a tube running through each section of the drill. The crushed rock reached the surface along with the drilling fluid. This provided geologists with up-to-date information on the borehole's composition as the rig drilled deeper.
As a result, several boreholes were drilled, branching out from a single central borehole. The deepest branch was named SG-3.
As one of the scientists on the Kola Geological Survey team put it: "Every time we start drilling, we find something unexpected. It's both exciting and alarming.".
Interesting fact
The first surprise the drillers encountered was the absence of the so-called basalt layer at a depth of approximately 7 km. Previously, the most up-to-date geological information about the deeper parts of the Earth's crust came from seismic wave analysis. Based on this, scientists expected to find a granite layer, and then, as they drilled deeper, a basalt layer. But, to their great surprise, as they drilled deeper into the Earth's interior, they found more granite and never reached the basalt layer. All drilling proceeded within the granite layer.
This is extremely important, as it relates to the theory of the Earth's layered structure. This, in turn, relates to ideas about how minerals are formed and distributed.
The Unsolved Mystery of the Kola Borehole
The Kola Superdeep Borehole is a source not only of valuable knowledge, but also of a terrifying urban legend.
Having reached a depth of 14,500 meters, the drillers allegedly discovered voids. After lowering equipment capable of withstanding extremely high temperatures, they discovered that the temperature in the voids reached 1,100 degrees Celsius. Before melting, the microphone recorded 17 seconds of audio, which was immediately dubbed "the sounds of hell." These were the screams of damned souls.
This story first appeared in 1989, and its first major publication was on the American television network Trinity Broadcasting Network. It borrowed material from a Finnish Christian publication called Ammennusastia.
The story was then widely reprinted in small Christian publications, newsletters, and so on, but received virtually no attention from the mainstream media. Some evangelicals cited the incident as proof of the existence of a physical hell.
- Those familiar with the operating principles of acoustic well logging simply laughed at this tale. After all, acoustic logging probes are used to capture the wave pattern of reflected elastic vibrations.
- The maximum depth of the SG-3 is 12,262 meters.. This is deeper than even the deepest part of the ocean, the Challenger Deep (10,994 meters).
- The highest temperature in it did not rise above 220 C.
- And one more important fact: it is unlikely that a microphone or drilling equipment could withstand hellish heat above a thousand degrees.
In 1992, the American newspaper Weekly World News published an alternative version of history that took place in Alaska, where 13 miners were killed after Satan broke out of hell.
If you're interested in this legend, you can easily find videos on YouTube with relevant investigations. Just don't take them too seriously; some (if not all) of the audio featuring the supposed cries of those suffering in the Underworld is taken from the 1972 film Baron Blood.
What did scientists find at the bottom?
- First, water was discovered at a depth of 9 km. It was thought that it simply shouldn't exist at this depth—and yet it was there. We now understand that even deep-seated granite can develop cracks that fill with water. Technically, water is simply hydrogen and oxygen atoms forced out by the enormous pressures of depth and trapped within the rock layers.
- Secondly, the researchers reported recovering mud that was "boiling with hydrogen." Such large quantities of hydrogen at such depths was completely unexpected.
- Thirdly, the bottom of the Kola borehole turned out to be incredibly hot – 220 °C.
- Undoubtedly, the biggest surprise was the discovery of life. Microscopic plankton fossils, preserved for three billion years, were discovered at depths of over 6,000 meters. In total, some 24 ancient species of microorganisms were discovered, somehow surviving the extreme pressures and high temperatures beneath the Earth's surface. This raised many questions about the potential survival of life at great depths. Modern research has shown that life can even exist in the oceanic crust, but at the time, the discovery of these fossils was a shock.
Despite the drillers' best efforts and decades of hard work, the Kola Superdeep Borehole has only traveled 0.181 TP3T to the Earth's center. Scientists believe the distance is approximately 6,400 kilometers.
Why was the SG-3 project closed?
Currently, SG-3 is empty of personnel and equipment. It is one of the most fascinating abandoned sites from the Soviet era. Only a rusty hatch in the ground remains as a reminder of this grandiose project, listed in the Guinness Book of World Records as the deepest human intervention into the planet's crust.
The project was shut down in 1995 due to (you guessed it) a lack of funding. Even earlier, in 1992, drilling operations at the well were halted when geologists encountered higher-than-expected temperatures—220 degrees Celsius. Heat damages equipment, and the higher the temperature, the more difficult it is to drill. It's like trying to create and maintain a hole in the center of a pot of hot soup.
By 2008, the research and production center operating at the well was completely closed. All drilling and research equipment was disposed of.
The ultimate goal
The valiant efforts of the Kola Geological Survey team spanned several decades. However, the ultimate goal—the 15,000-meter mark—was never reached. However, the work carried out in the USSR, and later in Russia, provided a wealth of information about what lies just beneath the Earth's surface, and it remains scientifically valuable to this day.
- Unique equipment and technology for ultra-deep drilling were developed and successfully tested.
- Valuable information was obtained about the composition and properties of rocks at different depths.
- Copper-nickel deposits of industrial significance were found at a depth of 1.6-1.8 km.
- The theoretical picture expected at the 5,000-meter mark was not confirmed. No basalts were found at this or any deeper sections of the borehole. However, a rather fragile rock called granite gneiss was unexpectedly discovered.
- Gold was discovered between 9,000 and 12,000 meters. However, mining from such depths was not considered profitable.
- Changes were made to theories about the thermal regime of the earth's interior.
- It turned out that the origin of the 50% heat flow is associated with the decay of radioactive substances.
SG-3 revealed many secrets to geologists. And it also raised many questions that remain unanswered. Perhaps some of these will be answered during the operation of other ultradeep boreholes.
The 10 Deepest Boreholes on Earth (Table)
| Place | Well name | Years of drilling | Drilling depth, m. |
|---|---|---|---|
| 10 | Shevchenkivska-1 | 1982 | 7 520 |
| 9 | Yen-Yakhinskaya superdeep well (SG-7) | 2000–2006 | 8 250 |
| 8 | Saatlinskaya superdeep well (SG-1) | 1977–1982 | 8 324 |
| 7 | Zisterdorf | 8 553 | |
| 6 | University | 8 686 | |
| 5 | KTB Hauptborung | 1990–1994 | 9 100 |
| 4 | Beiden Unit | 9 159 | |
| 3 | Bertha Rogers | 1973–1974 | 9 583 |
| 2 | KTB-Oberpfalz | 1990–1994 | 9 900 |
| 1 | Kola Superdeep Borehole (SG-3) | 1970–1990 | 12 262 |