The Russian bowels are rich in numerous minerals, which are found in priceless underground storage rooms practically throughout the territory of a huge country. This article contains a little information about the two largest deposits, interconnected only by their names.
This is the Bazhenovskoye asbestos field and the shale oil field. More detailed information about these objects in the article below.
First, let's talk about asbestos and about one of the Russian deposits.
What is asbestos?
Asbestos (translated from Greek as "unquenchable") is a generalized name for six natural minerals that have fibrous forms and belong to the class of silicates.
Asbestos minerals are found in the form of tangled and regular fibrous formations, and are divided into 2 groups: chrysotile and amphibole. Asbestos minerals in their chemical composition are hydrosilicates of iron, magnesium and partially sodium and calcium. The most industrially significant is chrysotile asbestos. It accounts for about 95% of the world's mineral production.
Fortunately, such a useful and important mineral was also found in the Urals, where the Bazhenovskoye deposit is located.
Chrysotile asbestos (parachrysotile, chrysotile) is often called “white asbestos” or “mountain flax.” It is a fibrous type of serpentine (translated from Latin as “serpentes” - a snake), which has a smooth, shiny surface similar to the skin of a snake. Its usual Russian the name is serpentine. The other five asbestos belong to another group - amphiboles (have a complex variable composition). These include amosite, crocidolite, antophyllite, actinolite and tremolite.
All of them differ in properties, but are characterized by good tensile strength, high chemical resistance and low thermal conductivity.
Brief description of the Bazhenovsky asbestos deposit
This field was discovered in 1885, and its development began only in 1965.
The deposit, which occupies a vast territory, is represented by thick layers of serpentinite and talc-carbonate rocks. Among them, the western, main asbestos-bearing strip stands out. In total, 34 deposits with a depth of up to 1000 meters were identified here.
An array of ultrabasic rocks is a branching dyke of diorites and granites, as well as crushing and fault zones oriented in different directions. Ultrabasic rocks are divided into blocks. The central parts are composed of peridotites, closer to the faults - serpentinite, chrysotile asbestos and talc. Industrial mineralization of chrysotile asbestos (veins and vein nets) is located on the periphery of the blocks. The veins and veins of asbestos have a width of 3 mm to 50 mm.
At the Bazhenovskoye field, deposits extend in length from 200 meters to 4000 meters. Their power is 40-300 meters.
Explored ore reserves in the deposit amount to about 66 million tons, but its asbestos content is only 2.28%. The development of the field is conducted in an open way (3 quarries have been created). On average, more than 700 thousand tons of rock mass is mined here annually.
The deposit is unique in the world in terms of fiber length and breadth of its set, in strength, and without the content of tremolite and crocidolite fibers harmful to human health.
Where is the Bazhenov asbestos deposit located?
The field, which is the richest in the world in terms of its reserves, is located near the city of Asbest, Sverdlovsk Region (administrative and industrial development center). Hence the name of the city. From Yekaterinburg it is located 60 kilometers in the north-east direction.
In geological terms, the object is located among an array (of the same name) of ultrabasic rocks. It is stretched for 28 kilometers in the meridional direction, with a width of about 1-4 km. On the surface, the area of the entire rock mass is approximately 75 square meters. km
Terrain
The Bazhenovskoye asbestos deposit is located on the slope of the Middle Urals (eastern) in the Sverdlovsk region. According to its relief, the territory is represented by a hilly, slightly dissected plain with absolute elevations within 220-233 meters.
The natural terrain is disturbed by various numerous dumps consisting of waste rock and waste from factories, as well as large quarries.
A bit of asbestos development history
The deposit was discovered by A.P. Ladyzhensky (surveyor-topographer - a member of the society of science lovers in the Urals) in 1885 in the process of performing the allotment of territories for the development of placer gold. Then the field was called Bazhenovsky, in connection with the location of the Bazhenovo railway station near it.
The first tons of asbestos were mined in 1889. Development at that time was conducted in an open way. Initially, the production was unsystematic - small holes were rummaged. There was no talk of intelligence at that time. At first there were several separate mining sites (mines) or mines: Korevinsky, Oktyabrsky, Voznesensky mines. All work was carried out manually using a shovel, Kyle, wheelbarrows, stretchers and horses.
A detailed study of the object by geologists was begun only in 1922. Until 1950, the field was fully explored from the surface, and explored in depths of up to 150 meters. At that time, the reserves of deposits were estimated at about 7-8 million tons. After additional exploration (1950-1960) to depths of 300-400 meters, reserves were recounted and estimated at 31 million tons.
About other deposits
The best asbestos quality, in addition to the Bazhenovsky deposit, in Russia is Molodezhnoye, located in the Muy district of the Republic of Buryatia. The mineral fibers are 8 cm long.
In addition to the Ural Bazhenovsky, similar deposits of asbestos are in Siberia, Canada, South Africa, and Germany. And in Russia - Ilchirskoye, Labinskoye, Aktovrakskoye and others.
What is shale oil?
It is extracted from shale deposits by drilling wells, followed by numerous hydraulic fractures in the Bazhenovsky shale oil field.
If in more detail, such "unconventional oil" is obtained from oil shale as a result of pyrolysis, thermal hydrogenation and dissolution, during which solid residues of organic matter from shale enriched with kerogen are converted into synthetic hydrocarbons (gas and oil). All this is a rather laborious and costly process.
About the Bazhenov Suite
The oil field (Bazhenov suite) belongs to Upper Jurassic deposits. The lithological composition is represented mainly by clay rocks, alternating with thin interlayers of siliceous and carbonate rocks. The rocks have the properties of reservoirs - micro-layered and leafy clays with well-developed horizontal microcracks in them, which determine their unstable nature.
These are oil source rocks identified in the territory (an area of about 1 million square meters) of Western Siberia. It is formed by sedimentary rocks of the seabed from the Titonian to Berriasian centuries (from the end of the Jurassic to the beginning of the Cretaceous), which is about 145 million years ago.
In Russia, as in many other countries, there are hydrocarbons in the fields of the Bazhenov formation. The suite lies at depths of 2-3 kilometers and has a relatively small thickness (on average 20-30 meters, but in the depot center more than 60 meters).
In Russia, most of the oil shale is concentrated in the Bazhenov formation. It contains both kerogen (solid organic matter) and light liquid oil of low permeability reservoirs (shale oil). Such reserves (in this suite) are considered difficult to recover.
Where is the oil field located?
The Bazhenov Formation is such a huge geological object that they did not even come up with a name for it. It spreads over the territory of two districts of Siberia and three regions.
Its entire area (1.2 million sq. Km.) Occupies half of the largest West Siberian lowland, where numerous and largest deposits in terms of recoverable reserves have been exploited for the extraction of ordinary oil and gas.
The composition of the suite and the assessment of its reserves
Many deposits have been identified in the Bazhenovskoye oil field (a total of 92, which contain approximately 500 million tons of recoverable reserves). The geologists of Surgut did a great job of studying the bazhen deposits. The general conclusion of their report: there is oil in the reservoirs, but its production is unprofitable under the current taxation.
According to some estimates, the suite contains 2 trillion barrels of oil. Of these, 74 billion tons of oil at the field today (estimates of 2013) are estimated technically recoverable with current capabilities.
The suite is composed mainly of siliceous and carbonate clayey rocks, in which the remains of plankton with a silicon skeleton (diatoms and radiolaria) became the source of organic matter. The organic matter content in the total mass is about 14% (including about 2.7% liquid, about 12% kerogen), and the rest is mineral (calcite, hydromica, silica, etc.).
The history of oil formation in the suite
Oil was formed with the release of energy, and therefore, the Bazhenov horizon has abnormally high temperatures (from 90 to 130 degrees) and pressure (from 350 to 460 atm.). The oil of the field is very light, given that its density varies over a fairly wide range (per cubic meter from 720 to 840 kg).
In the strata of the Bazhenovskoye field, geologists have identified 7 types of rocks containing oil, but not all of them are capable of delivering it.
About development challenges
In fact, the Bazhenov Formation is a unique and complex object of development. Very often, completely dry wells can be drilled near wells that provide a good industrial flow of oil. It is also observed that a sufficiently high oil production rate sharply decreases due to a drop in reservoir pressure.
Numerous studies (hydrodynamic listening to establish a hydrodynamic connection between neighboring wells) have shown that in many cases such a connection is not detected. So, at the Bazhenovskoye field, the reservoirs are randomly located and have a small area (local). It is very difficult (or even impossible) to predict the extension of a good formation under such geological conditions. Even if the results of getting into the reservoir are positive, there is a high probability that the oil in it will run out quickly.
