Oil shales are brown to black and sometimes gray sediments that are seen as thin and dense laminae. They have more than 20% organic matter and after burning, they leave about 30% ash. Organic materials of oil shales are insoluble in conventional solvents. These shales have been refined and extracted up to 120 kg/ton of liquid and gaseous hydrocarbons. Oil shale studies in Iran started in the 1350s and many resources have been identified in Zagros, but those studies have not reached the stage of production testing.
Oil shale is sometimes mistakenly called Kerogen shale, in any case, oil shale is considered synonymous with Torbanite.
Oil shales are found in Cambrian to Tertiary deposits and in many parts of the world, especially in the West.
and southwest of Iran, are found. Bituminous (oily) shale deposits of little or no economic value
Up to large reserves of several billion barrels of recoverable oil are found.
Global oil shale resources are estimated at 2.6 trillion barrels, but because the cost of extraction and
Extraction of crude oil from these shales is high, nowadays these sources are less used. With the reduction of oil production and
The increase in its price, oil shale is one of the potential sources and possibly the third world’s need for fossil fuels in the future.
It will be provided by the same sources.
Oil shales are a different group of rocks that contain organic substances and are mostly soluble in organic solvents, but their hydrocarbons can be extracted by heating (distillation). Organic materials make up about 4 to 5 percent of the stone’s weight. Oil shales have a significant amount of inorganic materials, which are mainly composed of quartz in the size of silt and clay minerals.
Some oil shales are actually siltstones and lichens rich in organic materials, although some limestones are also rich in organic materials.
Most of the organic materials in oil shale are scattered in the form of fine particles and have changed in such a way that the organisms that formed them cannot be recognized. Algal remains and algal spores are abundant in many oil shales, therefore it is assumed that most of the materials are of algal origin.
are. Plant fragments and megaspores may also be important constituents. Therefore, these are the components of the formation
They are different. The specific form of sedimentation in oil shale is the presence of specific lamination on the millimeter scale, an alternation of detrital and organic layers.
In most definitions, oil shale is a potential reserve for the extraction of oil and natural bitumen and gas. Oil shale organic materials are large molecules of carbon, hydrogen, oxygen and a small amount of sulfur and nitrogen that form a complex with a large molecular structure that cannot be dissolved in organic solvents (carbon sulfide).
There are different types of organic materials such as silicate and carbonate fine grain minerals in the form of slurry.
The ratio of organic materials to mineral materials from 0.75 to 5 to 1.5 to 5 is considered as a commercial classification.
Because the molecules of organic substances are large and insoluble, they should be heated up to 500 degrees Celsius.
be given to turn into oil and gas as a result of distillation. After distillation, the relative amount of organic carbon is added
which can be burned as fuel.
The difference between oil shale and coal is that organic matter in coal has less C/H and also the ratio of organic matter to mineral matter in it is usually more than 4.75 to 5.
Oil shales have been directly used as fuel like coal since ancient times. The new use of oil shale first started in 1850 in Scotland to produce petroleum products and then in other parts of the world. In 1847, Dr. Young James prepared grease and wax from coal and kerosene. Then he took the Edinburgh brewery where the oil shale was found. In 1850, he patented the cracking of oil into its components. Between 1857 and 1962, crude oil was extracted from oil shale, but in 1962, due to the very low price of oil, its production was stopped. Estonia started the extraction of oil shale deposits in 1920 and became almost the largest consumer of oil shale. Today, most of the oil shale is consumed in Estonia to produce electricity.
The oil shales of the distant and middle past, the silt deposits of the same time, the components of one organ in the bed of lakes and deep.
The sea is formed. The deposited materials are condensed under the pressure of the upper layers, and then their heat and pressure
A mixture of organic minerals and organic flowers turned solid, but the heat and pressure created were not as great as similar processes that form oil.
The environments of oil shale formation are diverse and wide and include brackish lagoons, lakes, continental sea basins and sea coasts. Oil shales have also been deposited in shallow lagoons or lakes along with coal peat in coastal marshy sedimentary environments. Most oil shales are formed in non-aerobic conditions and away from the presence of burrowing organisms that feed on organic materials.
Most of the oil shales show good lamination, which is a sign of low energy environments and strong and practically wavy currents. In the oil shale deposits of the River Green Formation in Colorado and Utah, organic materials are found in abundant beds and sometimes in a general laminar state with kilometers of lateral expansion. Signs
There is turbidity deposition in some deposits such as linear beds and fractures and faults.
Oil shale in the Eocene formation contains more dolomite and calcite and is in the form of rhythmic veins.
Although it was previously attributed to the origin of semi-deep waters, it is now believed that the sedimentation took place in temporary, relatively shallow lakes (which are often exposed to drying).
Small-scale cycles of oil shales that turn upward into evaporites reflect the expansion.
A continuous, non-saline layered lake is a saline lake and a saline basin. A shale composed of a single algal species is found in several horizons in the Lower Carboniferous in Hamilton, Scotland. These horizons are found in the freshwater lake in a deltaic complex where humic coals are also spread. Marine oil shale is known in the shallow seas of the continental platforms, the Devonian basin of eastern and central North America, the Jurassic of Europe and the Miocene of California. In some cases, these shales are formed along with uplift, because planktonic algae are the main source of organic matter and have a geological history.
Most oil shale contains organic materials derived from lake algae. In most oil shales, bacterial processes occur during their rapid deposition and diagenesis. Some of these processes can produce methane
Biologically, they produce carbon dioxide, hydrogen sulfide, and ammonia, and these gases can react with insoluble ions in sediments and form autogenic carbonates and sulfide minerals (calcite, dolomite, pyrite) and even rare autogenic minerals (budding tonite and ammonium feldspar). give
Oil shales were an unknown group of rocks until recent years. Hutton 1987 presented a workable scheme for the classification of oil shales based on the environment of their deposition and the type of different components of organic matter under the ultraviolet fluorescence microscope. Based on this study and information obtained from oil geochemistry, he was able to distinguish different components of organic materials in oil shale.
Hutton divided sedimentary rocks rich in organic matter into the following three groups:
– Humic coal and carbonate rocks
– Bitumen-rich rocks (tar sand oil reservoir rock)
– Oil shale
Based on the sedimentary environments, three main groups of rocks have been identified:
Coastal, lake and sea
– Coastal oil shales:
Lipid-rich materials such as resin, spores, cuticle (wax) and the hairy tissue of the roots and stems of tubular plants are formed in swamp and marsh coal formations.
– Lake oil shales:
They include lipid-rich organic materials from algae that live in fresh water, brackish water or lakes.
They live in water, they are derived.
– Marine oil shales:
from organic materials rich in lipids from seaweed (a single-celled microorganism of (unspecified) origin) and
Marine dinoflagellates (a unicellular organism with a shell) are characterized, formed.
Hutton recognized three major macerals in oil shale:
Telalginite
Lamalginite
Bituminite
Telalginite is composed of organic materials with a thick structure that is made of single-celled algae.
(Tasmanites) and (Botryococcus) have been derived.
Lamalginite is composed of organic materials with a delicate structure, which are single-celled algae that are seen as separate laminae.
Bituminite is an important compound in most oil shale, which is completely amorphous and
The submicroscope is characterized by low fluorescence. The composition and origin of these maserals have not been fully specified
But they are usually known as one of the most important organic substances in many marine oil shales.
Kerogen formation:
Kerogen is a complex geopolymer with high molecular weight, which is formed from the diagenesis of organic materials.
There are four main groups of organic compounds in living organisms:
Carbohydrates, lignites, proteins and lipids are O, N, S, H, Ca among the elements of kerogen compounds in oil shale, it is mainly type I, which has a high ratio of C/H and a low ratio of C/O. This type of deposits originated from lipid-containing algae. Some kerogens in oil shale may be type II, which are composed of vascular plant debris. Some metals such as vanadium, nickel, uranium and molybdenum are abundantly found in coastal, lake and sea oil shale.
Oil shale resources in the world are widely scattered, many of these resources have been investigated less and more exploratory excavations are needed to determine their reserves. Some deposits have been well identified through drilling and analysis, such as:
– River Green oil shale in Western America and the United States of America.
– Tertiary deposits in Queensland, Australia.
– Swedish and Estonian deposits.
Al-Lajn deposits in Jordan, and perhaps in France, Germany, Brazil, and Russia.
The largest deposits of oil shale are in the west of the United States of America, which includes a reserve of about 1.5
trillion barrels. There are reserves of about one trillion barrels in Colorado. Storage of black shales of Eastern Devonian
The United States is about 189 billion barrels.
Other important deposits are in Estonia, Brazil, Australia, Jordan and Morocco. All oil reserves of the world
It is around 4.6 trillion barrels, which is a conservative figure of the real amount of shale in the world, because
In many countries, the existence of these deposits has not been reported and no research has been done.
About 40% of the energy when producing oil from shale is used during the stages of mining, transportation, distillation and consumption. Also, water is needed to add hydrogen to the oil shale before it is transported to the oil refinery.
Economy:
The cost required to extract oil from oil shale is very high. The largest oil shale deposits in
The United States in western Colorado is a dry region without water. Oil shale can be transported in powdered form through a pipeline to a primary refining site.
The position of oil shale in the future:
The amount of oil from oil shale that can be obtained from a deposit depends on many factors. heat
Geothermal or other factors may decompose all or some of the deposit, thus yielding some energy.
shale may decrease.
Some deposits or parts of them, such as large parts of Dunedin shale in Eastern America, which are buried at a great depth, will be economically important in the future. The use of flat lands may reduce the available oil shale deposits, especially in industrialized western countries (that is, reduce their availability).
Sometimes the price of shale is comparable to crude oil and it is not much different from it, but with the reduction of oil resources
Crude in the future, shale oil will find a special place among the world’s fossil energies.
Below you can see pictures of oil shale mines.
Torbanite:
Turbanite mineral was taken from the name of a place called Turban Hill in Scotland, which was discovered for the first time in this place. Basically, it is a synonym name for coals whose origin is from algal sludge and they are called boghead
It is called coal, but it is often used for highly carbonized oil shales.
Bitumenite:
Another name is turbanite
Wollongongite:
Sometimes it is also written or read as (Wollongite) or (Wallongite). Coal-like shales are similar to turbanite. The name of the mineral is taken from the sample site located in Wollongong, which is a district in the state of NSW, Australia.
Kerogen:
It is the small particles of organic matter found in sedimentary rocks that are insoluble in conventional solvents such as: chloroform, benzene, methanol, etc. and in non-oxidizing acids such as hydrochloric and sulfuric.
It should be noted that the organic materials that settle together with the sedimentary materials in the sedimentary basins should not be added
Kerogen was wrong, because kerogen is a substance that is obtained from the transformation of organic substances during geological time, at the same time, if a sedimentary rock contains kerogen, it cannot be considered as bituminous or petroleum. Basically, kerogen is the main compound of oil and gas generation. Kerogen has the following types:
Alginite:
It is a kerogen that is completely obtained from the remains of algae bodies and has a marine origin. This kerogen has a very good hydrocarbon generation capacity. Alginite together with amorphous kerogens that have no internal structure and are created from algae fragments form a group of kerogens called type (1).
(Amorphous Kerogen)
They are composed of the remains of marine planktonic organisms and have no internal structure. These amorphous kerogens are
together with the type of oxynite (Exinite (group of type II kerogens)) which in terms of oil power-
Good fertility is classified.
(Exinite) Nitoxy:
As mentioned, it belongs to the group of type II (II) kerogens, but it has a land origin and is more than
The remains of the shells of pollen grains, spores and seeds of plants, as well as from the cuticle of the leaves of vegetable plants
The past originated.
Vitrinite:
It belongs to kerogen type (third III) and has a dry origin and fibrous and woody remains of plants and colloidal materials.
It has no derived structure and its hydrocarbon generation power is classified as appropriate. It is worth mentioning that the kerogens extracted from the source rocks in Zagros, such as Kozhdemi, Gro, Gadvan, Pabde and Gurpi formations, belong to types II and III.
(Internite) Internet:
This kerogen originates from the oxidized and recirculated woody remains of past terrestrial plants and is weak in terms of hydrocarbon generation. Internet is classified among type IV (fourth) kerogens.
