Already in the first decade of the 20th century, no one risked drilling an exploration well without preliminary geological substantiation. So, along with oil producers, a new profession appeared - an oil explorer.
Most of the large oil companies and concerns have acquired their own geological services or each time they turned to consultant geologists for help. Geological surveying has become widespread. A man with a hammer and a backpack walked through the terrain, collected rock samples, described the characteristic outcrops of rock strata to the surface ... surface relief terrain, but also about the nature of the bedding of mountain strata under it.
Key words: hydrocarbons, exploration, exploitation, deep water and technologies. This paper provides an overview of the world's deepwater fields, especially those in production. Key words: hydrocarbons, exploration, drilling, deep water and technologies.
This article offers a brief exposure of the world's deep sea fields. Without seeking to cover all aspects of this segment oil industry, he is exploring new exploration basins and especially active fields. Our hypothesis is that perforations in particular exploitation in deep seas have received such a significant boost in the current rise in prices that it could be argued to be a concomitant phenomenon.
And the results were not slow to show. If earlier oil produced at best one well out of 10 or even out of 20, then of the wells drilled taking into account geological predictions in the USA, for example, 85% were productive.
The authority of geologists has grown so much that every self-respecting American necessarily consulted with a specialist when buying land plot... And this was far from superfluous: landowners often embarked on all sorts of machinations in order to increase the price of land. For example, before the eyes of the buyer, oil began to be pumped from the well, oily spots were found throughout the territory ... And only an experienced eye of a specialist could determine that these spots were made on purpose, and oil was poured into the well the day before.
One of the goals of our research is to identify at least some of the innovations that have been made during the current boom, especially those aimed at shortening the cycle between discovery and commissioning of deep fields. Some technological advances will be applied to deposits in Mexico, with the dire consequences of the deposition of Mexican production.
We present this document when the country is discussing energy reform, and we intend to contribute to a more informed debate. The study is presented in 21 statistical tables with a list of discovered deposits and developments in the deep waters of the world. In the case of the United States, we exclude disaggregated information as this country contains more than half of the world's deep fields; including details, duplicate the length of our text, therefore, information about it is generalized.
And today, despite the development of new methods of geological exploration, the field work of geologists has not lost its practical significance. From year to year, every spring in different countries planets are sent geological expeditions. In search of minerals, they "comb" inch by inch of the most remote corners.
However, there are exceptions here as well. New deposits can be discovered where, it seemed, there was nothing to look for. So it was established that a large oil field is located under (literally) Paris - the capital of France.
Some considerations regarding search criteria for information. In the oil industry, there is no international convention for defining what is to be understood in deep terms. In the United States, where these activities began, deepwater is called 1000-foot layers, or about 300 meters.
After removing the question of definitions, our statistical tables in this text included only fields with a depth of more than 500 meters. Proved reserves or other estimates of potential have always been the subject of endless questions. When looking at the statistical tables of the world's reserves, the conclusion is that, with a few exceptions, the discoveries and the beginning of deep field operations, at least so far, have not affected world statistics; that is, the increase in proven deep sea water reserves was not significant.
But such cases are, of course, rare. More often geologists go to the "field". This is traditionally called a trip to the wilderness, although the "field" can be taiga, tundra, and desert ....
Day after day, geologists go out on routes, carefully study the rocks that come to the surface, the fossilized remains of prehistoric animals and plants, dig pits and clear search ditches so that the structure of the layers is more visible. This work is not romantic, but also very difficult. The bread of romance often turns out to be black: only from the outside it seems that spending the night in tents, dining by the fire is a very fun activity. It's one thing to go out into nature, to have a picnic, for a day or two, at most for a week, and it's quite another to live such a life for many months. And not just live, but work hard, endure great physical activity.
But there are exceptions. In two or three countries on the west coast of Africa, one of the fields in Malaysia, the other in Norway, there is no doubt that the deep waters offer important discoveries even gigantic and surprisingly supergiant fields as they appear to have recently been discovered in Brazil. Due to the interest of the above, in the current situation with supply problems in these cases, we will note the relevant data.
The graph included the entire universe: nine basins: the Gulf of Mexico, Brazil and the Niger Delta basin on the coast West Africa, West Coast Australia, southern China, coasts of Japan and India; Mediterranean and Atlantic Rim versus Norway and northern Scotland. The fields are distributed in 22 countries including Mexico.
But this kind of work is very much needed. Indeed, on the basis of the collected data, according to the results of subsequent office processing, geologists draw up a geological map, on which all possible deposits of minerals are marked. Then, as often happens, people of many other specialties follow in the footsteps of the pioneering geologist - drillers and road workers, assemblers and field workers ... deserted place a forest of towers, a village, and even a city grows.
The US Department of Energy explained that although research and appraisals began in the early 1990s and several discoveries were made, exploitation was delayed due to the high costs associated with deep-sea exploitation. Barrels of crude oil daily. Angola seems to have been the country where the big oil companies have developed the best and most numerous projects. Perhaps these large companies found political conditions less favorable than in Nigeria, and perhaps the geology is more magnificent.
Three giant fields were discovered: sunflower; production of Sachs and Batuk seven years ago, which barely went into operation in August. The number of deep fields off the coast of this nation is already almost 30, and more exploited than in Brazil. Equally important are the technical innovations that are developing in front of this segment of African coasts.
"Everything is visible from above"
“You can't see a face face to face - you can see big things at a distance,” the poet said, and hit, as they say, right on the spot. Already the first space flights have shown: having gone up several hundred kilometers, we can see what we can never see under our feet - the structure of the earth's interior, usually hidden under the cover of the soil, under the upper loose layers.
The first three deepwater fields were drilled in the second half of the 1990s, and all began operations the following year. How can we explain this sharpness, which we did not find in any other case in those years? We have only incomplete and scattered information.
Perhaps this postponed the development of activities off the coast of this country. Two new fields were discovered, the last of which was published in June. In this country, we also find deep sea fields, which, despite having been discovered since the 1990s, have hardly started operations. Production is expected to rise to 90,000 barrels per day, an exaggerated figure given the modest estimated reserves of 240 million barrels for the two fields now aligned for offshore production.
What benefit this can bring says at least such a fact. Pilot-cosmonaut of the USSR Oleg Makarov, leaving for a meeting with the inhabitants of Salekhard, took with him as a souvenir a photograph of the outskirts of this city, taken from the board of the Soyuz-22 spacecraft. The meeting was successful, but when Makarov presented his gift to the hosts, an unexpected question was raised:
Perhaps this is a country that has recently been included in the race to develop deep deposits. This is a small deposit that can be seen for its modest production of 15,000 barrels per day. As in Mauritania, this country is just beginning to drill and exploit its deep fields.
One study explains that some of the gas discoveries were made when the lack of a liquefied gas market hindered its development. Construction of equipment for Eskdale and Gorgon is underway. It currently operates over 20 wells and produces 40,000 barrels per day. In this area, a combined system of offshore platforms with onshore equipment has been built. It includes a stretched-legged platform, two floating blocks, and pipelines that lead hydrocarbons to land to a terminal called Santan, where they are processed.
How much is this picture worth?
Makarov was surprised:
Not at all. This is a gift.
However, the questioner (it was one of the geologists) did not calm down:
Can a photograph be deciphered?
Yes, - answered Makarov. - if you want, you can establish exactly when and under what circumstances it was made ...
Here the geologist sighed with relief and smiled:
Also in this country, the invasion of deep waters began. A year later, extensions of the same location were discovered. The project consists of 20 wells and includes 20 other injectors. Deep sea activities in this country are recent. A single camp was opened in front of the Hokkaido Islands; production trials were successful, but new deposit delineation holes failed.
India has also started operations in its deep waters in Ha, has discovered four fields, but none are working. Perhaps because he is in trouble, as reported by the international oil press. All products are for the United Kingdom.
Thanks. You just gave our city twenty million rubles!
This is the amount that would have cost aerial photography and the subsequent deciphering of photographs of the area, which the geologists were just going to do.
"Physics helps geologists"
Of course, both field and space surveys help specialists learn a lot about the underground structure of rocks. But this knowledge is often still not enough to judge with a sufficient degree of certainty whether there is oil here or not? To "probe" the subsoil better, they use geophysical methods of prospecting for minerals.
Ormen Lange is not found in the North Sea, but in the northern waters off the Norwegian coast, near the Arctic Circle. At temperatures near the freezing point, hydrates are formed in production currents; lest they install what was said, this is "the largest anti-freeze system in the world." But the main challenge appears to have been the construction of a pipeline from a processing station located in Norway and off the coast of the United Kingdom.
Since the first half of the 90s, this country has opened its first fields in its deep waters in the regions of the Atlantic rim. After almost 15 years, none of them have produced. Our research allows us to conclude that not a single field has been found in the North Sea at a depth of 500 meters or more, only three deep fields are located northwest of Scotland, near the Faroe Islands.
Geophysicists seem to see through the earth to a depth of 5-6 kilometers. How do they do it? To some extent, geophysical methods for studying the subsoil can be compared with X-ray transmission of the human body, or rather, with ultrasound diagnostics. A beam of oscillations is launched into the body of the Earth and judging by the reflection of waves from the layers of the rock geological structure the given area.
Immediately after the collapse of socialism, this country opened its sector of the Adriatic Sea to international tenders. The government itself has stated that the discovery is not commercial, it can never be used. Originally considered "disadvantageous" due to its remote location and limited supply, around 20 million barrels, it was developed with horizontal perforations, a subsidiary of which the Italians made important subsea developments. Three deep fields have been discovered in this country.
Nothing works. Recently, the American Noble Energy discovered what appears to be the most important field of this nation - Marie-B, with shallow and deep places... As anticipated, the country has built exploitation systems that combine offshore production facilities with land-processing equipment, and also include deposits and deep fields in shallow water. Thus, the fields of Siena, Simian, Scarab, in depth and others, as shallow as Sapphire, belong to a joint development project very close to the Nile Delta; the distance between the fields and gas processing facilities, on land, near Alexandria, is 120 kilometers.
Currently, four main geophysical methods are used: seismic, gravimetric, magnetic and electrical. Let's consider them in order.
Seismic exploration is based on the study of the features of the propagation of elastic vibrations in earth crust... Elastic vibrations (or, as they are also called, seismic waves) are most often caused by artificial means.
This country is an example similar to the situation in the United States, caused by a shortage, a decade advanced in deep water drilling, and from the early 1990s it was able to start using its fields, as can be seen in the following table, the Marlim case.
We emphasize the technological component in the results: three fields are in the old basin, where about 100 wells have already been drilled, that is, it is a “repeat”, with seismic instruments with better resolution, which allowed to improve images that overcome the problems of salt bodies in the subsurface.
Seismic waves propagate in rocks at a speed of 2 to 8 km / s - truly cosmic speeds! - depending on the density of the rock: the higher it is, the greater the speed of wave propagation.
At the interface between two media with different densities, some of the elastic vibrations are reflected and returned to the Earth's surface. The other part is refracted, overcomes the interface and goes deeper into the bowels - to a new interface. And so on until they finally fade out.
He argues that without the contribution of new deposits in the mentioned area, an even sharper drop in Mexican production will inevitably occur. A total of 4 trillion cubic feet per day has already been discovered in this area. Ten in Brazil, four in the Niger Basin in Africa, one in Italy and one in the Philippines. That is, the exploitation of oil in deep seas, with the exception of the United States and Brazil, was rare. The big push for deep sea exploitation is a consequence of the current rise in oil prices.
West Africa seems to be home to the greatest dynamism of discovery and exploitation. Angola alone now has 30 deep fields, a smaller number, but they can be compared with Brazil, which has 38 deep fields. The problem of price recovery is a special issue that requires special analysis, we do not know to what extent proposals and political issues interfere with it, which is the fact that a new branch or specialty of the oil industry is emerging in the industry.
Reflected seismic waves reaching earth surface, are captured by special receivers and recorded on the recorders. Having decoded the graphs, seismic prospectors then establish the boundaries of occurrence of certain rocks. Based on these data, maps of underground relief are constructed.
This method of reflected waves was proposed by the Soviet geologist V.S. Voyutsky in 1923 and became widespread throughout the world. At present, along with this method, the correlation method of refracted waves is also used. It is based on the registration of refracted waves formed when an elastic wave is incident on the interface at a certain pre-calculated critical angle. Used in the practice of seismic survey and other methods.
Previously, explosions were most often used as a source of elastic vibrations. Now they began to be replaced by vibrators.
The vibrator can be installed on a truck and survey a large area in a working day. In addition, the vibrator allows you to work in densely populated areas. The explosions would surely disturb the inhabitants of nearby houses, and the vibrations can be selected to such a frequency that they are not perceived by the human ear.
The only drawback of this method is the shallow depth of research, no more than 2-3 kilometers. Therefore, for more in-depth studies, an explosive energy converter is used. The source of the waves here is essentially the same explosion. But it no longer occurs in the soil, as before, but in a special explosive chamber. An explosive impulse is transmitted to the ground through a steel plate, and a mixture of propane and oxygen is often used instead of explosives. All this, of course, makes it possible to greatly speed up the process of sounding the subsoil.
The gravimetric method is based on the study of changes in the force of gravity in a particular area. It turns out that if under the surface of the soil there is a rock of low density, for example, rock salt, then the earth's gravity is somewhat reduced here. But dense rocks, such as, for example, basalt or granite, on the contrary, increase the force of gravity.
These changes are established by a special device - a gravimeter. One of its simplest options is a weight suspended from a spring. Gravity increases - the spring is stretched; this is indicated by a pointer on the scale. Gravity decreases, the spring contracts accordingly.
Well, how do oil and gas deposits affect Earth's gravity? Oil is lighter than water, and rocks saturated with oil or its indispensable companion - gas, have a lower density than if they were filled with water. And this, naturally, is noted by the gravimeter.
True, such gravitational anomalies can be caused by other reasons, for example, the occurrence of rock salt layers, as we have already said. Therefore, gravity prospecting is usually supplemented with magnetic prospecting.
Our planet, as you know, is a huge magnet around which a magnetic field is located. And this field can be effectively influenced, among other things, by the rocks that occur in this area. Maybe you've heard or read how deposits iron ore were discovered due to the fact that the pilots of the aircraft flying here were surprised strange behavior magnetic needle? .. Now this principle is used to search for other types of minerals, including oil and gas.
The fact is that oil very often contains metal impurities. And, of course, the presence of metal is felt, though not by a "magnetic needle", but by modern highly sensitive devices - magnetometers. They allow you to probe the earth's interior to a depth of 7 kilometers.
Another geophysical method for prospecting for minerals - electrical prospecting - was developed in 1923 in France and is still in use today. Actually, this is a kind of magnetic reconnaissance with the only difference that changes are recorded not in the magnetic, but in the electric field.
Since there is practically no natural electric field on Earth, it is created artificially, with the help of special generators, and the required area is probed with their help. Usually rocks are dielectrics, that is, their electrical resistance is high. But oil, as we said, can contain metals, which are good conductors. A decrease in the electrical resistance of the subsurface is also an indirect sign of the presence of oil.
V last years one more method has become more and more widely used - electromagnetic reconnaissance with the help of magnetohydrodynamic (MHD) generators. Depths of several kilometers have become available to electromagnetic waves, when minerals are being searched; up to hundreds of kilometers when it comes to general studies of the earth's crust.
The heart of the modern MHD generator is the rocket engine powered by gunpowder. But this gunpowder is not quite ordinary: the electrical conductivity of the plasma it creates is 16,000 times higher than that of conventional rocket fuel. Plasma passes through the MHD channel located between the magnet windings. According to the laws of magnetodynamics, an electric current arises in a moving plasma, which, in turn, excites an electromagnetic field in a special emitter - a dipole. With the help of a dipole, the Earth is probed.
In just a few seconds, the MHD installation develops a capacity of tens of millions of watts. And it dispenses with the bulky cooling systems that would be inevitable with traditional radiation sources. And the installation itself is several times lighter than other types of electric generators.
For the first time, the efficiency of the MHD installation was tested at the end of the 70s in Tajikistan. Then, in the area of the Peter 1 ridge, scientists conducted the first experiments on MHD sounding, trying to catch signs of an approaching earthquake. Signals from the powerful 20-megawatt Pamir-1 installation were recorded at a distance of up to 30 kilometers from it.
A little later, MHD installations were used to search for oil and gas fields... To begin with, a fairly well-known oil region was chosen - the Caspian lowland. Thanks to MHD sounding, one more opportunity has appeared not only to determine the presence of oil and gas bearing layers, but also to clearly delineate the fields. But usually for this you have to drill several expensive wells.
Having received the first reliable information about the reliability of the MHD method, scientists did not limit themselves only to exploration in the Caspian lowland. A new method of geophysical exploration of subsoil was used at Kola Peninsula, on the Shelf Barents Sea- in areas with thick layers of sedimentary rocks, in which oil usually hides. Analysis of the data obtained showed that the occurrence of oil here is quite probable.
The purpose of oil exploration is the identification, geological and economic assessment and preparation for the development of oil deposits. Oil exploration is carried out using geological, geophysical, geochemical and drilling operations in a rational combination and sequence.
At the first stage of the prospecting stage in basins with undetermined oil and gas content, or to study poorly explored tectonic zones or lower structural levels in basins with established oil and gas content, regional works are carried out. For this, aeromagnetic, geological and gravimetric surveys, geochemical studies of waters and rocks, profile crossing of the territory by electrical and seismic prospecting, drilling of reference and parametric wells are carried out. As a result, areas for further prospecting work are established.
At the second stage, a more detailed study of oil and gas bearing zones is carried out by means of detailed gravity prospecting, structural-geological survey, electrical and seismic exploration, and structural drilling.
Comparison of images of scales 1: 100.000 - 1: 25.000 is made. the assessment of forecasts of oil and gas content is refined, and for structures with proven oil and gas content, prospective reserves are calculated.
At the third stage, exploratory wells are drilled with the aim of discovering deposits. The first exploratory wells are being drilled at maximum depth... Usually the top floor is surveyed first, and then the deeper ones. As a result, a preliminary estimate of the reserves is given.
The exploration stage is the final one in the exploration process. The main goal is preparation for development. In the process of exploration, deposits should be delineated, lithological composition, thickness, oil and gas saturation should be determined. Upon completion of exploration, reserves are calculated and recommendations are given on putting the field into development. The search efficiency depends on the rate of field discoveries - the ratio of the number of productive areas to the total number of areas drilled out by prospecting drilling.
Oil production
Almost all of the oil produced in the world is recovered through boreholes supported by high-pressure steel pipes. To lift oil and associated gas and water to the surface, the well has a sealed system of lifting pipes, mechanisms and fittings, designed to work with pressures commensurate with reservoir pressures. The extraction of oil using boreholes was preceded by primitive methods: collecting it on the surface of water bodies, processing sandstone or limestone soaked in oil by means of wells.
Collecting oil from the surface of water bodies- This is, obviously, the first mining method in the time of its appearance, which was used in Media, Babylonia and Syria before our era. Oil collection in Russia, started from the surface of the Ukhta River F.S. Pryadunov in 1745. In 1858, on the Cheleken peninsula, oil was collected in ditches through which water flowed from the lake. In the ditch, a dam was made of boards with a passage of water in the lower part: oil accumulated on the surface.
Development of sandstone or oil-impregnated limestone, and the extraction of oil from it, first described by an Italian scientist
F. Ariosto in the 15th century. Not far from Modena in Italy, such oily soils were crushed and heated in boilers. Then the oil was squeezed out in bags using a press. In 1833-1845. oil was extracted from sand on the shore Sea of Azov... The sand was placed in pits with a sloping bottom and watered with water. The oil washed out of the sand was collected from the surface of the water in tufts of grass.
Extraction of oil from wells produced in Kissia, an ancient region between Assyria and Media in the 5th century BC, using a rocker to which a leather bucket was tied. A detailed description of oil well production in Baku was given by a German naturalist E. Kempfer ... The depth of the wells reached 27 m, their walls were lined with stones or reinforced with wood.
Oil production through wells began to be widely used in the 60s of the 19th century. In the beginning, along with open fountains and collection of oil into earthen pits dug near the wells, oil production was also carried out using cylindrical buckets with a valve in the bottom. Of the mechanized methods of operation, for the first time in 1865 in the United States was introduced deep pumping operation, which in 1874 was used in the oil fields in Georgia, in 1876 in Baku. In 1886 V.G. Shukhov proposed compressor oil production, which was tested in Baku in 1897. A better way to lift oil out of a well is gas lift- suggested in 1914 MM. Tikhvinsky .
The process of oil production, starting from its inflow through the reservoir to the bottom of the wells and up to external pumping of marketable oil from the field, can be conditionally divided into 3 stages.
ü The movement of oil through the reservoir to the wells due to the artificially created pressure difference in the reservoir and at the bottom of the wells.
ü The movement of oil from the bottom of the wells to their wellheads on the surface - the operation of oil wells.
ü Collection of oil and accompanying gas and water on the surface, their separation, removal of mineral salts from oil, treatment of formation water, collection of associated petroleum gas.
The development of an oil field is understood as the implementation of the process of transferring fluids and gas in reservoirs to production wells. Control of the flow of liquids and gas is achieved by placing oil, injection and control wells on the field, the number and procedure for putting them into operation, the operating mode of the wells and the balance of reservoir energy. The development system adopted for a particular deposit predetermines the technical and economic indicators. Before drilling a deposit, a development system is designed. Based on the data of exploration and trial operation, the conditions under which the operation will take place are established: its geological structure, reservoir properties of rocks (porosity, permeability, degree of heterogeneity), physical properties of fluids in the reservoir (viscosity, density), saturation of oil rocks with water and gas, reservoir pressures. Based on these data, they make an economic assessment of the system and choose the optimal one.
In case of deep bedding of reservoirs, high pressure gas injection into the reservoir is successfully used in some cases to enhance oil recovery.
Oil recovery from wells is carried out either by natural flowing under the influence of reservoir energy, or by using one of several mechanized methods of liquid lifting. Usually at the initial stage of development, there is flowing production, and as the flowing weakens, the well is switched to a mechanized method: gas-lift or airlift, deep-pumping (using sucker-rod, hydraulic piston and screw pumps).
The gas-lift method makes significant additions to the usual process flow diagram of the field, since it requires a gas-lift compressor station with a gas distributor and gas gathering pipelines.
Oilfield is a technological complex consisting of wells, pipelines, and installations for various purposes, with the help of which oil is extracted from the bowels of the Earth at the field.
A water supply system with pumping stations is being built in the fields developed using artificial waterflooding. Water is taken from natural reservoirs using water intake facilities.
In the process of oil production, an important place is occupied by in-field transportation of well products, carried out through pipelines. Two infield transport systems are used: pressure and gravity. With pressure systems, its own pressure at the wellhead is sufficient. With gravity, movement occurs due to the excess of the wellhead mark over the mark of the group collection point.
When developing oil fields, confined to the continental shelves, offshore oil fields are being created.
Oil refining
The first oil refinery was built in Russia in 1745, during the reign of Elizabeth Petrovna, in the Ukhta oil field. In St. Petersburg and Moscow then they used candles, and in small towns - torches. But even then, inextinguishable lamps were burning in many churches. They were filled with hot oil, which was nothing more than a mixture of refined oil and vegetable oil. Merchant Nabatov was the only supplier of refined oil for cathedrals and monasteries.
At the end of the 18th century, the lamp was invented. With the advent of lamps, the demand for kerosene increased.
Oil refining - removal of unwanted components from oil products that negatively affect the performance properties of fuels and oils.
Chemical cleaning produced by the action of various reagents on the removed components of the cleaned products. The simplest method is purification with 92-92% sulfuric acid and oleum, used to remove unsaturated and aromatic hydrocarbons.
Physico-chemical cleaning is produced using solvents that selectively remove unwanted components from the product being purified. Non-polar solvents (propane and butane) are used to remove aromatic hydrocarbons (deasphalting process) from oil refining residues (tar). Polar solvents (phenol, etc.) are used to remove polycyclic aromatic carbons with short side chains, sulfur and nitrogen compounds from oil distillates.
At adsorption cleaning unsaturated hydrocarbons, resins, acids, etc. are removed from petroleum products. Adsorption cleaning is carried out by contacting heated air with adsorbents or by filtering the product through adsorbent grains.
Catalytic cleaning- hydrogenation under mild conditions, used to remove sulfur and nitrogen compounds.
Distillation of oil
The Dubinin brothers were the first to create a device for distilling oil. Since 1823 the Dubinins began to export photogen (kerosene) in many thousands of poods from Mozdok to the interior of Russia. The Dubinins' plant was very simple: a boiler in a stove, a pipe goes from the boiler through a barrel of water into an empty barrel. A barrel of water is a refrigerator, an empty one is a container for kerosene.
In America, the first experiments on the distillation of oil were carried out in 1833 by Silliman.
In a modern plant, instead of a boiler, a false tube furnace is arranged. Instead of a tube for condensation and vapor separation, huge rectification columns are being built. And for the reception of distillation products, whole towns of reservoirs are being built.
Oil consists of a mixture of various substances (mainly hydrocarbons) and therefore does not have a specific boiling point. On tubulars, oil is heated to 300-325 o. At this temperature, the more volatile substances in the oil are converted to steam.
Furnaces in refineries are special. They look like houses without windows. Furnaces are laid out from the best refractory bricks. Inside, along and across, pipes stretch. The length of the pipes in the furnaces reaches a kilometer.
When the plant is operating, oil moves through these pipes at a high speed - up to two meters per second. At this time, flame rushes from a powerful nozzle into the furnace. The length of the tongues of flame reaches several meters.
At a temperature of 300-325 o, oil is not completely distilled. If the distillation temperature is increased, hydrocarbons begin to decompose.
Oil workers have found a way to distill oil without decomposing hydrocarbons.
Water boils at 100 about when the pressure is equal to the atmosphere, or 760 mm. rt. Art. But it can boil, for example, at 60 o. To do this, you just need to lower the pressure. At a pressure of 150 mm, the thermometer will show only 60 o.
The lower the pressure, the sooner the water boils. The same thing happens with oil. Many hydrocarbons boil at atmospheric pressure only at 500 ° C. Therefore, at 325 ° C these hydrocarbons do not boil.
And if you lower the pressure, then they will boil at a lower temperature.
Distillation under vacuum, i.e., under reduced pressure, is based on this law. In modern refineries, oil is distilled or under atmospheric pressure, or under vacuum, most often factories consist of two parts - atmospheric and vacuum. Such plants are called atmospheric vacuum plants. All products are simultaneously produced in these factories: gasoline, naphtha, kerosene, gas oil, lubricating oils and petroleum bitumen. There are much less non-evaporated parts during such distillation than during atmospheric distillation.
Evaporation of oil occurs more easily when steam is introduced into the installation.
The work of the rectification column is complex and interesting. In this column, not only the separation of substances takes place according to their boiling points, but at the same time additional multiple boiling of the condensed liquid is performed.
The columns are made very high - up to 40 m. Inside, they are separated by horizontal partitions - plates - with holes. Caps are placed over the holes.
The mixture of hydrocarbon vapors from the furnace enters the bottom of the column.
Superheated steam is fed towards the non-evaporated oil residue from the bottom of the column. This steam heats up the unevaporated residue and carries with it all light hydrocarbons up the column. The heavy residue, fuel oil, freed from light hydrocarbons, flows into the lower part of the column, and the vapors overcome plate by plate, striving to the top of the column.
First, vapors with high boiling points turn into liquid. This will be the solar fraction, which boils at temperatures above 300 o. Liquid solarium pours the plate up to the holes. The vapors coming out of the oven now have to bubble through the solarium layer.
The temperature of the vapors is higher than the temperature of the diesel fuel, and the diesel fuel boils again.
Hydrocarbons, boiling at temperatures below 300 o, break away from it and fly up the columns to the section of kerosene trays.
There is no gasoline or kerosene in the solar oil coming out of the column.
The columns contain 30-40 plates, divided into sections. Vapors pass through all the trays, on each of them they bubble through the layer of condensed vapors and in the intervals between them they meet drops of excess condensate that has not been removed to the upper tray falling from the upper tray.
The basic technological scheme of the installation for atmospheric-vacuum distillation of oil. Apparatuses 1, 3 - atmospheric distillation columns; 2 - furnaces for heating oil and fuel oil; 4 - vacuum rectification column; 5 - condensers - refrigerators; 6 - heat exchangers.
Lines: I - oil; II - light gasoline; III - stripped oil; IV - heavy gasoline; V - kerosene and gas oil; VI - water vapor; VII - fuel oil; VIII - decomposition gases;
IX - oil fractions; X is tar.
Complex, painstaking work is continuously going on in the column. Hydrocarbons are collected in boiling point sections. Each group of hydrocarbons in the column has its own sections and its own outlet.
Hydrocarbons will be grouped in their section only when there are no hydrocarbons of other boiling points in them.
When they get together, they go out of the column to the refrigerator, and from the refrigerator to the receiver.
It is not gasoline that comes from the uppermost sections of the column, but gasoline vapors, since the temperature at the top of the column is higher than the temperature of the easily boiling parts of gasoline. Gasoline vapors go first to the condenser.
Here they are converted into gasoline, which is also sent to the refrigerator, and then to the receiver.
Cracking of petroleum products
The yield of gasoline from oil can be significantly increased (up to 65-70%) by splitting long-chain hydrocarbons contained, for example, in fuel oil, into hydrocarbons with a lower relative molecular weight. This process is called cracking (from the English. Crack- to split).
Cracking is the process of the breakdown of hydrocarbons contained in oil, as a result of which hydrocarbons with fewer carbon atoms in a molecule are formed.
Cracking was invented by a Russian engineer V.G. Shukhov in 1891 In 1913 the invention Shukhova began to be used in America. Currently, 65% of all gasoline in the United States is produced in cracking plants.
Historical reference... Vladimir Grigorievich Shukhov (1853-1939). Builder and mechanic, oil and heat engineer, hydraulic engineer and shipbuilder, scientist and inventor. More than 500 steel bridges were built according to Shukhov's designs. Shukhov was the first to suggest using simple riveted joints instead of complex hinges. Shukhov's work on the construction of metal mesh shells is extremely interesting. Invented oil cracking. Oil pipelines through which oil is pumped are also made according to its formulas. Oil storage tanks are also his credit.
Our oilmen often talk about the litigation between two American firms. About 25 years ago, the American firm Cross went to court with a complaint that the firm "Dabbs" appropriated its invention - cracking. Firm "Cross" demanded on the other a large sum of money for "illegal" use of the invention. The court sided with the Cross. But at the trial, a lawyer for the Dabbs firm said that cracking was invented not by the same firm, but by a Russian engineer. Shukhov .Shukhov then he was alive. The Americans came to him in Moscow and asked how he could prove that cracking was invented by him. Shukhov took out documents from the table, from which it was clear that his cracking Shukhov patented 35 years ago before the litigation of these two firms.
The equipment for cracking plants is basically the same as for oil distillation. These are ovens, columns. But the processing regime is different. The raw materials are also different. The cleavage process is carried out at higher temperatures (up to 600 0 C), often at elevated pressure. At such temperatures, large hydrocarbon molecules are fragmented into smaller ones.
Fuel oil is thick and heavy, its specific gravity is close to one. This is because it is composed of complex and large hydrocarbon molecules. When fuel oil is cracked, some of its constituent hydrocarbons break down into smaller ones, and light oil products - gasoline, kerosene - are composed of small hydrocarbons.
When oil is cracked, it undergoes chemical changes. The structure of hydrocarbons is changing. Complex chemical reactions take place in the apparatus of cracking plants. These reactions are enhanced when catalysts are introduced into the apparatus.
One of these catalysts is specially treated clay. This clay in a finely crushed state - in the form of dust - is introduced into the plant's equipment. Hydrocarbons, which are in a vapor state, are combined with clay dust particles and are fragmented on their surface. This cracking is called pulverized catalyst cracking. This type of cracking is widespread.
The catalyst is then separated from the hydrocarbons. Hydrocarbons go their own way for rectification and into refrigerators, and the catalyst goes into their tanks, where its properties are restored.
The cracking process occurs with the rupture of hydrocarbon chains and the formation of simpler saturated and unsaturated hydrocarbons, for example:
C 16 H 34 C 8 H 18 + C 8 H 16
hexadecane octane octene
the resulting substances can decompose further:
C 8 H 18 C 4 H 10 + C 4 H 8
octane butane butene
C 4 H 10 C 2 H 6 + C 2 H 4
butane ethane ethylene (ethene)
Ethylene released in the cracking process is widely used for the production of polyethylene and ethyl alcohol.
The splitting of hydrocarbon molecules proceeds by a radical mechanism. Free radicals are formed first:
CH 3 - (CH 2) 6 - CH 2: CH 2 - (CH 2) 6 - CH 3 t
T CH 3 - (CH 2) 6 - CH 2 . + . CH 2 - (CH 2) 6 - CH 3
Free radicals are chemically very active and can participate in various reactions. In the process of cracking, one of the radicals abstracts a hydrogen atom (a), and the other adds (b):
a) CH 3 - (CH 2) 6 - CH 2 . CH 3 - (CH 2) 5 - CH = CH 2 + HO
b) CH 3 - (CH 2) 6 - CH 2 . + CH 3 - (CH 2) 6 - CH 3
There are 2 types of cracking: thermal and catalytic.
Thermal cracking
The splitting of hydrocarbon molecules occurs at more high temperature(470-550 0 C). The process proceeds slowly, hydrocarbons with unbranched carbon atoms are formed.
In gasoline obtained as a result of thermal cracking, along with saturated hydrocarbons, there are many unsaturated hydrocarbons. Therefore, this gasoline has a higher knock resistance than straight run gasoline.
Thermally cracked gasoline contains many unsaturated hydrocarbons, which are easily oxidized and polymerized. Therefore, this gasoline is less stable during storage. Burning out can clog various parts of the engine. To eliminate this harmful effect, oxidizing agents are added to such gasoline.
Catalytic cracking
The splitting of hydrocarbon molecules takes place in the presence of catalysts and at a lower temperature (450-500 0 С).
The main focus is on gasoline. They try to get more and always better quality. Catalytic cracking emerged precisely as a result of the long-term, stubborn struggle of oil workers to improve the quality of gasoline. Compared to thermal cracking, the process proceeds much faster, with not only the decomposition of hydrocarbon molecules, but also their isomerization, i.e. formed hydrocarbons with a branched chain of carbon atoms.
Compared to thermally cracked gasoline, catalytically cracked gasoline has an even higher detonation resistance, because it contains hydrocarbons with a branched chain of carbon atoms.
Gasoline of catalytic cracking contains less unsaturated hydrocarbons, and therefore oxidation and polymerization processes do not occur in it. Such gasoline is more stable during storage.
Reforming
Reforming - (from the English. Reforming - to alter, improve) an industrial process of processing gasoline and naphtha fractions of oil in order to obtain high-quality gasolines and aromatic hydrocarbons. In this case, the molecules of hydrocarbons are generally not split, but transformed. The raw material is the naphtha fraction of oil.
Until the 30s of the 20th century, reforming was a type of thermal cracking and was carried out at 540 0 С to obtain gasoline with an octane rating of 70-72.
Since the 40s, reforming is a catalytic process, the scientific foundations of which have been developed N. D. Zelinsky, and IN AND. Karzhev, B.L.
Moldavian. For the first time this process was carried out in 1940 in the USA.
It is carried out in an industrial installation with a heating furnace and at least 3-4 reactors at t 350-520 0 C, in the presence of various catalysts: platinum and polymetallic, containing platinum, rhenium, iridium, germanium, etc. in order to avoid catalyst deactivation by the compaction product coke, reforming is carried out under high pressure of hydrogen, which is circulated through a heating furnace and reactors. As a result of reforming gasoline fractions of oil, 80-85% gasoline with an octane number of 90-95, 1-2% hydrogen and the rest of gaseous hydrocarbons are obtained. From a tubular furnace under pressure, oil is fed into the reaction chamber, where the catalyst is located, from here it goes to the distillation column, where it is separated into products.
Reforming is of great importance for the production of aromatic hydrocarbons (benzene, toluene, xylene, etc.). Previously, the main source of these hydrocarbons was the coke industry.
