Chemically, oil is a complex mixture of hydrocarbons and carbon compounds; it consists of the following main elements: carbon (84-87%), hydrogen (12-14%), oxygen, nitrogen and sulfur (1-2%), the sulfur content increases sometimes up to 3-5%.

Oil contains hydrocarbon, asphalt-resinous parts, porphyrins, sulfur and ash parts.

The main part of oil consists of three groups of hydrocarbons: methane, naphthenic and aromatic.

The asphalt-resinous part of oil is a dark-colored substance. It is partially soluble in gasoline. The dissolved part is called asphaltene, the undissolved part is called resin. Resins contain oxygen up to 93% of the total amount in oil.

Porphyrins are special nitrogenous compounds organic origin. They are believed to be formed from plant chlorophyll and animal hemoglobin. At temperature, porphyrins are destroyed.

Sulfur is widespread in oil and hydrocarbon gas and is found either in a free state or in the form of compounds (hydrogen sulfide, mercaptans). Its amount ranges from 0.1% to 5%.

The ash part is the residue resulting from the combustion of oil. These are various mineral compounds, most often iron, nickel, vanadium, and sometimes sodium salts.

Oil varies greatly in color (from light brown, almost colorless, to dark brown, almost black) and density (from light 0.65-0.70 to heavy 0.98-1.05).

The boiling point of oil is usually above 280C. The pour point ranges from +300 to -600C and depends mainly on the paraffin content (the more there is, the higher the pour point). Viscosity varies over a wide range and depends on the chemical and fractional composition of the oil and resin content (the content of asphalt-resinous substances in it). Oil is soluble in organic solvents, in water at normal conditions practically insoluble, but can form stable emulsions with it.

Oil can be classified according to various criteria.

2. According to the potential content of fractions boiling up to 3500C

3. According to potential oil content

4. According to the quality of oils

The combination of class, type, group, subgroup and type designations constitutes the technological classification code for oil.

Depending on the field, oil has different qualitative and quantitative composition. For example, Baku oil is rich in cycloparaffins and relatively poor in saturated hydrocarbons. There are significantly more saturated hydrocarbons in Grozny and Fergana oil. Permian oil contains aromatic hydrocarbons.

2. Oil. Composition of oil.

Oil is a complex mixture organic compounds. Hundreds of hydrocarbons of various structures and numerous heteroorganic compounds were found in its composition. It is impossible to completely separate such a mixture into individual compounds, but this is not required for its technical specifications petroleum feedstock, nor for its industrial use.

An important indicator of oil quality is the fractional composition. The fractional composition is determined during laboratory distillation, during which, at a gradually increasing temperature, parts are distilled from the oil - fractions that differ from each other in their boiling point. Each fraction is characterized by its beginning and end boiling temperatures.

During the industrial distillation of oil, they do not use the laboratory method of gradual evaporation, but schemes with the so-called single evaporation and further rectification. Fractions boiling up to 350°C are selected at a pressure slightly higher than atmospheric pressure; they are called light distillates (fractions). Typically, atmospheric distillation produces the following fractions, the names of which are assigned depending on the direction of their further use:

n.k. (beginning of boiling point) - 140°С) – gasoline fraction

140-180°С – naphtha fraction (heavy naphtha)

140-220°С (180-240°С) – kerosene fraction

180-350°C (220-350°C, 240-350°C) – diesel fraction (light or atmospheric gas oil, diesel distillate)

The residue after the selection of light distillates (the fraction that boils above 350°C) is called fuel oil. Fuel oil is accelerated under vacuum, and depending on the direction of oil refining, the following fractions are obtained

To obtain fuels

350-500°C – vacuum gas oil (vacuum distillate)

>500°С – vacuum residue (tar)

To obtain oils

300-400°С (350-420°С) – light oil fraction (transformer distillate)

400-450°С (420-490°С) – medium oil fraction (machine distillate)

450-490°С – heavy oil fraction (cylinder distillate)

>490°С – tar

Fuel oil and the fractions obtained from it are called dark. Products obtained during secondary oil refining processes, as well as during primary distillation, are classified as light if they boil to 350°C, and dark if the boiling point is 350°C or higher.

Oils from different fields differ markedly in their fractional composition and the content of light and dark fractions. Thus, Yarega oil (Komi Republic) contains 18.8% light fractions, and Samotlor oil (Western Siberia) contains 58.8%.

Oil belongs to the group of sedimentary rocks along with sands, clays, limestones, rock salt, etc. It has one important property - the ability to burn and release thermal energy. Among other fossil fuels, it has the highest calorific value. For example, heating a boiler room or other installation requires significantly less oil by weight than coal.

All combustible rocks belong to special family, which received the name caustobioliths(from the Greek words “kaustos” - flammable, “bios” - life, “litos” - stone, i.e. flammable organic stone).

Chemically, oil is a complex mixture of hydrocarbons (HC) and carbon compounds.

Oil consists of the following main elements:

carbon (84-87%),

hydrogen (12-14%),

oxygen,

sulfur (1-2%).

The main part of oils are hydrocarbons that differ in their composition, structure and properties, which can be in gaseous, liquid and solid states. Depending on the structure of the molecules, oil is divided into three classes – paraffinic, naphthenic and aromatic. But a significant part of the oil is made up of hydrocarbons of mixed structure, containing structural elements of all three mentioned classes. The structure of molecules determines their chemical and physical properties.

1.1. Paraffin hydrocarbons

Paraffin hydrocarbons - alkanes C p H 2p + 2 - make up a significant part of the group components of oils and natural gases of all fields. Their total content in oils is 25 - 35% by weight (not counting dissolved gases) and only in some paraffin oils reaches up to 40-50% by weight. The most widely represented in oils are alkanes of normal structure and isoalkanes, predominantly monomethyl-substituted with different position methyl group in the chain. As the molecular weight of oil fractions increases, the content of alkanes in them decreases. Associated petroleum and natural gases are almost entirely composed of alkanes, while straight-run gasolines most often consist of 60-70%. In oil fractions their content is reduced to 5-20% by weight.

Gaseous alkanes. Alkanes C 1 - C 4: methane, ethane, propane, butane and isobutane, as well as 2,2-dimethylpropane, are in the gaseous state at zero.

Natural gases are extracted from pure gas fields. They consist mainly of methane (93 - 99% wt.) with a small admixture of its homologues, non-hydrocarbon components: hydrogen sulfide, carbon dioxide, nitrogen and rare gases (He, Ar, etc.). Gases from gas condensate fields and petroleum associated gases differ from pure gases in that methane is accompanied in significant concentrations by its gaseous homologues C 2 -C 4 and higher. Therefore, they are called fatty gases. From them they produce light gas gasoline, which is an additive to commercial gasoline, as well as compressed liquid gases as fuel. Ethane, propane and butanes, after separation, serve as feedstock for petrochemicals.

Liquid alkanes. Alkanes from C 5 to C 15 under normal conditions are liquids that are part of gasoline (C 5 - C 15) and kerosene (C 11 - C 15) fractions of oils. Research has established that liquid alkanes C 5 - C 9 have mainly a normal or slightly branched structure.

Solid alkanes, Alkanes C 16 and higher under normal conditions are solid substances that are part of petroleum paraffins and ceresins. They are present in all oils, most often in small quantities (up to 5% by weight) in a dissolved or suspended crystalline state. In paraffinic and highly paraffinic oils, their content increases to 10 - 20% by weight.

Depending on Tmel. Paraffin is divided into soft (below 45 C), medium-melting (45-50 C) and hard (50-60 C).

Petroleum paraffins are a mixture of predominantly alkanes of different molecular weights. When distilling fuel oil, solid alkanes C 18 - C 35 with a molecular weight of 250 - 500 enter the oil fractions. Higher melting alkanes C 36 - C 55 - ceresins, which differ from paraffins in their fine-crystalline structure and higher molecular weight (500 - 700) are concentrated in tars. and melting point (65-88°C instead of 45-54°C for paraffins). Research has established that solid paraffins consist predominantly of alkanes of normal structure, and ceresins consist mainly of cycloalkanes and arenes with long alkyl chains of normal and isostructure. Ceresins are also part of the natural combustible mineral - ozokerite.

From crude oil, paraffin is released in a fine crystalline state due to the presence of resinous substances, and also because ceresin impurities contained in paraffin retain oils.

Paraffins and ceresins are undesirable components in the composition of oil fractions of petroleum, since they increase their pour point. They find a variety of technical applications in many industries: electrical and radio engineering, paper, matches, leather, perfume, chemical, etc. They are also used in the production of greases, candle making, etc. A particularly important modern application is as a petrochemical feedstock for the production of synthetic fatty acids, alcohols, surfactants, demulsifiers, washing powders, etc.

1.2. Naphthenic hydrocarbons

Naphthenic hydrocarbons - cycloalkanes (cyclanes) - are part of all fractions of oils, except gases. On average, in oils of various types they contain from 25 to 80% of the mass. Gasoline and kerosene fractions of oils are represented mainly by homologues of cyclopentane (I) and cyclohexane (II), mainly with short (C 1 - C 3) alkyl-substituted cyclanes. High-boiling fractions contain predominantly polycyclic condensed and less often non-condensed naphthenes with 2 - 4 cycles with a general empirical formula

C p H 2p + 2 - 2Kts, where n is the number of carbon atoms, Kts-number of cyclane rings.

Polycyclic naphthenes can be represented by homologues of cyclanes with the same or different rings of bridged (III, IV, V), jointed (VI), isolated (VII) and condensed (VIII, IX, X) structure types:

I - cyclopentane; P - cyclohexane; III - bicyclo(3,2,1)octane*; IV -bicyclo(3,3,1)nonane; V-bicyclo(2,2,1)heptane; VI - bicyclo(5,5,0)dodecane; VII -methyl bicyclic o(5,4,0)un decane; VIII - bicyclo(3,3,0)octane; IX - bicyclo(4,3,0)nonane; X - bicyclo(4,4,0)decane – decalin

Naphthenic hydrocarbons are the highest quality components of motor fuels and lubricating oils. Monocyclic naphthenic hydrocarbons give motor gasoline, jet and diesel fuels high performance properties and are a higher quality raw material in catalytic reforming processes. As part of lubricating oils, naphthenes provide a small change in viscosity with temperature (i.e., a high oil index). With the same number of carbon atoms, naphthenes, compared to alkanes, are characterized by a higher density and, most importantly, a lower pour point.

The main elements that make up the components of oil are carbon and hydrogen. The content of carbon and hydrogen in various oils varies within relatively narrow limits and averages 83.5-87 wt.% for carbon, 11.5-14 wt.% for hydrogen. In terms of high hydrogen content, oil occupies an exceptional position among other caustobioliths. In humus coals the hydrogen content is on average 5% by weight, in solid sapropelite formations - 8% by weight. The increased hydrogen content explains the liquid state of oil.

Along with carbon and hydrogen, all oils contain sulfur, oxygen and nitrogen. Nitrogen in oils from 0.001-0.3 to 1.8% wt. The oxygen content ranges from 0.1-1.0% by weight. However, in some high-resin oils it can be higher.

Oils differ significantly in sulfur content. In the oils of many sulfur deposits there is relatively little 0.1-1.0% wt. But the share of sulfur oils with a sulfur content of 1 to 3% wt. V lately has increased significantly. There are also highly sulfurized oils with a sulfur content above 3% by weight.

Other elements are present in oils in very small quantities, mainly metals (vanadium, nickel, magnesium, chromium, titanium, cobalt, potassium, calcium, sodium, etc.). Phosphorus and silicon were also discovered. The content of these elements is expressed in small fractions of a percent. Germanium was found in various petroleum products with a content of 0.15 - 0.19 g/t.

In accordance with the elemental composition, the bulk of oil components are hydrocarbons. In the low-molecular-weight part of oil, to which we can conditionally include substances with a molecular weight of no more than 250-300 and distilling to 300-350 o C, the hydrocarbons with the simplest structure are present. They belong to the following homologous series:

C p N 2p+2 – paraffins, methane hydrocarbons, alkanes;

C p H 2p - cycloparaffins, monocyclic polymethylene

hydrocarbons, naphthenes, cyclanes (alkylcyclopentanes and alkylcyclohexanes);

C p H 2p-2 - dicycloparaffins, bicyclic polymethylene

hydrocarbons (five-membered, six-membered and mixed);

C p H 2p-4 – tricycloparaffins, tricyclic polymethylene hydrocarbons (five-membered, six-membered and mixed);

C p H 2p-6 – monocyclic aromatic hydrocarbons, benzene hydrocarbons, arenes;

C p N 2p-8 – bicyclic mixed naphthenic-aromatic hydrocarbons;

C p H 2p-12 – bicyclic aromatic hydrocarbons.

In the gasoline fraction, only three classes of hydrocarbons are practically present: alkanes, cyclanes and aromatic benzene series. In kerosene

and gas oil fractions, a significant proportion is made up of bi- and tricyclic hydrocarbons.

Unsaturated hydrocarbons with unsaturated bonds in the chain, as a rule, are not present in crude oils. There are some oils with an insignificant content of unsaturated hydrocarbons (Bradford, USA).

In addition to hydrocarbons, the low molecular weight part of oil contains: - oxygen compounds - naphthenic acids, phenols;

Sulfur compounds – mercaptans, sulfides, disulfides, thiophenes;

Nitrogen compounds – pyridine bases and amines.

The amount of all these heteroatomic substances distilled within 300-350 o C is small, since the bulk of oxygen, sulfur and nitrogen is concentrated in the high molecular weight part of the oil.

During the factory distillation of sulfurous oils, due to the thermal decomposition of complex heteroatomic compounds, up to 5 wt.% can accumulate in commercial light distillates. and lower molecular weight sulfur compounds.

When assessing the content of heteroatomic compounds, it must be taken into account that in sulfur, oxygen and nitrogen compounds, sulfur, oxygen and nitrogen are associated with various hydrocarbon radicals and 1 hour (wt.) of these elements accounts for 10 - 20 hours (wt.) of carbon and hydrogen.

The chemical composition of the high-molecular part of oil, which conventionally includes substances that distill above 350 o C, has been little studied. We are talking about fuel oil, oil fractions and tar. The molecular weight of the components of this part of the oil ranges from 300 to 1000. This part of the oil is a mixture of substances of various compositions and structures.

The main types of compounds included in this mixture are:

High molecular weight paraffin hydrocarbons C p H 2p+2;

Mono- and polycyclic cycloparaffin hydrocarbons with long or short paraffin side chains from C p H 2p to C p H 2p-10;

Mono- and polycyclic aromatic hydrocarbons with paraffin side chains from C p H 2p-6 to C p H 2p-36;

Mixed (hybrid) polycyclic naphtheno-aromatic hydrocarbons with paraffin side chains from C p H 2p-8 to C p H 2p-22;

A variety of organic compounds of a polycyclic hybrid nature, the molecules of which consist of purely carbon rings, cycles containing heteroatoms - sulfur, oxygen or nitrogen, as well as long or short paraffin chains;

Resinous-asphaltene substances – resins and asphaltenes; these most complex petroleum substances are characterized by a polycyclic structure and the obligatory presence of oxygen; they also contain the bulk of nitrogen and metals; The resin content in some oils reaches 30-40% by weight.

The main types of compounds included in oil. Paraffin hydrocarbons. Hydrocarbons of this class of organic compounds are present in all oils and are one of its main components. They are distributed unevenly among the fractions, concentrating in oil gases and gasoline-kerosene fractions. In oil distillates their content drops sharply. Some oils are characterized by the complete absence of paraffins in high-boiling fractions.

Gaseous hydrocarbons methane, ethane, propane, butane, isobutane, 2,2-dimethylpropane are in a gaseous state under normal conditions. All of them are part of natural and petroleum associated gases.

Gases from oil fields are called associated petroleum gases. These gases are dissolved in oil and are released from it when they reach the surface. The composition of associated petroleum gases differs from dry gases in the content of ethane, propane, butanes and higher hydrocarbons.

Liquid hydrocarbons. Due to their boiling points, hydrocarbons from pentane to decane and all their isomers must enter the gasoline distillate during oil distillation.

Solid hydrocarbons. Solid paraffins in oils are in a dissolved or suspended crystalline state. In paraffinic and highly paraffinic oils, their content increases to 10-20% by weight. When distilling fuel oil, paraffins with the composition C 18 -C 35 get into the oil fractions. Higher melting hydrocarbons C 36 -C 53 – ceresins – are concentrated in tars.

The presence of solid hydrocarbons in lubricating and special oils is unacceptable, as they increase the pour point and reduce the mobility of oils at low temperatures. Therefore, oils are subjected to special purification - dewaxing.

Methane hydrocarbons belong to the series С„Н 2п+2, they occupy an extremely important place among oil hydrocarbons. Thus, natural gases are represented exclusively by methane hydrocarbons and, most often, almost entirely by methane itself. Light fractions of any liquid oils also consist almost entirely of methane hydrocarbons. True, as the average molecular weight of oil fractions increases, the content of methane hydrocarbons in them sharply decreases. In the middle fractions, boiling away within the range of 200-300°C, methane hydrocarbons usually contain no more than 25-33%, and by 500°C the methane hydrocarbons of oil are almost completely eliminated. In higher fractions of oil, methane hydrocarbons are solid substances - paraffin and partially ceresin. In addition, side chains of methane radicals have a great influence on the structure and properties of complex polymethylene, aromatic and so-called hybrid hydrocarbons.

CONCLUSION: Specific oils may contain more or less methane hydrocarbons. In general, it is obvious that methane hydrocarbons form the basis of most natural gases and light fractions of liquid oil, which deserves special attention, since these components are the starting materials for modern organic and petrochemical synthesis to the greatest extent.

Naphthenic.

Cycloalkanes (C p H 2p) - naphthenic hydrocarbons - are part of all fractions of oils, except gases. On average, in oils of various types they contain from 25 to 80% of the mass. Gasoline and kerosene fractions are represented mainly by homologues of cyclopentane and cyclohexane, mainly with short (C 1 - C 3) alkyl-substituted cyclanes. High-boiling fractions contain predominantly polycyclic homologues of cyclanes with 2 - 4 identical or different cyclanes of a jointed or condensed type of structure. The distribution of cyclanes among oil fractions is very diverse. Their content increases as the fractions become heavier and falls only in the highest boiling oil fractions. The following distribution of cyclane isomers can be noted: among C 7 - cyclopentanes, 1,2 - and 1,3-dimethyl-substituted ones predominate; C 8 - cyclopentanes are predominantly trimethyl-substituted; Among alkylcyclohexanes, the predominant proportion is di- and trimethyl-substituted, which do not contain a quaternary carbon atom.

Naphthenic hydrocarbons began to be understood as not only monocyclic, but also polycyclic polymethylene hydrocarbons of petroleum origin.

Naphthenes are part of all oils and are present in all fractions. Their content increases as the fractions become heavier. Only in the highest boiling oil fractions their amount decreases due to an increase in aromatic structures.

Monocyclic naphthenes are represented by cyclopentane and cyclohexane structures. More than 80 individual representatives of this class of hydrocarbons of composition C 5 -C 12 were found in gasoline and kerosene fractions. The following are present in relatively large quantities in oils: methylcyclohexane, cyclohexane, methylcyclopentane, and some dimethyl homologues of cyclopentane. Cycloheptane and methylcycloheptane were found in small quantities. In fractions above 200 o C there are bicyclic and polycyclic naphthenes with the number of cycles no more than six.

CONCLUSION: Naphthenic hydrocarbons are the highest quality components of motor fuels and lubricating oils. Monocyclic naphthenic hydrocarbons give motor gasoline, jet and diesel fuels high performance properties and are higher quality raw materials in catalytic reforming processes.

Aromatic hydrocarbons.

Arenas are presented in oil as monocyclic and polycyclic. Typically oils contain 15-20% arenes. In aromatic (resinous) oils their content reaches 35%. Depending on the distribution of aromatic hydrocarbons among oil fractions, they can be divided into three groups:

naphthenic-aromatic - oils whose aromatic hydrocarbons (mainly polycyclic) are concentrated in higher fractions. These are heavy tarry oils with a density > 0.9;

naphthenic - oils whose aromatic hydrocarbons are concentrated mainly in the middle fractions. The density of such oils is 0.85-0.9;

3) paraffinic oils - oils whose aromatic hydrocarbons are concentrated in light fractions (up to 300°C).

Fractions up to 200°C (gasoline fractions) contain only benzene homologues. All benzene homologues have been found in oils, including C9. Monosubstituted benzene homologues containing 4 or more carbon atoms in the side chain are rare. The most common are toluene, ethylbenzene, xylenes (m-xylene predominates as more thermodynamically stable), then trimethylbenzenes, followed by cumene, propylbenzene, and methylethylbenzenes.

In fractions of 200-350°C, alkylbenzenes predominate, mainly di- and tri-substituted, the molecules of which contain methyl groups and an alkyl group of the composition C 7 -Cg. In addition to benzene homologues, these fractions contain naphthalene homologues (mono-, bi-, tri- and tetramethyl naphthalenes). Homologues of biphenyl have also been found. Naphthalene is rare.

Fractions >350°C, in addition to higher homologues of benzene and homologues of naphthalene, contain diarylalkane - hydrocarbons, in the molecules of which

isolated aromatic nuclei are linked to a hydrocarbon bridge, for example:

The higher fractions also contain small amounts of homologues of polycyclic hydrocarbons with fused rings, such as:

The main part of these hydrocarbons is concentrated in tar. Hydrocarbons of mixed structure are widely represented in the higher fractions of oils, the molecules of which contain, along with aromatic

Many closest homologues of benzene with one, two, three and four substituents in the nucleus have been found in oils. The substituent is most often a methyl radical; the presence of such hydrocarbons as isopropyl benzene (cumene), propylbenzene, butylbenzenes, diethylbenzene and homologues with various substituents in the side chains has been proven.

In the middle fractions of oil (200-350 o C), along with benzene derivatives, naphthalene and its closest homologues are also present, i.e. bicyclic condensed aromatic hydrocarbons.

In higher fractions of oil, more complex polycyclic aromatic hydrocarbons with three, four and five condensed rings were found. They are homologues of naphthalene, biphenyl, acenaphthene, anthracene, phenanthrene, pyrene, benzanthracene, chrysene, phenanthrene, perylene.

The presence of aromatic hydrocarbons in gasoline is highly desirable, since they have high octane numbers. On the contrary, their presence in significant quantities in diesel fuels(middle oil fractions) worsens the fuel combustion process. Polycyclic aromatic hydrocarbons with short side chains that enter oil fractions during oil distillation must be removed during the purification process, since their presence has a detrimental effect on the performance of lubricating oils. Individual aromatic hydrocarbons: benzene, toluene, xylenes, ethylbenzene, isopropylbenzene and naphthalene are valuable raw materials for many petrochemical and organic synthesis processes.

Hydrocarbons of mixed structure. A significant portion of petroleum hydrocarbons have a mixed or hybrid structure. This means that the molecules of such hydrocarbons contain different structural elements: aromatic rings, five- and six-membered cycloparaffin rings and aliphatic paraffin chains.

Oil fractions consist almost entirely of hydrocarbons of mixed structure. They can be divided into three types: paraffin-cycloparaffin; paraffin-aromatic; paraffin-cycloparaffin-aromatic.

Oxygen compounds. The bulk of the oxygen found in oil is contained in resinous substances, and only about 10% of it comes from acidic organic compounds - carboxylic acids and phenols. There are very few neutral oxygen compounds in oils. In turn, among acidic compounds, compounds characterized by the presence of a carboxyl group - petroleum acids - predominate.

Among them, acids of iso structure predominate, including isoprenoid acids and those with an even number of carbon atoms. Carboxylic acids - derivatives of monocyclic naphthenes with the general formula C p H 2p-1 COOH or C p H 2p - 2 O 2 are called naphthenic acids.

Of all the oxygen compounds of oil, only naphthenic acids and their naphthenate salts, which have good cleaning properties, are of industrial importance. Waste from alkaline purification of petroleum distillates - soap naft - is used in the manufacture of detergents for textile production.

Technical petroleum acids (asidol), isolated from kerosene and light oil distillates, are used as solvents for resins, rubber and aniline dyes, for impregnating sleepers, for wetting wool, etc. Sodium and potassium salts of naphthenic acids serve as demulsifiers for oil dehydration.

Sulfur compounds. Sulfur is the most common heteroelement in oils and petroleum products. Its content in oils ranges from hundredths to 5-6% by weight. less often up to 14% wt. Oils from the Ural-Volga region and Siberia are rich in sulfur-containing compounds: the amount of sulfur in Arlan oil reaches up to 3.0% by weight, and in Ust-Balyk up to 1.8% by weight. Of the foreign oils, the oils with the highest sulfur content are: Albanian (5-6% wt.), Ebano-Panuco (Mexico, 5.4% wt.), Rosel Point (USA - up to 14% wt.). In the latter case, almost all oil compounds are sulfur-containing.

The distribution of sulfur among fractions depends on the nature of the oil and the type of sulfur compounds. As a rule, their content increases from low- to high-boiling and reaches a maximum in the residue from the vacuum distillation of oil-tar. The following types of sulfur-containing compounds have been identified in oils:

Elemental sulfur and hydrogen sulfide are not directly organosulfur compounds, but appear as a result of the destruction of the latter;

Mercaptan-thiols, which, like hydrogen sulfide, have acidic properties and the most severe corrosive activity;

Aliphatic sulfides (thioethers) are neutral at low temperatures, but are not thermally stable and decompose when heated above 130-160°C with the formation of hydrogen sulfide and mercaptans;

Mono- and polycyclic sulfides are the most thermally stable.

Hydrogen sulfide is found in crude oils less frequently and in significantly smaller quantities than in natural gases, gas condensates and oils

Mercaptans (thiols) have the structure RSH, where R is a hydrocarbon substituent of all types (alkanes, cyclanes, arenes, hybrids) of different molecular weights. The boiling point of individual alkyl mercaptans C 1 -C 6 is 6-140°C at atmospheric pressure. They have a very unpleasant odor. This property is used in the practice of gas supply to cities and villages to warn about a malfunction of the gas line. Ethyl mercaptan is used as an odorant for household gases.

Based on the content of thiols, oils are divided into mercaptan and non-mercaptan. Mercaptans are found in abnormally high concentrations in gas condensates and oils of the Caspian lowland. Thus, in the 40-200°C fraction of Orenburg gas condensate, mercaptans account for 1% of the 1.24% mass. total sulfur. The following pattern was discovered: mercaptan sulfur in oils and gas condensates is concentrated mainly in the head fractions.

Elemental sulfur, hydrogen sulfide and mercaptans, as very aggressive sulfur compounds, are the most undesirable components of oils. They must be completely removed in the purification processes of all commercial petroleum products.

Sulfides (thioethers) make up the bulk of sulfur compounds in fuel fractions of oil (from 50 to 80% by weight of the total sulfur in these fractions). Petroleum sulfides are divided into 2 groups: dialkyl sulfides (thioalkanes) and cyclic dialkyl sulfides RSR" (where R and R" are alkyl substituents). Thialkanes are found mainly in paraffinic oils, and cyclic ones - in naphthenic and naphthenic-aromatic ones. Thioalkanes C 2 -C 7 have low temperatures boiling (37-150°C) and during the distillation of oil they end up in gasoline fractions. As the boiling point of oil fractions increases, the amount of thioalkanes decreases, and they are practically absent in fractions above 300°C. In some light and medium fractions of oils, RSSR disulfides were found in small quantities (less than 15% by weight of the total sulfur in these fractions). When heated, they form sulfur, hydrogen sulfide and mercaptans.

Monocyclic sulfides are five- or six-membered heterocycles with a sulfur atom. In addition, polycyclic sulfides and their various homologues have been identified in oils.

Thiocyclanes predominate in the middle fractions of many oils. Among thiocyclanes, monocyclic sulfides are usually more common. When distilling oils, polycyclic sulfides predominantly end up in oil fractions and are concentrated in oil residues.

All sulfur-containing petroleum compounds, except low-molecular mercaptans, are chemically neutral at low temperatures and have similar properties to arenes. They have not yet found industrial application due to the low efficiency of methods for their isolation from oils. In limited quantities, sulfides are isolated from the middle (kerosene) fractions of some oils for subsequent oxidation into sulfones and sulfonic acids. Sulfur compounds in oils are currently not extracted, but are destroyed by hydrogenation processes. The resulting hydrogen sulfide is converted into elemental sulfur or sulfuric acid. At the same time in recent years In many countries of the world, large-scale industrial processes for the synthesis of sulfur compounds similar to petroleum compounds, which are of great value, are being developed and intensively introduced. Among them, mercaptans are of greatest industrial importance. Methyl mercaptan is used in the production of methionine, a fuel gas odorant.

Thiols C 1 -C 4 are raw materials for the synthesis of agrochemicals; they are used for activation (sulfurization) of some catalysts in oil refining. Thiols from butyl mercaptan to octadecyl mercaptan are used in the production of additives for lubricating and transformer oils, for cutting and cooling emulsions used in cold working of metals, in the production of detergents, and ingredients for rubber compounds. Thiols C 8 -C 16 are: regulators of radical polymerization processes in the production of latexes, rubbers, and plastics. Tertiary dodecyl mercaptan and normal dodecyl mercaptan are most widely used as polymerization regulators. Mercaptans are used for the synthesis of flotation reagents, photographic materials, special-purpose dyes, cosmetics, pharmacology, and many other fields.

Sulfides serve as components in the synthesis of dyes, their oxidation products - sulfoxides, sulfones and sulfonic acids - are used as effective extractants of rare metals and flotation reagents of polymetallic ores, plasticizers and biologically active substances. The use of sulfides and their derivatives as components of rocket fuels, insecticides, fungicides, herbicides, plasticizers, complexing agents, etc. is promising. In recent years, the use of polyphenylene sulfide polymers has sharply increased. They are characterized by good thermal stability, the ability to maintain excellent mechanical characteristics at high temperatures, high chemical resistance and compatibility with various fillers. Hard coatings made of polyphenyl sulfide are easily applied to metal, providing reliable protection against corrosion, which has already been picked up by the foreign petrochemical industry, where there is a polyphenyl sulfide “boom”. It is also important to emphasize that in this polymer almost one third of the mass consists of sulfur.

Thiophene and 2-methylthiophene are effective removers of manganese compounds from carburetor engines when cis used as an antiknock agent. Currently, this antiknock agent is widely used in the United States, where about 40% of unleaded gasoline contains non-lead antiknock agents.

Considering the presence of significant resources of sulfur-containing compounds in oils, the problem of their extraction and rational use in the national economy is extremely relevant.

Nitrogen compounds. Organic nitrogen compounds in oils average no more than 2-3% by weight. and maximum (in high-resin oils) up to 10% of the mass. Most of the nitrogen is concentrated in heavy fractions and residual products.

Resinous-asphaltene substances (RAS) are concentrated in heavy oil residues (HOR) - fuel oil, half-tar, tar, bitumen, cracking residues, etc. The total content of RAS in oils, depending on their type and density, ranges from a fraction of a percent to 45% of the mass. . and in TNO it reaches up to 70% of the mass. Young oils of the naphthenic-aromatic and aromatic types are the richest in CAB.

CABs are a complex multicomponent mixture of high molecular weight hydrocarbons and heterocompounds, exclusively polydisperse in molecular weight, including, in addition to carbon and hydrogen, sulfur, nitrogen, oxygen and metals such as vanadium, nickel, iron, molybdenum, etc. Isolating individual CAAs from oils and solid waste is extremely difficult. Their molecular structure has not yet been precisely established. The current level of knowledge and the capabilities of instrumental physicochemical research methods only allow us to give a probabilistic idea of ​​the structural organization, establish the amount of condensed naphthenic-aromatic and other characteristics and build average statistical models of hypothetical molecules of resins and asphaltenes.

In the practice of studying the composition and structure of petroleum, coal and coke chemical residues, the Richardson solvent method is widely used, based on the different solubility of group components in organic solvents (weak, medium and strong). Based on this feature, the following conditional group components are distinguished:

Soluble in low molecular weight (weak) solvents (isooctane, petroleum ether) - oils and resins.

Resins are extracted from maltenes by adsorption chromatography (on silica gel or aluminum oxide);

Insoluble in low molecular weight alkanes C 5 -C 8, but soluble in toluene and carbon tetrachloride - asphaltenes;

Insoluble in gasoline, toluene and carbon tetrachloride, but soluble in carbon disulfide and quinoline - carbenes;

Insoluble in any solvents are carboids.

There are no carbenes and carboides in oils and native heavy fuel oil (i.e., not subjected to thermal destruction). The term “oils” usually means high-molecular hydrocarbons with a molecular weight of 300-500 of mixed (hybrid) structure. Using chromatographic separation, paraffin-naphthenic and aromatic hydrocarbons are isolated from oil fractions, including light (monocyclic), medium (bicyclic) and polycyclic (three or more cyclic). The most important are resins and asphaltenes, which are often called coke-forming components and which create complex technological problems when processing solid waste. Resins - viscous, sedentary liquids or amorphous solids from dark brown to dark brown color with a density of about one or slightly more. They are planar condensed systems containing 5-6 rings of an aromatic, naphthenic and heterocyclic structure, connected through aliphatic structures. Asphaltenes are amorphous, but crystal-like solids of a dark brown or black color with a density slightly greater than unity. When heated, they do not melt, but transform into a plastic state at a temperature of about 300 ° C, and at higher temperatures they decompose with the formation of gaseous and liquid substances and a solid residue - coke. Unlike resins, they form spatial condensed crystal-like structures. The most significant differences between resins and asphaltenes are manifested in such basic indicators as solubility in low molecular weight alkanes, C:H ratio, molecular weight.

Resins form true solutions in oils and fuel distillates, and asphaltenes in HFO are in a colloidal state. The solvent for asphaltenes in oils are aromatic hydrocarbons and resins. Thanks to intermolecular interactions, asphaltenes can form associates - supramolecular structures. The degree of their association is strongly influenced by the environment. Thus, at low concentrations in benzene and naphthalene (less than 2 and 16% by weight, respectively), asphaltenes are in a molecular state. At higher concentrations in the solution, associates consisting of a large number of molecules are formed. It is the ability to form associations that is responsible for the discrepancy of 1-2 orders of magnitude in the results of determining the molecular weight of asphaltenes, depending on the method of its determination.

The structure and properties of asphaltenes significantly depend on the origin of TNO. Thus, asphaltenes from residues of destructive origin are characterized, in comparison with native “loose” asphaltenes, by a lower molecular weight, preferential condensation in the plane, a smaller number and length of aliphatic structures and, therefore, greater compactness (and have lower viscosity).

The ratio of resins to asphaltenes in oils and solid waste varies widely - (7-9):1 in direct distillation residues, to (1-7):1 in oxidized residues (bitumens).

Carbenes and carboids appear in the TNO of thermodestructive processes.

Carbenes are linear polymers of asphaltene molecules with a molecular weight of (100-185) thousand, soluble only in carbon disulfide and quinoline.

Carboids are a cross-linked three-dimensional polymer (crystallite), as a result of which they are insoluble in any of the known organic solvents.

All CABs negatively affect the quality of lubricating oils (deteriorate color, increase carbon formation, reduce lubricity, etc.) and must be removed. As part of petroleum bitumen they have a number of valuable technical properties and give them qualities that allow them to be widely used. Main areas of use: road surfaces, waterproofing materials, in construction, production of roofing products, bitumen-asphaltene varnishes, plastics, pitches, cokes, binders for coal briquetting, powder ion exchangers, etc.

The classification of neutral resinous substances is based on their relationship to various solvents. On this basis, it is customary to distinguish the following groups:

Neutral resins, soluble in light gasoline (petroleum ether), pentane, hexane;

Asphaltenes, insoluble in petroleum ether, but soluble in hot benzene;

Carbenes, partially soluble only in pyridine and carbon disulfide;

Carboids are substances that are practically insoluble in anything.

Resins have a strong coloring ability. The dark color of distillates, like crude oil, is mainly due to the presence of neutral resins in them. Feature neutral resins - their ability to compact into asphaltenes under the influence of factors such as heating, treatment with adsorbents or sulfuric acid. This process occurs especially easily when heated and simultaneously blowing air.

Asphaltenes are the highest molecular weight heteroorganic petroleum compounds. In appearance, asphatenes are powdery substances of brown or black color. Their relative density is above unity, molecular weight is about 2000. In terms of elemental composition, asphaltenes differ from neutral resins in having a lower content of hydrogen and a higher content of carbon and heteroatoms.

All CABs negatively affect the quality of lubricating oils and must be removed. As part of petroleum bitumen, they have a number of valuable technical properties. The main areas of their use: road surfaces, waterproofing materials, production of roofing products, coke.

Neutral resins and asphaltenes are complex mixtures of high molecular weight heteroatomic compounds. They differ in molecular weight, elemental composition and degree of unsaturation. In the general formula (without heteroatoms) C n H 2 n - x, the x value in neutral resins ranges from 10-34, and for asphaltenes it can reach 100-120.

CONCLUSION: When considering the group chemical composition of oil, oil can be roughly divided into two parts of compounds: boiling away at approximately 360 ° C, consisting mainly of hydrocarbons and only a small part of heteroatomic compounds (oxygen - phenols, naphthenic acids; sulfur - mercaptans, sulfides, disulfides , thiophenes; nitrogenous - pyridine bases and imines), and boiling above 360 ​​° C, consisting mainly of heteroatomic compounds containing O, S and N molecules, and to a lesser extent of hydrocarbons (paraffins, hybrid hydrocarbons).

Self-test questions

What is the composition of paraffinic hydrocarbons in petroleum?

What structures are monocyclic naphthenes present in oil?

3. Why are naphthenes desirable components in motor fuels and lubricating oils?

4. What arenes are found in oils?

5. Which oil fractions consist almost entirely of hydrocarbons of mixed structure?

What classes of compounds are oxygen-containing compounds represented in oil?

How is sulfur distributed among oil fractions?

What are petroleum nitrogen compounds?

What are resins?

10. The main directions of use of resin-asphaltene substances.

11. What are asphaltenes in hydrocarbon composition?

Origin of oil

Properties of oil

Physical properties

Average molecular weight

Density

easily th, 0.831-0.860 - average, above 0.860 - heavy.

(usually > factional composition

Crystallization temperature paraffin light fractions

Viscosity factional composition oil and its temperature

Specific heat 1.7-2.1 kJ/(kg∙K).

43.7-46.2 MJ/kg.

2,0-2,5

from to .

Flash point

Chemical composition

General composition

Oil is a mixture of about 1000 individual substances, most of which are liquid hydrocarbons (> 500 substances or usually 80-90% by weight) and heteroatomic organic compounds (4-5%), mainly sulfur (about 250 substances), nitrogenous ( >

Hydrocarbon composition

paraffin naphthenic (10-20, less often 35%) and with mixed

Petroleum Geology

The rocks containing oil have relatively high porosity and sufficient permeability for its extraction. Rocks that allow free movement and accumulation of liquids and gases in them are called reservoirs. The porosity of reservoirs depends on the degree of sorting of grains, their shape and placement, as well as on the presence of cement. Permeability is determined by the size of the pores and their connectivity. The main oil reservoirs are sands, sandstones, conglomerates, dolomites, limestones and other highly permeable rocks embedded among low-permeability rocks such as clays or gypsum. Under favorable conditions, reservoirs can be fractured metamorphic and igneous rocks located in the vicinity of sedimentary oil-bearing rocks.

Various types oil deposits in hydraulically open (1-3) and closed (4-6) traps: 1 - strata dome oil and gas-oil deposits; 2 - massive domed gas-oil deposit; 3 - oil deposit in a protrusion of a paleorelief, primary (for example, a reef) or secondary (erosive); 4 - oil deposit, screened by stratigraphic unconformity; 5 - oil deposit in the trap of primary (facial, lithological) pinchout of the reservoir; 6 - tectonically shielded oil deposit; a - oil; b - gas; c - water.

Often an oil deposit occupies only part of a reservoir and therefore, depending on the nature of porosity and the degree of cementation of the rock (heterogeneity of the deposit), different degrees of oil saturation of its individual sections within the deposit itself are found.

Typically, oil in a deposit is accompanied by water, which limits the deposit down the dip of the layers or along its entire base. In addition, in every oil deposit, along with it there is the so-called. film, or residual water, enveloping rock particles (sands) and pore walls. In the case of pinching out of reservoir rocks or cutting it off by faults, thrusts, etc., disjunctive disturbances, the deposit can either be entirely or partially limited by low-permeability rocks. IN upper parts Oil deposits sometimes contain gas (the so-called “gas cap”).

When extracting oil from wells, it is not possible to completely extract all the oil from the deposit; a significant amount of it remains in the depths earth's crust. For more complete oil extraction, special techniques are used, of which the flooding method (outline, intra-outline, focal) is of great importance. The oil in the deposit is under pressure, as a result of which the opening of the deposit, especially with the first wells, is accompanied by the risk of gas and oil shows (very rarely, oil outbursts).

Several classifications of oil fields and deposits have been proposed both in Russia and abroad. Oil fields differ from each other in the type of structural forms and conditions of their formation. Oil and gas deposits differ from each other in the shape of reservoir traps and in the conditions for the formation of oil accumulations in them.

Oil grades

The introduction of grading is necessary due to the difference in oil composition (sulfur content, different content of alkane groups, the presence of impurities) depending on the field. The standard for prices is WTI and Light Sweet oil (for the Western Hemisphere and generally a reference point for other types of oil), as well as Brent (for the markets of Europe and OPEC countries).

To simplify export, certain standard grades of oil were invented, associated either with the main field or with a group of fields. For Russia, these are heavy Urals and light oil Siberian Light. In the UK - Brent, in Norway - Statfjord, in Iraq - Kirkuk, in the USA - Light Sweet and WTI. It often happens that a country produces two types of oil - light and heavy. For example, in Iran these are Iran Light and Iran Heavy.

Oil refining

The first oil refinery plant was built in Russia in 1745, during the reign of Elizaveta Petrovna, at the Ukhta oil field. In St. Petersburg and Moscow they used candles at that time, and in small towns they used splinters. But even then, unquenchable lamps burned in many churches. They were filled with mountain oil, which was nothing more than a mixture of refined petroleum and vegetable oil.

At the end of the 18th century, the kerosene lamp was invented. With the advent of lamps, the demand for kerosene increased. Oil refining is the removal of undesirable components from petroleum products that negatively affect the performance properties of fuels and oils. Chemical cleaning is carried out by exposing the removed components of the products being purified to various reagents. The simplest method is purification with 92-96% sulfuric acid or oleum, used to remove unsaturated and aromatic hydrocarbons. Physicochemical purification is carried out using solvents that selectively remove undesirable components from the product being purified. Non-polar solvents (propane and butane) are used to remove aromatic hydrocarbons from oil refining residues (tars) (deasphalting process). Polar solvents (phenol, etc.) are used to remove polycyclic aromatic carbons with short side chains, sulfur and nitrogen compounds from oil distillates. During adsorption purification, unsaturated hydrocarbons, resins, acids, etc. are removed from petroleum products. Adsorption purification is carried out by contacting heated air with adsorbents or filtering the product through adsorbent grains. Catalytic purification - hydrogenation in mild conditions, used to remove sulfur and nitrogen compounds.

Application of oil.

Crude oil is practically not used directly (crude oil, along with nerosine, is used for sand protection - securing dune sands from being blown away by the wind during the construction of power lines and pipelines). To obtain technically valuable products from it, mainly motor fuels, solvents, raw materials for chemical industry, it is processed. Oil occupies a leading place in the global fuel and energy balance: its share in total energy consumption is 48%. In the future, this share will decrease due to the increasing use of nuclear and other types of energy, as well as increasing costs and decreasing production.

Due to the rapid development of the chemical and petrochemical industries in the world, the need for oil is increasing not only to increase the production of fuels and oils, but also as a source of valuable raw materials for the production of synthetic rubbers and fibers, plastics, surfactants, detergents, plasticizers, additives, dyes, etc. (more than 8% of world production). Among the starting materials obtained from oil for these industries, the most widely used are: paraffin hydrocarbons - methane, ethane, propane, butanes, pentanes, hexanes, as well as high molecular weight (10-20 carbon atoms per molecule); naphthenic; aromatic hydrocarbons - benzene, toluene, xylenes, ethylbenzene; olefin and diolefin - ethylene, propylene, butadiene; acetylene. Oil is unique precisely because of its combination of qualities: high density energy (thirty percent higher than that of the highest quality coals), oil is easy to transport (compared to gas or coal, for example), and finally, it is easy to obtain a lot of the above-mentioned products from oil. The depletion of oil resources, rising prices and other reasons have led to an intensive search for substitutes for liquid fuels.

Petroleum products are also used in panels solar panels. Solar panels can help homeowners and businesses harness renewable energy such as solar energy, but most panels are still made from petroleum resins and plastic parts from photovoltaic cells. This may soon change as many companies have begun to develop new bio-resins and bioplastics that could replace petroleum-based battery components.

As already mentioned, Russia produces Urals oil, which is obtained by mixing heavy, high-sulfur oil from the Urals and Volga region with light West Siberian oil.

Urals is a grade of high-sulfur oil (sulfur content about 1.3%), which is a mixture of oil produced in the Khanty-Mansiysk Autonomous Okrug and Tatarstan. The main producers of Urals black gold are the organizations Rosneft, Lukoil, Surgutneftegaz, oil company Gazprom Neft, TNK-BP and the Tatneft group. The price of Russian oil is determined by discounting the price of Brent, since Russian oil is considered to be of lower quality due to its high sulfur content, as well as heavy and cyclic hydrocarbons.

Recently in Russian Federation a number of steps have been taken to improve the quality of Urals black gold by eliminating high-sulfur Tatarstan oil from it (in the Republic of Tatarstan it is planned to build new oil refining facilities in order to make gasoline from local oil, rather than putting it into the gas pipeline). West Siberian oil itself is of acceptable quality. Abroad it is known under the brand name Siberian Light.

Urals oil is supplied through Novorossiysk and the Druzhba gas pipeline system.

Siberian Light is a grade of oil (sulfur content about 0.57%) produced in the Khanty-Mansiysk Autonomous Okrug. The main producers of Siberian Light black gold are Rosneft, Lukoil, Surgutneftegaz, Gazprom Neft, TNK-BP.

In the heat supply industry, an oil refining product – fuel oil – has found its application as a fuel for steam boilers, boiler plants and industrial furnaces. Fuel oil, a dark brown liquid product, is the residue after separation of gasoline, kerosene and gas oil fractions from oil or its secondary processing products, boiling up to 350-360°C.

Fuel oil has almost one and a half times higher calorific value compared to the best coals. It takes up little space during combustion and does not produce solid residues when burned. Replacing solid fuels with fuel oil at thermal power plants, factories and in railway and water transport provides huge cost savings and contributes to rapid development main industries and transport.

Conclusion.

Thus, oil is a non-renewable resource. Proven oil reserves amount (as of 2004) to 210 billion tons (1200 billion barrels), undiscovered reserves are estimated at 52-260 billion tons (300-1500 billion barrels). By the beginning of 1973, the world's proven oil reserves were estimated at 100 billion tons (570 billion barrels). Thus, proven reserves have been growing in the past (oil consumption is also growing - over the past 35 years it has grown from 20 to 30 billion barrels per year). However, since 1984, the annual volume of world oil production has exceeded the volume of explored oil reserves.

World oil production in 2006 was about 3.8 billion tons per year, or 30 billion barrels per year. Thus, at the current rate of consumption, proven oil will last for about 40 years, and undiscovered oil will last for another 10-50 years.

Despite the existence of such forecasts, the Russian government plans to increase oil production to 530 million tons per year by 2030. There are also large oil reserves (3,400 billion barrels) in the oil sands of Canada and Venezuela. At the current rate of consumption, this oil will last for 110 years. Currently, companies cannot yet produce much oil from oil sands, but they are developing in this direction.

List of used literature.

1. http://ru.wikipedia.org – description of the properties of oil.

2. http://enc.fxeuroclub.ru – description of oil production.

3. http://omrpublic.iea.org/supplysearch.asp - accurate data on oil production.

4. Vinogradov A.P. Galimov E.M. “Carbon isotopy and the problem of the origin of oil.” - “Geochemistry”. 1970. No. 3

Oil: definition and description.

Petroleum - natural oily flammable liquid, consisting of a complex mixture of hydrocarbons and some other organic compounds. The color of oil is red-brown, sometimes almost black, although sometimes slightly yellow-green and even colorless oil is found; has a specific odor and is common in sedimentary rocks of the Earth. Today, oil is one of the most important minerals for humanity.

Oil is found together with gases at depths from tens of meters to 5-6 km. However, at depths greater than 4.5-5 km, gas and gas-condensate deposits with a small amount of light fractions predominate. The maximum number of oil deposits is located at a depth of 1-3 km. At shallow depths and at natural outcrops on the earth's surface, oil is converted into thick malta, semi-solid asphalt and other formations - for example, tar sands and bitumen.

Origin of oil

Oil formation is a staged, very long (usually 50-350 million years) process that begins in living matter. There are a number of stages:

· Sedimentation - during which the remains of living organisms fall to the bottom of water basins;

· biochemical - processes of compaction, dehydration and biochemical processes under conditions limited access oxygen;

· protocatagenesis - lowering of a layer of organic remains to a depth of 1.5-2 km, with a slow rise in temperature and pressure;

· mesocatagenesis or the main phase of oil formation (MOF) - the lowering of a layer of organic residues to a depth of 3-4 km, with a rise in temperature to 150 °C. In this case, organic substances undergo thermocatalytic destruction, resulting in the formation of bituminous substances that make up the bulk of micro-oil. Next, the oil is distilled off due to the pressure drop and the emigration of micro-oil into sandy reservoir layers, and through them into traps;

· apocatagenesis of kerogen or the main phase of gas formation (MFG) - the lowering of a layer of organic residues to a depth of more than 4.5 km, with a rise in temperature to 180-250 °C. In this case, organic matter loses its oil-generating potential and realizes its methane-generating potential.

I.M. Gubkin also identified the stage of destruction of oil fields.

The history of oil production dates back to the 6th millennium BC. The most ancient crafts are known on the banks of the Euphrates, in Kerch, in the Chinese province of Sichuan. The first method of extraction is the collection of oil from the surface of reservoirs, which was used in Media, Babylonia and Syria before our era.

Properties of oil

Physical properties

Oil is a liquid from light brown (almost colorless) to dark brown (almost black) in color.

Average molecular weight 220-300 g/mol (rarely 450-470).

Density 0.65-1.05 (usually 0.82-0.95) g/cm³.

Oil whose density is below 0.83 is called easily th, 0.831-0.860 - average, above 0.860 - heavy.

The density of oil, like other hydrocarbons, is highly dependent on temperature and pressure. It contains large number different organic substances and is therefore characterized not by boiling point, but boiling point of liquid hydrocarbons(usually >28 °C, rarely ≥100 °C in case of heavy oils) and factional composition- the yield of individual fractions distilled first at atmospheric pressure and then under vacuum within certain temperature limits, usually up to 450-500 °C (~ 80% of the sample volume boils away), less often 560-580 °C (90-95%).

Crystallization temperature from −60 to + 30 °C; depends mainly on the content in oil paraffin(the more it is, the higher the crystallization temperature) and light fractions(the more there are, the lower the temperature).

Viscosity varies widely (from 1.98 to 265.90 mm²/s for various oils produced in Russia), is determined factional composition oil and its temperature(the higher it is and the greater the amount of light fractions, the lower the viscosity), as well as the content resinous-asphaltene substances(the more there are, the higher the viscosity).

Specific heat 1.7-2.1 kJ/(kg∙K).

Specific heat of combustion (lower) 43.7-46.2 MJ/kg.

Permittivity 2,0-2,5

Electrical conductivity [specific] from to .

Oil is a flammable liquid. Flash point from −35 to +121 °C (depending on the fractional composition and the content of dissolved gases in it).

Oil is soluble in organic solvents, under normal conditions it is insoluble in water, but can form stable emulsions with it. In the technology for separating water and salt dissolved in it from oil, dehydration and desalting are carried out.

Chemical composition

General composition

Oil is a mixture of about 1000 individual substances, most of which are liquid hydrocarbons (> 500 substances or usually 80-90% by weight) and heteroatomic organic compounds (4-5%), mainly sulfur (about 250 substances), nitrogenous ( > 30 substances) and oxygen (about 85 substances), as well as organometallic compounds (mainly vanadium and nickel). The remaining components are dissolved hydrocarbon gases (C1-C4, from tenths to 4%), water (from traces to 10%), mineral salts (mainly chlorides, 0.1-4000 mg/l or more), solutions of organic salts acids, etc., mechanical impurities.

Hydrocarbon composition

Mainly present in oil paraffin(usually 30-35, less often 40-50% by volume) and naphthenic(25-75%). To a lesser extent - aromatic compounds(10-20, less often 35%) and with mixed, or hybrid structure (for example, paraffin-naphthenic, naphthenic-aromatic).

Everyone knows what oil and gas are. And at the same time, even experts cannot agree among themselves on how oil deposits are formed. This situation will not seem so strange if you start to get acquainted with the “biography” of this mineral.

IN the best variety coal - anthracite, for example, carbon accounts for 94%. The rest goes to hydrogen, oxygen and some other elements.

Of course, there is practically no pure coal in nature: its seams are always clogged with waste rock, various inclusions and inclusions... But in this case we are not talking about seams or deposits, but only about coal as such.

Oil contains almost the same amount of carbon as coal - about 86%, but more hydrogen - 13% versus 5-6% in coal. But there is very little oxygen in oil - only 0.5%. In addition, it also contains nitrogen, sulfur and other minerals.

Such commonality in elemental composition, of course, could not go unnoticed by scientists. And therefore oil, together with gas, belongs to the same class of rocks as coal (anthracite, stone and brown), peat and shale, namely, to the class of caustobiolites.

This intricate word is made up of three Greek words: kaustikos - burning, bios - life and lithos - stone. Now you can translate it yourself.

This name may not seem entirely accurate. How is it possible to include liquid oil, and even more so natural gas, in the class of stones, even if they are of organic origin, even if they are flammable?...

The remark is quite reasonable. However, you will probably be even more surprised when you learn that experts classify oil as a mineral (although Latin word minera means "ore". Together with gas, it is classified as a combustible mineral. This is how it happened historically, and it is not for you and me to change this classification. Just let's keep in mind that minerals aren't just hard.

Chemically oil is a complex mixture of hydrocarbons, divided into two groups - heavy and light oil. Light oil contains approximately two percent less carbon than heavy oil, but correspondingly more hydrogen and oxygen.

The main part of oils consists of three groups of hydrocarbons - alkanes, naphthenes and arenes.

Alkanes(in the literature you may also come across the names saturated hydrocarbons, saturated hydrocarbons, paraffins) are the most chemically stable. Their general formula is СnH(2n+2). If the number of carbon atoms in a molecule is no more than four, then at atmospheric pressure alkanes will be gaseous. At 5-16 carbon atoms these are liquids, and above them they are solids, paraffins. TO naphthenes include alicyclic hydrocarbons of the composition CnH2n, CnH(2n-2) and CnH(2n-4). Oils contain mainly cyclopentane C5H10, cyclohexane C6H10 and their homologues. And finally, arenas(aromatic hydrocarbons). They are significantly poorer in hydrogen, the carbon/hydrogen ratio in arenes is the highest, much higher than in oil in general. The hydrogen content in oils varies widely, but on average can be taken at the level of 10-12%, while the hydrogen content in benzene is 7.7%. And what can we say about complex polycyclic compounds, in the aromatic rings of which there are many unsaturated carbon-carbon bonds! They form the basis of resins, asphaltenes and other coke precursors, and being extremely unstable, they make life difficult for oil refiners.

Look at how the molecules of pentane C5H10, cyclohexane C6H12 and benzene C6H6 are structured - typical representatives of each of these classes:

In addition to the carbon part, oil contains an asphalt-resin component, porphyrins, sulfur and an ash part.

The asphalt-resinous part is a dark, dense substance that partially dissolves in gasoline. The dissolving part is called asphaltene, and the insoluble part, of course, is called resin.

Porphyrins are special organic compounds containing nitrogen. Many scientists believe that they were once formed from the chlorophyll of plants and the hemoglobin of animals.

There is quite a lot of sulfur in oil - up to 5%, and it causes a lot of trouble for oil workers, causing corrosion of metals.

And finally, the ash part. This is what remains after oil is burned. Ash usually contains compounds of iron, nickel, vanadium and some other substances. We will talk about their use later.

To what has been said, perhaps, we can add that the geological neighbor of oil - natural gas - is also a substance of complex composition. Most of all - up to 95% by volume - in this mixture methane. Ethane, propane, butanes and other alkanes are also present - from C5 and above. A more thorough analysis revealed small amounts of helium in natural gas.

The use of natural gas began a long time ago, but at first it was carried out only in places where it naturally comes to the surface. In Dagestan, Azerbaijan, Iran and other eastern regions, from time immemorial, ritual “eternal fires” burned, and temples flourished next to them at the expense of pilgrims.

Later, cases of the use of natural gas obtained from drilled wells or wells and pits constructed for various purposes were noted. Back in the first millennium AD, the Ziliutsin gas field was discovered while drilling wells for salt in the Chinese province of Sichuan. Practical people from Sichuan soon learned to use this gas to evaporate salt from brine. Here is an example of a typical energy application.

For many centuries, people have used such gifts of nature, but these cases cannot be called industrial development. Only in the mid-19th century did natural gas become a technological fuel, and one of the first examples was glass production, organized on the basis of the Dagestan Ogni deposit. By the way, currently more than 60% of glass production is based on the use of natural gas as a technological fuel.

Generally speaking, the advantages of gas fuel have become obvious quite a long time ago, perhaps since the advent of industrial processes for the thermal (without access of air) destruction of solid fuels. The development of metallurgy led to the replacement of primitive tar mills with coke ovens. Coke gas quickly found domestic use - gas horns appeared for lighting streets and premises. In 1798, gas lighting was installed in England for the main building of James Watt's manufactory, and in 1804 the first gas lighting society was formed. In 1818, gas lamps illuminated Paris. And very soon coking began to be used to produce not so much metallurgical coke, but first lighting and then household gas. Gasification of everyday life has become synonymous with progress, fuel gasification processes have been improved, and the resulting gas has become increasingly called “city gas.”

It is interesting to note that the improvement of pyrogenetic technology followed the path of more complete use of fuel potential. During dry distillation such as coking, no more than 30-40% of the fuel heat is transferred into gas. With oxidative gasification with the addition of oxygen, air, and water vapor, it is possible to convert up to 70-80% or more of the potential heat into gas. In practice, during gasification of solid fuel, no organic compounds remain in the ash residue.

However, the gas produced by oxidative gasification has a lower calorific value than gas produced by coking. Therefore, in the production of city gas, coking processes were combined with gasification processes. Subsequently, already in the 20th century, it became possible to increase the calorific value of household gas by including in the gasification scheme the operation of catalytic methanation - the conversion of part of the carbon monoxide and hydrogen contained in the oxidative gasification gas into methane. Thus, it was possible to achieve the heat of combustion of the resulting household gas required for normal operation of the burners of at least 16.8 MJ/m3 (4000 kcal/m3).

So, gas replaced other types of fuel, first for lighting, then for cooking and heating homes. But for almost a century, almost only artificial gas obtained from solid fuels was used for these purposes. What about natural gas?

The fact is that they began to seriously search for and develop natural gas deposits in the 20s of the 20th century. And only in the 30s, drilling technology to great depths (up to 3000 meters or more) made it possible to provide a reliable raw material base for the gas industry.

The development of the new industry was hindered by the Second World War. Nevertheless, already in 1944, survey work began on laying the first industrial gas pipeline Saratov-Moscow. This was the first-born, followed in the 50s by Dashava-Kyiv and Shebelinka-Moscow. In the following decades, the entire USSR was crossed by powerful routes through which huge quantities of natural gas are currently transmitted. That is why gas is gradually becoming the number one energy carrier for municipal needs and industrial power plants. The share of natural gas has exceeded 60 percent in the energy sector for the production of cement, glass, ceramics, and other building materials, approaches 50% in metallurgy and mechanical engineering. The use of natural gas in stationary power plants allows, taking into account the reduction in consumption for the own needs of power plants, to increase their efficiency by 6-7%, and increase productivity by 30% or more.