Origin of oil and gas

TÌM HIỂU VỀ MGIOONG GỐC CỦA DẦU MỎ VÀ KHÍ ĐỐT DUNG CHO BỘ MÔN HÓA HỌC DẦU MỎ CÁC PHUONG TRÌNH LIÊN QUAN ĐẾN QUAS TRÌNH TẠO RA VÀ HÌNH THÀNH DẦU MỎ KHÍ ĐỐT

VIETNAM NATIONAL OF UNIVERSITY HANOIHANOI UNIVERSITY OF SCIENCES

FACULTY OF CHEMISTRY

ASSIGNMENT ON:

PETROLEUM CHEMISTRYORIGIN OF OIL AND GAS

Lecturers: Assoc.Prof.Dr Do Van DangStudent: Dinh Thu Tra

Student code: 21001747

Hanoi-2024

ORIGIN OF OIL AND GAS

Researching the origin of oil and gas faces many difficulties, because we cannot directlyobserve the formation of oil and gas On the other hand, due to the special state of oil and gas,when When thermodynamic conditions change, oil and gas also change in both physicalproperties and chemical composition and form new products that are completely different fromthe original material, making it difficult to determine its nature of starting material.

Research on the origin of oil and gas is conducted experimentally in the laboratory, whichincludes preparing oil and oil products and studying geology in the field, geological structure ofoil reservoirs, and chemical mechanisms of oil and gas organic matter transformation processesin modern sediments, from which we can build hypotheses about the mechanism of oilformation.

To solve the problem of the origin of petroleum, one of the most important issues is toexplain the nature of the original material that creates petroleum, whether it is organic orinorganic Therefore, inorganic and organic schools were formed.

I HYPOTHESIS OF INORGANIC ORIGIN (MINERAL ORIGIN)

1 Carbide hypothesis

Mendeleev proposed this hypothesis on the basis of chemical experiments According tohim, the earth's core consists of molten metal (mainly iron), containing metal carbides, such asaluminum carbide (Al4C3), calcium carbide (CaC2)

Inside the earth, when water is applied, the following reaction occurs:3FemCn + 4mH2O → mFe3O4 + C3nH8m

Mendeleev hypothesized that the water participating in the above reaction seeped down fromthe surface along deep faults and tectonic cracks Hydrogen carbides are formed in a gaseousstate and, under the influence of high pressure, will follow cracks to the upper regions of theEarth There they condense and concentrate in rocks to form oil fields.

However, the above hypothesis does not convince geologists because of the following points: -Material inside the earth is in a plastic state, which eliminates cracks, a required condition ofthis hypothesis.

-If there are cracks in the earth, water cannot penetrate because the temperature is too high Another hypothesis similar to the above hypothesis is that the earth's interior contains metalcarbides such as Al4C3, CaC2 These substances are decomposed by water to produce CH4 andC2H2:

Al4C3 + 12H2O → 4Al(OH)3 + 3CH4CaC2 + 2H2O → Ca(OH)2 + C2H2

The above hypothesis is supported by the following experiments In 1866, Berthelotsynthesized aromatic hydrocarbons from acetylene at high temperature with catalysts In 1901,

Sabatier and Sendereus performed the hydrogenation reaction of acetylene on nickel and ironcatalysts at temperatures ranging from 200 to 300oC, obtaining a series of hydrocarbonscorresponding to the composition of oil Along with a series of experiments like the above, thehypothesis of the inorganic origin of oil has been accepted for quite a long time.

However, the above hypothesis is also doubted by the following points:

Using modern methods, people have analyzed that petroleum contains porphyrins of plantand animal origin.

In the earth's crust, the content of metal carbides is negligible.

Hydrocarbons are often found in sedimentary layers, where the temperature rarely exceeds150 ÷ 200oC (because the pressure is very high), so the temperature necessary for the synthesisreaction to occur is not enough.

2 Hypothesis of magma origin

Under conditions of high temperature and pressure, carbon is released from its compounds inthe magma solution In addition to free carbon, free hydrogen also exists in the magma solution.Hydrocarbons are formed by the combination of hydrogen and carbon Initially it can be CH4,then polymerization can create CnHm compounds Depending on the values of n and m, thesecompounds can create gas (small n) or liquid (large n).

II THE HYPOTHESIS OF ORGANIC ORIGIN

1 Theoretical basis

a Biogeochemical basis

The chemical composition of oil and gas includes two elements typical of organic matter:carbon and hydrogen In addition, the composition of petroleum also includes oxygen, nitrogen,sulfur and phosphorus, which are the basic elements that create living matter as well asflammable minerals.

Rare elements in petroleum ash and coal have general distribution rules.

Optical activity is one of the most important evidences of the organic origin theory ofpetroleum The optical activity in petroleum is due to cholesterol - an organic compound ofplant origin Synthetic oils are not optically active.

Through laboratory experiments, it is possible to transform organic matter in the direction ofcreating oil.

b Geological basis

-The majority (99.9%) of oil and gas fields are located in sedimentary rocks.

-The formation of oil and gas fields is closely related to the neo-tectonic movement regime ofthe sedimentary basin as well as paleogeographic conditions.

-In many oil and gas reservoirs, oil-bearing sandstone lenses have been discovered betweenimpermeable rock layers.

-In modern sediments, the transformation of organic materials in the direction of oil formationis observed and their content increases with depth.

2 Theory of organic origin of petroleum

This is the hypothesis about the formation of oil and gas from initial organic materials.Those materials are the remains of marine or terrestrial plants and animals but are washed out tosea by rivers over a long period of time (millions of people) years) are deposited on the seabed.In seawater, there are many types of aerobic and anaerobic organisms, so when plants andanimals die they are immediately decomposed (like albumin, carbohydrates) Bacteria attackfirst, forming substances that are easily soluble in water or gases that fly away Thesesubstances will not create oil and gas On the contrary, substances that are difficult todecompose (such as proteins, fats, alcohols, waxes, etc.) ) will be deposited to form asediment layer on the seabed These are the first organic materials of oil and gas Over millionsof years, these substances will form the initial hydrocarbons

According to author Petrov, plant fatty acids are usually unsaturated fatty acids γ-lactone andthen form naphthenes or aromatics.

These ketones can condense to form hydrocarbons of mixed structure, or into aromatic alkylsubstances

Based on the above process, hydrogen must be present to saturate the olefins to formparaffins And two hypotheses are put forward about the formation of H

-Due to radioactive rays in the ground, H2 is produced This hypothesis is less convincing

-Due to the anaerobic bacteria at the bottom of the sediment, they have the ability to fermentorganic matter to produce H2 Author J.Bell has found 30 types of bacteria capable offermenting organic matter to produce H2 These bacteria are often found in lake water and evenin sediment, which is the source of H2 for the reduction process.

In addition to bacterial factors, many scientists also believe that there are a series of otherfactors such as temperature, pressure, time, presence of catalysts (metals Ni, V, Mo, minerals).clay ) in the sediment layers creates favorable conditions for the reaction to occur.

The theory of organic origin of petroleum allows us to explain many real-life phenomena.For example, petroleum is in almost different places, and the difference may be due to theoriginal organic material For example, :if the original organic material is rich in fat, paraffinicoil can be created….

The original hydrocarbons of oil and gas often have very large molecular weights (C30 C40) or even higher These organic substances located in the sediment layer will undergo manychemical changes under the influence of temperature and pressure pressure, catalyst (clayminerals) It is seen that for every 30m of sinking, the temperature increases from 0.54-1.2ºC.And the pressure increases from 3-7.5at Thus, at a greater depth The temperature and pressureincrease and in the oil and gas sediment layer, the temperature can be up to 100-200ºC and thepressure is from 200-1000at Under such conditions, hydrocarbons have large molecular weight,long chains, and complex structure Impurities will be thermally decomposed to formsubstances with smaller molecular weights, simpler structures, fewer aromatic rings, etc.

Time is also a factor that accelerates the cracking process Therefore, the older the oil is, thedeeper the sinking depth is, and the more hydrocarbon molecules the formed oil contains withthe lower the molecular weight Deeper Moreover, methane is the most stable gas, so it has thehighest concentration That's why when increasing the depth of oil and gas exploration wells,the probability of finding gas is often higher oil leaves.

3 The conversion of organic matter into petroleum

A question that arises is how the components of organic matter participate in the oil creationprocess? There are two basic groups of views:

Some authors believe that during the postmortem transformation of living things, all theircomponents lose their individuality and the general mixture of organic matter turns entirely intopetroleum That is the hypothesis of total conversion to oil This view requires an explanation ofthe source of the large amounts of hydrogen needed to reduce organic matter On the contrary,the concept of converting a part of organic material into oil does not require this organic source,because the part converted into oil already has reducing properties.

The problem of transforming all or part of the original organic materials is related to theproblem of regulating their accumulation.Those who defend the total transformation viewbelieve that there is an accumulation of a large mass of starting material, while those whosupport the partial transformation view believe that petroleum is formed from organic materialdispersed in the sedimentary rock.

According to Xtadnikov, the starting material is mainly high-grade plants, while the forming component is mainly vegetable resins, and secondarily waxes and sometimes licnin.The original material accumulates and completely disappears when oil is formed Theappearance of oil hydrocarbons begins with the petrification phase, with bacterial activity beingthe basis Oil production continues and also ends in the postnatal transformation phase, whenthe primary factor causing hydrogenation of organic matter is the primary phase Thearchitecture of the original organic matter is completely destroyed Favorable for this process ishigh pressure and temperature of about 2000 C The intermediate formation between organicmaterial and oil, according to him, is viscosity (manta) with a multi-ring structure, also knownas "primal oil" ( protopetroleum ).

According to A F Dobrianxki, the original materials were floating organisms, partlyremains of land plants and animals All of this rotten sludge participates in the oil creationprocess, which occurs in the post-production transformation phase under the influence of hightemperature (but not exceeding 150-2500C) and alumosilicate catalyst It is the process ofdestroying carboxyl and hydroxyl The hydrogen required for the reduction of organic matter isobtained during the redistribution of hydrogen among the original organic constituents Thetype of oil originally created was heavy aromatic and then gradually methanized under theinfluence of heat and catalyst The intermediate formations between the starting organicmaterial and heavy oil are oxyasfan and lubricating oil (manta), similar to Xtadnikov's:primaryoil.

According to V B Porfirev and I V Grinberg (1949), organic materials initially accumulatein concentrated form and completely or almost completely form oil The transformation oforganic matter into oil occurs in the post-diagenetic and metamorphic phases The essence ofthis transformation is thermal fracturing at 3000C and pressure above 100 atm, the hydrogensource is bottom sediment water According to him, oil creation in the base zone is impossible,because in this zone the depth of subsidence is not enough to reach the necessary temperature

and pressure Therefore, all oil reservoirs in the basement area are related to the movement ofoil from neighboring geosynclinal areas.

The weakness of these views is the lack of geological basis First of all, large concentrationsof plant remains, although common, due to the conditions of accumulation, cannot preserve thelight hydrocarbons that make up the oil The idea that the oil creation temperature is about3000C contradicts some components of oil that are unstable at high temperatures, such asporfirin On the other hand, their opinions about the hydrogen source needed for the reduction(hydrogenation) reaction are completely artificial.

The second direction is supported by geologists According to this view, only the mostreduced fractions of organic matter in dispersed form participate in the oil formation process.These are lipids (fats), lipoids (wax, sterin, fotfotite ), they are soluble in organic solvents.Organic matter dissolved in organic solvents today is called “bitumen”.

If the content of “bitumen”-containing components is insignificant in organic matter, theneven the largest concentrations of plant remains can yield only a negligible amount ofpetroleum Meanwhile, many oil reservoirs in the world contain huge amounts of oil Therefore,I M Gubkin's view of "oil generation" or "stinking mud theory" was formed.

The basic sources of hydrocarbons that enter the composition of petroleum can be asfollows:

- The most recent research projects have proven that in many living organisms, hydrocarbonsof the oil series exist quite widely These discoveries allow us to hypothesize that hydrocarbidescontained in living matter were transferred directly into the sediment Modern marine sedimentresearch has proven the realism of this view P Smith (1965) observed in the present mud liquidhydrocarbons (of all three series: methane, naften and aromatic), which dating according toradioactive C14 content proved that these hydrocarbons were of the same age as surrounded bymud Research by V V Veber and A I Gorxki also confirmed that the hydrocarbons in bitumenof modern sediments are partly transferred directly from the remains of dead organisms andpartly are newly formed formations due to the living activities of living organisms.microorganism.

- Some new hydrocarbides are formed from materials other than hydrocarbide, under theinfluence of microorganisms The significance of this source is little studied.

- New hydrocarbides are formed from materials other than hydrocarbide or from pre-existinghydrocarbides whose structure is changed under the influence of high temperature, with theparticipation of catalysts In fact, no one denies this source, but some authors evaluate its roletoo highly There needs to be more complete research on this source, especially research undernatural conditions.

*Organic matter conservation factor:

When these products reach the bottom, they will create a reducing environment and they arenot destroyed by bottom-dwelling animals, so people often pay attention to environments withmany floating organisms and few bottom-dwelling organisms

Organisms are rapidly buried with large sediment loads and have conditions that promoterapid compaction and submergence of those sediments, subjecting them to the highertemperatures found in coastal environments, not very deep From there, people can imagine theoil-producing environment.

Crude oil itself has good solubility when lying in source rock, but when transferred to rockcontaining crude oil, the composition and chemical formula will change and it will not besoluble This proves that some precursors of petroleum such as fatty acids and alcohols aremore soluble in water than the hydrocarbons produced from them.

Table: Solubility of paraffins, acids and alcohol

During the oil and gas generation process: the formation of microscopic cracks is limited tovery large depths, corresponding to the period of strong oil generation when organic matterpresent in large quantities in the source rock has been transformed into petroleum components.

III CONTROLLING FACTORS

CO2 + 4H2 → CH4 + 2H2OSO4 + 4H2 = H2S + 3H2O + Base

R – COOH1070022003R - OH2600056001800

This reaction occurs easily thanks to the presence of a catalyst Changes in organic matter insediments.

Scientists give a problem: after one hour, the next generation of an individual bacteria cancreate 40,000 petroleum This cannot exist because bacteria destroy hydrocarbons Also due tothe disinfectant effect of sea water and the amount of organic matter present But on thecontrary, bacterial growth is extremely fast Bacteria have 3 roles:

-Creates favorable conditions for the development of the reducing environment radius.

-Creates a significant amount of organic matter that produces hydrocarbons within their cells.-Provides part of the energy needed for the synthesis of hydrocarbon molecules.

3 Radioactive elements

Radioactivity is an important factor in the formation of petroleum; some shales contain moreor less radioactive uranium, tobium and kalium compounds On the other hand, fatty acids arebombarded by particles, producing a petroleum-like liquid But today radioactivity cannotproduce hydrocarbons on a large scale, but only produces less than 1% of new sediment byweight.

The hydrocarbons formed during rock formation and especially immediately after depositionin the upper layer of mud under the action of bacteria whose proliferation can be an importantsource of organic and hydrocarbon sources The following processes take place duringcompaction where the gradual increase in temperature will gradually increase the conversionprocess.

It was found that many of the basins contained oil and that the richest basins were locatedadjacent to the existing sedimentary basins These basins show succession in space and time.Oceanographic and sedimentological research gives us a better understanding of the landscapeand sedimentary mechanisms of the new basin One can summarize the sedimentaryenvironment as a predominantly quiet water bath There is rapid burial of sedimentarymaterials, allowing good preservation of organic materials.

Areas with these conditions are: bays, bays, and estuaries This is where the main organicmaterials are deposited and will create cellulose debris This will be the origin of natural gasreservoirs.

Low-lying areas and more or less deep basins typically have a quiet environment far fromwater sources and there will sediment quite quickly to fill up organic matter Finally, at the baseof the continental slope, continental sediments will slide and pile up on top of each other in theform of mudflows that can form important hydrocarbon basins.

IV CURRENT OIL ORIGIN ISSUES

Although there are still many unclear and debated issues, the issue of the origin of oil hasbeen basically resolved Today, the organic origin of most oil and gas accumulations is beyonddoubt The ability to convert matter and its various components into oil has been demonstrated.It has been established that the transformation of organic matter into oil can occur in different

ways, when suitable conditions are created for each of them It is necessary to quantitativelyevaluate these transformation processes and clearly explain the role and meaning of the factorscausing change in specific geological conditions If the process of converting organic matterinto oil has been resolved to a large extent, the migration processes (especially primarymigration) of oil still have many problems that must be further researched and resolved It canbe said that in petroleum geology, this is also the field with the most unclear issues.

V REFERENCE