Theories of Oil and Gas Origin

I norganic theory. Early theories postulated an inorganic origin when it became apparent that there were widespread deposits of petroleum throughout the world. Dmitri Mendeleyev (1877), a Russian scientist and the father of the periodic table of elements, reasoned that metallic carbides deep within the Earth reacted with water at high temperatures to form acetylene (C H) which subsequently condensed to form heavier hydrocarbons. This reaction is readily reproduced in the

laboratory. Another inorganic hypothesis was suggested by Sokoloff (1890) who proposed a cosmic origin. His theory was that hydrocarbons precipitated as rain from original nebular matter from which the solar system was formed and then ejected from the earth’s interior onto surface rocks. This theory and others like it are referred to as the extraterrestrial hypothesis.

20th Century variants and a renewed interest to the inorganic mode of origin by others was caused by two discoveries: Existence of carbonaceous chondrites (meteorites) and the discovery that atmospheres containing methane exists for some celestial bodies such as Saturn, Titan, and Jupiter. The only known source for methane is through inorganic reactions.

It has been postulated that the original atmosphere of earth contained methane, ammonia, hydrogen, water vapor; add to this photochemical reactions (due to UV radiation) and the result is the creation of an oily, waxy surface layer that may have been host to a variety of developing pre-biotic compounds including the precursors of life.

There are problems however, with the inorganic hypotheses. First, there is no direct evidence that will show whether the source of the organic material in the chondritic meteorites is the result of a truly inorganic origin or was in an original parent material which was organically created. Similar reasoning applies to other celestial bodies.

Second, there is no field evidence that inorganic processes have occurred in nature, yet there is mounting evidence for an organic origin and third, there should be large amounts of hydrocarbons emitted from volcanoes, congealed magma, and other igneous rocks if an inorganic origin is the primary methodology for the creation of hydrocarbons.

Conclusion: The are unquestioned instances of indigenous magmatic oil but, the occurrences are rare and the volumes of accumulated oil (pools) are infinitesimally low. Other problematic issues: commercial accumulations are restricted to sedimentary basins and petroleum seeps and accumulations are absent from igneous and metamorphic rocks. Gas chromatography can fingerprint the organic matter in shales to that found in the adjacent pool. Thus current theory holds that most petroleum is formed by the thermal maturation of organic matter − An Organic Origin generated the vast reserves (pools) of oil and gas.

Organic Hypothesis: There are a number of compelling reasons that support an organic development hypothesis. First and foremost, is the carbon-hydrogen-organic matter connection.

Carbon and Hydrogen are the primary constituents of organic material, both plant and animal. Moreover, carbon, hydrogen, and hydrocarbons are continually produced by the life processes of plants and animals. A major breakthrough occurred when it was discovered that hydrocarbons and related compounds occur in many living organisms and are deposited in the sediments with little or no change.

Second were observations dealing with the chemical characteristics of petroleum reservoirs. Nitrogen and porphyrins (chlorophyll derivatives in plants, blood derivatives in animals) are found in all organic matter; they are also found in many petroleums. Presence of porphyrins also mean that conditions must have developed early in the formation process because porphyrins are easily and rapidly oxidized and decompose under conditions. Additionally, low Oxygen content also implies a reducing environment.

Thus there is a high probability that petroleum originates within an anaerobic and reducing environment.

Third were observations dealing with the physical characteristics. Nearly all petroleum occurs in sediments that are primarily of marine origin. Petroleum contained in non-marine sediments probably migrated into these areas from marine source materials located nearby.

Furthermore, temperatures in the deeper petroleum reservoirs seldom exceed 300 oF (141 oC). But temperatures never exceeded 392oF (200oC) where porphyrins are present because they are destroyed above this temperature. Therefore the origin of petroleum is most likely a low-temperature phenomenon.

Finally, time requirements may be less than 1MM years; this is based on more recent oil discoveries in sediments.

However, physical conditions on the Earth may have been different in the geologic past and therefore it may have taken considerably more time to develop liquid petroleum.

Organic Hypothesis − Summary. The organic theory became the accepted theory about the turn of the century as the oil and gas industry began to fully develop and geologists were exploring for new deposits. Simply stated, the organic theory holds that the carbon and hydrogen necessary for the formation of oil and gas were derived from early marine life forms living on the Earth during the geologic past − primarily marine plankton. The ocean contains an abundance of them and over 95% of living matter in the ocean is plankton. The Sun’s energy provides energy for all living things including plankton and other forms of marine life. As these early life forms died, their remains were captured by the processes of erosion and sedimentation. Successive layers of organic-rich mud and silt covered preceding layers of organic rich sediments and over time created layers on the sea floor rich in the fossil remains of previous life. Thermal maturation processes (decay, heat, pressure) slowly converted the organic matter into oil and gas.

Add additional geologic time (millions of years) and the organic rich sediments were converted into layers of rocks. Add more geologic time and the layers were deformed, buckled, broken, and uplifted; the liquid petroleum flowed upward through porous rock until it became trapped and could flow no further forming the oil and gas that we explore for at present. But the chemistry of the hydrocarbons found in the end product (oil, gas) differ somewhat from those we find in living things. Thus transformation takes place between the deposition of the organic remains and the creation of the end product. Therefore, the basic formula for the creation of petroleum (oil, gas) is: Petroleum End Product = ([Raw Material + Accumulation + Transformation + Migration] + Geologic Time).

Грамматика: aртикли

Артикль в английском предложении никогда не употребляется самостоятельно. Его роль артикля в английском предложении очень велика, несмотря на существование точки зрения, что артикли не оказывают на восприятие речи почти никакого влияния. Часто неправильное применение артикля может сильно исказить смысл предложения. Если сказать, например: My father is the engineer, то англичанин может подумать, что ваш отец является единственным инженером во всей округе. Артикль никогда не употребляется, если перед существительным есть местоимение.

A, an − the Indefinite Article − неопределенный артикль

- нулевой артикль, его отсутствие;

The − the Definite Article − определенный артикль.

Разделим все существительные на нарицательные и собственные. Соответственно, нарицательные существительные разделим на исчисляемые и неисчисляемые.

Применение артиклей с исчисляемыми существительными:

1) в качестве существительного в предложении имеется конкретный предмет или понятие, хорошо известные собеседнику. В этом случае применяется артикль the:

- Ann, press the button on the fax (единственное число);

- The workers have left the tools lying around (множественное число);

2) в предложении необходимо впервые назвать предмет, понятие, которые до этого в разговоре не затрагивались. Тогда для единственного числа применяется А, а для множественного числа - определители some, any:

- He bought a book yesterday;

- He bought some books yesterday.

3) предмет в предложении назван вторично: A man was calling you - the man told he’ll call later;

4) описательные. Артикль А или отсутствует (заменяется на определяющие слова):

- Such: Our project manager asked where I had heard such a term.

- All: All engineers are busy checking the drawings;

5) количественные числительные: that morning i found three letters in the mail box;

6) субстантированные прилагательные: the rich, the blind, the unknown;

7) единственные в своем роде предметы и понятия: the sun, the ground;

8) понятия: the present, the west, the radio.

Применение артиклей с неисчисляемыми существительными. Артикль не употребляется:

1) отвлеченные неисчисляемые существительные (anger, beauty, freedom, time, love, indifference, etc.): Love conquers all.

2) названия веществ: Saudi Arabia is a land of oil and gas.

3) существительные собственные:

- имена людей. The inorganic theory of oil origin was firstly introduced by Mendeleev;

- географические названия. Перед наименованиями океанов, морей, рек, каналов, озер, хребтов, пустынь, групп островов, водопадов ставится артикль the. Перед остальными географическими названиями артикль не ставится, но есть исключения: the Ukraine, the Argentine, the Congo, the Hague, the Netherlands, the USA, the Antlantic Ocean, the Ural.

9) названия учреждений, газет, объектов. Артикль не ставится перед названиями газет. Он используется перед названиями театров, музеев, банков, партий, гостиниц, кораблей: the Metropolitan Opera, the British Museum, the Tories, the Queen Mary.

Грамматические упражнения

1. Найдите и выделите в тексте определенный и неопределенный артикли.

2. Объясните, почему был выбран неопределенный или определенный артикль, обоснуйте это, используя вышеприведенные правила.

Дополнительный материал