Download Chapter Two Origin of Crude oil The main origin of crude oil is still

Chapter Two
Origin of Crude oil
The main origin of crude oil is still unknown, the first theories
about the origin of crude oil referred to non-organic origin as raw
resources for the formation of oil, but the recent theories assume
the organic resources as raw resource of oil. And most scientists
agreed on that, but still the processes that are applied on those
organic resources a controversial point. Generally, when we study
the formation of oil origin, we have to read conditions called
geological wall and they are:1- Oil exists in sedimentary rocks that are accumulated in water
ocean
2- Oil is a mixture of very complex hydrocarbonic resources
because of the variety of resources that form it or the variety of
natural conditions that help forming it.
3- Oil is usually existed in rocks that are formed in geological ages
between (pecandren – pelsteren) before about (13-600) million
years
4-usually, temperature is not more than 100%.
5- Oil is formed in a medium that the proportion of oxygen
decreases in.
6- When oil is found its pressure is between (14.7 – 10000 psi).
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7- The time of oil formation, moving, and accumulation is one
million year approximately.
The non-organic theories assume that there are chemical reaction
among water CO2 and other organic materials like carbides and
carbonates in the underground. Although oil can be prepared in
laboratory by some non-organic reactions, geological proofs refer
to the lack of these materials in nature. Oil is formed in
(big
oil accumulations)
But organic theories refers to that oil may be formed by the
decomposition of organic materials that were parts of the
composition of animals bodies that lived in geological ages.
Classification of Crude Oil
There is no inclusive and satisfying classification. Of the most
known classification is which depends on molecular weight.
1- Classification depends on one of the physical properties of oil
like specific gravity (API) by the standard of the American
petroleum institute and weight by the standard of (Bume). This
classification clarifies what crude oil contains of light and heavy
compounds.
Ex:1- Crude oil of 35 oC
2- Crude oil of 30 oC
API= sp.Gr=0.85
API= sp.Gr=0.85
Oil unit measurement is API according to American petroleum
institute.
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When Sample 1 is distilled, it gives light distilled like Gasoline by
higher proportion than the second type gives.
* API value is inversely relative with specific weight.
2- Classification depends on hydro carbonic composition for crude
oil
Based on this classification, oil crude divided into:A- Paraffin Base
B- Asphalt Base
C- Mixed Base
There is another type of Hybrid Base which contains Naphthenic and
quantity of paraffin candles . This classification is made by taking a sample
from oil to be classified, and is distilled, then the remain of the distillation is
taken and examined if contains less than 20% of paraffins, then it is
Asphalt. If 20% -50% then it is mixed base, if more than 50% is considered
paraffin base. This classification is considered as useful for oil refineries
that it gives real clue about the nature of the oil products and how to refine
crude oil and the difficulties the factory faces.
3- The third classification depends on hydro carbonic composition for two
of crude oil distilled to be classified.
That they both are considered as a guide to the classification like (A)
Kerosene: which is the first guide between ( 275-300) Co in normal air
pressure
(B) Lubricating oil (second guide) between (275 – 300) Co in pressure (40)
ML mercury according to the specific weight (API) for these two distilled of
oil. See table (1-2) P.38
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