Crude oil

Crude oil is a good resource of transportation such as the land, sea, and air transport and these types of transportation usually rely on products refined from crude oil. As a result, refineries transform around 80% of crude oil into transportation fuels. Moreover, crude oil is a central part of modern life and the world’s most important energy resources which is utilized to heat houses, commercial buildings, electricity generation, and also in the industry of medicines, cleaning products, waxes, plastics, artificial rubber, and asphalt. Respectively, the manufacturing of crude oil supplies hundreds of jobs in many different fields such as exploration, production, transportation, refining, and marketing. Besides, it cooperates with various research and technological development.

The origin of crude oil was the topic of much discussion, but it is currently acceptable that it is originally organic and that the raw materials were groups of marine creatures with the plant life deposited in water. Oil is a remnant of those living creatures and plants that have long-lived for in a nautical environment. Over time, the remnants were covered with a layer of clay. The heat and pressure of those layers associated the residue to convert it into crude oil.

Crude oil is essentially a complicated mixture of organic and inorganic materials, providing trace elements which can be gathered into categories of inorganic compounds. The importance of identifying trace elements present in crude oils helps in obtaining more information about exploration, utilization, production, and refining process. Both Hitchon and Filby mentioned that crude oils can be categorized based on the mineral-trace content present in identical litho-stratigraphic circumstances in families. There are problems of marine contamination in various origins in which trace elements can be used to distinguish crude oils, according to an ecological site estimation, these sites contaminated with petroleum are an expansion of pollution. Crude oils are categorized according to trace minerals as a heavy, medium, light, and remnant fraction


  • Refining light crude oil requires a lower expense compared to heavy crude oil due to the low level of mineral content, adding hydrogen H or product waste because of the carbon C rejection may result in higher costs.


Alkanes, cycloalkanes, aromatic compounds, and a few other organic compounds that contain Sulfur, Oxygen, and Nitrogen are the main components of crude oils. Furthermore, the following minerals (Iron, Nickle, Copper, and Vanadium) are present in the crude oil at a minimum quantity. The ratio of the chemical elements of the crude oils is somewhat similar but the molecular components vary from each other. Crude oils range in color from a light color to dark one, and in intensity from liquid form to bitumen such as solid materials. Crude oils contain Carbon around 84 % to 87.4 %, Hydrogen about 10.9 % to 13.8 %, Sulfur from 0.05 % to 6.89 %, Oxygen 0.078 % to 1.80 %, Nitrogen 0.03 % to 1.20 %, metals, salts and others around 0.001 % to 0.15 %.

History of Crude Oil

Crude oils have been recognized for a long-term ago. Crude oil was reported by archeologists who have been using and extracting for almost 5,000 years before the era of Christ, the Kerch and Ephrata shore in China’s Sichuan province are among the oldest known oil wells. Several centuries ago, crude oil had some civilian works and also a few applications for medical purposes. For instance, many prescriptions for medicines that involved petroleum has been illustrated by the Greek scientist Hippocrates. In one of the old manuscripts has written “patients should be rubbed with oil so that the disease is eliminated. White oil eliminates cough disease. Black oil removes the logic of coughing.

In addition, the ancient Egyptians used crude oil for many medical goals, supposedly as like as a covering of a wound, laxative, and ointment. After many centuries, crude oil in Peru, Cuba, Bolivia, and Mexico has been discovered by Spanish explorers. The demand for cheaper and appropriate energy sources increased due to the industrial revolution. Crude oil has been considered an easy way to transfer the energy source. The industrial revolution improved at the beginning of the twentieth century to the point the that industry of oil became the primary resource of energy, broadly due to the appearance of cars. The use of oil as the main energy supplier over the course of time in the history of mankind will be a matter for some centers, however, it will have a deep impact on the global industry.

So far, military service or construction work has been the main field of crude oil use. So it is therefore difficult to assume that what our life would be like without petroleum. Crude oil is utilized as lubrication for a different part of the machinery, and it also brings energy and heat to our homes and our machines. A barely modern device would work without depending on different crude oil products. The actual production of petroleum may have started on August 25, 1860, as the first 22-meter-deep industrial crude oil was opened in Oil Creek, Pennsylvania. Despite that, crude oil can be dated back over 2,000 years. Subsequently, there was the beginning of quick progress in the production and processing of crude oil. A few years later, NCBN was launched by a Swedish businessman named Alfred B. Noble simultaneously with his brothers. The naphtha Co. transported the crude oil extracted in Baku, Russia to refineries through the pipelines. In recent years, significant progress has been made in the production of crude oil and reserves all over the world. As shown in Figure 1.1. Production of crude oil all over the world 2018, source: U.S. Energy Information Administration the production of crude oil worldwide in 2018.

Production of crude oil all over the world

Historically and at the current time, Iraq occupies a significant site in improving policy and economical orientation of the global oil market. The confirmed reservoirs of Iraqi oil amounting to 116 billion barrels-and maybe to some extend overvalued while Saddam Hussein ruled-are in between the biggest in the world. The kingdom of Saudi Arabia is the first resource base in the world, and the second-largest base is Iraq, moreover, the important component in determining international oil supplies and pricing has been Iraq’s policy of exporting for more than 30 years.

The current crude oil production in Iraq is about 2.50 percent of total global oil resources or 2.00 million bpd. The third-largest crude oil production in the world after Saudi Arabia and Iran is Iraq, whose crude oil reached 4 million bpd in 1979. Before the battle between Iraq and Kuwait in 1990, the production of crude oil was approximately 3.400 million bpd, started to descend in the nineties century as a result of the Gulf War and putting international sanctions on Bagdad. In 2003, as the U.S.A. military moved into Iraq, the capacity of oil production in Iraq was evaluated about 2.40 -2.60 million barrels per day. Average production was significantly lower than average in the latest years, reaching 1.50 million barrels per day in 2003, 2.0 million barrels per day in 2004, and in 2005 it has reached 1.80 million barrels per day. As shown in Figure 1.3. Production of crude oil in Iraq from 1993 to 2005. At the beginning of 2006, average oil production rates in Iraq were about 2.060 million barrels per day, which is much lower than the expected goal of the Iraqi government at 2.50 million barrels per day for 2006. Nevertheless, the Iraqi government was capable to achieve its budget profit goals because the oil prices were higher than expected.

Production of crude oil in Iraq from 1993 to 2005

Classification of Crude Oil

Crude oil is a complicated mixture consisting of different hydrocarbons such as (paraffinic, naphthenic, olefinic, and aromatic compounds) that combine with changeable quantities of organic sulfur substances and a quite minimal amount of nitrogenous materials and oxygen. The most important saturated hydrocarbons contain only carbon-carbon single bonds in crude oil known as paraffines or (alkanes) which is named methane chain. The boiling point of paraffin is approximately between 40-200 °C which makes this compound liquid at room temperature. The most significant constituents of the production of refined liquids are naphthenes or (cycloalkanes), which are saturated cyclic hydrocarbon compounds. Unsaturated hydrocarbon compounds contain carbon-carbon multiple bonds (double, triple, or both). These are unsaturated because they contain fewer hydrogens per carbon than paraffines. Unsaturated hydrocarbons are known as olefins. Those that contain carbon-carbon double bonds are called alkenes, while those that contain carbon-carbon triple bonds are known as alkynes. Moreover, the aromatics are generally unsaturated closed-loop chain, which makes up a tiny portion of all the oil raw materials. Consequently, Benzene is an almost common aromatic compound that exists in most crude oils.

Most of the crude oil contains approximately 84.0% to 87.4% C, and 10.9% to 13.8% H therefore crude oils mostly rely on Carbon and Hydrogen. There are a few other elements present with a tiny portion of crude oil such as Sulfur, Oxygen, and Nitrogen. The presence of sulfur in crude oil is approximately less than 6.0%, and as a result, sulfur is measured as the third most available component of crude oil after Carbon and Hydrogen. In general, a high amount of Sulfur in crude oil means a high specific gravity that leads to heavy crude oil. The other elements, such as Oxygen exist in most crude oils commonly not more than 2.0% (found in organic compounds such as carbon dioxide, phenols, ketones, and carboxylic acids) occurring in crude oils in different quantities. Subsequently, crude oils contain very low amounts of Nitrogen compounds, not more than 1.0%. The Nitrogen compounds in crude oils might be categorized as basic or non-basic. Basic Nitrogen compounds contain pyridines, and the non-basic Nitrogen compounds are a greater part of nitrogen in crude oils that usually content of pyrrole types. In addition, small amounts of metals such as Vanadium, Nickel, Iron, and Copper are also present in crude oil  as shown in Table 1.2.

Table 1.2. The chemical composition of some elements present in most of the crude oils.

Elements Composition (wt%)
Carbon (84.0-87.4)%
Hydrogen (10.9-13.8)%
Sulfur (0.053-6.0)%
Oxygen (0.06-2.0)%
Nitrogen (0.03-1.0)%
V, Ni, Cu and Fe (0.1-2000) ppm

Crude oils have many properties. How crude oil is categorized hugely relies on how the classification is used. The characterization of oils can be slightly beneficial depending on their geographical exporter. The crude oils are categorized into 7 categories by Carpatica Classification based on the percentage of paraffines, naphthenes, and aromatic compounds. These categories are divided into 12 groups specified by the content of wax, asphalt, and resin compound and sulfur content.


According to the Environmental Protection Agency (EPA) crude oil can be classified into 4 classes:

  1. First class, light volatile oil, this category is poisonous to humans and many other forms of life, therefore most of the light crude oil products are involved in this category.
  2. Second class, non-viscous oil, contains medium-to-heavy paraffin-based oil and less poisonous than the first class.
  3. Third class, viscous and heavy oil, low toxicity, and also contains medium-to-heavy crude oil with the remaining fuel.
  4. Fourth class, non-liquid oil, is comparatively non-toxic and contains heavy crude oils, weathering oils, a few paraffin oils, and the remaining oils.


Another classification of crude oil is based on the level of Sulfur contents; crude oil is categorized as (sour or sweet). The high sulfur concentration in crude oil is referred to as high sulfur or “sour”. While the low concentration of sulfur in crude oil is referred to as low sulfur or “sweet”. The sweet crude oil is usually more required and desirable than the sour crude oil due to the high amount of Sulfur in sour oils which can be considered hard to refine, undesirable, unsafe for extraction, and difficult for transportation compared to sweet crude oil. Since sulfur is high in sour crude oil, it needs more refining, which includes both financial and environmental costs.

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