Oil

We explain what oil is, its origin and how this hydrocarbon is formed. Also, its properties and various uses.

What is oil?

Oil is called a bituminous substance, dark in color and viscous in texture composed of a mixture of organic hydrocarbons insoluble in water, also known as black gold either raw. Its physical properties (color, density) can be diverse, depending on the concentration of hydrocarbons present, which includes the following:

• Paraffins (saturated hydrocarbons).
• Oleifins (ethylene hydrocarbons containing a carbon-carbon double bond).
• Acetylenic hydrocarbons (contain a carbon-carbon triple bond).
• Cyclic or cyclanic hydrocarbons.
• Benzene or aromatic hydrocarbons.
• Oxygenated compounds (derived from ethylene hydrocarbons by oxidation and polymerization).
• Sulphurous compounds.
• Cyclic nitrogenous compounds.
• Dissolved content of nitrogen, sulfur, oxygen, cholesterol, porphyrins and traces of nickel, vanadium, nickel, cobalt and molybdenum.

Given its complex chemical composition, petroleum It is a non-renewable natural resource of enormous economic value. It is used as a raw material for the production of various organic materials (obtained in the petrochemical industry), various solvents and, above all, it is used as a fossil fuel to generate electrical and other types of energy.

For this reason, it is massively extracted from its place of formation: the subsoil. Using extraction facilities known as wells, their deposits (usually close to natural gas deposits) are located in the lower layers of the subsoil, and the liquid is extracted using various techniques, according to the nature of the soil and the geographical layout, which It can be on land, or on the seabed or in rivers, lakes, etc.

Oil marketing is the main economic activity of numerous countries such as Venezuela Saudi Arabia, Russia, Iraq or Iran, most of which organize their crude oil production around the guidelines of the Organization of the Petroleum Exporting Countries (OPEC), founded in 1960 and currently headquartered in Vienna, Austria.

Origin of oil

The oil It is considered a hydrocarbon of fossil origin that is, it is due to the accumulation of large amounts of organic matter millions of years ago, such as zooplankton (plankton of animal origin that feed on processed organic matter) and algae from lacustrine regions (lakes or freshwater reservoirs). ) dried out over the centuries, whose anoxic bottoms (without oxygen) were buried under layers of sediments.

Under these conditions, the pressure and heat would have caused chemical and physical transformation processes (natural cracking) that would produce various substances as products: bitumen, natural gases and other hydrocarbons such as oil.

There is also another theory about its origin, which attributes it to abiogenetic sources (not from organic matter). This theory is not completely ruled out, but it has the support of the minority of scholars on the subject, given that it cannot explain many of the contents present in oil without the prior presence of living beings.

How is oil formed?

The chemical processes of oil formation are quite complex and are linked with geological traps (oil traps), which are subsoil structures conducive to the accumulation of oil, since they keep it trapped and without the possibility of escaping into the pores of a permeable underground rock (repository rock), or other similar structures. This is how oil fields arise.

The process of oil formation is related to the decomposition of organic matter over millions of years. The organic matter will suffer an increase in temperature and pressure due to the layers of sediment deposited on it. This entire process that organic matter undergoes until it becomes oil can be divided into several phases:

• Diagenesis (anaerobic decomposition) At certain depths of the Earth's surface there is not abundant oxygen, which is why anaerobic bacteria decompose organic matter until it is transformed into kerogen (a mixture of organic compounds present in sedimentary rocks).
• Catagenesis (transformation of kerogen into fossil fuels) Kerogen is an intermediate product between organic matter and fossil fuels. Kerogen can come from algae, plankton and woody plants. Due to catagenesis, kerogen can be converted to anthracene and equivalent compounds, or to methane and similar compounds. Thus, at high temperatures it transforms into liquid hydrocarbons and gas.
• Metagenesis It is the process in which gases are formed due to high temperatures.
• Metamorphism They degrade from the hydrocarbons generated in the previous phases.

Oil properties

Oil is a dense, viscous liquid, with colors that tend to be black or yellow (according to its hydrocarbon concentration). with an unpleasant smell (product of sulfates and nitrogen) and with enormous caloric power (11,000 kcalories per kilogram). These properties will vary according to the type of oil we are talking about: paraffin-based (fluid), asphalt-based (viscous) and mixed-based (both).

Uses of oil

Oil is a powerful source of industrial materials, Solvents, fuels, fuels, alcohols and plastics are obtained from it. To do so, crude oil must be subjected to various refining and distillation processes (fractional distillation), in order to separate and extract its ingredients.

Heated progressively from 20ºC to 400ºC, the oil separates into the following phases:

• Natural gas (20 °C). Combustible hydrocarbon gases such as ethane, propane and butane (liquefied petroleum gases), which are used to fuel stoves, lighters, etc.
• Naphtha or ligroin (150 °C) A substance called benzine or petroleum ether, a mixture of very flammable and volatile compounds that is used as a non-polar solvent, or as a base for other organic compounds.
• Gasoline (200 °C) The fuel par excellence for internal combustion engines (such as those in motor vehicles or certain electricity generation plants) varies in range according to its octane (purity) and is one of the most coveted petroleum derivatives.
• Kerosene (300 °C) Also called kerosene, it is a fuel of low purity and low performance, but much more economical than gasoline, used as a solvent, as a base for pesticides and for lamps or rural stoves.
• Diesel (370 °C) Known as diesel, it is a fuel composed of paraffins, ideal for heaters and outboard motors (diesel engines), which are more economical but have much lower performance.
• Fuel oil (400 °C) It is the fuel derived from the heaviest petroleum that can be derived at atmospheric pressure, used to feed boilers, furnaces and as a material to be distilled again, to obtain asphalt, lubricating oils and other substances.