Petroleum, also known as "crude" or "crude oil", is a complex mixture of liquid hydrocarbons, composed mainly of carbon and hydrogen; with small amounts of nitrogen, oxygen and sulfur, formed by the decomposition and transformation of remains of animals and plants that have been buried at great depths for several centuries.

SOURCE: https://www.google.co.ve/search?q=PETROLEO&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiDtdL_qo_ZAhVDi1kKHU1NAPYQ_AUICigB&biw=1366&bih=637#imgrc=S5pxGwlepZOXTM:

It is a natural non-renewable resource of generally liquid and thick consistency, have colors ranging from pale yellow, brown with greenish reflections, to dark black and even there are some colorless; it is insoluble in water, that is, it is not mixed with water, have a strong smell similar to kerosene and gasoline and it is very flammable, that is, it is easily ignited. For this reason, it is an excellent fuel.

For petroleum to be suitable for use, it is necessary to treat it by applying different processes among them: exploration, drilling, extraction and refining.

SOURCE: https://www.google.co.ve/search?q=exploration,+drilling,+extraction+and+refining+of+petroleum&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjHv_fjrI_ZAhURqlkKHVdMBkQQ_AUICigB&biw=1366&bih=588#imgrc=mU9Om4GWSHMfMM:

The exploration and location of oil consists of the search of oil wells with mechanical, seismic, acoustic and chemical techniques to proceed to the drilling of the well with large steel drills and subsequent to the extraction that is the obtaining of the petroleum by natural fluidity to pressure, or by techniques of mechanical pumping. After this, the oil is transferred through pipes and tankers to a treatment and refining plant where the components of the oil are separated and their derivatives are obtained.

Very important derivatives like natural gas, gasoline, kerosene, diesel, lubricating oils, asphalt, fertilizers, detergents, paints, alcohol and hundreds of other products are extracted from the oil.

Today oil is the most important non-renewable natural resource for society because it needs it to meet many of its energy needs.

However, the world availability of this matter has declined in recent years, and its relative cost has increased. According to experts, they estimate the probability that the crude supply will only reach the first decades of the 21st century.

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