Petroleum is an oily flammable liquid composed by hydrocarbons, which is found naturally beneath the Earth's surface by drilling wells, and it is usually called crude oil. The color of petroleum can be colorless, which is usually for gasoline, and heavy black which is high in asphalt content. It consists of a mixture of hydrocarbons, with traces of various nitrogenous and sulfurous compounds. 50-90% of petroleum is hydrocarbons and the remaining is composed chiefly of …showed first 75 words of 528 total…

…showed last 75 words of 528 total…from a new well will come to the surface under its own pressure. Later the crude oil must be pumped out or forced to the surface by injecting water, gas, or air into the deposits. The widespread use of petroleum has created serious environmental problems. The great quantities that are burned as fuels generate most of the air pollution in industrialized countries, and oil spilled from tankers and offshore wells has polluted oceans and coastlines.