The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by oil tankers and pipelines), and marketing petroleum products. The largest volume products of the industry are fuel oil and gasoline (petrol). Petroleum is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, and plastics. The industry is usually divided into three major components: upstream, midstream and downstream. Midstream operations are usually included in the downstream category.

Petroleum is vital to many industries, and is of importance to the maintenance of industrialized civilization itself, and thus is a critical concern to many nations. Oil accounts for a large percentage of the world’s energy consumption, ranging from a low of 32% for Europe and Asia, up to a high of 53% for the Middle East. Other geographic regions’ consumption patterns are as follows: South and Central America (44%), Africa (41%), and North America (40%). The world at large consumes 30 billion barrels (4.8 km³) of oil per year, and the top oil consumers largely consist of developed nations. In fact, 24% of the oil consumed in 2004 went to the United States alone.[1] The production, distribution, refining, and retailing of petroleum taken as a whole represent the single largest industry in terms of dollar value on earth.

Natural history
Petroleum is a naturally occurring liquid found in rock formations. It consists of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds. It is generally accepted that oil, like other fossil fuels, formed from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth's crust over hundreds of millions of years. Over time, the decayed residue was covered by layers of mud and silt, sinking further down into the Earth’s crust and preserved there between hot and pressured layers, gradually transforming into oil reservoirs.

Modern history
 
Galician oil wellsImperial Russia produced 3,500 tons of oil in 1825 and doubled its output by the mid-century.[5] After the oil drilling began in what is now Azerbaijan in 1848, two large pipelines were built in the Russian Empire: the 833 km long pipeline to transport oil from the Caspian to the Black Sea port of Batumi (Baku-Batumi pipeline) and the 162 km long pipeline to carry oil from Chechnya to the Caspian.

At the turn of the 20th century, Imperial Russia's output of oil, almost entirely from the Apsheron Peninsula, accounted for half of the world's production and dominated international markets.[6] Nearly 200 small refineries operated in the suburbs of Baku by 1884.[7] As a side effect of these early developments, the Apsheron Peninsula emerged as the world's "oldest legacy of oil pollution and environmental negligence"[8] In 1878 Ludvig Nobel and his Branobel company "revolutionized oil transport" by commissioning the first oil tanker and launching it on the Caspian Sea.

The first modern oil refineries were set up by Ignacy Łukasiewicz near Jasło, Poland in the years 1854-56..[9] They were initially small as there was limited demand for refined fuel. They produced oil for artificial asphalt, machine oil and lubricants, in addition to Łukasiewicz's kerosene lamp. As kerosene lamps gained popularity, the refining industry grew in the area. The first large oil refinery opened at Ploieşti, Romania in 1856. The first oil drilling in the United States began in 1859, when oil was successfully drilled in Titusville, Pennsylvania. In the first quarter of the 20th century the United States overtook Russia as the world's largest oil producer. By the 1920s, oil fields had been established in many countries including Canada, Poland, Sweden, the Ukraine, the United States, and Venezuela.
In 1938, the Superior Oil company constructed the first offshore oil platform off the Gulf Coast of Louisiana.

 

Corporations
During the 1960s, multinationals such as Mobil, BP, and Shell had access to more than 80 percent of global oil and natural gas reserves. Western multinationals control just 10 percent of the world's oil, while state-run firms exercise exclusive control over roughly 77 percent, according to a November 2007 paper from Rice University's James Baker Institute