Petroleum Industry

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 industrial civilization itself, and thus is a critical concern for many nations. Oil accounts for a large percentage of the world’s energy consumption, ranging from as low of 32% for Europe and Asia, up to a high of 53% for the Middle East.
Other geographic region’s consumption patterns are as follows: South and Central America (44%), Africa (41%), and North America (40%). The world consumes 30 billion barrels (4.8 km³) of oil per year, with developed nations being the largest consumers. The United States consumed 25% of the oil produced in 2007. The production, distribution, refining, and retailing of petroleum taken as a whole represents the world's largest industry in terms of dollar value.
The American Petroleum Institute divides the petroleum industry into five sectors: upstream (exploration, development and production of crude oil or natural gas); downstream (oil tankers, refiners, retailers and consumers); pipeline; marine; service and supply.
Oil companies used to be classified by sales as "supermajors" (BP, Chevron, ExxonMobil, ConocoPhillips, Shell, Eni and Total S.A.), "majors", and "independents" or "jobbers". In recent years however, National Oil Companies (NOC, as opposed to IOC, International Oil Companies) have come to control the rights over the largest oil reserves; by this measure the top ten companies all are NOC.
Some petroleum industry operations have been responsible for pollution through by-products of refining and oil spills. The combustion of fossil fuels produces greenhouse gases and other air pollutants as by-products. Pollutants include nitrogen oxides, sulphur dioxide, volatile organic compounds and heavy metals.
As petroleum is a non-renewable natural resource the industry is faced with an inevitable eventual depletion of the world's oil supply. The BP Statistical Review of World Energy 2007 listed the reserve/production ratio for proven resources worldwide. The study placed the prospective life span of proven reserves in the Middle East at 79.5 years, Latin America at 41.2 years and North America at only 12 years.
The Hubbert peak theory, which introduced the concept of peak oil, questions the sustainability of oil production. It suggests that after a peak in oil production rates, a period of oil depletion will ensue. Since virtually all economic sectors rely heavily on petroleum, peak oil could lead to a partial or complete failure of markets.
According to research by IBISWorld, biofuels (primarily ethanol, but also biodiesel) will continue to supplement petroleum. However output levels are low, and these fuels will not displace local oil production. More than 90% of the ethanol used in the US is blended with gasoline to produce a 10% ethanol mix, lifting the oxygen content of the fuel
Source : http://en.wikipedia.org/wiki/Petroleum_industry

The topic of this article is about petroleum industry.
The main idea of paragraph 1 is “The largest volume products of the industry are fuel oil and gasoline (petrol).” There’s a coherence between the main idea of paragraph 1 and the topic.
The main idea of paragraph 2 is “Petroleum is a critical concern for many nations.” There’s a coherence between the main idea of paragraph 2 and the topic.
The main idea of paragraph 3 is “The production, distribution, refining, and retailing of petroleum taken as a whole represents the world's largest industry in terms of dollar value.” There’s a coherence between the main idea of paragraph 3 and the topic.
The main idea of paragraph 4 is “The American Petroleum Institute divides the petroleum industry into five sectors” There’s a coherence between the main idea of paragraph 4 and the topic.
The main idea of paragraph 5 is “Oil companies used to be classified by sales as ‘supermajors’, ‘majors’, and ‘independents’.” There’s a coherence between the main idea of paragraph 5 and the topic.
The main idea of paragraph 6 is “Some petroleum industry operations have been responsible for pollution.” There’s a coherence between the main idea of paragraph 6 and the topic.
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The main idea of paragraph 8 is “After a peak in oil production rates, a period of oil depletion will ensue” There’s no coherence between the main idea of paragraph 8 and the topic.
The main idea of paragraph 9 is “According to research by IBISWorld, biofuels will continue to supplement petroleum.” There’s no coherence between the main idea of paragraph 9 and the topic.