Oil well
By produced fluid

Natural gas, in a raw form known as associated petroleum gas, is almost always a by-product of producing oil. The short, light-gas carbon chains come out of solution when undergoing pressure reduction from the reservoir to the surface, similar to uncapping a bottle of soda where the carbon dioxide effervesces. If it escapes into the atmosphere intentionally it is known as vented gas, or if unintentionally as fugitive gas.

Unwanted natural gas can be a disposal problem at wells that are developed to produce oil. If there are no pipelines for natural gas near the wellhead it may be of no value to the oil well owner since it cannot reach the consumer markets. Such unwanted gas may then be burned off at the well site in a practice known as production flaring, but due to the energy resource waste and environmental damage concerns this practice is becoming less common.

Often, unwanted (or 'stranded' gas without a market) gas is returned back into the reservoir with an 'injection' well for storage or for re-pressurizing the producing formation. Another solution is to convert the natural gas to a liquid fuel. Gas to liquid (GTL) is a developing technology that converts stranded natural gas into synthetic gasoline, diesel or jet fuel through the Fischer–Tropsch process developed in World War II Germany. Like oil, such dense liquid fuels can be transported using conventional tankers for trucking to refineries or users. Proponents claim GTL fuels burn cleaner than comparable petroleum fuels. Most major international oil companies are in advanced development stages of GTL production, e.g. the 140,000 bbl/d (22,000 m /d) Pearl GTL plant in Qatar, scheduled to come online in 2011. In locations such as the United States with a high natural gas demand, pipelines are usually favored to take the gas from the well site to the end consumer.
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