About 85% of natural gas produced from conventional wells is methane, a highly flammable compound made up of one carbon atom and four hydrogen atoms. It is colourless and, in its pure form, odourless. As the gas has no odour, gas companies often add a chemical to the gas to give it a distinctive smell so that gas leaks may be detected by smell.
The units of measurement used for natural gas are generally based on volume and measured in cubic feet (a cubic foot being one foot long, by one foot wide, by one foot deep). This volume is usually expressed in BCF (billion cubic feet), TCF (trillion cubic feet) and MCF (thousand cubic feet).
According to the US Department of Energy, for many years natural gas was considered worthless and discarded, and is still released by flaring today in many countries.
Natural gas can be found as either associated gas, non-associated gas, wet gas (a type of non-associated gas) or coal bed methane.
Non-associated gas is gas which is found in reservoirs which do not contain significant quantities of crude oil. It often occurs at greater depths where heat has split all of the hydrocarbons into smaller, lighter gas molecules. Shale gas is one type of unconventional non-associated gas.
Associated gas is found in association with crude oil, either dissolved in the oil or as a "cap" of free gas above the oil. Where it cannot be used, associated gas is either reinjected into the well, flared or vented.
Coal bed methane (CBM) or coal seam gas (CSG) is the natural gas extracted from coal beds during underground coal mining.
In the absence of pipelines, through the 1800s the natural gas which was found was used almost exclusively as a fuel for lamps. However the invention of the "bunsen burner" in 1885 proved that gas could be used to provide heat for cooking and warming buildings.
The construction of pipelines allowed natural gas to be brought to new markets. One of the first substantial pipelines was built in 1891 in the US, however few pipelines were built until after the Second World War in the 1940s.
The International Energy Association estimated in 2011 that natural gas could overtake coal and rival oil by 2035 to account for over 25% of global energy demand.
According to the London-based Petroleum Economist, the growing interest in gas as an element in today's energy mix represents a "structural shift in energy markets." Natural gas holds several benefits as a fuel for a low-carbon future, including: the lowest carbon footprint of all fossil fuels. a shorter lead time to build gas-fired power plants and greater operational flexibility. ability to reduce greenhouse gas emissions by 25% in the transport sector compared to traditional motor fuels.
The International Energy Agency (IEA) also points out that gas can help to diversify energy supply and so improve energy security.
1.↑ "Oil and Gas Resources and Their Uses" TEEIC, retrieved 13 February 2012.
2.↑ "Natural Gas" US Department of Energy, retrieved 13 February 2012.
3.↑ "Natural Gas Measurement" KGM, retrieved 13 February 2012.
4.↑ "Natural Gas" US Department of Energy, retrieved 13 February 2012.
5.↑ "Oil and Gas Resources and Their Uses" TEEIC, retrieved 13 February 2012.
6.↑ "NON-ASSOCIATED GAS DEFINITION" Oil and Gas Glossary, retrieved 13 February 2012.
7.↑ "Oil and Gas Resources and Their Uses" TEEIC, retrieved 13 February 2012.
8.↑ "Oil and Gas Resources and Their Uses" A Barrel Full, retrieved 13 February 2012.
9.↑ "The History of Natural Gas" US Department of Energy, retrieved 13 February 2012.
10.↑ "Gas could make up 25% of global energy mix by 2035: IEA" Platts, 2011.
11.↑ "Unconventional Gas's Global Potential" Petroleum Economist, 18 July 2011.
12.↑ "Are We Entering a Golden Age of Gas?" IEA, 2011.