The liquids thus formed may get trapped by depositing in the pores of the gas reservoir. One method to deal with this problem is to reinject dried gas free of condensate to maintain the underground pressure and to allow reevaporation and extraction of condensates.
Natural gas is often informally referred to as simply gas, especially when compared to other energy sources such as electricity. Before natural gas can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane.
Quantities of natural gas are measured in normal cubic meters (corresponding to 0°C at 101.325 kPaA) or in standard cubic feet (corresponding to 60 °F (16 °C) and 14.73 PSIA). The gross heat of combustion of one normal cubic meter of commercial quality natural gas is around 39 megajoules (≈10.8 kWh), but this can vary by several percent. In US units, one standard cubic foot of natural gas produces around 1,030 British Thermal Units (BTUs). The actual heating value when the water formed does not condense is the net heat of combustion and can be as much as 10% less
The price of natural gas varies greatly depending on location and type of consumer. In 2007, a price of $7 per 1,000 cubic feet (28 m³) was typical in the United States. This corresponds to around $7 per million BTU's, or around $7 per gigajoule. In April 2008, the wholesale price was $10 per 1,000 cubic feet (28 m³) ($10/MBTU) [4]. The residential price varies from 50% to 300% more than the wholesale price. At the end of 2007, this was $12-$16 per 1000 ft3 (or MBTU) [5]. Natural gas in the United States is traded as a futures contract on the New York Mercantile Exchange. Each contract is for 10,000 MMBTU (gigajoules), or 10 billion BTU's. Thus, if the price of gas is $10 per million BTU's on the NYMEX, the contract is worth $100,000.
Natural gas is also traded as a commodity in Europe, principally at the United Kingdom NBP and related European hubs, such as the TTF in the Netherlands.
In the rest of the world, LNG (liquified natural gas) and LPG (liquified petroleum gas) is traded in metric tons or mmBTU as spot deliveries. Long term contracts are signed in metric tons - and to convert from one system to the other requires should better be described here, than a very isolated market. A cubic foot is a volumetric measure, MT is weight. The LNG and LPG is transported by special ships/containers, as the gas is liquified - LPG cryonic. The specification of each LNG/LPG cargo will usually contain the energy content, but this information is in general not available to the public.
The major difficulty in the use of natural gas is transportation and storage because of its low density. Natural gas pipelines are economical, but are impractical across oceans. Many existing pipelines in North America are close to reaching their capacity, prompting some politicians representing colder areas to speak publicly of potential shortages.
LNG carriers can be used to transport liquefied natural gas (LNG) across oceans, while tank trucks can carry liquefied or compressed natural gas (CNG) over shorter distances. They may transport natural gas directly to end-users, or to distribution points such as pipelines for further transport. These may have a higher cost, requiring additional facilities for liquefaction or compression at the production point, and then gasification or decompression at end-use facilities or into a pipeline.