What is natural Gas

Monday, September 21, 2009 by ShoXee

What Is Natural Gas?

Natural gas is a subcategory of petroleum that is a naturally occurring,
complex mixture of hydrocarbons, with a minor amount of inorganic
compounds. Geologists and chemists agree that petroleum originates from
plants and animal remains that accumulate on the sea/lake floor along
with the sediments that form sedimentary rocks. The processes by which
the parent organic material is converted into petroleum are not under-
stood. The contributing factors are thought to be bacterial action; shearing
pressure during compaction, heat, and natural distillation at depth; pos-
sible addition of hydrogen from deep-seated sources; presence of cata-
lysts; and time (Allison and Palmer 1980).
Table shows composition of a typical natural gas. It indicates that
methane is a major component of the gas mixture. The inorganic com-
pounds nitrogen, carbon dioxide, and hydrogen sulfide are not desirable
because they are not combustible and cause corrosion and other problems
in gas production and processing systems. Depending upon gas composi-
tion, especially the content of inorganic compounds, the heating value of
natural gas usually varies from 700 Btu/scf to 1,600 Btu/scf.
Natural gas accumulations in geological traps can be classified as reser-
voir, field, or pool. A reservoir is a porous and permeable underground
formation containing an individual bank of hydrocarbons confined by
impermeable rock or water barriers and is characterized by a single nat-
ural pressure system. A field is an area that consists of one or more reser-
voirs all related to the same structural feature. A pool contains one or
more reservoirs in isolated structures. Wells in the same field can be clas-
sified as gas wells, condensate wells, and oil wells. Gas wells are wells with producing gas-oil-ration
(GOR) being greater than 100,000 scf/stb;