Page 61 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

2% CO 2. Acid gas fields with up to 90% CO 2 exist, but the normal
range for sour raw gas is 20-40%.
o Condensates are a mixture of hydrocarbons and other components
in the above table. These are normally gaseous from the well but
condense out as liquid during the production process (see previous
chapter). This is a refinery and petrochemical feedstock.

Raw gas is processed into various products or fractions:
o Natural Gas in its marketable form has been processed for a
specific composition of hydrocarbons, sour and acid components
etc. and energy content. Content is typically 90% methane, with 10%
other light alkenes.
o Natural Gas Liquids (NGL) is a processed purified product
consisting of ethane, propane, butane or some higher alkenes
separately, or in a blend. It is primarily a raw material for
petrochemical industry and is often processed from the condensate.
o Liquefied Petroleum Gas (LPG) refers to propane or butane or a
mixture of these that has been compressed to liquid at room
temperature (200 to 900 kPa depending on composition). LPG is
filled in bottles for consumer domestic use as fuel, and is also used
as aerosol propellant (in spray cans) and refrigerant (e.g. in air
conditioners). Energy to volume ratio is 74% of gasoline.
o Liquefied Natural Gas (LNG) is natural gas that is refrigerated and
liquefied at below -162 °C, for storage and transport. It is stored at
close to atmospheric pressure, typically less than 125 kPa. As a
liquid, LNG takes up 1/600 of the volume of the gas at room
temperature. Energy to volume ratio is 66% of gasoline. After
transport and storage it is reheated/vaporized and compressed for
pipeline transport.
o Compressed Natural Gas (CNG) is natural gas that is compressed
at 2-2,2 MPa to less than 1% of volume at atmospheric pressure.
Unlike higher alkenes, methane cannot be kept liquid by high
pressure at normal ambient temperatures because of a low critical
temperature. CNG is used as a less costly alternative to LNG for
lower capacity and medium distance transport. Methane for vehicle
fuel is also stored as CNG. Energy to volume ratio is typically 25% of
gasoline.

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