Natural Gas Liquids
Producers of Natural Gas, otherwise known as methane (which is a gas at atmospheric pressure), also produce a significant quantity of hydrocarbon liquids. These liquids include ethane, propane, butane (normal and iso), and pentanes. These liquids must be separated from the methane gas in order to move the product efficiently down the pipeline, but also because the methane and the liquids can have dramatically different uses or intended destinations. The methane is mostly used as a heating or industrial fuel. The liquids can be used as a fuel, but also as a feedstock to the chemical industry, or for blending into unleaded gasoline.
Thus the raw gas is quickly sent from the producer's well-head to a separation plant to remove the liquids and then the liquids are run through a fractionation plant. Fractionation is the process through which each of the liquids is chemically separated into the individual ethane, propane, butanes, and pentanes. The individual liquids can then be sent to their intended destination via pipeline, railcar, truck, or ship. Safety, in addition to logistics, is a factor in determining how the individual products are moved.