Natural gas liquids

From Wikimarcellus

Natural gas liquids (aka NGLs) are hydrocarbons such as propane, ethane, butane, and pentanes that are mingled with methane in wet gas areas of the Marcellus shale such as southwestern Pennsylvania and northern West Virginia. These must be separated from the methane before it can be transported by gas pipelines. Wet gas develops in lower pressure areas of the Marcellus play. "Dry gas" occurs in higher pressure areas that tend to be more mountainous.

NGLs can be separated from methane in a cryogenic processing plant.