(1) (n.) Production Testing. Natural gas that contains a few or no liquefiable liquid hydrocarbons. Lean gas is also called dry gas. Alt. form: dry gas. See: Liquid Hydrocarbons, Natural Gas. (2) (n.) Production Testing. Residual gas, mainly methane and ethane, that remains after the heavier hydrocarbons have been condensed in thewellhead. When the lean gas is liquefied, it is called liquefied natural gas (LNG). See: Liquefied Natural Gas, LNG