Abstract: Natural gas admixed with nitrogen is flowed through an absorber at approximately 250-300 psia and at ambient temperature. An absorbent comprised primarily of a petroleum base fluid having a low vapor pressure and a high boiling point is flowed countercurrently through the absorber. The natural gas is absorbed preferentially to the nitrogen in the absorbent. The nitrogen is exhausted from the absorber. The rich absorbent is flowed into a desorber through a regulator reducing the pressure to approximately 65 psia, thus effecting desorption of the natural gas. The desorbed natural gas is then flowed to market. The lean absorbent is repressurized and recycled to the absorber. Two or more absorbers may be connected in series.