Abstract Oil and gas condensate from the Jurassic Smackover Formation in Eylau and Flower Acres fields in Bowie County, Texas, and in Texarkana field in Miller County, Arkansas, yield 60 per cent nitrogen. The producing rocks are associated with intrusive igneous rocks and hydrogen sulfide in the two Texas fields. The Texarkana field is in the same diabase petrographic province. Origin of the nitrogen gas is uncertain, but close association with oil and gas-condensate accumulation suggests a related origin.