The Big Piney–La Barge complex, with cumulative gas production of 1.2 Tcf, has been the leading gas-producing area in Wyoming since 1956. It also contributes significant oil production, which has amounted to about 65 million bbl. Ultimate reserves are estimated to be 2.5 Tcf of gas and 75 million bbl of oil. In addition, condensate production averages about 3 bbl/MMcf of gas.
Production is from rocks as young as Paleocene and as old as Triassic. The major gas reservoir in the area is the Cretaceous Frontier Formation. Structural, stratigraphic, and combination traps are all common in the Big Piney—La Barge area. Probably significant to trapping the hydrocarbons in the Paleocene strata was the transgression of Paleocene units onto the Big Piney—La Barge platform or anticline. The area was anticlinally folded during Late Cretaceous and early Paleocene times, and Mesaverde units reflect the influence of the Moxa arch to the south and the Monument Buttes–Blue Rim arch to the southeast. Accumulations in the Frontier are essentially structurally controlled west of the La Barge thrust; however, east of that thrust, production is mainly from stratigraphic traps.