Southwestern Wyoming and adjacent areas in n6rthwestern Colorado and northeastern Utah have had a favorable depositional and structural history for the formation and accumulation of significant amounts of hydrocarbons. The 89,420 cu mi (373,685 cu km) sedimentary package contains sediments of all periods except the Silurian. Hydrocarbons are produced from all but Ordovician and Devonian age sediments in a variety of structural and stratigraphic traps. An optimistic future is predicted to greatly improve the estimated original in place reserves of I .R billion bbl of oil and 7.3 trillion cu ft of gas, by deeper drilling on producing structures, and presently undefined structural and stratigraphic traps in the deeper portions of the basins.