· Abstract

· Acknowledgments

· Introduction—Video of Exploration and Production Through Time

· Units of Measure

· Undiscovered Oil and Gas Resources in the Southwestern Wyoming Province

· Undiscovered Gas in the Mesaverde Total Petroleum System

· The Almond Continuous Gas Assessment Unit

· The Rock Springs–Ericson Gas Assessment Unit

· Undiscovered Gas in the Mesaverde–Lance–Fort Union Composite Total Petroleum System

· The Mesaverde–Lance–Fort Union Continuous Gas Assessment Unit

· Undiscovered Gas in the Lewis Total Petroleum System

· The Lewis Continuous Gas Assessment Unit

· Undiscovered Gas in the Hilliard-Baxter-Mancos Total Petroleum System

· The Hilliard-Baxter-Mancos Continuous Gas Assessment Unit

· Undiscovered Gas in the Mowry Composite Total Petroleum System

· The Mowry Continuous Gas Assessment Unit

· Undiscovered Gas in the Lance–Fort Union Composite Total Petroleum System

· The Lance–Fort Union Continuous Gas Assessment Unit

· Reservoirs That Contain the Majority of Undiscovered Gas Resources

· Live Data and Maps

· In Summary

· References Cited

Undiscovered Gas in the Lance–Fort Union Composite Total Petroleum System

The Lance–Fort Union Composite TPS, as shown in the generalized stratigraphic chart (fig. 21), contains undiscovered gas resources in continuous accumulations, including potential basin-centered gas and coalbed-gas resources, and gas and oil resources in shallow conventional accumulations (Roberts, 2005). Within the TPS four AUs have been defined: the Lance–Fort Union Continuous Gas AU, the Lance Coalbed Gas AU, the Fort Union Coalbed Gas AU, and the Lance–Fort Union Conventional Oil and Gas AU. Conventional accumulations are more maturely explored, whereas continuous accumulations are only partially explored or essentially untested (Roberts, 2005). Most of the historical production has targeted shallow sandstone reservoirs in conventional traps along Cherokee ridge and, to a lesser degree, on the Wamsutter arch (Roberts, 2005). A limited number of wells have produced or are producing gas from sandstone reservoirs interpreted to be within continuous (basin-centered) accumulations in the Washakie and Great Divide Basins (Roberts, 2005). These accumulations are at depths where overpressured and low-permeability reservoir conditions exist, and where thermal maturities in Lance and (or) Fort Union source rocks are above the maturity threshold for thermogenic gas generation (Roberts, 2005). To date, there has been limited testing but no commercial production of coalbed gas from formations within the TPS (Roberts, 2005). Coal beds and associated noncoal, carbonaceous strata within the Lance and Fort Union Formations are considered to be the primary source rocks for hydrocarbon generation within the Lance–Fort Union Composite TPS (Roberts, 2005).