Wyoming's Historical Oil Fields I and II: Still Producing (A Lot) After All These Years
Ranie Lynds, Rachel N. Toner, and Alan J. Ver Ploeg
Wyoming State Geological Survey
Oil production began in Wyoming in 1884 with the drilling of the discovery well for the Dallas Dome field in central Wyoming. Since then, oil production has occurred from over 49,000 wells in 1,410 fields. The top five most-productive oil fields in Wyoming, including Salt Creek (696.4 million barrels of oil, MMBO), Oregon Basin (481.3 MMBO), Elk Basin (472.9 MMBO), Lost Soldier (270.5 MMBO), and Hamilton Dome (269.1 MMBO), were discovered before 1918. Wyoming's oil fields are the result of a fortuitous overlap of geology and paleogeography. The hydrocarbon sources include the organic-rich shallow-marine shales of the Permian Phosphoria Formation as well as the Upper Cretaceous shales deposited as part of the Western Interior Seaway. Folding and faulting associated with Laramide-age tectonics formed the basin-margin anticlinal traps that today hold the bulk of Wyoming's conventional oil fields. The most prolific oil producing formation in Wyoming is the Pennsylvanian Tensleep Sandstone; a marginal marine sandstone interbedded with nearshore limestones and shales. Oil has also been recovered in significant quantities from the Upper Cretaceous Frontier Formation, Cody Shale, and Mesaverde Group/Formation. The Dallas Dome discovery well sparked interest in Wyoming's oil fields, and Salt Creek was soon discovered in 1889 on the southwest flank of the Powder River Basin. The Salt Creek field is an asymmetric anticline that has produced far more than any other field in Wyoming. At nearly 3.8 million barrels of oil in 2012, Salt Creek is still the second largest oil producer in the state, in part due to tertiary recovery methods such as enhanced oil recovery with carbon dioxide (CO2-EOR), which began in 2004. Wyoming's historical oil fields have helped define an industry. Many of the methods associated with secondary and tertiary recovery techniques (six fields in Wyoming are currently under CO2-EOR), as well as advancements in drilling and production technologies, were developed in these historic fields and resulted in increased field longevity. In 2012, 128 years after discovery, the Dallas Dome field produced 75,628 barrels of oil. The lessons learned from these historic oil fields helped pave the way for Rocky Mountain oil production as well as oil production around the world. Engineering and geological knowledge gained from these fields will also help guide the future success of those involved in new and 'unconventional' frontiers of the oil business.
AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013