The Denver Basin
The Denver Basin is an asymmetrical foreland-style structural basin that is approximately oval, stretched north to south and encompassing more than 70,000 square miles in eastern Colorado, southeastern Wyoming, and western Nebraska and Kansas. It is bounded on the west by the Front Range of the Rocky Mountains, on the north by the Hartville uplift, and the southeast by the Las Animas arch.
The Denver Basin has a long and rich history of petroleum exploration and production. The first producing oil well in the Denver Basin was discovered in 1881 in the Florence Field, which continues to produce today and is the oldest continuously operating oil field in the United States. In 1901, oil was discovered in fractured Pierre Shale at the McKenzie Well, part of the Boulder Oil Field in Boulder County. Fast forward to today and more than 100,000 wells have been drilled and the basin contains over 1,500 individually discovered oil and gas fields.
The Wattenberg Gas Field, one of the largest petroleum deposits in the United States, is located just north of the Denver metropolitan area. The major producing reservoirs in the field have been the J Sandstone, Codell Sandstone, Niobrara Formation, and the Hygiene and Terry Sandstones, which are all Cretaceous in age. The focus of most of the current activity in the basin revolves around accessing large remaining hydrocarbon reserves in the Niobrara and Codell formations.
The Powder River Basin
The Powder River Basin (PRB), located in northeastern Wyoming and southeastern Montana, developed during the Laramide orogeny similar to other Rocky Mountain foreland structural basins. The basin is asymmetric with a steep western flank and a shallowly dipping eastern flank. The deepest part is located in the southern portion of the basin and can be 17,000 ft or more from surface to the top of the Precambrian basement.
Development of hydrocarbons in the PRB followed similarly to the other Rocky Mtn Basins. The first producing oil well was discovered in 1889 just north of the Salt Creek Oil Field, which is still the most productive oil field in Wyoming. Numerous other oil fields were discovered in the following years. In the 1990’s and 2000’s the PRB became a significant natural gas producing region with the development of large coal bed natural gas resources.
Today the energy industry has once again turned it’s focus to the PRB with it’s significant unconventional shale resources. As technology has improved operators are able to reduce costs and improve economics allowing them to find new opportunities in historic producing basins, like the PRB. The primary exploration efforts are focused on the Cretaceous aged Parkman, Sussex, Niobrara, Turner (Frontier), and Mowry formations. All of these zones are targets for horizontal well drilling and can be stacked in one location making the PRB a tremendous potential resource.