Production of over 2.4 million barrels of oil (MMBO) and 750 million cubic feet of gas in the past two years from recently discovered Waulsortian-like buildups in North Dakota has prompted a regional re-evaluation of the geology and hydrocarbon potential of the Lodgepole Formation. In Daly Field, Manitoba Lodgepole shelf (or shelf edge) carbonate facies have produced over 39 MMBO. Before the 1993 discovery, hydrocarbon production from the Lodgepole in the United States was marginal, and no Lodgepole production in the region was known to be coming from carbonate buildups.

Recent studies of outcrops, cores, wireline logs, and the literature indicate that buildups are more common than previously recognized. (The term "buildup" is used because "Waulsortian mound" may not be appropriate for all structures.) These buildups crop out at seven locations in three mountain ranges in central Montana: Bridger Range, Big Snowy Mountains, and Little Belt Mountains. The stratigraphic variability of buildups within the Lodgepole is indicated by the conodont biostratigraphy and the varying elevation of the buildups above the Devonian/Mississippian boundary. In addition, their composition and architecture span the spectrum from mud-dominated mounds to grainstone buildups in the Little Belt Mountains, highly fossiliferous wackestone to boundstone textures in the Big Snow Mountain buildups, and textures in between these end members in Saskatchewan and North Dakota. The spectrum of compositional types is believed to be controlled by local variations in oceanographic conditions relative to the paleodepositional setting of each buildup. Interpretations of the depositional settings responsible for each type of buildup will be discussed.

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