Print this pageAbstract: Crazy Mountains Area: Geology, Exploration History, and Production Potential of Natural Gas Province in South-Central Montana
The Crazy Mountain structural basin and positive structural features forming the basin perimeter are herein referred to as "The Crazy Mountain area." The stratigraphic column of this area includes sedimentary rocks ranging in age from Precambrian to Tertiary.
Exploration drilling prior to 1970 resulted in discovery of Cretaceous oil reserves at Dry Creek, Golden Dome, Mosser Dome, and Lake Basin. Natural gas reserves were found in Cretaceous rocks at Dry Creek, Golden Dome, Lake Basin, Rapelje, and Big Coulee. Jurassic Morrison gas reserves also were found at Big Coulee.
Renewed drilling activity since 1970 has resulted in reopening Lake Basin and Rapelje gas fields and extension of Big Coulee gas field. Pipeline deliveries from these projects began in late 1974 and now exceed 1.5 BCFG.
The untapped natural gas potential of the Crazy Mountains area lies mainly in Cretaceous sandstone reservoirs. This potential relies on extension of known gas reserves in the eastern part of the area and in development of indicated, but as yet unconfirmed, gas reserves in the central and western parts of the Crazy Mountains area.
Substantial net thicknesses and areal extent of sandstone reservoir zones make finding gas in place fairly common. Limited permeability and susceptibility to formation damage make proper evaluation and production of the gas reserves most difficult.
AAPG Search and Discovery Article #90971©1976 AAPG-SEPM Rocky Mountain Sections 25th Annual Meeting, Billings, Montana