Exploratory drilling decreased in 1967 but success ratios were better in Wyoming and North Dakota. Development drilling increased, but production declined. Developments late in 1967, however, should result in an increase in all categories in 1968. The most significant developments in the Northern Rockies were the discoveries in the Lower Cretaceous Muddy sand at Bell Creek in Montana, and Recluse and Kitty in Wyoming. These discoveries have led to lease and drilling activity in Montana, North Dakota, South Dakota, and Wyoming, which will lead to extensive exploration in these states in 1968. The significance of Bell Creek is the fact that this large accumulation was found through a program of stratigraphic drilling and could not have been found by any other conventional e ploration program.

The northern Powder River basin continues to be the most active exploration area in Wyoming; however, the target for exploration has shifted from the Minnelusa to the Muddy. New Minnelusa pools continue to be found adding to the previously discovered reserves. The discovery of a significant accumulation in southeastern Montana at the Bell Creek field sparked the drilling of wildcat wells based on scant geologic information. The result was several dry holes and no additional discoveries which caused a low discovery ratio for the area and state. The Tiger Ridge gas field appears to be a large field by Montana standards, and probably will prove to be one of the larger gas accumulations in the state. Discoveries and new pays in the Williston basin assure continued exploration in this area both central Montana and the Sweetgrass arch had some exploratory activity and success.

North Dakota remains an attractive area in which to operate because of shallow depths, low drilling costs, available acreage, and a favorable market and price for oil. Continued exploration for and discoveries in deeper pays both on and off the Nesson anticline offer incentives to keep deeper exploration alive in search for large stratigraphic traps. Bell Creek already has touched off major lease activity in this state which will lead to considerable Newcastle (Muddy) exploration in 1968.

South Dakota's reserves still elude the explorationist; the impact of Muddy discoveries in Wyoming and Montana probably will lead to exploration for this objective in South Dakota in 1968.

There was no drilling in Idaho in 1967.