Developments in Northern Rockies in 1966

Substantial increases in all phases of exploratory drilling resulted in numerous significant discoveries in the Northern Rockies. In Wyoming, 445 exploratory wells were drilled, a new record. The success percentage increased to 13, and 106 million bbls. of proved reserves were added. Exploratory drilling in Montana increased 48%, and the success rate rose from 5.5% to 10%. Drilling activity in North Dakota and South Dakota was near the lowest level in recent years. The North Dakota success rate was 10.5% compared to 4.8% in 1965. There were no discoveries in South Dakota.