Exploratory drilling set new records in Wyoming during 1951. The 200 wells drilled with a total footage of 1,038,762 feet represented an increase of 14 per cent in wells drilled and 22 per cent in footage drilled over the previous record exploratory year, 1950. In 1951, 42 successful exploratory wells were completed, the discovery rate being 21 per cent as compared with 23 per cent in 1950. In the new-field wildcat category, 11 of the 110 tests (10 per cent) were successful. Seismic exploration was employed in 10 of the new-field discoveries. The majority of the 42 discoveries in 1951 involved stratigraphic trap or fault trap conditions controlling the accumulations. Faulting is considered an important accumulation factor in 7 of the 11 new fields discovered in 1951. Sign ficant discoveries included Whistle Creek, West Sussex, North Fork, and East Salt Creek as new fields, and new pools at South Cole Creek, Sussex, Beaver Creek, and South Elk Basin. The Slick Creek field was considerably enlarged.

Geophysical activity in Wyoming was moderately greater in 1951 than in 1950, with 1,295 crew-weeks of seismic and 243 crew-weeks of gravity effort. Of the total seismic effort 65 per cent was concentrated in the Powder River and Big Horn basins.

Wyoming oil production in 1951 set a new record of about 69 million barrels, 14 per cent above the 1950 production. Gas production totalled 83 million MCF, 5 per cent above the 1950 production. Sulphur production from the processing of natural gas totalled about 111,900 long tons in 1951.

Idaho continued as a state having no oil production. Developments during 1951 were restricted to southeastern Idaho where a deep Mississippian test was drilled on Juniper anticline and where blocks of leases were taken on other surface structures.