New records were established in development drilling during 1952 in Colorado, Nebraska, and Utah. Completions, up 40 per cent over the previous year and totalling 363, had an over-all success ratio of 70 per cent. Utah, with seven development tests, had a success ratio of 86 per cent, while Colorado and Nebraska, with 356 development tests, were credited with a combined success ratio of 69 per cent. Equally outstanding, exploratory drilling, up 40 per cent over 1951, accounted for 501 tests, of which 16.6 per cent were successful. New-field, pool, and extension discoveries totalled 83. Of this number, Utah, with 23, was up 12 per cent over the previous year for a success ratio of 31 per cent and Colorado and Nebraska, with 30 each, registered only slight changes.

In Colorado and Nebraska, Cretaceous sands continued to account for the majority of the new-field discoveries and to be the main objectives for development drilling. In Utah, Tertiary and Cretaceous possibilities were given most attention.

New pays were established in this three-state area during the year. These included the Morrison and Frontier in the North Park Basin, the Fort Union (Tertiary) and Lance (U. Cret.) in the Sand Wash Basin, and the Morrow (Penn.), which yielded gas in non-commercial amounts in the southeastern Denver-Cheyenne Basin.

In the Denver-Cheyenne Basin, the Pennsylvanian and other Paleozoics were objectives in a number of exploratory tests. Oil showings, as well as zones of porosity and permeability, seem to assure a continued and increased interest in pre-Cretaceous possibilities.

Seismic activity decreased slightly in 1952, particularly in Nebraska. Gravity-meter work increased 14 per cent in the area as a whole. The majority of the exploratory tests in the Denver-Cheyenne Basin were drilled on seismic leads. In Utah and western Colorado surface geology provided the principal basis for the tests. In both instances, economics and lack of adequate subsurface control were undoubtedly contributing factors.

Leasing activity continued strong, with selected areas carrying most of the weight. A few lease blocks were assembled in the Denver-Cheyenne Basin, particularly along the perimeter and in previously unleased areas. In the North Park Basin leasing of previously mapped structures followed discovery of Frontier oil in the Coalmont anticline. Areal and checkerboard plays were most pronounced in the North Park Basin and in the Wasatch Plateau area.

By providing market outlets, the completion of the Platte Pipe Line, the construction of a gas line from the Clear Creek pool to Salt Lake City, and the announcement of a proposed gas line from the Four Corners area to the Pacific Northwest are further expected to stimulate leasing and drilling activity during 1953.