Exploratory drilling in western Nebraska increased 3.8% while development drilling decreased 8.8%. For the second consecutive year, and as a result of a slow-down in the Denver basin, exploratory and development drilling in Colorado declined with a 31.4% decrease in exploratory tests and a 40.8% decrease in development wells from 1956 activity. In terms of wells drilled the Denver basin remained the most active area; however, exploratory drilling showed definite gains in the Paradox basin of southwestern Colorado and in southeastern Colorado.

Western Colorado, especially the Paradox basin, received increased attention from both gravity and seismic crews.

In Nebraska the major exploratory effort was again centered in Banner and Kimball counties where seven significant fields were found. The first commercial field was discovered in Scotts Bluff County. Total Nebraska oil production in 1957 amounted to 19,401,099 bbls., an increase of 16% over the 16,687,645 bbls. produced in 1956.

Colorado discoveries in the Denver basin, as in previous years, were concentrated in the "D"-"J" sand fairways in Washington, Logan, and Weld counties. In the Paradox basin of southwestern Colorado the first commercial Pennsylvanian production was established. Accelerated drilling activities in the northwestern Colorado sedimentary basins resulted in discovery of nine oil and gas fields. With the development of pipeline outlets, there has been a rapidly expanding search for natural gas. The Phillips Petroleum Company's Mannel No. 1, in northwestern Colorado, established a new depth record for the state, 17,033 ft. The Sun Oil Company completed a development well in the Divide Creek field with surface elevation of 10,482 ft., which is the highest gas well in the state. Total Colorado p oduction in 1957 amounted to 54,794,024 bbls., representing a decrease of 6% under the 58,524,172 bbls. produced in 1956.

Exploratory activities in the Cretaceous fairway in the Denver basin should continue at present levels. Development of Morrow gas production in the McClave area on the Las Animas arch continues to emphasize the importance of stratigraphic accumulation in southeastern Colorado. Exploratory drilling in the Colorado part of the Paradox basin will probably be maintained or increased in 1958. The stratigraphic potential of late Cretaceous and early Tertiary of the Piceance and Sand Wash basins will continue to attract attention. Although the Denver basin should surpass all other areas in the amount of drilling, the search for additional stratigraphic traps elsewhere in Colorado will dominate the industry's exploration program. The search for Pennsylvanian oil fields throughout Colorado wil continue to be one of the major exploration goals.