Drilling activity in Colorado and Nebraska reached new record levels in 1955 with 32% more wells drilled than in 1954. Exploratory drilling in Colorado registered a gain of 38%. In Nebraska it was up 82%. Most active area was again the Denver basin, where 7 counties along the main 160-mile long and 70-mile wide northeast-southwest producing trend accounted for 79% of all wells drilled in the two-state area.

Cretaceous sands in the Denver basin continued to account for the majority of new-field discoveries and to be the main objectives for development drilling. Encouraged by favorable exploratory success, Industry interest tended to shift northward in the Denver basin from its previous heavy concentration in northeastern Colorado.

Discovery of oil and gas in the Pennsylvanian at Bents Fort on the Las Animas arch was of outstanding importance, as was the discovery of oil in the Pennsylvanian-Weber on the Thornburg structure in northwestern Colorado. Of academic interest was the finding of first production in the Cretaceous Codell sandstone at Soda Lakes pool, 7 miles southwest of Denver.

Marginal producing areas became more attractive explorationwise through the increased adaptation of Hydrafrac and Aquafrac completion methods.

Daily average production in the two-state area was up approximately 20% over 1954. Nebraska's production was up 50% over the year previous and Colorado's production was up 15%. Nebraska's proved oil reserves increased from 38,031,000 barrels to 57,697,000 barrels during the year, a 52% increase, and Colorado's went from 328,651,000 barrels to 334,003,000 barrels, an increase of 2%.

The trend in oil-finding techniques remained relatively unchanged from that used in previous years. Seismograph and combined surface and subsurface work continued as dominant background factors in locating tests in the Denver basin. In western Colorado, prospects continued to be located by surface geology and by combined surface and subsurface methods. The study of hydrodynamics appears to be an important exploratory tool heretofore overlooked to a degree by Industry.

Aquafrac treatment of Cretaceous sands in San Juan basin wells developed in mid-1955 is resulting in such deliverabilities and economies that it should remain an accepted completion technique.

Search for uranium and other fissionable minerals attracted considerable interest during the year. Several companies actively participated in the search, including the establishment and staffing of special sections. Others had personnel studying feasibility of joining in an active search. Still others were watchfully awaiting further developments.

Oil shale, as a competitive source for oil, was given a boost during the year with announcement of one major company's plans for a $5 million pilot oil-shale plant in western Colorado.

Favorable economic aspects of the search for oil in the Denver basin, the pending completion of the Pacific Northwest gas pipeline, the relatively low density of exploratory tests in the sedimentary areas, and the increase in crude outlet facilities to eastern markets point toward accelerated explorational activity in this two-state area during the next few years.