The Cache field in southwestern Colorado is the most productive field in the Colorado part of the Paradox basin. The field was discovered in October, 1964, and currently there are 18 producing wells with 40-acre spacing. Gas and high-gravity oil are produced from limestone and dolomite in the Ismay zone (Pennsylvanian) at a depth of 5,600 ft. Within the productive intervals, average porosity is 8-10% and average permeability is 20-25 md. The average net-pay thickness is approximately 40 ft. and there have been initial flowing potentials in excess of 3,000 b/d of oil.

The productive area trends northwest, is 2 mi. long by ½ mi. wide, and encompasses 740 acres. Subsurface control indicates the existence of approximately 50 ft. of closure at the top of the Ismay zone. However, the accumulation is controlled primarily by the development of porosity and permeability within "stacked" algal bioherms which grade laterally into anhydrite.

Cumulative production to May 1, 1966, was 1,519,251 bbls. of oil. Estimated recoverable reserves are 4.6 million bbls. of oil.

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