Geology of Vermilion Creek Gas Area in Southwest Wyoming and Northwest Colorado

Abstract

The Vermilion Creek gas area, located on both sides of the state line between southwest Wyoming and northwest Colorado, is now the field terminus of a 330-mile $20,000,000.00 gas line built in 1929 and supplying Salt Lake City, Utah, and adjacent towns with natural gas. The gas developed here is the first important commercial gas developed in the Tertiary formations of the Rocky Mountain region. Six closed domes, three of which are associated with considerable faulting and four of which are controlled by one main line of anticlinal folding, are developed. The folding in the gas area is a direct consequence of the older and more severe regional structural movements in the Uinta Mountains on the south and west and the Rock Springs uplift on the northwest. To date two of the domes have been proved for commercial gas, one well yielding a total of 65,000,000 cubic feet per day from four separate sands. The gas is produced from irregular sand bodies, very lenticular and physically different, in the lower Wasatch formation of Eocene Tertiary age. The producing horizons are of fresh-water origin only. Gas accumulation is controlled by the folding of the Tertiary beds into closed structures. The source of the gas, which is of excellent quality, is not exactly known. Examination of outcrops and of drill cuttings reveals comparatively scanty evidence of organic life in the lower Tertiary beds. It has been suggested that the underlying Cretaceous beds are the source, but the preponderance of evidence does not support this view. Production from the gas area commenced in September, 1929. Insufficient gas has been run to date to make possible accurate estimates on the life of wells and total reserves.