Rangely Oil Field, Rio Blanco County, Colorado1
W. Y. Pickering, C. L. Dorn, 1948. "Rangely Oil Field, Rio Blanco County, Colorado", Structure of Typical American Oil Fields: A Symposium of the Relation of Oil Accumulation to Structure, J. V. Howell
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The Rangely oil field is in northwestern Colorado in the central Rocky Mountain region and on the northeastern edge of the Uinta basin. The structure is an asymmetrical fold trending northwest and southeast, with 1,900 feet of surface closure. Dips range from 15º to 35º on the southwest flank and from 4º to 6° on the northeast side. Major production in the field is from the Weber sandstone of Permian-Pennsylvanian age. Some shale oil is produced from the Mancos of Upper Cretaceous age. One well produces from the Triassic Shinarump conglomerate. Prior to the completion of a pipe line from Rangely to Wamsutter, Wyoming, in September, 1945, oil was hauled by truck to Salt Lake City, Utah, and Craig, Colorado. By December 26, 1946, the pipe line had moved 8,867,014 barrels of oil.
Weber sand production at Rangely was discovered in 1932 by The California Company’s Raven A-1. Subsequently the discovery well was shut in until the war-time drilling program began in 1943. At the height of the drilling campaign in the summer of 1946, 52 rigs were active in the field. By January 1, 1947,185 Weber wells had been completed, 17 were pumping, and one well was producing from the Shinarump conglomerate.
The Weber formation, a dense cross-bedded sandstone, produces commercially from the upper 550 feet of section, of which 30 per cent is estimated as being effective. Throughout the field the sand’s permeability ranges from 0 to 330 millidarcys and may average about 20 millidarcys. Its porosity ranges from 9 to 16 per cent. Despite the dense characteristics of the sand, some wells have produced as high as 1,000 barrels per day on initial production tests through ¼-inch choke. The oil column embraces a total of 830 feet. A gas cap is present with the gas-oil contact placed 330 feet subsea and the oil-water contact tentatively established at 1,160 feet subsea. Surface and subsurface structure maps of the Rangely field are marked by simplicity. No faults of major importance have yet been found.
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Structure of Typical American Oil Fields: A Symposium of the Relation of Oil Accumulation to Structure
Modern petroleum geology in the United States had its beginning in the first decade of the 20th Century when the U.S. Geological Survey began mapping the structure of the rocks in and near old fields in order to discover the various types of structural conditions under which oil and gas are trapped. Structural geology has evolved as a branch of the broader science far more rapidly than have methods of mapping the attitude of rocks at the surface. This volume, published in the late 1920s, was designed to afford authoritative and modern descriptions of the structure of typical oil fields in the United States. Each of the 39 fields contained here is described by an author who is intimately familiar with the available data. The relationship of structure at the surface and at depth for different terranes is clearly set forth wherever the strata are not parallel. The volume concludes with a summary paper on the role of geologic structure in the accumulation of petroleum. Fields include: Florence, Colorado; Stephens, Arkansas; Kevin-Sunburst, Montana; Bradford Pennsylvania; and Salt Creek, Wyoming.