Commercial production of natural gas in Utah began in 1937 at Clay basin, Daggett County. Before 1937, gas

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had been produced from several fields for carbon-black plants and local markets. Commercial oil production began in 1948 with discovery of Ashley Valley field, Uintah County. Minor production elsewhere had been recorded since the early 1900s.

A small amount of gas was produced from 1937 through 1952. Gas production increased rapidly from 1953 through 1963, reached a peak in 1964, and since has declined irregularly. Oil production showed a major increase from 1949 to 1959, when the greatest annual production (39,960,000 bbl) was attained (average of 109,000 b/d). A second peak of 92,000 b/d was recorded in 1963. Since 1963 production has declined to an average of about 65,000 b/d. Production peaks have resulted from flush production in Utah's two giant fields, greater Aneth (Paradox basin) and greater Red Wash (Uinta basin). These two giants account for 80% of Utah's all-time cumulative production and 67% of current production.

Geology and productivity of several newer and smaller fields are reviewed: Bridger Lake, Bluebell, Lisbon, and others. Production from these fields in part effects the overall decline in Utah production that results from the steadily decreasing production at Aneth.

Although many prospective areas remain in Utah, the principal prospective areas are those along the overthrust flanks of the Uinta Mountains, the west and north parts of the Uinta basin, and the salt anticlines of the northern Paradox basin. Several potential oil and gas accumulations may be present in areas where recent surface mapping, geophysical data, and drilling information have been integrated. Multibillion-barrel deposits of oil-impregnated sandstone also are present in Utah. Potential for discovery and development of major new petroleum reserves in Utah is considered to be excellent.

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