Successful oil exploration in the Paradox basin began in 1907 with the discovery of Pennsylvanian oil at Mexican Hat field in San Juan County, Utah. Accelerated exploration began with the discovery of oil in the Pennsylvanian Paradox Formation at Aneth field in 1956 and lasted into the 1960s. Cumulative production at greater Aneth field exceeds 271 million bbl of oil. A second major oil producing zone, the Mississippian Leadville, was established at Lisbon field in 1960. By 1978, its 25 wells had produced 40 million bbl of oil and 310 Bcf of gas. Recently, exploration in the area has been minimal with the exception of the current exploration for carbon dioxide for secondary recovery projects.

The Paradox Formation, the major producing unit in the basin, can be subdivided into both genetic units and facies subzones using sample and mechanical log information. Recognition and mapping of the major facies--hypersaline, penesaline, and marine shelf--for each genetic unit can delineate fairways most favorable for the development of algal mounds in which the best production occurs.

Perhaps the most significant remaining potential is in the Mississippian Leadville formation. Exploration for structural traps within this carbonate unit is difficult owing to the thick overlying Pennsylvanian salt section present over much of the basin. A pilot gravity modeling study in the Lisbon field area has shown that the salt effect can be removed and the underlying structure mapped. Regional gravity modeling of the remaining salt basin may define similar Lisbon-type structures.

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