The Paradox Salt Basin, Utah and Colorado: Recognition of New Types of Salt Features and Their Impact on Salt-Related Traps

Abstract

The Paradox Basin in southeastern Utah and southwestern Colorado has a long history of successful near-salt hydrocarbon production utilizing a relatively simple stratigraphic play strategy of Pennsylvanian & Permian siliciclastic reservoirs upturned against long, linear salt walls. With the continuously improving seismic imaging of salt systems and voluminous well-bore datasets acquired from salt basins worldwide, new types of near-salt features and associated traps have been identified and successfully tested recently, particularly in the Gulf of Mexico. However, these new features have not been previously recognized in the Paradox salt basin. Utilizing 2D seismic lines, well logs and new detailed outcrop studies of Gypsum Valley in the Paradox Basin, we highlight several of these newly recognized salt features that indicate that the Paradox Basin is a much more dynamic and complex salt system than previously thought. Identification of these new structures at other Paradox salt walls may provide new exploration concepts in this mature salt basin and also lead to a reinterpretation of the basin evolution and salt tectonic history. Newly recognized salt features include: 1) megaflaps comprising steeply dipping panels of Pennsylvanian Honaker Trail and uppermost Paradox reservoir strata that extend 2.5 km up the side of the salt walls; 2) lateral carbonate caprock that formed during Permian and Triassic caprock events and have been misidentified in the past as Pennsylvanian Honaker Trail Fm..; 3) halokinetic radial faults, which extend short distances (<2 km) away from the salt wall and are concentrated at the arcuate ends of salt walls; 4) counterregional faults merging into the proximal margins of the salt walls and detaching on autochthonous salt at depth; 5) shoulder anticlines, which are salt-margin dissolution anticlines that are present where the steep edges of diapirs step abruptly inward. Megaflaps are commonly blown traps, or areas of poor pressure protection. Lateral caprock may form salt-flank reservoir facies or trap thief zones. Radial faults can provide reservoir seal or may compartmentalize salt flank traps. Counterregional faults may form low angle 3-way closure against salt. Shoulder anticlines are newly identified traps with excellent charge scenarios.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017