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Abstract: Using Brining Previous HitCyclesNext Hit as a Guide to Hydrocarbon Exploration in the Wolfcampian Council Grove and Admire Groups (Permian), Alliance Basin, Nebraska

Steven M. Goolsby, Mathew D. Goolsby

Significant Paleozoic hydrocarbon resources have recently been identified in the Alliance basin of the Nebraska Panhandle. Several fields are now producing from the Wolfcampian Council Grove and Admire groups in this evolving play. The recognition of repetitive brining Previous HitcyclesNext Hit in these stratigraphic units can aid in the exploration for productive hydrocarbon reservoirs. Each brining cycle represents a sedimentary sequence in which the Alliance basin fluctuated between restricted and open marine conditions with deposition controlled by variations in water salinity. The repetitiveness and symmetry of the brining Previous HitcyclesNext Hit is strong evidence for glacioeustatic Previous HitseaNext Hit Previous HitlevelNext Hit changes during deposition of these Previous HitsequencesNext Hit.

The base of an ideal Previous HitcarbonateNext Hit cycle begins with a sharp irregular contact representing a flooding event over a subareal desiccation surface. Algal dolostones and thin, black, anoxic shales deposited under hypersaline conditions normally overly this surface. Open-marine Previous HitcarbonateNext Hit shoaling Previous HitcyclesNext Hit typically occur next in the sequence. A return to hypersaline conditions is then signaled by the advent of algal-laminated facies, and ultimately by subaqueous evaporite deposition. Thus, each onlap sequence is a symmetrical brining cycle created by deposition under successive subareal, hypersaline, open marine, hypersaline, and subareal conditions. Siliciclastic Previous HitcyclesNext Hit develop where sand was blown into the area during subareal exposure and subsequently reworked by marine processes. Although s me production has been established in the algal-dominated hypersaline facies, superior pore systems are developed in facies deposited when wave energy was highest, or during the Previous HitseaNext Hit Previous HitlevelTop highstands.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994