--> Abstract: Probable Reservoir Facies, Wapanucka Limestone (Morrowan), Frontal Ouachita Mountains, Southeastern Oklahoma, by D. L. Mauldin; #91012 (1992).

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ABSTRACT: Probable Reservoir Facies, Wapanucka Limestone (Morrowan), Frontal Ouachita Mountains, Southeastern Oklahoma

MAULDIN, DARRELL L., Baylor University, Waco, TX

Although gas production in the Ouachitas has been primarily from the Spiro Formation (Atokan), the Wapanucka Formation is locally a gas reservoir and thus is a secondary objective. Outcrop study of surface imbrications form a basis for predicting the character of rocks in the subsurface.

Thick successions of repetitive subtidal carbonate cycles of platform, platform margin, and basinal facies characterize the Wapanucka Formation in outcrop, except for most of the basinal ridges, in which cyclicity is not evident. Each repetitive sequence records aggradation and southward progradation of the ramp-like shelf margin. Pebble conglomerates were deposited as island beaches. Oolitic and bioclastic calcarenites accumulated as shallow shelf bars, while algal boundstones and wackestones developed near the shelf edge. Spiculitic limestones characterize the platform margin, and slope and basinal depositional environments are inferred for the noncalcareous spiculites and shale.

Several facies are potential hydrocarbon reservoir rocks. These include pebble conglomerate, oolitic grainstone, algal boundstone, and spiculitic packstone. The first two lithologies might preserve primary porosity; the algal units could develop secondary porosity; while the latter facies would develop fracture porosity in certain structural configurations. Thus, mapping the surface is significant because well control and seismic data do not provide this kind of information. Detailed surface work in association with the subsurface geology will aid in locating hydrocarbon reservoirs.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)