Evaluating Ooid Grainstone Geobodies of the Grayburg in the Guadalupe Mountains, NM
The importance of understanding ooid grainstones in terms of reservoir potential is recognized when looking at the large amount of hydrocarbons found in the facies as well as heterogeneities which cause issues with production. The Grayburg formation (Late Permian, Guadalupian) is a known producing interval in the Delaware and Midland basins; one characteristic of the mixed carbonate-siliciclastic system is the abundant ooid grainstone geobodies. Outcrops at Shattuck Escarpment provide a chance to gain a high resolution geospatial and paleocurrent understanding of the Grayburg's ooid geobodies that would assist in characterizing their subsurface counterparts. Promontories along the escarpment provide outstanding exposures to observe dip oriented changes from the grainstones in the High Frequency Sequence (HFS) G11 (Kerans and Kepter, 2002) or HFS 2 (Barnaby and Ward 2007). Preliminary data has shown the grainstones most up-dip limit has a maximum height of 3 meters, and pinches out 2 kilometers down dip. Coincident with these bed height changes are internal bedform changes that predominantly dip south-east towards the Grayburg shelf margin that is roughly 5 kilometers from the outcrop location ( Kerans and Kempter, 2002). Geospatial and paleocurrent measurements will be compared to the modern analysis of strike continuous ooid grainstone deposits of the Bahamas characterized by Rankey et al. 2006, Hine 1977, and Harris 2010. Collectively the results will provide insight into sedimentary architectural variability of ooid grainstone shoals, which can be used to understand issues with production, as well as predict the extent of these grainstones in analogous subsurface ooid grainstone reservoirs.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013