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The AAPG/Datapages Combined Publications Database

Tulsa Geological Society


2003 Midcontinent Section Meeting (Tulsa) Papers and Abstracts, 2003

Cromwell Previous HitSandstoneNext Hit Core Studies and Prediction of Previous HitReservoirNext Hit Trends, Haskell County, Oklahoma: Abstract

Bryant Reasnor1, Dennis Kerr2


Previous HitReservoirNext Hit quality in the gas-productive Morrowan Cromwell Previous HitSandstoneNext Hit is a challenge to correlate and map. This is mainly due to the low well log (GR and fO) contrast between Previous HitreservoirNext Hit and nonreservoir quality sandstones and a poorly understood depositional setting in previous studies. Facies architecture analysis using two cores and approximately 100 well logs covering four townships provide a means for better prediction of Previous HitreservoirNext Hit quality.

From detailed core studies, the Cromwell is regarded as having been deposited in a storm-dominated shelf setting. Physical and biogenic structures coupled with Previous HitporosityNext Hit determined from thin section analysis indicate that better quality Previous HitreservoirNext Hit rock is developed in the thickest part of sand-ridge deposits. These sandstones exhibit low-angle cross strata with superimposed ripple stratification, and are very well sorted with modal class of upper very fine sand with 10% clay matrix. Primary intergranular Previous HitporosityNext Hit is quartz overgrowth and carbonate cement reduced. Thin section Previous HitporosityNext Hit of 10% is combined primary Previous HitporosityNext Hit and carbonate cement dissolution enhanced secondary Previous HitporosityNext Hit.

Parasequence scale correlation and mapping is key to Previous HitpredictingNext Hit sand-ridge trends. Locally, the informal Cromwell lithostratigraphic unit is made up of five retrogradational parasequence sets and includes two third-order sequence boundaries. Parasequence isopach maps delineate the geometry and trends of the sand ridges. Given the surrounding facies and retrogradational architecture, the best Previous HitreservoirTop quality sandstones are located in the middle of the parasequence sets.


Acknowledgments and Associated Footnotes

1 The University of Tulsa, Tulsa, OK

2 The University of Tulsa, Tulsa, OK

Copyright © 2006 by the Tulsa Geological Society