Chemostratigraphy of the Pennsylvanian-Permian Section in the Midland Basin of West Texas with Focus on the Wolfcamp Series: Developing a Stronger Mudrock Correlation and Paleo-Depositional Framework

Milton Cortez III¹, Robert Baumgardner², H. Scott Hamlin², and Harry Rowe¹
¹ University of Texas at Arlington, Arlington, Texas 76019
² Bureau of Economic Geology, Austin, Texas 78713–8924

The purpose of this research is to develop a chemostratigraphy dataset for West Texas Midland Basin drill cores that focuses on the late Pennsylvanian to early Permian strata. Interpretation of the dataset will help to refine well-to-well correlation and to better understand well-log results, and the spatial variability in depositional environments around the basin. Furthermore, chemostratigraphic data may also prove valuable for assessing post-depositional signatures that may vary across the basin. Ultimately, it is anticipated that a well-defined chemostratigraphy will be developed from Atokan-age clastics, stratigraphically upward through the lower Permian-age Upper Spraberry Formation. Four cores have been analyzed in Martin and Reagan counties. Preliminary handheld energy-dispersive x-ray fluorescence (HH-ED-XRF) results will be shown from the Atoka, Strawn, Dean, Spraberry, and Wolfcamp series. Powder samples for a subset of intervals were analyzed for TIC and TOC, as well as stable carbon and nitrogen isotopes of organic matter. Samples taken from sandstone beds were not analyzed due to low concentrations of carbon and lack of a matrix-matched calibration for the XRF. Mineralogical results, determined using x-ray diffraction (XRD), have been related to XRF results in order to support findings. A comparison of geochemical and well-log data of all four cores will be presented. The ultimate goal of the research is to correlate sedimentary stratigraphic trends and assumptions to chemostratigraphic findings in order to refine our overall knowledge of the Midland Basin.

AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012