Chemostratigraphy and Geochemical Analysis Comparing Two Drill Cores from the Mississippian Barnett Shale, Fort Worth Basin, Texas

The objective of the project is to develop and interpret the geochemistry of the Mesquite #1 Barnett Shale core in Hamilton County for the purposes of 1) comparing to the Blakely core, Wise County, TX from a previously published report that has chosen to remain anonymous, 2) developing a system to correlate various Barnett Shale cores using trace metals, and 3) refining the stratigraphy of the area for the oil and gas industry. Methods used to carry out the project include: real-time geochemical analysis using x-ray fluorescence (XRF) of the core face, LECO Sulfur and total organic carbon (TOC) analysis. The Mesquite #1 core shows stratigraphically conformable boundaries with the lower unit, the Ellenberger Limestone as well as with the upper unit, the Marble Falls Limestone. The geochemical results of this core demonstrate three discrete units based on %Ca content and/or variability. The Ellenberger Limestone, ~3 feet at the base of the core, is characterized by very high %Ca concentrations (46% to 80% CaCO3). The main shale unit in the middle, approximately 140 feet thick, has overall significantly lower %Ca concentrations (4% to 10% CaCO3) with much lower variability, but does have calcite concretions and nodules throughout. The top of the shale unit shows a gradational change to higher %Ca concentrations as it becomes the Marble Falls Limestone with %Ca content similar to that of the Ellenberger Limestone.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California