Tying Core Descriptions and Optical Petrography With XRF Geochemical Data for a Detailed Characterization of the Mississippian Barnett Formation in the Southern Fort Worth Basin of North-Central Texas

Abstract

The Barnett Formation is a Mississippian mudrock succession located in the Fort Worth Basin, FWB, of north-central Texas. It was deposited over a 25-million year time period in a foreland basin that resulted from the collision of Laurasia and Gondwana. In the northern FWB, the East Newark Field has been developed as an unconventional shale-gas play. This study examined a dense, 30-core network that covers the southern reach of the FWB, an area extending through four counties adjacent to the Llano Uplift. Characterization of the Barnett Formation in the study area was achieved by integrating core descriptions and optical petrography, with XRF data in order to look at the mudrock facies at a high-resolution. Hierarchical cluster analysis was used to analyze the XRF data which helped in identifying the litho-chemo-facies present in the suite of cores. The litho-chemo-facies helped to define the stratal architecture (leading to continuity of strata) and distinguish the variability of the paleoceanographic conditions throughout the section. The high-resolution geochemical data highlights reservoir heterogeneities that are not apparent from core attributes alone. The methodology outlined for this study examines an unconventional mudrock system at a scale that is useful for improving reservoir drainage by understanding and characterizing reservoir heterogeneity. The data has allowed for an improved understanding of the stratal architecture and a refined depositional model for the formation has been developed. The results on stratal architecture and litho-chemo-facies continuity can be applied to other shale-reservoir systems such as the Barnett Shale.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016