Reconstructing the provenance, depositional environment, and burial history of late Paleozoic shale of the Midland Basin (West Texas) – an integrated organic matter maturation and clay diagenesis study

Abstract

The Midland Basin is a long-standing significant hydrocarbon basin within the larger Permian Basin of southern United States. However, despite being highly prolific, very limited research has emphasized on clay mineralogy, trace element geochemical data, and organic matter of unconventional shale reservoirs, especially within the margins of the Midland Basin. Increased interest in unconventional shales has provided an opportunity to study these shales through various analytical techniques to understand the origin, depositional, and diagenetic histories of both inorganic and organic constituents. Late Paleozoic (Mississippian, Pennsylvanian, and Permian) shale core sections from the Midland Basin margin and interbasin will be the focus of this study. Analytical techniques such as XRD, SEM-EDS, and QEMSCAN will be used to determine modal mineralogy and petrography, with emphasis on clay morphology and phase chemistry. Trace element geochemistry will be determined by ICP-MS. Organic petrography will be used to determine dominant organic constituents needed to elements the nature of depositional environment as well as the conditions of peak thermal maturity. The latter can then be combined with clay mineral indices to provide a robust diagenetic model to better understand the dynamics of burial and distribution of reservoir characteristics of these shales. Research objectives are aimed to establish characteristics of unconventional shale reservoirs within an understudied area of the Midland Basin. Data collected will then be applied to known models to better understand the dynamics of shale constituent genesis and diagenetic development. Diagenetic effects on fine-grained clastic rocks inherently influence reservoir characteristics such as microporosity, permeabilitiy, and level of organic matter maturation, therefore essential features identified in this investigation can be applied to furthering the workflow of evaluating and assessing unconventional shale reservoir quality and distribution within known and prospective areas.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects