--> Thermal Maturity Modeling of Organic-Rich Mudrocks in the Delaware Basin Using Raman Spectroscopy of Carbonaceous Material

AAPG ACE 2018

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Thermal Maturity Modeling of Organic-Rich Mudrocks in the Delaware Basin Using Raman Spectroscopy of Carbonaceous Material

Abstract

Raman spectroscopy of carbonaceous material (RSCM) is an emerging tool to investigate the peak temperature organic-rich sediments reach during burial and exhumation. Previously, peak temperature has been commonly determined using vitrinite reflectance (%Ro), which is subject to user bias, organic material composition, hydrogen-index, and pressure suppression. Because thermal maturity of organic material is an important factor in determining source rock viability, RSCM presents an opportunity to develop a quick, objective, and cost-effective alternative to %Ro immune to the bias of supression. This study proposes to test the viability of RSCM thermometry on well cuttings retrieved from Permian through Ordovician intervals of the Delaware Basin in West Texas to further investigate peak temperatures and paleogeothermal gradients. The Delaware Basin displays counterintuitive gas-oil ratios, with higher ratios in the shallower western portions than in the deeper eastern portions. This suggests that western portions were previously buried deeper and later exhumed to modern depths, or subject to a variable geothermal gradient as a result of increased heat flow from igneous intrusions. This study will construct a paleogeothermal profile of the basin by incorporating 12 wells along five E/W and N/S trending cross sections, including wells which have intersected igneous intrusions. RSCM measurements will be compared against existing %Ro and pyrolysis data to constrain regional thermal maturity patterns. Igneous bodies will be dated using Zircon U-Th/He LA-ICP-MS to determine timing of elevated maturity. Combined with 1D and 2D backstripping methods, this study will provide insights to the lateral distribution of subsidence, exhumation, and elevated heat flow.