--> Understanding biogeochemical controls on spatiotemporal variations in total organic carbon in cores from Marcellus Shale Energy and Environment Laboratory

AAPG Eastern Section Meeting

Datapages, Inc.Print this page

Understanding biogeochemical controls on spatiotemporal variations in total organic carbon in cores from Marcellus Shale Energy and Environment Laboratory

Abstract

Shale reservoirs are a critical and rapidly growing area of energy where research lags behind exploration and production activity. Since shale is not only a hydrocarbon source but also a reservoir, one of the key geological factors controlling its hydrocarbon potential is the concentration of organic matter (OM), its maturity, and its type. In the course of the last 15 years, hydrocarbon exploration of shale reservoirs has revealed significant temporal and spatial variations in the quality and quantity of total organic carbon (TOC). This variability is directly attributed to geological and biotic conditions at the time of deposition however, the major controls on, and thus predictability of, organic-rich black shale deposition are still debated. The availability of pristine sidewall cores and an entire full hole core from Marcellus Shale Energy and Environment Laboratory (MSEEL) provides us the unique opportunity to significantly increase the resolution of subsurface stratigraphic characterization integrated with molecular /isotopic /elemental geochemistry to better understand the controls on lithofacies, including dilution by terrigenous detritus, OM productivity, preservation and decomposition in organic-rich black shales. Some of the traditional techniques like source rock analysis used to understand sources and types of OM have limited application in mature to highly mature shales due to their low hydrogen and oxygen indices. Biological markers or biomarkers are excellent indicators of OM sources, redox, and maturity. Biomarkers are chemically stable during sedimentation and early burial but their preservation potential also decreases with maturity. The availability of samples at MSEEL enables us to optimize extraction and analytical methods to characterize the abundance and type of biomarkers present in the highly mature dry gas window of Marcellus Shale. The biomarker data will be used in conjunction with C/N/S isotopes and elemental geochemistry to develop elemental and molecular fingerprints of source/type of OM, microbial cycling of OM, and paleoenvironment during deposition of MSEEL core.