New models for determining thermal maturity and hydrocarbon potential in Marcellus Shale
Progress in hydraulic fracturing and horizontal drilling techniques for shale gas production has revolutionized the US energy sector. Despite these advancements, there is a still a low recovery of gas in place (~20-30%) and a rapid decline in well productivity in unconventional shale gas wells. One of the major limitations in improving the production efficiency is the lack of understanding of molecular-level properties of shales, especially that of kerogen. Kerogen is an insoluble geo-macromolecule component of black shales that controls and the amount and type of hydrocarbons (HCs) generated and expelled. Significant advancements have been made recently to develop kerogen structural models using spectroscopic and molecular simulation techniques. However, a large gap still exists in understanding the evolution of structural components of kerogen with maturation and their HC generative potential. In this study, we characterized different molecular components (structural parameters) of kerogen in a Marcellus Shale maturity series (VRo ranging from 0.8 to 3) using 13C solid-state NMR. The variations in these molecular components provided knowledge about the evolution of the nanostructure of kerogen with increasing thermal maturation and the key molecular contributors of HC generation. Additionally, we utilized the variations in kerogen molecular parameters of the maturity series to develop new regression models for accurate determination of thermal maturity and HC generative potential of Marcellus Shale.
AAPG Datapages/Search and Discovery Article #90335 © 2018 AAPG 47th Annual AAPG-SPE Eastern Section Joint Meeting, Pittsburgh, Pennsylvania, October 7-11, 2018