Significance of isotopically labile organic hydrogen in the thermal maturation of source rocks

Status Start Date End Date Locations
completed Jan 1, 2000 Mar 31, 2009 All Counties
Director: Maria Mastalerz
Other Researchers: and Arndt Schimmelmann (Indiana University Dept. of Geological Sciences)
Issue: There is growing acceptance that the original organic hydrogen in immature kerogen is insufficient to account for all the organic hydrogen found in natural gas, oil, bitumen, and residual kerogen, after the process of thermal maturation in sedimentary basins. Hydrogen isotopic evidence suggests that hydrogen from formation waters reacts with kerogen to form “abiogenic organic” hydrogen, and can potentially boost yields of oil and gas in sedimentary basins. Reactions between inorganic water-hydrogen and kerogen through thermal maturation can be traced isotopically and, therefore, are highly relevant to understanding the formation of oil and natural gas from kerogen, and the thermal maturation of coal.
Objective: The main objective of the project is to evaluate the geochemical magnitude and significance of hydrogen isotopic exchangeability in kerogens.
Approach: We will quantify and chemically characterize the isotopic exchange of hydrogen between kerogen and ambient water-hydrogen across a wide range of thermal maturity, in artificial heating experiments of up to 1.5-yr duration, as well as in suites of kerogen samples reflecting natural gradients in maturity. Our analyses will focus on the classic kerogen types I, II, IIS, and III, but also characterize ambient water, extracted bitumen, and expelled oil. Further experiments will use artificial thermal maturation of model compounds.
Products: This multiyear project resulted in eight publications in international journals, one Ph.D. thesis, and support for two graduate students who adopted this project to be part of their Ph.D. thesis.
Benefits: The results will help describe and explain chemical reactivity of organic hydrogen in kerogens and fossil fuels, and aid in further understanding the influence of hydrogen on the hydrocarbon potential of sedimentary basins.