Structural analysis of some marine kerogens through a combined chemical and thermal degradation approach

Abstract

Approximately 95% of the sedimentary organic matter in the geosphere exists in the form of kerogen, a macromolecular substance that is insoluble in water and normal organic solvents. There have been numerous attempts to elucidate the chemical structure of kerogens since kerogen is the main precursor of crude oil. However, since kerogens consist of high-molecular weight compounds that are not amenable to chromatographic analysis, it is difficult to elucidate their structures. The objective of the research described in this thesis was to gain a better insight in the chemical composition of marine kerogens the predominant precursors of crude oils. In the first part (Chapters 2-3) two different combinations of techniques, i.e. combined pyrolysis and stable carbon isotope analysis and combined chemical and thermal degradation, are introduced. These techniques are used to study several kerogens of different ages and origins in order to determine the various constituents present in kerogen and in order to gain information on the origin and importance of these constituents. In the second part (Chapters 4-7) some of these constituents present in kerogen and the reactions during thermal degradation are studied in more detail.