AAPG Middle East Region, Shale Gas Evolution Symposium

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Optical Characterization and Hydrocarbon Potential Determination of Organic Matter in Early Paleozoic Organic-Rich Shales


Despite the importance of pre-Devonian organic-rich shales as source rocks, the composition of the organic matter is usually unknown. Typically the organic matter composition is inferred from bulk geochemical analysis, as it is rapid and generic classification schemes exist. The results are a weighted average of the characteristics of the individual organic matter component types, mixed together in one sample. Optical kerogen analysis uses both transmitted and fluorescent light microscopy to identify the nature of the organic components that have been separated from a sample (Jaeger, 2013). Based on this optical characterization of the organic matter at an organic component level, it is possible to: a) Identify the organic components along with their relative abundances. b) Quantify the ratio of hydrocarbon productive versus nonproductive organic matter. c) Determine the proportions of potentially oil-prone versus gas-prone organic matter. d) Analyze the preservation of OM groups as an indicator of depositional conditions and degree of hydrocarbon generation, as well as the identification of reworking. This poster illustrates some of the knowledge gained, during optical kerogen analysis of a proven hydrocarbon sourcing pre-Devonian organic-rich shale.