SOURCE-ROCK DISPERSED ORGANIC-MATTER CHARACTERIZATION - TSOP RESEARCHSUBCOMMITTEE RESULTS

Because sedimentary organic matter consists of a diverse mixture of or ganic components with different properties, a combination of chemical and petrographic results offers the most complete assessment of source rock properties. The primary purpose of this Society for Organic Petr ology (TSOP) subcommittee is to contribute to the standardization of k erogen characterization methods. Specific objectives include: (1) eval uation of the applications of different organic matter (petrographic) classifications and terminology, and (2) integration of petrographic a nd geochemical results. These objectives were met by completing questi onnaires, and petrographic, geochemical and photomicrograph round-robi n exercises. Samples that were selected for this study represent diffe rent petrographic and geochemical properties, and geologic settings to help identify issues related to the utilization of different classifi cations and techniques. Petrographic analysis of the organic matter wa s completed using both a prescribed classification and the individual classification normally used by each participant. Total organic carbon (TOC), Rock-Eval pyrolysis and elemental analysis were also completed for each sample. Significant differences exist in the petrographic re sults from both the prescribed and individual classifications. Althoug h there is general agreement about the oil- vs gas-prone nature of the samples, comparison of results from individual classifications is dif ficult due to the variety of nomenclature and methods used to describe an organic matter assemblage. Results from the photomicrograph exerci se document that different terminology is being used to describe the s ame component. Although variation in TOC and Rock-Eval data exists, ge ochemical results define kerogen type and generative potential. Recomm endations from this study include: (1) A uniform organic matter classi fication must be employed, which eliminates complex terminology and is capable of direct correlation with geochemical parameters. (2) A stan dardized definition and nomenclature must be used for the unstructured (amorphous) organic matter category. Subdivisions of this generalized amorphous category are needed to define its chemical and environmenta l properties. (3) Standardized techniques including multimode illumina tion, types of sample preparations and data reporting will help elimin ate variability in the type and amount of organic components reported.