Source rock/dispersed organic matter characterization-TSOP research subcommitee results

Because sedimentary organic matter consists of a diverse mixture of organic 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 Petrology (TSOP) subcommittee is to contribute to the standardization of kerogen characterization methods. Specific objectives include: (1) evaluation of the applications of different organic matter (petrographic) classifications and terminology, and (2) integration of petrographic and geochemical results. These objectives were met by completing questionnaires, and petrographic, geochemical and photomicrograph round-robin exercises. Samples that were selected for this study represent different petrographic and geochemical properties, and geologic settings to help identify issues related to the utilization of different classifications and techniques. Petrographic analysis of the organic matter was 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 results from both the prescribed and individual classifications. Although there is general agreement about the oil- vs gas-prone nature of the samples, comparison of results from individual classifications is difficult due to the variety of nomenclature and methods used to describe an organic matter assemblage. Results from the photomicrograph exercise document that different terminology is being used to describe the same component. Although variation in TOC and Rock-Eval data exists, geochemical results define kerogen type and generative potential. Recommendations from this study include: (1) A uniform organic matter classification must be employed, which eliminates complex terminology and is capable of direct correlation with geochemical parameters. (2) A standardized 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 environmental properties. (3) Standardized techniques including multimode illumination, types of sample preparations and data reporting will help eliminate variability in the type and amount of organic components reported

Source rock/dispersed organic matter characterization-TSOP research subcommitee results

Because sedimentary organic matter consists of a diverse mixture of organic 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 Petrology (TSOP) subcommittee is to contribute to the standardization of kerogen characterization methods. Specific objectives include: (1) evaluation of the applications of different organic matter (petrographic) classifications and terminology, and (2) integration of petrographic and geochemical results. These objectives were met by completing questionnaires, and petrographic, geochemical and photomicrograph round-robin exercises. Samples that were selected for this study represent different petrographic and geochemical properties, and geologic settings to help identify issues related to the utilization of different classifications and techniques. Petrographic analysis of the organic matter was 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 results from both the prescribed and individual classifications. Although there is general agreement about the oil- vs gas-prone nature of the samples, comparison of results from individual classifications is difficult due to the variety of nomenclature and methods used to describe an organic matter assemblage. Results from the photomicrograph exercise document that different terminology is being used to describe the same component. Although variation in TOC and Rock-Eval data exists, geochemical results define kerogen type and generative potential. Recommendations from this study include: (1) A uniform organic matter classification must be employed, which eliminates complex terminology and is capable of direct correlation with geochemical parameters. (2) A standardized 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 environmental properties. (3) Standardized techniques including multimode illumination, types of sample preparations and data reporting will help eliminate variability in the type and amount of organic components reported

Classification of liptinite – ICCP System 1994

The liptinite maceral group has been revised by ICCP in accordance with the ICCP System 1994. After the revision of the classifications of vitrinite (ICCP, 1998), inertinite, (ICCP, 2001) and huminite (Sykorova et al., 2005) this liptinite classification completes the revised ICCP maceral group classifications. These classifications are collectively referred to as the “ICCP System 1994”. In contrast to the previous ICCP Stopes Heerlen (ICCP, 1963, 1971, 1975, 1993) this new classification system is applicable to coal of all ranks and dispersed organic matter. The classification as presented here was accepted in the ICCP Plenary Session on September 11, 2015 at the ICCP Meeting in Potsdam. The decision to publish this classification in the recent form was accepted at the ICCP Plenary Session on September 23, 2016 in Houston

Testing reproducibility of vitrinite and solid bitumen reflectance measurements in North American unconventional source-rock reservoir petroleum systems

An interlaboratory study (ILS) was conducted to test reproducibility of vitrinite and solid bitumen reflectance measurements in six mudrock samples from United States unconventional source-rock reservoir petroleum systems. Samples selected from the Marcellus, Haynesville, Eagle Ford, Barnett, Bakken and Woodford are representative of resource plays currently under exploitation in North America. All samples are from marine depositional environments, are thermally mature (T >445 °C) and have moderate to high organic matter content (2.9–11.6 wt% TOC). Their organic matter is dominated by solid bitumen, which contains intraparticle nano-porosity. Visual evaluation of organic nano-porosity (pore sizes 1.0 produced lowest R values, generally ≤0.5% (absolute reflectance), similar to a prior ILS for similar samples. Other traditional approaches to outlier removal (outside mean ± 1.5*interquartile range and outside F10 to F90 percentile range) also produced similar R values. Standard deviation values < 0.15*(VR or BR) reduce R and should be a requirement of dispersed organic matter reflectance analysis. After outlier removal, R values were 0.1%–0.2% for peak oil thermal maturity, about 0.3% for wet gas/condensate maturity and 0.4%–0.5% for dry gas maturity. That is, these R values represent the uncertainty (in absolute reflectance) that users of vitrinite and solid bitumen reflectance data should assign to any one individual reported mean reflectance value from a similar thermal maturity mudrock sample. R values of this magnitude indicate a need for further standardization of reflectance measurement of dispersed organic matter. Furthermore, these R values quantify realistic interlaboratory measurement dispersion for a difficult but critically important analytical technique necessary for thermal maturity determination in the source-rock reservoirs of unconventional petroleum systems.This research was funded by the USGS Energy Resources Program