Understanding and distinguishing reflectance measurements of solid bitumen and vitrinite using hydrous pyrolysis: Implications to petroleum assessment
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- 1 June 2018
- journal article
- research article
- Published by American Association of Petroleum Geologists AAPG/Datapages in AAPG Bulletin
- Vol. 102 (06), 1119-1140
- https://doi.org/10.1306/08291717097
Abstract
Solid bitumen is a common organic component of thermally mature shales and typically is identified by embayment against euhedral mineral terminations and by groundmass textures. However, because these textures are not always present, solid bitumen can be easily misidentified as vitrinite. Hydrous- pyrolysis experiments (72 hr, 300 degrees C-360 degrees C) on shale and coal samples show that solid-bitumen reflectance (BRo) in shales is less responsive to thermal stress than vitrinite reflectance (R-o) in coal. This effect is most pronounced at lower experimental temperatures (300 degrees C-320 degrees C), whereas reflectance changes are more similar at higher temperatures (340 degrees C-360 degrees C). Neither a "vitrinitelike" maceral nor "suppressed vitrinite" was identified or measured in our sample set; instead, the experiments show that solid bitumen matures slower than vitrinite. The data may explain some reports of "R-o suppression," particularly at lower thermal maturity (R-o <= 1.0%), as a simple case of solid bitumen being mistaken for vitrinite. Further, the experimental results confirm previous empirical observations that Ro and BRo are more similar at higher maturities (R-o > 1.0%). It is suggested that Ro suppression, commonly reported from upper Paleozoic marine shales of early to midoil window maturity, is a misnomer. This observation has important implications to petroleum exploration models and resource assessment, because it may change interpretations for the timing and spatial locations of kerogen maturation and petroleum generation.Keywords
This publication has 33 references indexed in Scilit:
- Review and update of the applications of organic petrology: Part 1, geological applicationsInternational Journal of Coal Geology, 2012
- Experimental kinetic study of organic matter maturation: Time and pressure effects on vitrinite reflectance at 400°COrganic Geochemistry, 2011
- Three common source rock evaluation errors made by geologists during prospect or play appraisalsAAPG Bulletin, 2009
- The effect of water pressure on hydrocarbon generation reactions: some inferences from laboratory experimentsPetroleum Geoscience, 2009
- Timing and petroleum sources for the Lower Cretaceous Mannville Group oil sands of northern Alberta based on 4-D modelingAAPG Bulletin, 2009
- Polyphase thermal evolution in the Infra-Cambrian Ara Group (South Oman Salt Basin) as deduced by maturity of solid reservoir bitumenOrganic Geochemistry, 2007
- The influence of extractable organic matter on vitrinite reflectance suppression: A survey of kerogen and coal typesInternational Journal of Coal Geology, 2007
- Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessmentAAPG Bulletin, 2007
- Geologic framework of the Mississippian Barnett Shale, Barnett-Paleozoic total petroleum system, Bend arch–Fort Worth Basin, TexasAAPG Bulletin, 2007
- The petroleum generation potential and effective oil window of humic coals related to coal composition and ageInternational Journal of Coal Geology, 2006