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TitleEffects of nanoporosity and surface imperfections on solid bitumen reflectance (BRo) measurements in unconventional reservoirs
AuthorSanei, H; Haeri-Ardakani, O; Wood, J M; Curtis, M E
SourceInternational Journal of Coal Geology vol. 138, 2015 p. 95-102,
Alt SeriesEarth Sciences Sector, Contribution Series 20140569
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS83G/10; 93P/08; 93P/10
Lat/Long WENS-115.0000 -114.5000 49.7500 49.5000
Lat/Long WENS-120.5000 -120.0000 55.5000 55.2500
Lat/Long WENS-120.5000 -120.5000 55.7500 55.5000
Subjectseconomic geology; geophysics; fossil fuels; bitumen; bitumen classification; porosity; thermal maturation; oil; hydrocarbon generation; petroleum exploration; petroleum resources; source rocks; bitumen reflectance; Paleozoic; Triassic; Jurassic
Illustrationsphotomicrographs; graphs; tables
ProgramShale Reservoir Characterization, Geoscience for New Energy Supply (GNES)
AbstractBitumen reflectance (BRo) is an alternative maturity indicator to vitrinite reflectance (VRo) in Lower Paleozoic and marine rocks where few higher plant macerals can be found. In unconventional petroleum rocks, locally exuded and/or migrated oil are retained in the tight rocks and thermally and diagenetically consolidated into solid bitumen and pyrobitumen. Finding suitable bitumen macerals for BRo measurements pose a challenge in indicating the proper thermal maturity. This study reports the effects of surface imperfections caused by nanoporosity, surface granularities, and impurities on measuring BRo in core samples from the Jurassic Nordegg Shale (shale oil) and the Triassic Montney siltstone (tight gas) in the Western Canada Sedimentary Basin. The degree that bitumen's surface imperfections influence any given reflectance measurement was controlled by changing the probe size area. The larger the measuring probe, the higher the degree of surface imperfections is included in BRo readings. The effect is quantified in this paper, showing up to 27% diminishment of mean BRo values when the probe size increased from 0.31 to 5.85 ?m2. The mode in which bitumen accumulates within the rock has a strong influence on the degree of surface imperfections. Bitumen which is disseminated within clay matrix introduces a high degree of nanoporosity and mineral interference and hence will result in lowest BRo. In contrast, inclusions of high reflecting micrinite or diagenetic minerals such as pyrite result in higher BRo. These effects can vary at the microscopic scale leading to multiple populations of reflectance readings and difficult interpretations of thermal maturity.
Summary(Plain Language Summary, not published)
This article discusses the effects of nano-porosity and measuring probe size on bitumen reflectance measurements. In this study, a best practice for reliable bitumen reflectance measurements was provided.