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TitleSolid bitumen in the Montney Formation: diagnostic petrographic characteristics and significance for hydrocarbon migration
AuthorWood, J M; Sanei, H; Ardakani, O H; Curtis, M E; Akai, T; Currie, C
SourceInternational Journal of Coal Geology vol. 198, 2018 p. 48-62, https://doi.org/10.1016/j.coal.2018.09.004
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20180053
PublisherElsevier
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html; mp4 (Windows Media Players)
Subjectsfossil fuels; geochemistry; sedimentology; petroleum resources; hydrocarbon potential; hydrocarbon migration; oil; gas; fluid flow; pore structure; petrographic analyses; bedrock geology; lithology; sedimentary rocks; shales; siltstones; structural features; bitumen; pyrobitumen; kerogen; thin section microscopy; scanning electron microscope analyses; core samples; wells; sedimentary structures; diagenesis; ichnology; depositional environment; reservoir rocks; Montney Formation; organic petrology; methodology; organic matter; unconventional energy resources; tight gas; Phanerozoic; Mesozoic; Triassic
Illustrationstables; photomicrographs
ProgramShale Reservoir Characterization, Geoscience for New Energy Supply (GNES)
Released2018 09 05
AbstractThe petrographic study of organic matter (OM) in fine-grained, shale and tight rocks can be complicated by ambiguities in distinguishing primary kerogen (deposited OM) from secondary solid bitumen (migrated and solidified petroleum). In this study, complementary thin-section, field emission scanning electron microscopy (FESEM) and organic petrology methods are used to examine core samples acquired from petroleum wells drilled into the Triassic Montney Formation in western Canada. The results show that OM in the medium- to coarse-grained siltstones of the Montney tight-gas and hydrocarbon liquids fairway is composed almost entirely of pore-filling solid bitumen/pyrobitumen. Here, we document a range of petrographic characteristics that are diagnostic of the solid bitumen and its origin as migrated liquid petroleum. These solid bitumen characteristics include (1) void-filling habit, (2) enclosure of earlier authigenic minerals, (3) margins with smoothly curved meniscate form, (4) internal flow structure, (5) entrained and aligned clay minerals, (6) isopachous rims along inorganic pore walls, (7) globular/granular aggregates and (8) fracture-filling habit. The petrographic results also show that the migration and flow of original oil through the thick Montney Formation (up to 340 m) was controlled at the micro-scale by sedimentary, ichnological, diagenetic and structural features. These features combined to form highly complex pathways and baffles for hydrocarbon migration. Petrographic recognition of OM as secondary migrated solid bitumen rather than primary deposited kerogen has vital significance for assessing unconventional shale and tight hydrocarbon plays including OM typing from Rock-Eval pyrolysis, interpreting depositional facies and environments, and evaluating reservoir quality.
Summary(Plain Language Summary, not published)
In this study, we use complementary thin-section, field emission scanning electron microscopy (FESEM) and organic petrology methods to examine core samples acquired from petroleum wells drilled into the Triassic Montney Formation in western Canada in order to provide diagnostic petrographic characteristics of solid bitumen in the Montney Formation.
GEOSCAN ID308248