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TitleOrganic petrography and scanning electron microscopy imaging of a thermal maturity series from the Montney tight-gas and hydrocarbon liquids fairway
AuthorWood, J M; Sanei, H; Ardakani, O H; Curtis, M E; Akai, T
SourceThe Montney play of Western Canada: deposition to development; Bulletin of Canadian Petroleum Geology vol. 66, no. 2, 2018 p. 499-515
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20180003
PublisherCanadian Society of Petroleum Geologists
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceAlberta; British Columbia
NTS83M/03; 83M/04; 83M/05; 83M/06; 83M/11; 83M/12; 83M/13; 83M/14; 93P/01; 93P/02; 93P/07; 93P/08; 93P/09; 93P/10; 93P/15; 93P/16
Lat/Long WENS-121.0000 -119.0000 56.0000 55.0000
Subjectsfossil fuels; petroleum resources; hydrocarbons; gas; oil; bitumen; asphalt; paraffin content; heavy oil; hydrocarbons, light; condensate; thermal maturation; thermal history; petrographic analyses; scanning electron microscope analyses; drill core analyses; hydrocarbon migration; source rocks; bedrock geology; lithology; sedimentary rocks; siltstones; pressure-temperature conditions; organic residues; porosity; pore structure; wells; Montney Formation; Western Canada Sedimentary Basin; burial depths; organic matter; dissociated fractions; Phanerozoic; Mesozoic; Triassic
Illustrationslocation maps; geoscientific sketch maps; tables; photomicrographs; flow diagrams
ProgramShale Reservoir Characterization, Geoscience for New Energy Supply (GNES)
Released2018 06 01
AbstractOrganic petrography and field emission scanning electron microscopy (FESEM) images of drill-core samples from five wells comprising a thermal maturity series through the Montney Formation are used to document and interpret the thermal evolution of migrated secondary organic matter (bitumen and oil) from the late oil window into the dry gas window. The present-day organic matter (OM) consists almost entirely of pore-filling secondary OM that migrated into the organic-lean siltstones of the Montney Formation as liquid hydrocarbons. With increasing burial depth and changing temperature, pressure and compositional conditions, the originally introduced oil became unstable and dissociated into different fractions. These dissociated hydrocarbon fractions underwent secondary cracking resulting in a range of solid and fluid hydrocarbon products including: natural gas, condensate, light oil, fluid-like hydrocarbon residue (FHR) and solid bitumen and pyrobitumen. The solid to semi-solid secondary OM products have distinct characteristics in each of the late oil, wet gas and dry gas windows. The wide range of OM textures observed undoubtedly reflect a complex interplay of many organic maturation mechanisms: however, petrographic observations in this study suggest important distinctions in how the different dissociated fractions of the original oil matured. The dissociated asphalt-rich fraction, which precipitated as globular or granular aggregates in the central portions of large open pores, matured and consolidated into solid bitumen (oil and wet gas windows) and pyrobitumen (dry gas window). Solid bitumen/pyrobitumen accumulations have different degrees of organic porosity that partially reflect the variable composition of the precursor asphalt fraction. The early paraffin-rich heavy oil fraction matured into paraffin wax (late oil window), FHR (wet gas window) and carbon residue (dry gas window) that coats grain surfaces and fills the finer interstices of the original pore network. Differences in OM maturity operated at the micrometer scale such that, in the dry gas window, non-porous pyrobitumen in large pores is commonly observed next to highly porous pyrobitumen associated with clays in smaller pores.
Summary(Plain Language Summary, not published)
Organic petrography and field emission scanning electron microscopy (FESEM) images of drill-core samples from five wells of the Montney Formation are used to document and interpret the thermal evolution of migrated secondary organic matter (bitumen and oil) from the late oil window into the dry gas window.
GEOSCAN ID308114