Petrology and geochemistry of migrated hydrocarbons associated with the Albert Formation oil shale in New Brunswick, Canada

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Samples of the Carboniferous oil shale of the Albert Formation in New Brunswick, Canada, were examined using reflected white and fluorescence light microscopy, Rock-Eval pyrolysis, and ICP-MS (for elements). The presence of fractured filled solid bitumen in contact with, and within the Albert Formation oil shale, particularly in fractures at the right angle to the bedding of oil shale indicated that migrated oil had enough force to overcome the tensil strength of oil shale matrix, and penetrating the oil shale. Migrating fluid also caused thermal alteration of the oil shale matrix, as evident by the presence primary bitumen and oil droplets. The evidence of oil migration included the presence of solid bitumen and crystalline carbonates in contact with the immature oil shale. The low permeability oil shale acted as a seal/aquitard and created a diagenetic ‘front’ by reducing/slowing the advance of migrating oil, resulting in the formation of a reaction zone. Oil droplets were found in this reaction zone. Albertite was the only solid bitumen reported in the Albert Mine area previously. However, the present study found that migrated solid bitumen consisted of both soluble solid bitumen types such as gilsonite and glance-pitch, and non-soluble solid bitumen such as wurtzilite and albertite. The high hydrocarbon yield of oil shales in the Albert Mine area was due to the presence of various solid bitumen types associated with the oil shale and possibly slight thermal alteration that the oil shale experienced when it came in contact with migrating oil. The variation of Th/K ratio and TOC (wt%) indicates that most of oil shales from the Albert Mine area and within the vicinity of oil migration have higher content of TOC (17-25 wt%) as compared to the other Albert oil shales ( TOC=<10 %). The oil shales examined in this study were immature to marginally mature and had a wide range of hydrocarbon yield (2-213 L/Tonne). The highest hydrocarbon yield range (66-199 L/Tonne) was associated with oil shale outcrop samples collected in the Albert Mine itself, where the oil shale was heavily impregnated by migrated solid bitumen.

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Publication type Article
Publication Subtype Journal Article
Title Petrology and geochemistry of migrated hydrocarbons associated with the Albert Formation oil shale in New Brunswick, Canada
Series title Fuel
DOI 10.1016/j.fuel.2019.115922
Volume 256
Year Published 2019
Language English
Publisher Elsevier
Contributing office(s) Eastern Energy Resources Science Center
Description 115922, 17 p.
Country Canada
State New Brunswick
Other Geospatial Alberta Formation
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