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

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 indicated that migrated oil had enough force to overcome the tensile strength of oil shale matrix and penetrate the oil shale. Migrating fluid caused thermal alteration of the 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 oil shale. The low permeability oil shale acted as a seal/aquitard and created a diagenetic ‘front’ by slowing the advance of migrating oil, resulting in the formation of a reaction zone. Migrated solid bitumen consisted of both soluble solid bitumen types such as gilsonite and glance-pitch, and insoluble solid bitumen such as wurtzilite and albertite. 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%) compared to the other Albert oil shales (TOC =