Geochemical characterisation of heavily biodegraded tar sand bitumens by catalytic hydropyrolysis

Catalytic hydropyrolysis was used to release the aliphatic biomarkers covalently bound within the asphaltene structure of highly biodegraded Nigerian tar sand bitumens. Unlike the free aliphatic hydrocarbons extracted from the bitumen, the hydropyrolysis products of the asphaltenes afford aliphatic biomarkers having the characteristics of the initial unaltered oil, which had been trapped within the asphaltene matrix of the bitumen and protected from biodegradation processes. The biomarker profiles obtained allow proper characterisation of the bitumen in terms of source and thermal maturity. Catalytic hydropyrolysis is also capable of releasing aromatic hydrocarbons that can be used in the geochemical characterisation of the bitumen.