Source rock heterogeneity and migrated hydrocarbons in the Triassic Shublik Formation and their implication for unconventional resource evaluation in Arctic Alaska

This organic geochemical study of the Triassic Shublik Formation aims to investigate source rock heterogeneity, facies variation, and source and maturity of migrated hydrocarbons in the Tenneco Phoenix-1 well (OCS-Y-0338), drilled in offshore Arctic Alaska in 1986. Recovered continuous core is nearly 90 m thick continuous section throughout the entire Shublik Formation. Guided by previously published analyses of the Phoenix-1 core by Robison et al. (1996), this study provides the most detailed core-based analysis of the Shublik Formation to date. Analysis of biomarkers and diamondoids combined with Rock-Eval pyrolysis results indicates evidence of mature migrated hydrocarbons that may have affected previous interpretations of organic matter type and maturity of this core. Despite the variable lithology, four identified source rock intervals contain oil-prone type I kerogens with maturity ranging from immature to marginally mature. Biomarker analysis indicates the presence of two organic facies deposited under anoxic clay-poor and suboxic clay-rich environments that likely generated genetically distinct oils.