The Paleozoic Hudson Bay Basin in Northern Canada: New Insights Into Hydrocarbon Potential of the Last North-America Conventional Frontier Basin

Abstract

The Hudson Bay Basin is the largest intracratonic basin in North America although it is the only one without any proven hydrocarbon reserves. The stratigraphic succession that fills the basin consists mainly of Paleozoic strata, with a maximum preserved thickness of about 2500 m. The Paleozoic succession includes Ordovician to Devonian shallow marine carbonates, reefs and shales with locally thick Devonian evaporites. The Paleozoic strata are locally unconformably overlain by a thin Mesozoic/Cenozoic cover of non-marine and marine strata. From 1964 to 1985, over 46,000 line-km of seismic reflection data were acquired and 4 onshore and 5 offshore exploration wells drilled. The data acquired at that time led to pessimistic conclusions on source rocks and the thermal rank of the basin and resulted in the stoppage of exploration activities. However, hydrocarbon shows or indicators were identified in well log data and seismic reflection profiles. The likelihood of active petroleum system has also been recently supported by recognition of pockmarks on the seafloor and possible marine oil slicks identified on satellite images. New studies of geological, geophysical and biostratigraphic data reveal that the Hudson Bay Basin had an irregular subsidence and uplift history. Syn-tectonic deposition occurred during the Late Ordovician (?) to Early Devonian and sag-basin deposition during the Middle to Late Devonian. The basin contains four unconformity-bounded sequences, with significant depocenter migration over time. Analyses of petroleum-system data indicate the Hudson Bay Basin has higher petroleum potential than previously considered. Porous platform limestones, reefs, hydrothermal dolomites, and siliciclastics form potential hydrocarbon reservoirs. Upper Ordovician organic-rich shales with Type II-S organic matter are recognized at several locations in the basin. Newly acquired organic matter reflectance and Rock-Eval Tmax data indicate Ordovician – Silurian strata locally reached the oil window. Basin modelling demonstrates significant potential for oil generation and expulsion from Ordovician source rocks. Five petroleum play types are identified in the Hudson Bay Basin, including an untested fault-sag/hydrothermal dolomite play. The synthesis of the petroleum system information indicates that the Hudson Bay Basin is, at least locally, prospective for oil accumulations.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015