Characterization of the Cretaceous in the Sable Sub-Basin, Offshore Nova Scotia, by Detailed Stratigraphic and Sedimentological Analysis to Determine Source Rock and Correlation to Worldwide Oceanic Anoxic Events

Abstract

The Sable sub basin in the Scotian Basin located offshore Nova Scotia has been explored during the past fifty years with over 200 wells drilled. The Play Fairway Analysis produced by the Nova Scotia Department of Energy with OETR (Offshore Energy Technical Research) and RPS Energy UK in 2009 concluded that there are large reserves of both oil and gas in the area, huge tracts of which are largely unexplored. Oil and gas discoveries have been made in Lower Cretaceous fluvial-deltaic sequences of the Logan Canyon and Missisauga formations, both of which are producing in the sub basin. Source rocks for these deposits are unproven but suspected to be lower Jurassic shales. However, speculation to the existence of Cretaceous shale source rocks can also be made. Detailed lithostratigraphic analysis of the drill cuttings and cores from the 57 wells from the Cretaceous in the Sable sub-basin elucidate the stratigraphy, sedimentology and diagenesis associated with these deposits. Calcareous and siliceous diagenetic cements impact reservoir quality. Patterns of deposition during pulses of transgression and regression along the shelf can be delineated. In addition to establishing correlations on a basinal level, wireline logs have been found to be of qualitative use in establishing TOC richness. Relevance of this methodology will be reviewed. At the same time, mapping of glauconite, black and green shale, and carbonaceous material point to ocean anoxia that can be linked to worldwide oceanic anoxic events (OAE's).

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016