Petroleum System Modeling of the Shelburne Sub-Basin: An Insight on the Petroleum Potential of the SW Nova Scotia

Abstract

Abstract

The Department of Energy and the Offshore Energy Research Association (OERA) have published in 2015 an integrated hydrocarbon (HC) exploration study concerning the offshore of the SW Nova Scotia. It extends the 2011 Play Fairway Analysis (PFA) to the western limit of the Canadian Atlantic Shelf, covering the Shelburne Sub-basin area. The HC resources assessment is based on a 3D model TemisFlow (TF) with a Full Darcy migration of fluids. The Shelburne Sub-basin (SS) contains until 15 km of sedimentary column composed of basal Triassic deposit overlain by a thick salt cover and Jurassic (JR) to present-day sediments. No well has been ever drilled on the basin's slope and deepwater area. Two wells were drilled in the shelf area: Bonnet P23 and Mohawk B93 showing only HC stained intervals. The TF model consist of a 36 layer grid with 351×199 cells of 1 Km side representing the post-salt to present-day interval including reservoirs, carrier, salt bodies and five source rock (SR). The SR intervals considered in the model represent a Lower JR Complex grouping potential Hettangian to Toarcian type II source rocks; two type II – III source rocks placed at the Callovian and Tithonian position and finally two type III source rocks placed at the Valanginian-Aptian levels. Potential JR – Cretaceous reservoirs consist of shelf carbonates, deltaic sandstones, slope toe carbonate breccia and clastic to carbonate turbidites. The spatial distribution of these facies was estimated using a forward stratigraphic model. The TF results showed suitable condition for oil generation in the JR interval, Cretaceous SR's are immature or at their earlier stage of maturity with no sensible expulsion. The best maturity conditions are present in the Hettangian to Toarcian interval with only local maturity windows in the Callovian and Tithonian SRs. HC accumulations correspond mainly to flank traps on salt cored anticlines, roll-over structures, traps under salt canopy and basin floor turbidites. HC phase is oil at reservoir conditions with API ranging from 25° to 40°. HC resources in the Lower JR interval were estimated in around 6 to 1 BBL OOIP mainly related with slope toe carbonate breccia reservoirs. The Upper JR accumulations correspond to clastic and carbonatic turbidites in the SS with HC resources estimated in around 5 to 3.7 BBL OOIP. The Tithonian to Albian interval contains estimated resources of around 1.5 to 0.8 BBL OOIP mainly in deepwater clastic and carbonate turbidites.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016