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Exploration Risk Assessment Using Forward Stratigraphic Modelling: Flemish Pass Basin, NL, Canada


The Flemish Pass Basin recently gained attraction with the oil discoveries made in 2009 (Mizzen 0-16) and 2013 (Bay du Nord C-78). The area has also just closed its first scheduled land sale NL15_01EN in November 2015. This study reports an exploration risk assessment method based on a forward stratigraphic model capable of quantifying the reservoir, seal and source rock presence and effectiveness. A comprehensive stratigraphic / paleoenvironment interpretation of the Flemish Pass Basin serves as the basis to the construction of Gross Depositional Environment (GDE) maps characterizing paleoenvironments at time of deposition providing constraints on the paleobathymetry. When coupled with seismic thickness maps, these maps allow computing of accommodation maps (creation of available space for sedimentation), which are the main input for the numerical model. A forward stratigraphic simulation was performed using DionisosFlow™ in order to characterize the 3D sedimentary architecture of the basin and quantify the sedimentary volumes at the basin scale. This modelling was performed encompassing source rock, reservoir and seal, in sequential time steps of 0.1 Ma with a 4×4 km grid. For each time step, three main environmental parameters were taken into account: the accommodation (subsidence & eustasy); the sediment supply (with in situ erosion and drainage basins) and macro-scale sediment transport laws (equation of diffusion). The 890 layer model is calibrated to respect lithologies at wells, seismic thickness and seismic stratigraphic architecture. Based on the 3D volume reservoir, seal and source rock maps are calculated to provide quantified constraints on their presence and effectiveness. The reservoir maps are generated using cut off on net sand, the presence and cumulated thickness of individual sand beds thicker than 5 m and thicker than 20 m. The seal map effectiveness is generated by characterizing net shale maps with continuous layers of at least 5, 10 and 20 m. Source rock maps are generated by combining shale prone areas (net shale) with that of low water flow energy calibrated to TOC measurements at wells. Final exploration risks maps are obtained by combining reservoir, seal and source rock maps. The use of DioniosFlow™ forward stratigraphic model grid allows spatially constrained and quantified exploration risk maps to be adressed at the model cell scale in poorly constrained exploration areas.