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A Regional Framework With New Insights Into the Petroleum Systems of the Carson-Bonnition-Salar Basins, Offshore Newfoundland and Labrador, Canada

Abstract

The Carson-Bonnition-Salar (CBS) Basins have seen recent offshore oil and gas activity with the acquisition of new geological and geophysical surveys over the past 5 years. Multiclient long offset broadband 2D seismic data in a 5km x 5km grid has been acquired throughout the shelf, slope and deepwater regions. Seismic interpretations of the 2D data have provided an opportunity to evaluate the subsurface in this region with the focus on the Mesozoic-Cenozoic strata. With increased seismic coverage, a detailed structural and stratigraphic analysis of the region has been conducted resulting in a refined regional framework of the CBS Basins. In addition to seismic, in the summer of 2018, a multibeam bathymetry, backscatter imaging and seabed coring survey focused on geochemical evaluation of potential hydrocarbon (HC) seeps in the CBS basins. Situated southeast of the prolific petroleum producing Jeanne d’Arc Basin, the CBS Basins have undergone similar structural and stratigraphic processes as the Jeanne d’Arc region, resulting in the opportunity for similar petroleum system elements. Two main rift episodes have influenced the deposition along this margin. A Late Triassic to Early Jurassic initial rift event has resulted in the deposition of terrestrial clastic deposits, and a second rift event from the Late Jurassic to Early Cretaceous has resulted in the deposition of fluvial-deltaic to shallow marine clastic deposits, both of which are followed by thermally subsiding marine carbonates and shales which are proven seal intervals. Evidence of potential source rocks exists in the area, through well data analysis, throughout the Jurassic and Cretaceous intervals. Past industry drilling has been focused on the shelf, with no commercial success. Early results from the seabed coring analysis within the CBS basins indicate multiple areas with elevated dry to wet gas ratios, C2 to C5 measurements, ethane to ethene ratios as well as total scanning fluorescence indicating a thermogenic HC signature. Coupled with the modern seismic data, these thermogenic signatures are seen over areas with varying play types imaged throughout the subsurface. These results provide insight into a potential working petroleum system in a frontier area where few prior petroleum indications have been encountered.