IS THERE A VIABLE PETROLEUM SYSTEM IN THE CARSON AND SALAR BASINS, OFFSHORE NEWFOUNDLAND?

J.B.W. Wielens*⁺, C.D. Jauer* and G.L. Williams*

* Geological Survey of Canada Atlantic, PO Box 1006, Dartmouth, NS, B2Y 4A2, Canada.

⁺ author for correspondence, email: hwielens@nrcan.gc.ca

The Carson Basin on the eastern Grand Banks of Newfoundland has been penetrated by four wells - Bonnition H-32, Osprey H-84, Skua E-41 and St. George J-55 - which were drilled along its western margin. The adjacent deeper-water Salar Basin to the east remains undrilled with the exception of ODP holes 1276A and 1277. The Carson Basin wells contain a thick Mesozoic and Cenozoic sedimentary section which includes reservoirs and seals; but source rocks, such as those present in the adjacent Jeanne d’Arc Basin, have not been found. To assess the petroleum system, well samples were collected to provide Rock Eval and vitrinite reflectance data, and analysed biostratigraphically to obtain ages and depositional environments. These analyses indicate that a Late Jurassic source rock, similar to the Egret Member (of the Rankin Formation) of the Jeanne d’Arc Basin, may be present in the deeper-water, distal parts of the Carson and Salar Basins; this is based on a regional palaeotectonic reconstruction, together with gravity and magnetic data, including sea-floor spreading magnetic anomalies. We interpret the absence of the Egret Member in the four wells to reflect the wells’ locations rather than the Member’s absence from the two basins.

An integrated 4D model of the Carson Basin was built from biostratigraphy and seismic surfaces, to which an Egret-like source rock was added. The modelling showed that significant volumes of hydrocarbons could have been generated, mostly during the main Late Cretaceous drifting event in the area. Hence, significant volumes of hydrocarbons could be present in the Carson and Salar Basins, mainly in stratigraphic traps in Early Cretaceous clastic reservoirs.

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