Thirty-nine exploratory wells drilled on the Grand Banks of Newfoundland failed to encounter commercial petroleum accumulations. The absence of major discoveries is attributed to problems of source rock quality and maturity throughout the sedimentary sequence.

The area contains potential Paleozoic, Mesozoic, and Tertiary reservoir rocks in both sandstone and carbonate facies within a marine and continental stratigraphic sequence. These formations were tested on a variety of structural and stratigraphic configurations that had the capability of holding major hydrocarbon reserves. Several oil and gas shows were reported.

The Avalon Uplift, an Early Cretaceous tectonic feature, had a profound effect on the central Grand Banks area. Potential source rock intervals were deeply eroded and reservoirs that may have received hydrocarbon accumulations during the Jurassic were breached.

Source rock quality and maturity trends show a reasonable correspondence to isopach and facies trends. Source rock characteristics in undrilled areas were predicted from extrapolations of contours. The deeper parts of the South Whale and Jeanne d'Arc Basins may contain oil- and gas-prone source rocks with the quality and maturity necessary to have generated commercial accumulations of petroleum.