PETROLEUM GEOLOGY OF THE CONTINENTAL-MARGIN SOUTH OF THE ISLANDS OF ST-PIERRE AND MIQUELON, OFFSHORE EASTERN CANADA

The portion of St. Pierre Moratorium Block south of 46-degrees-N contains Laurentian Subbasin, a deep Mesozoic depocentre which forms part of the larger Scotian Basin. The subsurface geology of the area may be considered an eastward extension of the Scotian Shelf which has a similar sedimentary, structural and thermal history. The rift-phase Orpheus Graben of northeastern Scotian Shelf widens eastward into the St. Pierre Block and deepens into Laurentian Subbasin. Thick Jurassic, Cretaceous and Tertiary sequences have filled the depocentre and have been structured by typical Atlantic-type margin extensional tectonics. Some salt tectonism is present but shallow piercements are rare. Approximately 300 structural leads have been identified and a preliminary assessment of recoverable hydrocarbon reserves, based on a revised Sable Island model, gives an average expectation of about 250 billion cubic metres (8 to 9 TCF) of gas and 100 million cubic metres (600 to 700 million barrels) of oil. Low probability (speculative) estimates are several times those levels.