ABSTRACT: Hydrocarbon Prospectivity of Lower Paleozoic Sediments, Anticosti Basin, Offshore Western Newfoundland

SINCLAIR, IAIN, Canada-Newfoundland Offshore Petroleum Board, St. John's, Newfoundland, Canada

The presence of hydrocarbons within Cambrian-Ordovician sediments of the Humber Zone of western Newfoundland has been recognized from numerous oil and gas seeps as early as 1812. Lower Paleozoic sediments exposed along the west coast of Newfoundland extend westward beneath the Gulf of St. Lawrence.

Seismic exploration of the area from 1969 to 1977 did not result in significant drilling. However, the offshore Anticosti Basin is poised for an upsurge in activity, as eight licenses were awarded to five companies in 1990 and 1991, and some 4357 km seismic was shot during the past summer. Recent discoveries in basins strung along the inboard margin of the Appalachian thrust front of the eastern United States has spurred renewed interest in the fractured lower Paleozoic carbonates.

Western Newfoundland has experienced late Precambrian to Early Cambrian rifting; Middle Cambrian to Early Ordovician thermal subsidence; low-angle thrusting during the Middle Ordovician Taconic orogeny; and high-angle thrusting during the Middle Devonian Acadian orogeny. Fracturing along high-angle Acadian reverse faults and leaching by waters likely generated long, linear, highly porous reservoirs along structural fronts. The common occurrence of oil and gas in wells drilled on Anticosti Island indicates the presence of mature, organic-rich source rocks. The identification of structural features associated with porosity development/enhancement is the major component required to generate highly prospective drilling targets.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)