Abstract

The structural geology, stratigraphy, and economic geology relative to oil and gas are summarized separately for each of the five geological provinces within the St. Lawrence Lowlands, Gaspe and Gulf of St. Lawrence areas. The Quebec and Anticosti Basins contain relatively undisturbed lower Paleozoic beds, occupying the area lying between the Canadian Shield and the front of the Appalachian Mountains. The Gaspe Fold Belt and Western Newfoundland Fault Belt involve lower and middle Paleozoic beds now occurring in potentially favorable thrust-faulted and folded structures. The Maritimes Basin — a successor basin within the Appalachian Mountain system — has an upper Paleozoic section with a variety of structural and stratigraphic-trap possibilities.

Hydrocarbon occurrences have been known in the region since 1812 and occur in many localities in all five geological provinces. However, exploratory drilling has been slow-paced and has resulted in very limited commercial production, due to a combination of several important factors: (1) paucity of porous units in the “favorable” formations, (2) structural complexity in many parts of the region, (3) difficulties in delineating stratigraphic-trap plays, (4) widely-spaced drilling except in the vicinity of surface shows, (5) large offshore areas, where exploration has only begun, (6) small oil and gas reserves found to date, and (7) pre-Mesozoic age of the prospective rocks.

The Stony Creek Field in New Brunswick has provided oil and gas for local use for over 60 years and the Pointe-du-lac Field in Quebec has yielded limited gas production since 1961. At several other localities in past years, there have been (1) commercial mining of albertite (similar to gilsonite), (2) experimental work, mining and retorting of oil shale, and (3) small production of oil. The total recorded production from the region to December, 1970, has been about 735,000 barrels of oil and 27 billion cubic feet of natural gas, most of which have come from the Stony Creek Field.

Estimates of the potential total hydrocarbons in-place in the five geological provinces of the region are four billion barrels of oil and 34 trillion cubic feet of gas. Future drilling will test new structures and also stratigraphic trends. Increasing prices and demand for both oil and gas will foster continuing exploration, but these areas need an important discovery to attract any marked increase in exploratory effort.