Updated Subsurface Stratigraphic Synthesis for Southern Ontario: An Improved Framework for Exploration

Derek K. Armstrong¹, Terry R. Carter², and A. P. Hamblin^3
1 Ontario Geological Survey, Sudbury, ON
² Ministry of Natural Resources, London, ON
³ Geological Survey of Canada, Calgary, AB

The Lower and Middle Paleozoic strata of southwestern Ontario include a diverse assemblage of lithologies up to about 1500 m thick, deposited in portions of both the Michigan and Appalachian Basins. During almost 150 years of hydrocarbon exploration in this region over 50,000 wells have been drilled. To date, 137 oil and 262 gas pools have been discovered and 12.7 million m3 (80 million bbl) of oil and 34 billion m³ (1.2 Tcf) of gas have been produced. Over 70% of the oil is now produced from recently discovered Ordovician reservoirs while gas production is still dominated by Silurian strata.

As expected in a diverse assemblage of lithologies and depositional settings housed within two major basins of different tectonic origins and evolutions, the known hydrocarbon plays in southwestern Ontario are varied. They include combinations of up-dip pinch-outs, numerous unconformities, internal facies and porosity/permeability variation, subtle structural drape and faulting/folding with accompanying dolomitization.

The main objective of this project, funded by Natural Resources Canada through the Targeted Geoscience Initiative program, is to produce an updated guide to the subsurface Paleozoic stratigraphy of southern Ontario. Since the last such guide was published in 1967, over 5,000 wells have been drilled, including 450 to Precambrian basement and more than a dozen continuously cored to basement. A stratigraphy synthesis is constructed with data from approximately 70 reference wells and 36 reference outcrops, and presented in 12 regional cross sections oriented parallel and perpendicular to major tectonic elements and depositional strike.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005