ABSTRACT: Trenton-Black River Oil and Gas Reservoirs in Ontario: The Play Goes On

T. R. Carter, Petroleum Resources Centre, Ministry of Natural Resources, London, ON, Canada, and R. A. Trevail, Orion Resources Consulting, London, ON, Canada

Exploration for dolomite traps in Ordovician marine carbonate rocks of the Trenton and Black River Groups is currently the most active oil play in Ontario. Ordovician pools currently account for 75% of Ontario's annual oil production of approximately 1.5 million barrels, and an increasing proportion of the natural gas, with cumulative production of over 15 million barrels of oil and 23 billion cubic feet of natural gas to the end of 1999. Recoverable reserves in individual pools range up to 3 million bbl at an average depth of 800 m. The Ordovician play is an extension of the giant Lima-Indiana trend to the south, with trapping relationships analogous to the Albion-Scipio oil field in Michigan. The Albion-Scipio field has produced over 125 million barrels of oil and 205 billion cubic feet of natural gas. Similar reservoirs have recently been discovered in northwestern Ohio and southern New York.

The oil and associated gas in these pools are derived from Ordovician carbonates of the Trenton and Black River Groups where they have been dolomitized and fractured adjacent to vertical faults. The resulting linear Ordovician reservoirs reach up to several kilometres in length and several hundred metres in width, often with several isolated pods of production. There is commonly a structural depression over the dolomitized zone, vertical displacement of the underlying Precambrian basement surface, and a change in character on seismic records within the dolomitized zone. The reservoirs are laterally bounded by non-porous limestones, and are overlain by grey marine shales of the Blue Mountain Formation.

Activity in the play is centred in eastern Essex County and the southern part of Kent County. In the past 5 years 120 wells have been drilled in this area, resulting in 70 oil wells and one gas well. In the past two years most of the wells in this play have been horizontally drilled. Development of oil reservoirs beneath the waters of Lake Erie utilizing horizontal wells located on land began in 1998.

Search and Discovery Article #90907©2000 AAPG Eastern Section Meeting, London, Ontario, Canada