A new exploration concept to develop the hydrocarbon potential in Québec

Jean-Yves Laliberté, eng. M.Sc
Direction du développement des hydrocarbures

Explorationists are increasingly optimistic

Activities related to oil & gas exploration are thriving in Québec. Oil & gas exploration licences now cover nearly 5 million hectares, a new twenty-year peak.

Map showing licensed areas (PDF Format, 421 Kb)

Seismic reflection geophysical surveys carried out by the MRNFP over the past three years have undoubtedly contributed in improving the geological understanding of the Bas-Saint-Laurent and Gaspésie regions and have spurred interest in these two resource-based regions. This new flurry of activity centered on the hydrocarbon potential in Québec may also be fuelled by numerous discoveries in nearby basins. These new fields are for the most part located in the carbonate complex that formed along the margin of the North American continent during the Ordovician marine transgression.

The concept of hydrothermal dolomites

The classic example of this type of carbonate-sequence reservoir is the Albion-Scipio and Stoney Point fields in the Michigan basin, where the HTD-RF (Hydrothermal Dolomite Reservoir Facies) model was developed in recent years.

This type of deposit occurs in sedimentary units equivalent to those in the St. Lawrence Lowlands, and more specifically those of the Black River and Trenton groups. Reservoir development is intimately linked to orogenic and diagenetic processes. Consequently, they always occur along extensional faults that were active during the Taconic Orogeny (Ordovician), i.e. shortly after the deposition of the Black River and Trenton groups.

These faults played a crucial role, by facilitating the migration of high-pressure high-temperature fluids. The hydrothermal fluids leached, dolomitized and fractured Black River and Trenton limestones, thereby creating breccias and secondary porosity, which allowed hydrocarbons to build up.

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The HTD model, Tedesco 1994

This relatively new model now constitutes a prime target for companies involved in hydrocarbon exploration. The model has never been tested in Québec, while in Ontario, Michigan and New York, major discoveries are piling up. For example, Talisman Energy Inc. announced on September 2, 2003, the completion of a new natural gas well in New York State, with an output capacity of 10 million cubic feet per day.

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Cross-section of the Gloades Corner reservoir in New York State
Provided by AAPG Explorer-March 2001

Basins in the St. Lawrence Lowlands and Anticosti are highly prospective for this type of deposit. Recent seismic reflection geophysical surveys, mentioned above, have proven useful in determining the location of future drilling targets.

A new approach

This new type of hydrocarbon deposit represents quite a challenge for explorationists. Rather than searching for conventional structures likely to trap hydrocarbons such as anticlines, faults or stratigraphic wedges, explorationists must now look for collapse structures associated with faults, where the seismic signature of reflectors has been fairly altered due to the action of hydrothermal fluids.

Existing data must be re-examined in a new light!

Québec Exploration 2003

Under the theme “New Frontiers”, Québec Exploration 2003 will offer a series of oral presentations namely dealing with new geological data, new regions to explore as well as new technologies and new exploration models.

A speaker session entitled Oil & Gas will focus on the latest developments related to hydrocarbon exploration in Québec and the search for HTD-type deposits. Mr. Graham R. Davies, internationally renowned geologist in this specific field, will be our keynote speaker for the occasion.