Utica and Other Ordovician Shales: Exploration History in the Quebec Sedimentary Basins, Eastern Canada.

Jean-Sebastien Marcil, Peter K. Dorrins, Jérémie Lavoie, Nabila Mechti, and Jean-Yves Lavoie
Junex inc., Quebec-City, QC, Canada, [email protected]

Since the announcement in April 2008 about the potential of shale gas Lowlands of St. Lawrence in southern Quebec, 25 new wells were drilled in the area. This announcement has created a small revolution in a region known worldwide for its hydroelectric potential but definitely not for its oil potential. The Ordovician calcareous shales of the Utica Group, rich in organic matter are the main target of recent exploration efforts. This renewed interest marks a new stage in the history of oil exploration of sedimentary basins in Quebec.

Cradle of oil exploration in Canada, the Province of Quebec has seen oil rigs searching of this territory since the 1860s. Several exploration wells have been drilled without much success, but several gas shows were encountered in the... shales. The first tests with the objective to assess the gas potential of the Ordovician shale were taken to the early 1970s by Shell Canada and SOQUIP. Obviously, the tests have not met the expected economic goals. The same result was realized for the unsuccessful attempt to achieve a horizontal well in the Lorraine Shales in 1992. It was not until 2004, after taking knowledge of successful development results in the Antrim Shale of Michigan and the Barnett Shale of Texas, Junex initiated an evaluation of modern shale gas potential of the Ordovician of Quebec. In partnership with Forest Oil, the vertical well A250-Junex Becancour no.8 was drilled and tested using the technique of massive hydraulic fracturing during the year 2007. The positive results of these tests that will be subsequently repeated by other operators in the basin will launch a series of exploration wells to estimate the gas potential of the Utica Shales of the Saint Lawrence Lowlands.

Current knowledge of the geology of the region have led operators subdivide the shale gas potential in different play types. To date, most operations were performed in about 1/3 of the shale basin in the deep thermogenic shale gas play (1000-2000 meters), located in the central plain of the St. Lawrence Lowlands. With OGIP estimates ranging from 120 to 160 Bcf per section, the deep play is considered promising.

Based on exploration work conducted in recent years in Quebec, five play types have been described: 1) thermogenic shale gas or liquid-rich shale at shallow to middle depth, 2) overthrusted shale gas, 3) biogenic gas shale, and 4) intra-Appalachian sub-basin shale gas, and last but not least 5) the oil-rich shale of the Macasty Formation (Anticosti Basin).

The exploration history of Ordovician shales in Quebec is a combination of science, intuition, perseverance and adaptability. But the premises of the story remain similar to those found in other sedimentary basins: the presence of brittle shale which acted as a major source rock. The people living in Quebec are energy intensive and more than half of this energy comes from oil and natural gas. The development of oil and gas potential of Québec will generate significant economic benefits for citizens and will have positive impacts on the competitiveness of its sources of supply.

AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012