Anticosti
History

FIRST GEOLOGICAL WORK

Although not new, oil and gas exploration of the Anticosti sedimentary basin is the most recent in Quebec. It began nearly a century after the first exploratory work in the Gaspé region and the St. Lawrence Lowlands.

The first geological work dates to the mid-19th century and was recorded in Geological Survey of Canada reports. In the early 20th century, the work of paleontologist W. H. Twenhofel helped better characterize the type and age of the island's surface rock. He noted the presence of blocks of black oil shale on the island's north coast and anticipated the formation's oil potential.

First test wells

The first test wells were drilled on Anticosti Island in 1962 and the first seismic surveys were conducted the following year. Some twenty wells followed in short, successive waves. Shell and others launched an exploration campaign in the 1990s with the acquisition of numerous seismic profiles and wells. Hydrocarbon shows were reported, but were not considered economically viable.

Until 2010, the year Pétrolia and Corridor Resources drilled three wells to test the potential of the Trenton/Black River formations, exploration work had targeted deposits in the limestone formations of the lower sedimentary sequence, which were related to hydrothermally dolomitized limestone and the creation of secondary porosity. Hydrothermal dolomitization occurs most often near fault zones and is associated with subsided areas called “sags”. Drilling in these dolomitized areas did not deliver the expected results.

Since 2010

In 2010, Pétrolia and Corridor Resources extracted and analyzed a 9 m long core sample from Macasty source rock to assess the formation's oil potential. Further to positive laboratory core analysis results, the primary objective in the Anticosti Basin has been exploring the Macasty Formation.

To confirm the results, in 2012 Pétrolia and Corridor Resources drilled three coreholes in the western part of the island. The coreholes were located on seismic traces to validate seismic interpretation of the depth and thickness of the Macasty Formation. Samples were taken from the formation at 50 cm as soon as the core sample was extracted from the corer. The samples were immediately coated in paraffin wax to preserve the hydrocarbons and analyzed to assess the hydrocarbon content and characteristics. Other analyses helped determine the composition of the rock and its petrophysical qualities such as permeability and porosity.

In addition to these core samples, 14 previously drilled holes were analyzed to determine their organic richness and maturity (using the Rock Eval method of geochemical analysis). In total, about 900 samples were analyzed. The results indicate that the Macasty Formation is an excellent source rock with a high organic content.

In addition, a recent study compared the 2012 results for the Macasty Formation to those for the Point Pleasant Formation (Utica) in Ohio, and found them similar in thickness, organic content, composition, etc. The Macasty Formation is the lateral equivalent of the Utica Formation