Premier Pauline Marois announced deals with the firms Petrolia, Corridor Resources, Junex, and Maurel & Prom to carry out two exploration programs in two phases.
The government will invest a total of $115 million in the projects.
Earlier in the day, Quebec government officials distributed erroneous information saying the number of barrels of oil was estimated at 46 million.
The news of the exploration comes as speculation swirls around a possible provincial election in which opposition parties have said they will target the lacklustre economic record of Marois' minority government.
The accord with Petrolia (TSXV:PEA), Corridor Resources Inc. (TSX:CDH), and Maurel & Prom will see them invest $100 million. Quebec will kick in $56 million via Ressources Quebec, which will provide an additional $13.3 million to Corridor Resources for additional participation.
Under that deal, Ressources Quebec will have a 35 per cent share in the joint venture to carry out the exploration.
The agreement with Junex (TSXV:JNX) will see it, Ressources Quebec and a so far undetermined participant in a $90-million joint venture.
The provincial government estimates there will be $45 billion in economic benefits during the next 30 years if the project is a success.
The first phase of exploration and exploitation under the agreements will begin this year and next year.
Quebec says the deals will allow it to control 50 per cent of the licences on Anticosti and obtain 60 per cent of the benefits from the petroleum exploitation.
"Today, Quebec is asserting its rights over the natural resources that belong to it," Marois told a news conference Thursday.
Environmental hearings on the exploitation will be carried out if exploration shows the projects would be profitable.
Although the announcement was made after the end of trading on the Toronto Stock Exchange, trading on Junex, Petrolia and Corridor Resources was temporarily halted.