Natural Gas Potential in the Saint Lawrence Lowlands of Quebec: A Case Study

Abstract Since the announcement made in April 2008 concerning the shale gas potential of the Southern Quebec Lowlands, almost 15 new wells have been drilled in the area. The calcareous and organic-rich Middle Ordovician Utica Shale is the main target of this recent exploration effort. Current knowledge of the area's geology have led operators subdivide the shale gas potential into different play types. To date, most operations have been performed in approximately 1/3 of the shale basin in the medium to deep thermogenic shale gas play (1,000-2,000 meters), located in the central part of the Saint Lawrence Lowlands. With OGIP estimates ranging from 120 to 160 Bcf per section, the deep play is considered to be promising. Current efforts focus on determining the highest gas prone unit within the Utica. The remaining 2/3 of the shale basin has not been largely tested yet, but the potential remains promising. Based on exploration work carried out over the past five years in Southern Quebec, four other play types have been described: 1) shallow to medium depth thermogenic shale gas; 2) overthrusted shale gas; 3) biogenic shale gas; 4) Intra-Appalachians sub-basin shale gas. They are less explored than the deep shale play, but also present interesting potential. This paper describes the above mentioned plays using basin geology, shale mineralogy, organic matter type, gas geochemistry, structural style and infrastructure access. The characteristics of the above plays are reviewed from geological, geochemical, structural and production perspectives. Results of evaluations using the concept of flow units, and volumes of original-gas-in-place calculated by various organizations are compared with a recent evaluation using the Petroleum Resources Management System (PRMS). It is concluded that there is promising hydrocarbon potential in the Saint Lawrence Lowlands of Quebec that continue to stimulate operators to pursue the exploration and development of these plays.