Shale Gas Potential of Devonian Strata, Northeastern British Columbia

M. Hayes and W. Walsh
British Columbia Ministry of Energy, Mines and Petroleum Resources, Victoria, BC

With increasing demand for natural gas, greater emphasis is being placed on exploration of unconventional resources. Devonian age shales of the Exshaw, Muskwa and Fort Simpson formations in northeastern British Columbia have the potential for large-scale reservoirs with rich organic intervals. These units have been assessed to determine their gas capacity and potential gas in place. This poster is based on the study “Gas Shale Potential of Devonian Strata, Northeastern British Columbia” by CBM Solutions with additional mapping and analysis by the Ministry of Energy, Mines and Petroleum Resources.

To determine the zones with the highest potential for gas in place, samples from 17 cored wells were taken to measure sorption capacity, total organic carbon (TOC), porosity, thermal maturity, clay mineralogy, aerial extent and shale zone thickness. The results of these measurements show that the examined shales exhibit potential for high sorbed gas capacity and extensive gas in place.

The Exshaw and Muskwa formations are both organic rich shale intervals, which are widely distributed throughout northeastern British Columbia. The maximum thickness of the Exshaw Formation is 86m and the average TOC is 5% while the maximum thickness of the Muskwa Formation is 75m and the average TOC is 3.1%. Due to high organic contents, both of these shales have the potential for high sorbed gas capacity.

The Fort Simpson Formation is a thick marine shale unit that is pervasive throughout the study area. Maximum thickness reaches approximately 800m. The overall organic content of the formation is extremely low, averaging 0.4%, resulting in low sorbed gas capacities. However, due to large vertical thickness and lateral extent as well as high shale porosities (potential free gas porosity), the Fort Simpson shale section has potential for extensive gas in place.