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Methane Gas Potential and Sequence Stratigraphy of Lower Cretaceous Shales, Northeastern British Columbia, Canada 

Gareth Chalmers, Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada, gchalmer@eos.ubc.ca

 

Unconventional shale gas is considered a self-sourcing reservoir. The organic matter distribution within a shale unit is critical to the understanding of the reservoir because it produces and stores methane on microporous surfaces. Gas capacity is dependant of the concentration, maturity and type of organic matter. A testable hypothesis is: the gas shale potential will increase proportionally with the abundance and maturity of Type-III organic matter. 

The Lower Cretaceous Moosebar and Buckinghorse shales in northeastern British Columbia are the stratigraphic focus of this research. The adjacent Gates Formation shoreline oscillated in north-south direction, responding to relative sea level changes. A second hypothesis states that: in a fixed location, the progradation of the shoreline will increase the Type-III kerogen content. Enhancement of the permeability may result from the associated facies changes of progradation.  

Lithological trends and other sedimentary features from core and well logs will provide insight into depositional environments while petrographic, SEM and XRD analyses will identify subtle mineralogical and textural changes. The stratigraphic variation in organic matter will be determined by Rock-Eval pyrolysis and organic petrology. Samples will be analysed for the methane sorption capacity using an isothermal volumetric apparatus. The porosity of the reservoir will be determined by subtracting the skeletal density from the bulk density.  

Sequence stratigraphy combined with the organic matter distribution will provide the stratal architecture of the potential pay zone and focus future drilling projects. The study will also provide a clearer understanding on how shoreline movements influence organic matter in basinal sediments.