Coalbed Methane and CO2 Sequestration Potential of the Westphalian (Carboniferous) Coal Seams from Onshore Carboniferous Basins of Nova Scotia, Eastern Canada

Mukhopadhyay (Muki), Prasanta K.¹, Paul J. Harvey², D. Jack MacDonald² (1) Global Geoenergy Research Limited, Halifax, NS (2) Nova Scotia Department of Energy, Halifax, NS

Coal-bed methane potential of Carboniferous coals (Westphalian A-C) from three major onshore basins (Cumberland, Stellarton, and Sydney) has been evaluated in relation to both the geological framework and physical or chemical properties of major coal seams. The current data suggests that coal composition, maturation and structural stress have a close relationship with the production characteristics, adsorption properties and the porosity or permeability of various coal seams.

The production data from the major coal seams from these three suggests that 5-20 cm3 of methane per gram of coal could be produced. The higher gas content is mainly concentrated within the Cumberland and Sydney Basin coals and is closely related to the amount of mineral matter, type of vitrinite macerals, and inhanced maturity. Evidence of gas seepages and gas releasing pores within various high to medium volatile bituminous coal seams of these two basins indicate that both free and adsorbed gases are readily available in those coals. Volumetrically, the Cumberland, Sydney, Stellarton Basin coals have 1.5 Tcf, 0.5-0.75 Tcf and 1.5 Tcf, of methane generation potential, respectively. The east-central part of the Stellarton Basin, Springhill and Athol areas of the Cumberland Basin, and the shallow offshore portion of the Sydney basin are considered to have major potential for coalbed methane. The adsorption characteristics of both methane and carbon dioxide suggest that some of the major coal seams (example: Foord and Cage seams within the Stellarton Basin) from all three basins could be the major trap for CO2 sink.