Early Jurassic Nordegg Member, Northeastern British Columbia: Gas Shale Potential

Daniel J. K. Ross¹ and R. Marc Bustin^2
1 University of British Columbia, Vancouver, BC
² UBC, Vancouver, BC

To assess gas shale resources, methane adsorption capacities of Jurassic Nordegg samples from the Peace River district (northeastern British Columbia) were investigated. The Nordegg Member is a 15 to 30 m thick organic-rich, fine-grained mudrock and as such, is considered a potential gas shale. We have quantified the organic carbon content (TOC), organic maturity and gas sorption capacity and mapped potential gas shale facies.

Sorbed gas capacities of moisture-equilibrated samples (at a pressure of 6.5 MPa and 30 0C) increases with total organic carbon content (TOC) over a range of 0.5 – 14 wt% organic carbon. Methane adsorption capacities range from 0.05 cc/g to over 2 cc/g in organic-rich zones. Methane capacity generally declines with increasing moisture content. However no direct relationship exists between moisture and gas capacity, suggesting moisture has a greater importance than purely a competitor for methane adsorption sites. Pores and pore throats are likely blocked by moisture rendering many adsorption sites inaccessible to methane. Porosity ranges from 0.7 to 7% which yields free gas capacities (assuming Sw=0) that comprise between 20 to 80% of the total gas storage capacity. Total gas-in-place ranges from 1 – 24 BCF/section. The areas with the greatest gas in place are to the south-west of the study area (between 93-P-07 to 93-P-12). In this region TOC concentrations (up to 20 wt%), thickness, maturity and potential for fracture permeability associated with thrust faults exist.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005