Measuring Aqueous CH4 Concentration Profiles in Shales and Tills to Define Source, Transport, and Fate of Organic Gases

Abstract The rapid development of unconventional shale resource plays has generated public concern with respect to potential contamination of potable groundwaters and surface waters by fugitive natural gases dominated by methane (CH 4 ). Continuous core samples collected at six drill sites to a maximum depth of 240 m below ground were used to define the vertical distribution of dissolved CH 4 and conservative Cl − through Cretaceous shales and overlying glacial tills in the Williston Basin, Canada. The interpretation of potentially reactive CH 4 depth profiles in conjunction with conservative profiles provide insights into the source, transport, and fate of CH 4 in aquitards-aquifer sequences and present baseline gas concentrations for use in fugitive gas migration investigations.