Identifying the regional impact of deep thermogenic gas on aquifers in Alberta, Canada by comparing multilayered isoscape maps of domestic water wells and fugitive gases from energy wells
<p>The origin and distribution of unwanted thermogenic gas in aquifers and domestic water wells in petroliferous basins are of continuing concern. Most published studies to date consider only a few water wells with little or no information on fugitive gases from nearby energy wells. &#160; We mapped &#948;<sup>13</sup>C of&#160; hydrocarbons in 1,124&#160; domestic water wells and fugitive gases (many thousands) from energy wells of Alberta, Canada.&#160; About 90% of the water wells that exsolve hydrocarbons produce methane derived locally by microbes. The &#948;13C of these biogenic methanes vary regionally and follows topography,&#160; suggesting in situ generation of methane within a flowing aquifer perhaps following a Rayleigh constrained generation process. Some domestic water wells have free thermogenic butanes, propane and ethanes indicating the impact of thermogenic gas on the aquifer.&#160; The &#948;<sup>13</sup>C of these thermogenic sourced gases impacting domestic water wells matches those of nearby energy wells indicating their failure as the ultimate source of thermogenic gas in domestic water wells.&#160; The impacted water wells are geographically grouped. Our regional mapping of hydrocarbon gases in domestic water wells has identified specific, kilometre scale regions needing detailed hydrogeological and geochemical investigation.</p>