Mayer, BernhardRiley, Dylan James Terence2023-06-052023-06-052023-05-26Riley, D. J. T. (2023). Baseline soil gas characterization at a pilot CO2 injection site in Alberta, Canada (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/116596https://dx.doi.org/10.11575/PRISM/41439A baseline soil gas characterisation was performed on the upper 2.0 m of the CO2 and CH4 soil gas system at CMC’s Containment and Monitoring Institute, a geological CO2 storage field research station. Part of this characterisation was to investigate potential gas migration (GM) at the site’s infrastructure (wells and boreholes). Constant depth soil gas surveys following the endorsed methods outlined in the Alberta Energy Regulator's (2016) Directive-020 guideline were performed at six new wells, five legacy boreholes and three background locations at the site. Additionally, multi-level soil gas sampling surveys were conducted at four new wells and three background locations. Soil gas samples were analysed for CO2, N2, O2, CH4, ẟ13CCO2, and ẟ13CCH4. Soil gas surveys were conducted in the spring, summer and fall in 2017 and 2018. Additionally, SCVF was investigated at three new wells on site. The baseline soil gas characterisation concluded soil gas methane was likely sourced from the atmosphere and that there was no detectable GM present in the soil surrounding any of the site’s ground penetrations. However, GM was confirmed at one well during previous sampling in 2016, but its duration lasted less than one year. SCVF composed principally of methane (i.e. 7.4% to 97.3%) measured at three wells, was predominantly of biogenic origins with minor contributions from immature thermogenic methane. The SCVF at all three wells was sourced from the same zone, 195 m – 200 m bgs. The GM from the one well was noted as being of the same origins and source depth as the SCVF. The CO2 soil gas baseline conditions at the site demonstrated the CO2 was naturally sourced predominantly from biological respiration with minor inputs from methane oxidation. The baseline assessment found no evidence of exogenous CO2 in the soil gas system. Spatial (horizontal and vertical) and temporal (seasonal) variation in [CO2] and ẟ13CCO2 values across the site was demonstrated to be statistically significant. Ultimately, the baseline soil gas characterisation will be used to compare against future surveys to determine if CO2 leakage has occurred from the CO2 storage reservoir and migrated into the shallow vadose zone.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.stable isotopessoil gasgeochemistrygas migrationcarbon storageGeologymaster thesis