A meta-analysis of the surface soil gas measurement monitoring and verification (MMV) program at the Aquistore project

• Published in: International journal of greenhouse gas control 2018-08, Vol.75, p.189-197
• Main Authors: Tarakki, Nadia, Risk, David, Spafford, Lynsay, Fougère, Chelsea
• Format: Article
• Language: English
• Subjects: Aquistore; CCS; MMV; Radiocarbon isotope; Soil gas; Stable isotope
• ISSN: 1750-5836; 1878-0148
• DOI: 10.1016/j.ijggc.2018.06.007

[Display omitted] •First thorough description of the surface soil gas MMV program at Aquistore site.•Describes pre- and post-injection surface soil geochemical values for a CCS site.•Containment is intact and there is no reason to suspect CO2 leakage.•Has pre-existing baseline of old radiocarbon CO2 in surface soil, which is unusual.•We describe how the monitoring program is being actively shaped by observed data. Carbon Capture and Storage (CCS) is playing a greater role in reducing CO2 emissions. The Aquistore project at Estevan, Saskatchewan, Canada is an operational CCS demonstration and research site. Surface soil gas geochemistry is one method of Measurement, Monitoring, and Verification (MMV) techniques used for detection of leakage at CO2 injection sites. We have been operating the surface soil gas MMV program for several years, which has involved measuring gas concentrations of CO2, O2, N2, CH4, the stable isotope of CO2 (δ13C), and radiocarbon isotope Δ14CO2 as tracers for storage containment analysis. Soil CO2 surface flux measurements were also conducted during the baseline monitoring program. At Aquistore, CO2 concentration is typically elevated relative to the mean for the location, but such values are characteristic in this area. Ratio-based tracer analyses, such as O2 vs. CO2, CO2 vs. N2, and CO2 vs. N2/O2, all indicated that storage is secure. The Δ14CO2 values observed in soil gas were interesting in the parts of the site which had a more depleted baseline than expected. To date, there have been no changes in the soil gas indicators since the injections started. These observations will help to inform new research aimed at improving the effectiveness and efficiency of soil gas MMV at Aquistore and similar projects worldwide.