• journal_title：Environmental & ; Engineering Geoscience
• Contributor：Changbing Yang ; Katherine Romanak ; Susan Hovorka ; Ramon Triveno
• Publisher：Association of Environmental & Engineering Geologists
• Date：2013-08-01
• Format：text/html
• Language：en
• Identifier：10.2113/gseegeosci.19.3.207
• journal_abbrev：Environmental & Engineering Geoscience
• issn：1078-7275
• volume：19
• issue：3
• firstpage：207
• section：Articles

A small-scale, controlled carbon dioxide (CO₂) release experiment was conducted at the Brackenridge Field Laboratory, Austin, Texas, to simulate CO₂ leakage from a geological sequestration site. The main purpose of the experiment was to assess impacts of soil physical properties on soil CO₂ measurements for detecting near-surface CO₂ leakage signals. The field site includes one shallow CO₂ injection well (1.1-m depth) and three wells for monitoring soil CO₂ concentrations. CO₂ was released at a depth of 1.1 m below the surface for approximately 6 hours. CO₂ concentrations at the sensor locations clearly showed the arrival of CO₂ from the injection well. A numerical model accounting for CO₂ diffusion and dissolution into soil pore water was constructed and then calibrated with the CO₂ measurements from the experiment. Using the calibrated numerical model, a set of sensitivity runs was conducted to assess effects of soil physical properties on modeled CO₂ concentration (or flux). Results of the sensitivity runs show that CO₂ concentrations (or fluxes) are sensitive to change in soil physical properties. Peak CO₂ concentrations modeled in the sensitivity runs are most sensitive to soil porosity, and peak CO₂ fluxes are most sensitive to the soil impedance factor. This study indicates that soil physical properties can have significant impacts on the soil CO₂ measurements used for detecting CO₂ leakage signals.