We assess the performance of an inverse Lagrangian dispersion technique for its suitability to quantify leakages from geological storage of CO2. We find the technique is accurate ((QbLS/Q)=0.99, sigma=0.29) when strict meteorological filtering is applied to ensure that Monin–Obukhov Similarity Theory is valid for the periods analysed and when downwind enrichments in tracer gas concentration are 1% or more above background concentration. Because of their respective baseline atmospheric concentrations, this enrichment criterion is less onerous for CH4 than for CO2. Therefore for geologically sequestered gas reservoirs with a significant CH4 component, monitoring CH4 as a surrogate for CO2 leakage could be as much as 10 times more sensitive than monitoring CO2 alone. Additional recommendations for designing a robust atmospheric monitoring strategy for geosequestration include: continuous concentration data; exact inter-calibration of up- and downwind concentration measurements; use of an array of point concentration sensors to maximise the use of spatial information about the leakage plume; and precise isotope ratio measurement to confirm the source of any concentration elevations detected.

Formula in abstract: Copy and paste this file into a MathML-aware program such as Mathematica or Maple-->(〈QbLS/Q〉=0.99,σ=0.29)

Supplement to: Zoe, Loh; Leuning, Ray; Zegelin, Steve; Etheridge, David; Bai, Jia-Chi; Naylor, Travis A; Griffith, David W T (2009): Testing Lagrangian atmospheric dispersion modelling to monitor CO2 and CH4 leakage from geosequestration. Atmospheric Environment, 43(16), 2602-2611