Soil Surface Leak Detection From Carbon Storage Sites Using ∆(CO2:O2) Measurements

Abstract:

The early detection and remediation of CO₂ leaks from Carbon Capture and Storage (CCS) sites is essential for the safety and public support of the technology. A model that integrates gas diffusion, mass flow and biological processes in soils was developed and used to predict the ∆CO₂ and ∆O₂ concentration differential between the soil surface and the bulk atmosphere under a wide range of environmental conditions that include temperature, soil gas and water content, soil respiratory quotient and rate of O₂ uptake, soil porosity and CO₂ leakage rate. The results predicted that measurement of ∆(CO₂:O₂) measurements at the soil surface relative to air should be able to detect a CCS leak as low as 2 µmol/m₂/sec. To test this hypothesis, a gas analysis system was designed and constructed. It should allow a series of experiments under controlled conditions to test all aspects of the model. It is hoped that the results from this work will ultimately lead to the development of a new instrument and protocol for the early detection of CO₂ leaks from a geological storage sites.