IEA GHG International Research Network, Wellbore Integrity

The IEA Greenhouse Gas R&D Programme operates a research network on Wellbore Integrity, bringing together experts from research and industry. The network aims to determine the effects of CO2 on wellbore materials and assess the resulting implications for CCS and storage security. The network has identified significant threats to storage integrity, including the presence of old wells, the legacy of poor or inadequate abandonment techniques and the high potential costs involved with the future use of CO2 resistant cements and materials. Potential corrosion of old wells due to prolonged exposure to CO2 could in some cases, cause rapid degradation of wellbore cements and casings, giving rise to leakage pathways from storage reservoirs to the surface. Leakage from old wells could be the main risk factor for storage in depleted hydrocarbon fields, where large numbers of old wells are present. More recently, the network has highlighted a shift from laboratory experiments and modelling, towards practical field studies and the frequent disparity between these two sets of information. For example, laboratory tests frequently show poorer performance of wellbore materials than field observations; further work is required to resolve these discrepancies and allow more realistic risk modelling.