The IEA Weyburn CO₂ Monitoring and Storage Project – The European dimension

The IEA Weyburn CO₂ Monitoring and Storage Project is currently analysing the effects of a miscible CO₂ flood into a carbonate reservoir rock at a mature onshore Canadian oilfield. Anthropogenic CO₂ is being injected as part of an enhanced oil recovery operation. The European contribution includes the analysis of the long term safety and performance of CO₂ storage via construction of a Features, Events and Processes (FEP) database. This will allow the integrity of deep storage of CO₂ in sedimentary rocks to be investigated objectively. Initial work has also been focussed on better understanding the pre-injection hydrogeological and geochemical conditions in the reservoir in order to recognise changes resulting from injection of the CO₂. The baseline studies also include analysing gas concentrations in soil and groundwater to determine potential migration pathways; two soil gas surveys were undertaken in July and September 2001. The CO₂ distributions are irregular and reflect anthropogenic, or near surface phenomena and seasonal variations in CO₂ fluxes are present. There are no correlations between gas anomalies and injection wells or pipelines. Changes from these baseline conditions as a result of CO₂ injection are also under investigation and will be the focus of future activities. Geochemical experiments, predictive computer modelling, microseismic monitoring and soil gas surveys will be carried out to investigate CO₂ migration pathways and the rate and extent of chemical reactions of the injected CO₂ with the host formation and adjacent strata.