Geological Storage of CO2: Mathematical Modelling and Risk Assessment

Storage of CO2 in deep geological formations is regarded as a promising option for mitigating climate changes caused by anthropogenic green-house gases. In this proposal we describe the formation of an international team of US, German and Norwegian invest igators and students to address fundamental science issues associated with injection of supercritical carbon dioxide into deep subsurface formations. Our proposal is motivated by the need for fast methods to characterise the uncertainty involved in geolo gical storage in formations relevant to Norwegian activities. Storage of CO2 in continental sedimentary basins involves risk associated with leakage from abandoned wells and bore-holes, which has been recently studied and quantified. In contrast, off-shor e basins are characterised by low number of wells, and as such the uncertainties in fluid flow paths are related not to anthropogenic conduits, but rather to the fractured nature of the host formation. These fracture networks are in general not known, and at best possible realizations can be generated based on the properties of sample rocks. To get a proper understanding of the expected fluid flow, numerous realizations must be generated, and accurate flow fields calculated for each realization. Finally, the vast amounts of output generated by such an approach must be analysed to produce meaningful information. The computational effort required by conventional simulations makes such analysis prohibitive with todays technology. It is therefore clear that without significant research into reducing the computational effort associated with obtaining accurate predictions of fluid flow, the risks associated with geologic storage of CO2 in the North Sea cannot be properly understood and assessed. This project a ims at remedying this situation through theoretical analysis of fractured media and development of specialised streamline simulation techniques.