As the storage capacity especially in the shallower region is critically dependent on the phase behaviour of CO2 a modelling of the geothermal gradient with emphasis on the Miocene and Pliocene strata where CO2 may accumulate was performed. The geothermal model included the transient temperature changes due the long glacial cycles because they have a penetration depth that affects the Utsira formation. The results showed that CO2 can be stored in dense phase up to a depth of approximately 500 m below mean sea level (MSL) which is significantly shallower than previously suggested. If a significant fraction of any closed aquifer shall be utilised for storage the pressure has to be controlled by production of water out of the aquifer to avoid pressure build up that could jeopardize the integrity of the sealing rock. The storage capacity of the Utsira formation was studied both by static volume estimates and by reservoir simulation of injection with up to 210 injection wells distributed over the whole formation. In simulation of several 300 years injection scenarios it was demonstrated that 7% of the pore volume corresponding 40 Gtonne (Gt) CO2, could be utilised for storage while pressure control and CO2 break-through control in the production wells was observed. The optimal filling will depend of the number of wells and is accordingly a result of an economic optimisation. The simulation results indicate that a cost effective utilisation of the reservoir could be in the range of 20 to 60 Gt

For investigation of the risks associated with future geological storage of CO2, and for determining the minimum requirements for the quality of geological storage sites, detailed study of possible leakage mechanisms is necessary. Mechanisms for potential leakage from primary CO2 storage in deep saline aquifers have been studied. A buoyancy-driven flow of CO2 through a percolating network of permeable bodies in an otherwise sealing cap-rock has been simulated on a geological model of the overburden composed of geological features characteristic for a marine sediments. Channels and lobes from turbidite flows are significant constituents to form a possible leakage pathway in this study

An automated version of the weather type classification scheme was performed over Japan to characterize daily circulation conditions. A daily gridded field of mean sea-level pressure (MSLP) from the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis dataset (ERA-interim) and the THORPEX Interactive Grand Global Ensemble (TIGGE) daily forecast dataset were used. The weather type is advantageous as it provides an opportunity to improve global rainfall prediction by refining statistical bias correction. We distinguished 11 weather types: anticyclone, cyclone, hybrid and eight purely wind directions. The results indicate that the main weather types contributing to the total volume of rainfall are cyclone, hybrid, purely westerly and northwest winds. A gamma-based bias correction decreases the global rainfall forecast root mean square by 10%, while specific weather type gamma bias correction accounts for 5–10% root mean square error reduction, with a total decrease of errors up to a maximum of 20%. Both global and weather type bias corrections improve the extreme dependency scores (EDS), but for different extreme rainfall thresholds. The study advocates the use of weather type bias-correction methods for extreme event rainfall intensity corrections higher than 100 mm/d.