EPSRC Project: DiSECCS - Diagnostic Seismic toolbox for the Efficient Control of CO2 Storage

The year 2011 recorded the highest ever global consumption of energy, estimated at more than 12 billion tonnes of oil equivalent. Because of this, and despite increasingly widespread deployment of renewable energy generation, annual global emissions of greenhouse gases are continuing to rise, underpinned by increasing consumption of fossil fuels. Carbon capture and storage (CCS) is currently the only available technology that can significantly reduce CO2 emissions to the atmosphere from fossil fuel power stations and other industrial facilities such as oil refineries, steel works, cement factories and chemical plants. However, achieving meaningful emissions reduction requires wide deployment of large scale CCS and will involve long term storage of very large volumes of CO2 in the subsurface. Ultimately, if CCS were to be rolled out globally, volumes of injected carbon dioxide could become comparable, on an annual basis, to world hydrocarbon production. The most likely sites for CO2 storage are depleted oil and gas fields or saline aquifers. Understanding and monitoring geomechanical processes within different types of storage site is crucial for site selection, for achieving long term security of storage and for instilling wider confidence in the safety and effectiveness of CCS. In many cases depleted hydrocarbon fields have experienced strong pressure decrease during production which may have affected the integrity of the caprock seal; furthermore, CO2 injection into saline aquifers will displace large volumes of groundwater (brine). In all cases, as injection proceeds and reservoir pressures increase, maintaining the geomechanical stability of the storage reservoir will be of great importance. Understanding and managing these subsurface processes is key to minimising any risk that CO2 storage could result in unexpected effects such as induced earthquakes or damage to caprock seal integrity. Experience from existing large-scale CO2 injection sites shows that monitoring tools such as time-lapse 3D seismic, micro-seismic monitoring and satellite interferometry have the potential to make a significant contribution to our understanding of reservoir processes, including fine-scale flow of CO2, fluid pressure changes, induced seismic activity and ground displacements. The DiSECCS project will bring together monitoring datasets from the world's three industrial scale CO2 storage sites at Sleipner (offshore Norway), Snohvit (offshore Norway) and In Salah (Algeria) to develop and test advanced and innovative monitoring tools and methods for the measurement and characterisation of pressure increase, CO2 migration and fluid saturation changes and geomechanical response. A key element of the research will be to identify those storage reservoir types that will be suitable for large-scale CO2 storage without unwanted geomechanical effects, and to develop monitoring tools and strategies to ensure safe and effective storage site performance. In addition, our research will explore public attitudes to CO2 storage. Grant number: EP/K035878/1.