The main benefit of full-scale (1M+ te CO2) demonstration is the experience gained from large-scale injection into different types of reservoir. All three key projects involved detailed seismic monitoring which was used to track the progress of CO2 plumes. The pattern and rate of migration could then be compared with different types of reservoir model. These three sites, and the other examples presented at the meeting, have highlighted the strength of field demonstration, particularly at large-scale. Although techniques like 4D and 3D seismic are expensive they are valuable for tracking plume development with time. They also provide a history-matching template to compare and integrate with different models. Improving model performance is an area for future research.
The risk assessment component of the meeting explored a number of themes including the impact of regulation, the necessity for incentives and the perception of risk from different stakeholders. Risks posed by technical constraints specifically fault stability and induced seismicity were also discussed. The attitude to risk across integrated capture – storage programs was explored during the meeting. Utility companies regard power supply contracts, and escalating capital and operating costs associated with CCS, as the biggest areas of uncertainty. In contrast, storage operators are more concern with reservoir uncertainty. There was a general consensus that both regulators and those directly involved in CO2 storage need to work together to resolve the challenges facing them. This approach has already been adopted in the US and Norway.
The meeting concluded that mitigation and remediation could be improved by adopting practices from other industries, for example gas storage. Different risk assessment methodologies can be effective for anticipating uncertainties. It is also clear that communication, especially with the public, needs to be unambivalent and presented in an appropriate style that can be understood. A key message to convey is that there needs to be a balance between risk and benefits and not just risk in isolation.