ASSESSING RISK IN CO_2 STORAGE PROJECTS

摘要

A key challenge to researchers involved with geological storage of CO_2 has been to develop an appropriate methodology to assess and compare alternative CO_2 injection projects on the basis of risk. Technical aspects, such as the risk of leakage and the effectiveness of the intended reservoir, clearly need to be considered, but so do less tangible aspects such as the value and safety of geological storage of CO_2, and potential impacts on the community and environment. The RISQUE method has been applied and found to be an appropriate approach to deliver a transparent risk assessment process that can interface with the wider community and allow stakeholders to assess whether the CO_2 injection process is safe, measurable and verifiable and whether a selected alternative delivers cost-effective greenhouse benefits. In Australia, under the GEODISC program, the approach was applied to assess the risk posed by conceptual CO_2 injection projects in four selected areas: Dongara, Petrel, Gippsland and Carnarvon. The assessment derived outputs that address key project performance indicators that: 1. are useful to compare projects; 2. include technical, economic and community risk events; 3. assist communication of risk to stakeholders; 4. can be incorporated into risk management design of injection projects; and 5. help identify specific areas for future research. The approach is to use quantitative techniques to characterise risk in terms of both the likelihood of identified risk events occurring (such as CO_2 escape and inadequate injectivity into the storage site) and of their consequences (such as environmental damage and loss of life). The approach integrates current best practice risk assessment methods with best available information provided by an expert panel. The results clearly showed the relationships between containment and effectiveness for all of the four conceptual CO_2 injection projects and indicated their acceptability with respect to two KPIs. Benefit-cost analysis showed which projects would probably be viable considering base-case economics, greenhouse benefits, and also the case after risk is taken into account. A societal risk profile was derived to compare the public safety risk posed by the injection projects with commonly accepted engineering target guidelines used for dams. The levels of amenity risk posed to the community by the projects were assessed, and their acceptability with respect to the specific KPI was evaluated. The risk assessment method and structure that was used should be applied to other potential CO_2 injection sites to compare and rank their suitability, and to assist selection of the most appropriate site for any injection project. These sites can be reassessed at any time, as further information becomes available.