Lessons learned from using expert elicitation to identify, assess and rank the potential leakage scenarios at the Heletz pilot CO2 injection site

Expert elicitation is a useful approach to synthesis expert knowledge, experience and insight when the input data and analysis is limited. During the early stages of the EU FP7 MUSTANG pilot CO2 injection experiment at Heletz, Israel there was very little input data available, yet decisions had to be made regarding data collection, drilling, operation and monitoring strategies. An expert elicitation study was undertaken to identify, assess and rank potential CO2 leakage scenarios at Heletz to provide guidance to support the decision making processes. This paper presents a critique of the expert elicitation process undertaken, presenting the methodology and a discussion of the results. We present the lessons learned during the expert elicitation process, highlighting its advantages and limitations and provide suggestions on ways to overcome these limitations. Our findings show that prudent expert elicitation can make a valuable contribution to decision making, however if done improperly it can equally lead to invalid or misleading results and wrong decisions.