Geological sequestration of CO2:: Is leakage unavoidable and acceptable?

Geological sequestration Of CO2 requires careful risk analysis to avoid unintended consequences of the subsurface injection. One potentially serious problem associated with injection into mature sedimentary basins is the possible leakage of injected CO2 through or along existing wells. Over long time scales, these wells may serve as short-circuit pathways for leakage, with possible contamination of shallow subsurface zones, and ultimate leakage back into the atmosphere. Transport models for leakage analysis and overall risk assessment must include proper representation of the effects of existing wells. A multi-scale framework offers a guide for inclusion of existing wells into practical simulators.