Impact of Realistic Geologic Models on Simulation of CO2 Storage

This proposal addresses the need for realistic geological test labs for simulations of injected CO2 in subsurface geological formations. The vision is to provide a framework for realistic risk assessment for CO2 storage. Comprehensive risk assessment will be essential when evaluating CO2 capture and storage (CCS) as a means of mitigating emissions of anthropogenic green house gases. Academic studies of CO2 injection frequently employ simplified or conceptualized reservoir descriptions in which the mediu m is considered nearly homogeneous. However, geological knowledge and experience from petroleum production show that the petrophysical characteristics of potential CO2 sequestration sites can be expected to be heterogeneous on the relevant physical scales ; regardless of whether the target formation is an abandoned petroleum reservoir or a pristine aquifer. Geological uncertainty introduces tortuous subsurface flow paths, which in turn influences reservoir behavior during injection. It is paramount that th e effect of the geological heterogeneity is quantified by the research community. This will facilitate both improved understanding of subsurface flow at operational CO2 injection sites, and allow comparison with simulated flow in ideal homogeneous models and upscaled versions of these. A key challenge when assessing the impact of heterogeneity is the uncertainty associated with the precise spatial structure of formation properties. To provide a statistically sound frame of reference for understanding the behaviour of injected CO2 in subsurface formations, several sedimentological scenarios need to be evaluated. The present proposal aims to set up the roadmap for establishing a comprehensive suite of geologically realistic, generic reservoir models for use by the CCS community. Furthermore, it will initiate the compilation of this suite of benchmark models by defining a number of synthetic cases, and analyze their CO2 injection characteristics.