Multiscale modeling approaches for CO ₂ injection, migration, and leakage

One of the many challenges associated with CO ₂ storage involves quantitative modeling of the injection, migration, long-term fate, and possible leakage of CO ₂ as well as fluids displaced by the injected CO ₂. Injection into deep saline aquifers involves two-phase flow with interphase mass transfer, strong gravity override, and unfavorable viscosity ratios. While the resulting problem can become quite complex mathematically, it is also possible to simplify the system by developing a multi-scale modeling framework based on characteristic length and time scales associated with the problem. These multi-scale models apply to a range of problems - examples will include injection studies for an aquifer underlying the North Sea, and injection and leakage studies for a sequence of formations in the Alberta Basin. We will also compare results from a full three-dimensional multi-phase model to those obtained using our simplified multi-scale approaches, and comment on modeling needs from both scientific and regulatory perspectives.