CO2 Sequestration at Material rates: Inherent limits and Engineering Solutions

AbstractThe most important technical challenge now facing geologic carbon storage (GCS) involves rates of storage, not volumes. The factors governing well injectivity combine to make achieving material storage rates (of order 0.1 Gt CO2/y in a basin or region) difficult. One such factor is the correlation between injectivity and storage volume of structural traps, which restricts access to much space that is desirable for secure storage for centuries. This limitation is exacerbated by the reduction in fracture pressure when injected CO2 is cooler than the storage formation. Changing the storage paradigm, so that brine is extracted from the storage formation as CO2 is injected, is the only robust option for materiality. A solution to the resulting brine disposal problem is to dissolve CO2 into the brine, then reinject it into the storage formation. This and other alternatives to injection-only storage must be examined if GCS is to play a substantive role in mitigating CO2 emissions over the course of decades