Can Deformation Bands Act as Mini Structural Traps for Secure Geological Storage of CO2?

Small-scale deformation bands in the Penrith Sandstone are used for CO2 flow simulation to assess the extent to which these features can act as effective mini-traps. A set of simulation scenarios applied to the cluster of deformation bands to test the effect of deformation bands density, deformation bands orientation against a major fault, and also the contrast in host rock/deformation band permeability on fluid movement. The simulation exercise demonstrates that the presence of the zone of the deformation bands alone may not be a positive contribution to CO2 safe storage as there needs to be an optimum number of deformation bands that do not excessively damage reservoir communication, nor reduce bulk porosity reduce reservoir porosity. In addition, the observations show the amount of mobile CO2 that reaches the caprock or any leaky faults is not only controlled by the contrast in permeability, but also by the geometrical architecture of the deformation bands. Therefore, some types of deformation band demonstrate a more positive contribution to storage security, while other types may compromise it.