Impact of Fractures on CO2 Storage Monitoring - An Integrated Approach

The monitoring of CO2 storage in fractured reservoirs (depleted hydrocarbon field or brine aquifers) requires the study of the impact of fracturation and fluid substitution on seismic data. Seismic data can provide information about the additional compliance due to the fractures and to the fluids through the analysis of seismic azimuthal anisotropy and the introduction of a rock physics model providing a realistic description of fractured media (where porosity, multiphasic fluid phases, inherent seismic anisotropy, the presence of multiple sets of fractures and their connection with porosity can be considered). Seismic methods by themselves cannot fully describe fracturation and must be associated with other methods through an integrated approach. First, borehole and outcrop geological information can give the upper limit of the fracture density expected at depth in the same formation. Second, rock mechanics helps understanding the fracturation state at depth.