Seismic-derived geomechanical properties of potential CO2 storage reservoir and cap rock in Smeaheia area, northern North Sea

Geologic CO2 storage site selection requires reservoir, seal, and overburden investigation to prevent injection- and storage-related risks. Three-dimensional geomechanical modeling and flow simulation are crucial to evaluate these mechanical-failure-related consequences; however, the model input parameters are limited and challenging to estimate. This study focuses on geomechanical properties extracted from seismic-derived elastic property cubes. The studied reservoirs (Middle Jurassic Sognefjord, Fensfjord, and Krossfjord formation sandstones) and cap rocks (Heather and Draupne formation shales) are located in the Smeaheia area, northern North Sea, and are evaluated for a potential CO2 storage site. From the elastic property cubes, i.e., acoustic impedance, P- to S-wave velocity ratio, and bulk density, we obtained geomechanical property cubes of Young's modulus, Poisson's ratio, shear modulus, lambda-rho, and mu-rho. Petrophysical property cubes such as porosity and shale volume were also available and were extracted from the elastic property cubes using deterministic methods. We evaluated the geomechanical properties to observe their relationship with depth, compaction/cementation, and petrophysical properties to characterize the cap and reservoir rocks. We found good coherence between the geomechanical and petrophysical properties and their relationship with compaction as a function of depth. The brittleness analyses using elastic property crossplots reveal that both the cap and reservoir rocks are mainly ductile to less ductile, posing lower fracturing risk during CO2 injection. This also indicates lower risks of associated microseismic and possible CO2 leakage.