Effect of overburden spatial variability on field-scale geomechanical modeling of potential CO2 storage site Smeaheia, offshore Norway

Abstract

Although geological CO2 sequestration is an essential solution for reducing anthropogenic carbon dioxide from the atmosphere, the method needs critical evaluation of injection-induced mechanical risks for safe and reliable CO2 storage. 3D field-scale geomechanical modeling is a preeminent solution for assessing mechanical risks of subsurface geological CO2 storage. However, data scarcity of seals and overburden rocks might limit building the 3D field-scale geomechanical model. This study focuses on seismic data-derived 3D field-scale geomechanical modeling of potential CO2 storage site Smeaheia, offshore Norway. The geomechanical properties inverted from seismic data are resampled in the 3D grid to consider spatial variabilities of seal and overburden rock properties. This method allows us to investigate the effect of overburden rock spatial variability imposed in seismic data on the 3D geomechanical model of Smeaheia. The model was built in Petrel-2019, while the one-way geomechanical simulation is iterated using the finite element method. Simplified constant overburden property models are also constructed to analyze the sensitivity of the overburden rock properties. The results reveal that the seismic data-driven spatially distributed overburden properties model workflow used in this study is a convenient and robust solution for 3D field-scale geomechanical modeling. The maximum vertical estimation of rock deformation is doubled in the simplified (isotropic) overburden rock property model compared to the new spatially variable (anisotropic) overburden rock property model. The Mohr-Coulomb failure envelope reveals that the new modeling approach is less prone to failure than the simplified (isotropic) model, which might influence the project decision. Moreover, our study demonstrates the importance of considering the spatial variability of overburden rock properties in building the 3D field-scale geomechanical model.