Time-lapse poroelastic modelling for a carbon capture and storage (CCS) project in Alberta

Shahin Moradi, Donald C. Lawton, Edward S. Krebes

A finite-difference algorithm was developed based on the Biot's equations of motion for modelling the wave propagation in poroelastic media. In contrast with the elastic modelling, in the poroelastic approach the properties of the pore fluid are taken into account in the algorithm. Poroelastic modelling could be useful in cases where the fluid content of the rock is of interest, i.e. Carbon Capture and Storage (CCS) projects. We examined our program using a model based on the Quest CCS project in Alberta to investigate the detectability of CO₂ after one year of injection. This was done by defining two models for baseline and monitor scenarios that represented the subsurface before and after injecting CO₂. The difference between the calculated seismic sections for the two scenarios shows that the residual amplitude is comparable with the signal amplitude. With this result, the injected CO₂ in the Quest project over a year could be detected providing the data have good bandwidth and a high signal-to-noise ratio. The effect of the porosity and the fluid properties on the output of the algorithm is being examined in an ongoing study.