Poroelastic model-based time-lapse modeling of the Quest carbon storage project in Alberta

A finite-difference algorithm was developed based on the Biot’s equations of motion for modelling 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 the baseline and monitor scenarios that represented the subsurface before and after injecting CO2, respectively. 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. Furthermore, a comparison between the poroelastic algorithm and the elastic algorithm shows that the time-lapse effect in the poroelastic case is smaller than the one in the elastic case. In the fluid saturated media some of the wave energy dissipates due to the fluid induced flow, and the poroelastic approach helps us to take this loss into account in the modeling process.