This work presents an indirect hydro-mechanical (HM) coupling concept to study the caprock integrity with regards to CO2 storage in saline aquifer by means of numerical simulations. The HM coupling concept is realized by developing an effective mean stress dependent permeability model and an effective mean stress dependent Biot's coefficient model in reservoir sandstones. The developed models are implemented into the numerical HM-simulator TOUGH2MP-FLAC3D by writing functions with Fortran 90 in an open source code TOUGH2MP and FISH Language in FLAC3D, respectively.
The pilot project for CO2 storage in Ketzin is chosen as a case study to validate the developed HM concept. The numerical simulations are performed using the modified HM coupling simulator TOUGH2MP-FLAC3D. The good agreement of the simulation results with the existing research data suggests that the developed coupling concept can be used for the caprock integrity analysis in the pilot project at Ketzin. In addition, a generic model with reasonable assumption is adopted to study the caprock integrity with regards to CO2 storage in saline aquifer under commercial injection conditions, and the results confirm that the developed coupling concept can be applied to CO2 storage in commercial scale.