Improvement of the compositional simulation capabilities for reactive transport of carbon dioxide in underground geological storage sites in connection with CCUS.
CO2 storage is a multiphysics process involving multiphase (gas-liquid-solid) equilibrium and multispecies geochemical reactions. Accurate analysis of most phenomena in CO2 storage requires a compositional description with geochemical reactions as well as geomechanics for assurance of long-term safety. A challenge in using compositional simulation for reliable technical risk assessment is that compositional simulation with mentioned reactions is computationally demanding and often suffers convergence problems. Therefore, a next-generation compositional CO2 storage simulator with multiphase geochemical reactions, applicable for a wide range of reservoir types, will be developed with improved robustness and efficiency.
This will be achieved by utilizing the novel RAND-based multiphase reaction algorithms recently developed at DTU, which provide new formalism for compositional CO2 storage simulation with multiphase reactions. The algorithms are minimization-based and guaranteed to converge, give a smaller set of equations for multiple phases and a second-order convergence rate, and are therefore highly-efficient.
The algorithms treat phase and chemical equilibrium simultaneously, avoiding the conventional sequential solution and are especially suited to situations with many phases and reactions, like in CO2 storage. Additionally, a non-isothermal formulation will be adopted because isothermal conditions do not apply in the near wellbore region. The developed simulator will be able to handle both the near-wellbore and the reservoir-scale simulations during the injection and post-injection period.
Furthermore, in collaboration with Stanford University, the simulator will be coupled with GEOSX, a simulator developed by Stanford University, LLNL and TotalEnergies.GEOSX is a subsurface, non-compositional simulator with coupled multiphase flow and geomechanics. It is mainly designed for long-term analysis after the completion of CO2 injection, including the pressure and stress variation and the CO2 plume development, which can be used not just for long-term forecast but also a potential coupling with monitoring.
Main supervisor
Wei Yan