This study investigates the geomechanical and hydrodynamic behaviour of CO₂ plumes during injection into saline aquifers, with a focus on the hydraulically communicating water-oil zones by analysing numerically the CO2 interface evolution and the associated pressures in geological carbon storage. Using the multiphysics capabilities of ANSYS Fluent, the research explores two critical challenges: (1) the interaction between CO₂-brine-oil phase fluid dynamics, and (2) the associated pressure creation from the process to assess caprock integrity. The study employs the suit of methods Volume of Fluid (VOF) to simulate plume-brine-oil displacement and derives the pressure profiles for different time steps to assess caprock integrity qualitatively. Before final results, a series of auxiliary models were constructed to investigate the inlet boundary conditions satisfying (a) the no buoyancy analytical solution, (b) injection through a perforation and (c) planar injection simulating infinite number of wells storing carbon dioxide. Furthemore, we have investigated the influence on the interface evolution and associated pressure build-up when CO2 is being injected in pure oil. Upon realising the physics of two-phase flows we combined it into a three-phase flow multiphysics model to simulate CO2 injection in a domain where hydraulic communication is allowed between the brine and the oil zones. Computational results align with the no buoyancy analytical solution, with slight deviations near injection points attributed to sharp pressure gradients. For the case of planar injection we have derived the analytical solution for predicting both the interface evolution and pressure build-up. The findings reveal that (i) for the cases of the auxiliary models all cases agree with the no buoyancy solution, (ii) the new analytical solution of the planar injection is in full agreement with the computational model and (iii) time-wise the three-phase interface delays in reaching the caprock mostly due to the high viscous behaviour of oil while below the CO2 displaces much easier the brine below the oil leg. T This work enhances the predictive accuracy of simulation tools and provides practical insights for evaluating interface dynamics while optimizing storage performance.
Αργύρης Ν. Αναγνωστόπουλος (Wed,) studied this question.