Numerical simulations of pressure buildup and salt precipitation during carbon dioxide storage in saline aquifers

• Massive CO2 injection into saline aquifers causes multi-scale phenomena.
• Pressure buildup, CO2 plume and salt precipitation occur at large to small scales.
• The large scale pressure change is affected by boundaries of the storage systems.
• The small scale salt precipitation occurs adjacent to the injection well.
• Salt precipitation leads to the degradation of CO2 injectivity.

The storage of large amounts of carbon dioxide (CO2) captured from fossil fuel fired power plants in deep saline aquifers can be an effective and promising measure for reducing the emissions of greenhouse gases. Massive CO2 injection into saline aquifers may cause multi-scale phenomena such as pressure buildup in a large scale, CO2 plume evolution in a medium scale and salt precipitation in a small scale. In this study, three-dimensional simulations are performed to investigate the propagation of pressure and the impact of salt precipitation on the process of large scale CO2 injection into the saline aquifers. Apart from the different scales of the processes, the numerical results show clearly different behaviours of the pressure changes in saline aquifers with different boundaries. Different types of salt precipitation occur adjacent to the injection well, presenting distinct impacts on the fluid flow. Affected by salt precipitation, the porosity and permeability are reduced, leading to declined transportation and degraded injectivity with different boundary conditions. The interplay between pressure buildup and solid saturation is compared in saline aquifers with different boundary conditions.