CO2 Mineral Trapping in Basaltic Formation During CO2 Storage

Abstract The rise in global warming is due to the high emissions of greenhouse gases (GHG) around the world. Carbon dioxide (CO2) gas emissions, a by-product from the petroleum industry, is contributors to climate change. One technology that may help curb CO2 gas emissions is injecting the gas into the subsurface reservoir. In this study, CO2 mineral trapping behaviour and its reactions within a wet basaltic rock containing Olivine mineral are captured and simulated in a full field numerical simulation model. A 2-stage approach was planned to develop the full field numerical model. In the first stage, a single cell model was developed, assessed and matched to the literature experiments with several assumptions considered and applied. Following this, the second stage involved developing a full field model to observe and analyse the distribution and concentration of CO2 during injection, as well as its sequestration as a solid phase (i.e., mineral trapping). The overall volume ratio of injected CO2 versus water was also assessed to ensure enough CO2 were injected into the basalt rock ensuring clear distribution of CO2 in the rock either in dissolved, trapped, or mobile state. In this study, the injected volume covered 4% of the total water volume. Results show that mineralization occurs faster than expected when CO2 gas was introduced to the wet basaltic rock especially near the CO2 injector wellbore. The mineralization speed depends on the reaction rate, modelling (cell) surface area and volume as well as the reaction rate coefficient where it was tuned to match the experimental results. The time required for the CO2 component to travel within the rock was also assessed to give a clear picture of the CO2 distribution where it took 10 years to reach 1000 ft away from the injector wellbore within a 440 ft thick reservoir.