A numerical model for gas CO2 migration in a fault zone

Understanding how fractures and faults impact the migration of fluids is critical in the evaluation and monitoring of geological storage sites, and to assess the conditions promoting fluid flow from a reservoir and mitigate the risk of migration via faults. Here, we present a three-dimensional numerical modeling of flow of CO2 gas into a fault zone, based on detailed field data acquired on a fault exposed in the Roman Valley Quarry (Majella Mountain, Italy). The numerical modeling was performed using the multiphase flow simulator PFLOTRAN. The aim of this paper is to present a methodology that combines small-scale field data with numerical modeling to assess the influence of fault components on the migration of CO2. Simulations results indicate that most of the gas migrates through the high permeable footwall damage zone, where the injection occurs. Some of the gas can also migrate through the hanging wall damage zone and the fault core. The buildup of gas pressure in the vicinity of the injection wells demonstrates the need of increasingly accurate modeling of the injection conditions to avoid possible faults reactivation.