Understanding And Quantifying The Risk Associated With Subsurface Fluid Injection

In several engineering applications, fluids are disposed in deep underground repositories to reduce their potential to pollute the enviroment. An example is Geological Carbon Storage (GCS), which consists of the disposal of carbon dioxide (CO2) into deep geological formations, in order to reduce direct emissions to the atmosphere, and thus mitigate climate change effects. However, a global impact can only be achieved if GCS is cost effectively and safely implemented on a massive scale. A major risk of GCS is represented by upward leakage of CO2 from the storage formation through weak areas of sealing layers (caprock). Leakage pathways are constituted by pre-existing, poorly-completed "passive" wells, caprock fractures and faults. In this project, the students will learn to use either analytical or semi-analytical flow models, developed to simulate the spatio-temporal distribution of fluid ovepressure induced by CGS and the fluid leakage. The analytical features of these models make them particularly adequate to run first-hand screening tests and risk analyses. Finally, the student will apply such model, in both hypothetical and real-world case studies, to assess leakage CO2 risk in relation to site characteristics, such as CO2 injection rates, thickness and depth of the storage formation, and most relevant hydro-geomechanical properties, such as permeability and compressibility.