A Methodology for Geological Hazard Assessment in Temporary Storage Facilities

Abstract

The main risks and hazards related to fluid storage in subsurface are associated with reservoir rocks deformation, pore pressure change and/or change in stress around faults (depending on their properties and orientations): a change in pore pressure due to injection or extraction of fluid from a well, may change the stress acting on a nearby fault; this change in stress may induce slip or movement along that fault creating a seismic event. Compaction or dilation of reservoir volume induce stress changes inside the reservoir and the surrounding caprock, also generating ground movements: subsidence and uplift,, in consequences of fluid withdrawing or fluid injection in reservoir, are related to reservoir performances, geological setting and reservoir/caprock mechanical properties. Despite an increased understanding of the basic causes of their hazards, these kinds of energy projects will retain a certain level of risk for inducing seismic events, manufacture integrity, and ground movements. For assessing geological hazards associated to subsurface temporary storage, we develop a 3-step, quite fast and easy procedure; starting from a real reservoir, converted to temporary storage facility, we quantify 1) reservoir deformations, 2) induced stress changes and 3) areas in the caprock which are more affected by stress changes distribution.