CCS in the Goldeneye Field, UK - A Geomechanical Assessment of Containment

For any CCS project, geomechanics plays a key role in determining the containment of the injected CO2. The high potential routes for loss of containment include fracturing the caprock and/or migration along discontinuities through the caprock. Leakage processes are dominated by the in-situ stresses, formation pressures, injection pressures and temperature of the reservoir, all of which vary with time. Whilst injection of gas and fluids in subsurface formations is common practice, we identify key geomechanical challenges associated with CCS projects. These key challenges are explained within the context of the Goldeneye CCS project. Geomechnaical modelling was conducted for assurance of containment for the full life-cycle of the field. Numerical tools have been used to evaluate caprock integrity, reservoir deformation, fault stability and the impact of thermal cooling in terms of fracturing of the reservoir as well as the caprock. We also discuss the impact of thermal cooling adjacent to the injection well and the impact this could have on development of micro-annuli as potential leakage pathways. The results of the geomechanical analysis support injection of CO2 into the depleted Goldeneye reservoir which provides reliable containment over the planned injection period, as well as long-term sequestration within the storage complex.