Publications

More countries are making commitments to attain net zero emissions in the coming decades hoping to limit the global temperature rise. Carbon Capture and Storage (CCS) will play a crucial role in the transition to net zero on energy-related carbon dioxide emissions. It is thus necessary to keep evolving our knowledge and developing innovative technologies to enhance efficiency and reduce risks. When CO2 is injected in geological formations, due to complex procedure involved and full Thermo-Hydro-Mechanical-Chemical (THMC) interaction at downhole condition, the risk on safety, formation integrity and injection efficiency is significant. Residual risks such as leakage continue after injection stops; hence it is necessary to assess the risks in both short and long terms. Digital technologies integrating multi-disciplines such as seismic, geology, petrophysics, fluid-flow, chemistry and geomechanics enables to identify the risks and suggest mitigation prior to happening. This study demonstrates the importance of coupling THMC processes in successfully modelling of CO2 storage into a depleted oil field, while reservoir storage capacity, cap-rock integrity, fault stability assessment and well integrity were analyzed. A 3D Mechanical Earth Model (3D MEM) was built to represent pre-injection pressure, temperature, and stress condition of a sandstone reservoir. Supercritical CO2 was injected for 20 years into the reservoir from six wells. Coupled fluid-flow and geomechanics interaction with time (4D MEM) was performed through dynamic fluid flow and geomechanics simulators. Simulated stresses, strain, and displacement at 10 timesteps at 2 years interval were analyzed to assess maximum storage capacity without causing failure to the caprock and reactivating the faults. In addition, maximum ground heave was also calculated which can be a useful information for planning platform and well trajectory. Results obtained from the study indicate that there is a possibility of reactivating some of the faults if injection rated exceed 90000 sm3/day. Also, temperature of the injected CO2 showed noticeable effect on the stability of both caprock and fault. While a lower temperature of injected CO2 is good for the stability of caprock, it makes the faults more susceptible to reactivation.