Integrated Geomechanical and Fault Activation Modeling of the Wasia Reservoir: A Study Focused on Ground Uplift, Stability Analysis, and CO2 Leakage

The excessive burning of the biomass materials and hydrocarbons produces more carbon dioxide than the nature can absorb. The increase in the CO2 concentration in the atmosphere is also due to the excessive deforestation and increased industrialization. The extra CO2 in the atmosphere will contribute to the global warming by absorbing and re-emitting the infrared radiations from the sun. Carbon dioxide storage in underground sedimentary reservoirs is one of the possible options that can help in mitigating the effect of global warming. During the geological carbon dioxide storage process, CO2 is injected at higher injection pressure to the underground sedimentary reservoir, which causes the base pore pressure of the reservoir to increase excessively. Any possible injection of CO2 near to the already existing fault can activate the fault and can cause the leakage of the stored carbon dioxide to the overburdened potable water layers and to the atmosphere. In this paper, an integrated geomechanical and fault activation modeling study is performed for the Wasia reservoir in Saudi Arabia. During the geomechanical modeling process, a fault passing through the Wasia and Aruma geological layers is also considered. The pore pressure buildup and ground uplift were calculated during carbon dioxide injection into the reservoir for the case of absence of a fault across the reservoir, as well as the case with a fault. The Mohr-Coulomb failure criterion was utilized to perform the stability analysis of the reservoir for the case of absence of a fault across the reservoir, as well as the case with a fault. The integrated geomechanical and fault activation modeling performed in the current study has provided estimates for the safe injection parameters of CO2 based on the magnitudes of the reservoir pore pressure and stresses in the reservoir.