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Ensuring long-term wellbore integrity is critical for CO2 injection and storage operations. Conventional cement degrades in CO2-rich environments, compromising zonal isolation and increasing leakage risks. This study presents a novel self-healing cement formulation incorporating Barite, Pozzolan, and Chalcedony, optimized using a Design of Experiment (DOE) approach. Geochemical simulations were conducted using PHREEQC and Python to evaluate porosity evolution, mineral stability, and self-sealing efficiency under CO2 exposure. The results demonstrate that the optimized formulations significantly reduce porosity (within 7–14 days) through the formation of calcium silicate hydrate (C-S-H) gels, enhancing crack sealing and mechanical resilience. Saturation index and phase volume analyses confirm the long-term stability of ECSH2 and Calcite, reinforcing the cement matrix. Compared to conventional cement, the self-healing formulations exhibit improved durability, lower permeability, and superior resistance to CO2-induced degradation. These findings support the use of self-healing cement in carbon capture and storage (CCS), geothermal energy, and deep-well applications, offering a cost-effective and durable solution for long-term wellbore integrity. However, further experimental validation and field-scale evaluation are needed to confirm the practical performance of these formulations under real-world reservoir conditions.
Alsubaih et al. (Tue,) studied this question.