Reactive Transport Simulation of CO₂ Injection Effects on the Hith Caprock Integrity - A Preliminary Analysis

The long-term effectiveness of carbon dioxide storage depends on the sealing capacity of the caprock. Thus, our study investigates the sealing capacity of the anhydrite evaporite Upper Jurassic Hith Formation in the Arabian Plate using the PFLOTRAN reactive transport simulator. A 2D numerical model representing the Arab reservoir and the overlying Hith formation was developed with parameters derived from the literature. CO2 was injected steadily for 10 years at supercritical temperature and pressure, and was monitored for 990 years. Results show that the CO₂ plume remained beneath the caprock, with minimal diffusion (<0.02% of injected CO₂₎ likely due to convective brine mixing at the reservoir seal interface. These findings suggest that the Hith formation is an excellent seal for CO2 in the Arabian Plate.