DOI: https://doi.org/10.55373/mjchem.v28i2.299

Keywords: Salt precipitation, CO₂ injection, permeability, potassium ferricyanide, saline aquifers

Abstract

Salt precipitation in the near-wellbore region of deep saline aquifer during CO₂ injection can alter permeability, reduce injectivity, and increase operational costs, thereby reducing the effective storage capacity and raising remediation costs. While previous studies have explored the potential of polymers, acids, and complex synthetics to address this issue, yet few have directly focused on inhibiting salt precipitation. Inhibiting salt precipitation can help maintain storage efficiency and support long-term climate objectives. This study evaluates the effectiveness of potassium ferricyanide (PFC) as a chemical inhibitor for salt precipitation under typical storage conditions. A static test was conducted to assess the interaction between CO₂, PFC, and brine at salinities of 30,000 and 100,000 ppm, and at PFC concentrations of 200 and 500 ppm. Inhibition efficiency, determined through weight difference measurements, showed that at 30,000 ppm salinity, PFC achieved 63.75% and 87.5% inhibition at 200 and 500 ppm, respectively. In contrast, at 100,000 ppm salinity, efficiencies declined to 0% and 19.76%. These results were further supported by NaCl atomic percentage trends and salt mapping. Dynamic core flooding tests showed that the treated core experienced only a 5% reduction in permeability, compared to a 69.3% reduction in the base case. This work highlights PFC as a promising and effective salt inhibitor for enhancing CO₂ injectivity, especially in low-to-moderate salinity conditions.