Potential risk of H2S generation and release in salt cavern gas storage

To ensure constant gas quality over time, the gas and the brine must be analyzed continuously and technical methods must be applied when the H2S(g) concentration increases. According to the modelling results, H2S(g) generation is inhibited by addition of dissolved ferrous iron to the brine. Dissolved ferrous iron reacts with sulfide-sulfur to form mackinawite (FeS(s)) so that aqueous sulfide is no longer available for H2S(g) generation. Another method is the addition of NaOH to increase the pH of the brine. Then, higher fractions of generated sulfide-sulfur are transformed to free S2−(aq) instead of H2S(g) and H2S(aq).