Modeling of fate and transport of coinjection of H_2S with CO_2 in deep saline formations

摘要

The geological storage of CO_2 in deep saline formations is increasingly seen as a viable strategy to reduce the release of greenhouse gases into the atmosphere. However, costs of capture and compression of CO_2 from industrial waste streams containing small quantities of sulfur and nitrogen compounds such as SO_2, H_2S, and N_2 are very expensive. Therefore, studies on the coinjection of CO_2 containing other acid gases from industrial emissions are very important. In this paper, numerical simulations were performed to study the coinjection of H_2S with CO_2 in sandstone and carbonate formations. Results indicate that the preferential dissolution of H_2S gas (compared with CO_2 gas) into formation water results in the delayed breakthrough of H_2S gas. Coinjection of H_2S results in the precipitation of pyrite through interactions between the dissolved H_2S and Fe~(2+) from the dissolution of Fe-bearing minerals. Additional injection of H_2S reduces the capabilities for solubility and mineral trappings of CO_2 compared to the CO_2-only case. In comparison to the sandstone (siliciclastic) formation, the carbonate formation is less favorable to the mineral sequestration of CO_2. In sandstone and carbonate formations, the presence of Fe-bearing siliciclastic and/or carbonate is more favorable to the H_2S mineral trapping.