Potential of storing gas with high CO2 content in salt caverns built in ultra‐deep water in Brazil

Salt caverns have been identified as one of the best options for the underground storage of gases due to salt rock's excellent sealing capabilities and interesting mechanical properties, such as self‐healing when damaged or cracked. It is feasible to build salt caverns in the Brazilian pre‐salt ultra‐deep water environment for gas storage. However, the peculiar geology of the Brazilian province considered here is characterized by the stratification of thick layers of halite with intercalations of carnallite and tachyhydrite salt rock, whose creep strain rate is almost two orders of magnitude higher than halite's creep strain rate under the same conditions of temperature and pressure. Computational mechanics is being used for the design of offshore salt caverns opened by dissolution mining for the storage of natural gas. The challenge presented in this paper requires the storage of natural gas with high CO2 content offshore in ultra‐deep water (2140 m) in salt caverns. If the economics proves feasible, this offshore gas storage station will be the first of its kind in the world. A technical feasibility rock mechanics study of giant salt caverns, 450 m high by 150 m in diameter, has shown that one cavern can store 4 billion Sm3 or 7.2 million tons of CO2. The salt dome studied can accommodate the construction of 15 caverns, thus providing the confinement of approximately 108 million tons of gas. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.