Collapse behavior of thick interlayers in bedded salt caverns during the leaching phase

Global warming has led to a notable increase in the demand for natural gas, highlighting the urgent need to develop large-scale salt cavern gas storage. However, the complex collapse behavior of thick interlayers within bedded salt strata poses a considerable challenge to the regular and efficient establishment of salt caverns. In this work, a series of new physical models with layered salt stratigraphic structures is created via staggered stacking of Pakistani high-purity salt blocks and artificial interlayer materials. The impacts of various factors, including water injection flow, properties of the interlayer materials, interlayer thickness, and string column position, are examined through physical simulations of the morphological evolution of the caverns. Additionally, changes in the concentration and volume of the brine are monitored. Four potential collapse modes during the actual cavern-leaching process are identified and validated. The diverse collapse behaviors of interlayers with geometric thickness as the controlling parameter are discussed, the formation mechanism of the irregular cavern morphology is analyzed, and the limitations are acknowledged. The findings of this research provide valuable theoretical insights that can guide the efficient construction of underground gas storage in bedded salt rock formations.