Numerical Analysis of Time-Dependent Behavior of Salt Cavern with Weak Interlayer

Natural gas consumption fluctuates due to seasonal demand, extraction limitations, price changes, and political conflicts. These fluctuations necessitate the storage of natural gas. Among various storage methods, salt caverns have several advantages for storing hydrocarbons compared to other methods. These advantages include the low permeability of rock salt and the low cost of construction. However, salt caverns may be affected by weak layers such as marl or mudstone within the formation’s layering sequence. This research aimed to numerically study the long-term behavior of a salt cavern excavated in interbedded salt rock with weak interlayers. The effects of placement angle (۰°, ۳۰°, ۴۵° and ۶۰°), layer thickness (۱۰, ۱۵ and ۲۰ meters), number of (۱ or ۲ or ۳) and three different levels on operational time were analyzed. FLAC۳D finite difference software was selected because of its Cpower creep behavior model. A total of twenty-two numerical models were executed. The results emphasize the importance of level, placement angle, thickness and interlayers numbers on displacement, stability and safety of a salt cavern over its operational time. The Ratigan dilatancy safety factor is not suitable for assessing the effects of geometric parameters of interlayers on salt cavern stability. Generally, constructing a cavern in salt layers containing weak interlayers is not recommended.

کلیدواژه ها:

Gas storage ، Salt layer ، Weak interlayer ، Numerical modeling ، creep