Modeling the construction of energy storage salt caverns in bedded salt

Abstract

During the construction of energy storage salt caverns in bedded salt, the unpredictable failure of interlayers results in irregularly shaped caverns with lower storage capacity and with potential safety hazards. A model is established of the coupled salt dissolution and interlayer failure during the construction of a salt cavern. Equations of the salt dissolution rate and of the brine concentration-flow field of the dynamic cavern development are introduced. Failure of the interlayers with a soluble skeleton is described in three steps as disintegration, fall and accumulation. Failure of the interlayers with an insoluble skeleton is modeled by location determination, strength calculation and collapse implementation. A C++ program is developed for the implementation of the model. A cavern, JT86, in Jintan Gas Storage, China, is simulated by the proposed model and by a traditional model. The disintegration, collapse, fall and accumulation of the insoluble interlayers can be simulated by the proposed model, which results in a more accurate cavern shape prediction. The simulation shows a dissolution-collapse-dissolution cycle and a self-locking condition, which might be the reason for the uneven development of caverns in inclined bedded salt. To increase the cavern stability, an extra leaching stage is suggested around the overhanging interlayers to bring the collapse under control.