Multi-well combined solution mining for salt cavern energy storages and its displacement optimization

Improving the water solution mining rate of the salt rock layer while reducing energy consumption is the core idea for promoting the construction of salt cavern energy storage. In this work, a novel multi-well combined solution mining method for salt cavern energy storages was presented, and a displacement optimization model incorporating sub-models for outlet brine concentration, solution mining rate, and energy consumption of water injection was proposed to maximize the solution mining efficiency. The accuracy of the proposed model is verified by comparing the simulated results with the field data. The results show that under basically the same solution mining rate, the energy consumption of brine injection can decrease by 18.82 %. If 0.49 % of the solution mining rate of the salt cavern can be sacrificed, energy consumption can be reduced by 7.40 %. A special focus was given to the well selection schemes, which indicated that optimization of well selection schemes could reduce energy consumption by 3.61 %. This work could add further insights into the inter-coupling relationship between outlet brine concentration, solution mining rate, and energy consumption of water injection, and help to reduce the energy consumption of water injection and improve solution mining rate.