A numerical simulation for the solution mining under natural gas of salt-cavern gas storage

To provide the guidance for the repair of partially dissolved or irregular caverns by means of solution mining under natural gas (SMUNG), it is necessary to carry out the numerical simulation research. In order to ensure the safety of cavern top in the process of cavern repair, the operation is conducted only at the target depth to prevent the cavern top from extending further. A large amount of blankets is demanded, so natural gas whose source is convenient is taken as the blanket. A mathematical model was established and a simulation program was developed for SMUNG of salt-cavern gas storage. In the simulation, the upper dissolution characteristic of salt rock was taken into consideration. Then, this technology was applied to simulate the SMUNG of Well L in Jintan salt-cavern gas storage. SMUNG can be used to optimize the shape and volume of single-cavern, improve the utilization rate of high-quality salt bed and reduce the effect of cavern irregularity on gas injection de-brining operation, and consequently caverns can meet the safety requirements. It is indicated that the simulation program can effectively simulate the development of cavern shape in the process of SMUNG and its simulation results are consistent with the field operation data. The research results are of great significance to improve the effective volume and cavern stability of single-cavern.