Modeling Horizontal Salt Cavern Leaching in Bedded Salt Formations

Summary The leaching of a salt cavern will trigger a series of rock-fluid interactions, including salt rock dissolution, cavity expansion, and brine transport caused by convection, turbulence, and diffusion effects. These interactions have influences on one another. The primary objectives of this study include developing a 3D multiphysical coupled model for horizontal salt cavern leaching and quantifying these interactions. The species transport equation and standard κ-ε equation were combined to describe the brine transport dynamics within the cavity. Based on the velocity and concentration distribution characteristics predicted, the interface movement equation implemented with mesh deformation techniques was applied to describe the cavity expansion. Next, the Volgograd cavern monitored data were collected for model validation. The predicted results are consistent with the field data. The average relative errors are 11.0% for brine displacing concentration and 4.5% for cavity volume. The results suggest that the cavity can be divided into three regions, including the main flow region, circulation region, and reflux region. The results also suggest that the brine concentration distribution is relatively uniform. With the dissolution threshold angle and anisotropic dissolution rates considered, the resultant cavity cross section is crown top and cone bottom. The results also show that the cavity can be divided into dissolution and erosion sections according to its position relative to the injection point.

Influence of the Variability of Compressed Air Temperature on Selected Parameters of the Deformation-Stress State of the Rock Mass Around a CAES Salt Cavern

The article presents the results of a numerical simulation of the deformation-stress state in the rock mass around a salt cavern which is a part of a CAES installation (Compressed Air Energy Storage). The model is based on the parameters of the Huntorf power plant installation. The influence of temperature and salt-creep speed on the stability of the storage cavern was determined on the basis of the three different stress criteria and the effort of the rock mass in three points of the cavern at different time intervals. The analysis includes two creep speeds, which represent two different types of salt. The solutions showed that the influence of temperature on the deformation-stress state around the CAES cavern is of importance when considering the stress state at a distance of less than 60 m from the cavern axis (at cavern diameter 30–35 m). With an increase in cavern diameter, it is possible that the impact range will be proportionately larger, but each case requires individual modeling that includes the shape of the cavern and the cavern working cycle.