Simulation of Flow Field of Solution Mining Salt Cavities for Underground Gas Storage

Abstract

Salt cavern solution mining is a complicated process of fluid dynamics and chemical dynamics, including salt boundary dissolution, cavern expansion, brine flow, and species transport. The reaction processes occur simultaneously and interact with each other. In this study, a multiphysical coupled model is established to evaluate the real time 3D salt cavern shape expansion, the velocity field, and the brine concentration distribution. Then, the predicted results are compared with the field data of a Jintan Gas Storage Well in China. The average relative deviations with the turbulent flow are 5.7% for outlet brine concentration and 4.0% for cavern volume. The results show that salt cavern can be divided into four regions, including the shock region, plume region, reflow region, and suction region. The results also indicate that the turbulent flow will stimulate the formation of the vortex, thus affecting the distribution of brine concentration. And, the brine concentration distribution primarily influences cavern corrosion. The results suggest that adjusting the inject velocity and the tube position can change the cavern construction rate and the cavern shape. Overall, these results have guiding significance for the design and engineering practice of salt cavern construction for energy storage.

Comprehensive Research on Construction and Stability of Horizontal-Well Cavity Natural Gas Storage in Thinly Bedded Salt Rocks in China

“…At a fixed flow rate, the relative influence of freshwater injection (relative to the total cavity volume) decreases with increasing cavity volume, while the gravitational influence of the concentration gradient within the cavity increases [35]. Although the design of horizontal-well cavities differs in many aspects from that of single-well cavities in many ways, the key to controlling the shape of the cavity is still largely influenced by the concentration distribution [36]. Although the effective volume of a horizontalwell cavity natural gas storage is larger, the control of a horizontal-well cavity involves more factors [17,22], so the economics, construction efficiency and long-term stability of horizontal-well natural gas storage must also be considered when designing cavity construction parameters [18,37].…”

Comprehensive Research of Construction and Stability of Horizontal-Well Cavity Natural Gas Storage in Thinly-Bedded Salt Rocks in China

“…At a fixed flow rate, the relative influence of freshwater injection (relative to the entire cavity volume) decreases with increasing cavity volume, while the gravity impact of concentration gradient in the cavity increases [41]. Despite the many differences between horizontal well water-solution mining and single-well water-solution mining, the key to controlling the shape of the cavity is still largely influenced by the concentration distribution [42], i.e., the effect of concentration on dissolution. Although the effective volume of horizontal-well cavity natural gas storage is larger, the cavity control of horizontal-well cavity involves more factors [43,44], thus the economic and construction efficiency, and stability of horizontal-well natural gas storages at later stages also need to be considered in the design of the cavity process parameters [45,46].…”