The small-spacing dual-well (SSDW) technique plays a crucial role in the establishment of underground salt cavern gas storage reservoirs. However, during the cavity dissolution and brine discharge processes, insoluble sediment is prone to being carried into the discharge tubing with the brine, leading to tubing blockages or clogging, which disrupts injection and withdrawal operations and severely affects both project efficiency and the safety of the gas storage facility. This study systematically analyzes the influence of the gap between the injection and discharge tubing and the surface of the sediment-on-sediment movement, deposition, and tubing safety in SSDW salt caverns. Through numerical simulations, this study investigates the influence of tubing layout on the internal flow field distribution of the cavern and the suspension behavior of sediment, revealing the changing trend of the risk of sediment entering the tubing at different distances. The results show that a rational tubing distance can significantly lower the risk of sediment backflow and tubing entry, while maintaining high brine discharge efficiency. Based on the simulation results, an optimized tubing layout design suitable for SSDW salt caverns is proposed, offering technical direction to guarantee the safe and effective functioning of underground salt cavern gas storage sites.