Research on Ground Subsidence Prediction and Risk Assessment for Deep Potassium-Rich Brine Extraction

Potash is a strategically critical mineral resource essential for ensuring national food security, thereby necessitating the exploration of new deposits to sustain long-term supply. This study systematically evaluates the risk of ground subsidence associated with a “brine extraction–replenishment equilibrium” mining scheme through an integrated framework combining three-dimensional geological modeling and numerical simulation. The research focuses on deep potassium-rich brine resources in the Sanshui Basin, Guangdong Province, China. Geological data from 95 boreholes were processed to construct a high-resolution three-dimensional geological model (61.40 km × 35.20 km × 3.50 km) using Petrel software. Numerical simulations based on poroelastic theory were conducted under multiple extraction scenarios, and the predicted subsidence was assessed against relevant engineering standards for highways and building foundations. The results indicate that: (1) brine extraction from consolidated sandstone represents a fluid displacement process, where the equilibrium scheme induces only minor effective stress redistribution without forming dissolution cavities; (2) global subsidence investigations suggests consolidation primarily affects Quaternary unconsolidated strata, making consolidated sandstone extraction associated with extremely low risk; (3) the maximum subsidence is 5.55 mm and 6.82 mm in the primary and secondary exploration areas, with corresponding surface inclinations of 0.00047‰ and 0.00040‰; (4) unlike solution mining that creates large cavities, deep brine extraction generates no significant inter-stratal pressure differentials. These findings demonstrate that under the extraction–replenishment equilibrium scheme, ground subsidence remains well below the regulatory limits, posing no risk to surface infrastructure. This research provides a scientific foundation for safe development of similar deep brine resources globally.