Study On Theoretical Model And Numerical Simulation Of Surface Subsidence Caused By Gas Storage Of Rock Salt

Solution mining of salt caverns are often used as the energy storages，rock saltunderground gas storage is the need of national strategic reserve and business reserve.The surface subsidence of reservoir area is related to resources, environment, life andproperty security, and it is also an important criterion of gas storage stability of the saltcavern. In this paper, by means of theoretical analysis and numerical simulation, studyon surface subsidence caused by the setting of gas storage of rock salt was carried out.And then, the rusult is tested by the mathematical model. The surface subsidencecontrol measures are also proposed.①Comprehensive study the research achievements of domestic and foreignresearch， the main influencing factors of surface subsidence were analyzed, and thecreep constitutive equation, and the material physical and mechanical parameters wereselected. with Chinese salt geological conditions, the simplified model numericalsimulation was set。②The paper studies single-chamber gas storage by numerical simulation in the10kinds of work conditions, and it discusses the deformation basic rule of single rock-saltcavern’s surface, and analyzes the factors’ influence on the effect of surfacesubsidence,such as internal pressure, buried depth, volume, creep time and so on, and italso analyzes the relationship between factors. According to the distribution of the gasstorage chamber for plastic zone, cavity week’s displacement contour maps and volumeweek’s shrinkage to analyze the gas storages’ stability。③In order to establish the two cavern model, the paper discusses the size of thecavity spacing’s influence on the surface subsidence, then combines with the gas storagecavities’ stability to draw reasonable cavity spacing. It establishes a reasonable cavityspacing to further discuss the role of internal pressure on the dual-chamber reservoirsurface subsidence, and analyzes the law of the surface subsidence and the stability ofthe gas storages.④It establishes three chambers and17chambers gas storages by a reasonablecavern spacing to analyze the law of the surface subsidence and the stability of the gasstorages. It compares with single lumen, double caverns and a group of caverns’ law ofsurface subsidence and cavities’ contraction comprehensively.⑤According the surface subsidence’s3d calculated integral formulas to calculate surface subsidence’s radius and surface subsidence’s depth, and they are comparedwith the results of numerical simulation. According to the ground surface settlementtime function Knothe shortages of some commonly used "S" shape growth curve modelof the function of the characteristics of the analysis, the selection and the actual processof surface subsidence conform to the MMF function as the ground surface settlementtime function model, and the model parameters are determined, indicates that thetheoretical results compared with the numerical simulation results are close At last, thepaper summarizes the control measures of the surface subsidence, and the gas storageconstruction and operation can draw lessons from them.