Research On Cavity’s Stability In Solution Mining For Salt Cavern Gas Storage

In recent years,global energy storage has enormously aggravated and become more serious than ever before. Oil pad method in single well is salt cavern gas storage construction methods that commonly used at home and abroad. In the production practice,there are lots of projects get deformed cavern and even scrapped cavern due to the shape design of cavity. Stability of these cavity birth defects exist, it is difficult to meet the operational requirements of the salt cavern gas storage. Therefore, the research on cavity’s stability in solution mining for salt cavern gas storage that avoid accidents and risks has important application value.Base on the project in a domestic gas storage construction that carried out salt rock salt dissolution and non-sandwich corrosion test. Based on the test results imitate the shape of cavity forms in different stages and process parameters, and then use numerical analysis software to analysis the mechanical stability of the simulative shape. Eventually get the optimal shape meet the gas storage stability requirements, and provide the basis for gas storage design. Details are as follows:(1)Through comprehensive research scholars for controlling cavern’s shape in the construction of salt cavern gas storage,summarized two categories of factors. First type is the characteristics of salt, grade of salt and other geological conditions. The second type is tubing string’s combination, displacement, cycle ways and other construction crafts, which only construction craft is controllable factors.(2)Dissolution test carried out on the halite sample.Achieve the content of undissolved substance, side solution angle, top dissolution rate, side dissolution rate and other important control parameter.(3)Corrosion test carried out on the interbed sample. Reveal the mode of failure is delamination and brief analysis the failure mechanism of interbed, provide the basis for simulation.(4)Based on test results, divide solution mining into several key stages with related stratigraphic information and on-site construction technology.then use different design to simulate. Provide the basis for stability analysis in the process of solution mining.(5)Use finite difference simulation software to calculate and analysis the deformation characteristics of the above simulation cavity,and stability of cavity which interbed is under brine weakening. Obtained the optimal cavity design by contrast,and how to avoid the unstable cavities by reasonable processes.