Method for determining thickness of sleeve-cement sheath composite structure top plate of salt-cavern gas storage

The invention designs a method for determining the thickness of a salt cavern gas storage casing-cement sheath composite structure top plate. The method comprises the following steps: firstly, carrying out field exploration, determining a storage building target burial depth according to data, counting the density and depth of each overlying stratum, and calculating overlying stratum pressure and stratum pore pressure; in-situ coring is carried out from a proposed area to carry out an indoor test to obtain stratum parameters and rock mechanical parameters, and a gas storage casing-cement sheath composite structure form numerical model is established; evaluating deformation and failure characteristics of a gas storage roof cement sheath and surrounding rock under the influence of different roof pre-salinized layer thicknesses, roof interlayer geometric characteristics and injection-production pressure limit value factors, and comparing a surrounding rock penetration influence range with a leakage law, and pref