Position design of the casing shoe of an abandoned horizontal salt cavern to be used for gas storage

China's salt mines have a typical bedded structure, composed of many interlayers and salt rock layers. If the conventional vertical single cavern leaching technology is used, the shape control of the caverns is difficult. Horizontal salt cavern gas storage (HSCGS) can be built in thicker pure salt sections. The internal pressure, casing shoe position and the range of plastic, dilatation, and failure zones are significant factors to be considered in the design. The yield behavior of rock salt can be described by the Tresca yield criterion. The second invariant of the plastic strain was used as the hardening parameter to analyze the hardening behavior. The dilatancy boundary is defined to determine the dilatation zone. Based on the Mohr-Coulomb criterion, a failure criterion of rock salt is established. The constitutive model was modified and the state parameters were self-defined in FLAC3D. Thus a Yield-Dilatancy-Failure (YDF) model is established. Based on the YDF model, the rock surrounding a HSCGS is divided into four zones: elastic, plastic, dilatation and failure zone. The casing shoe position should be outside the dilatation zones. When the dilatation zone of the HSCGS in the middle part is prevented from developing. The minimum pressure (9 MPa) is determined that prevents the formation of a dilatation zone around the middle part of the HSCGS. The research results can provide a reference for determining pressure and casing shoe position of an HSCGS.