Optimal selection of shape stability for horizontal cavities in salt cavern gas storage

At present, salt cavern gas storages are mainly built in a vertical cavity pattern with single well, however, for thin salt layers, this method will lead to small cavity volume and low utilization rate of salt layers, which is unsuitable. The above-mentioned problem can be effectively solved by adopting horizontal cavity-built pattern with double wells, and the shape of the horizontal cavities is crucial to the stability and gas storage capacity. In order to optimally select the best shape, a method for optimally selecting the shape of the horizontal cavities was proposed. The horizontal cavity models with different morphologies were obtained through the physical simulation experiment, and then by modeling with reverse engineering, the statics and the constant-pressure rheological stability were evaluated and optimally selected with the help of the FLAC^3D software. The results show that the shapes of the horizontal cavities can be divided into 4 types, this is, hump type, one end large and one end small type, both ends large and middle slender type, and flat top type. According to deformation, plastic zone distribution, and comprehensive evaluation of volume shrinkage rate, the stability of the hump cavity is significantly better than that of other shapes. Therefore, it is recommended to adopt a cavity-built pattern with horizontal multi-step method on site, and to design and build hump horizontal cavities, which can improve the cavity stability and gas storage capacity.