Feasibility analysis of using horizontal caverns for underground gas storage: A case study of Yunying salt district

Rock salt of Yunying salt district, Hubei province, China, has a typical bedded structure, composed of many thin interlayers and thin salt layers. When the conventional single-well leaching method is used for the construction of caverns, the construction efficiency is low and the usable volume of the caverns is small. However, horizontal caverns (HCs) can be built in the formation with a high salt content, which can eliminate the shortcomings caused by the conventional single-well leaching method. Tests have been carried out on samples prepared from the cores obtained from the target formation to determine their mechanical properties. A 3D geomechanical model of the HC is developed based on the characteristics of Yunying salt district and on the mechanical properties obtained from the tests. The safety of the rock mass surrounding the HC under different conditions is simulated. Taking into account the failure characteristic of rock salt, a comprehensive evaluation index system for the feasibility of HC is proposed, including the displacements, plastic zones, equivalent strains, volume shrinkages and safety factors. The results show that the HC has a good feasibility in Yunying salt district. The internal gas pressure, roof structure and dimensions, and the relative location between HC and tin interlayers are the key factors affecting the safety of the HC, and should be highlighted in the actual design and construction. The study provides the design parameters for the proposed HC in Yunying salt district, and can also be a reference for similar engineering in other areas. (C) 2016 Elsevier B.V. All rights reserved.