Stability Analysis of Pillars Between Bedded Salt Cavern Gas Storage Groups Under Triangular Well Layout

Abstract

ABSTRACT: Salt caverns have low porosity, low permeability, self-healing damage, high plastic deformation ability, simple hydrogeological conditions and wide distribution. Salt rock deposits in China are mainly multi-layer salt rock. The characteristics of salt formations present challenges to the design and safety evaluation of reservoirs in multi-layer salt rock deposits. In this paper, the numerical simulation method is used to establish a three-dimensional numerical model of the layered rock-salt cavern gas storage in the Jintan Salt Mine, Jiangsu Province, and the strain softening model is used for numerical calculation. According to the influence laws of the plastic zone, the maximum displacement around the cavern, equivalent strain and volume shrinkage rate, the stability of the salt cavern gas storage when the wells are arranged in a triangle pattern is analyzed. And the pillar width of the salt-cavern gas storage is optimized. The comprehensive results show that the plastic zone, maximum displacement around the cavern and volume shrinkage rate increase with the increase of the pillar width when the wells are arranged in a triangular well pattern. The suggested widths of pillars are 1.60 times of salt cavern diameter. This study provides basic data and reference for engineering problems such as optimizing the pillar distance of the newly built cavern, increasing the number of wells in the salt cavern mining area, and increasing the storage capacity of the salt cavern gas storage. 1. INTRODUCTION In recent years, with the adjustment of the domestic energy structure, natural gas, as a relatively low-emission green energy, plays a more important role in improving air quality, improving energy efficiency and maintaining sustainable economic development. The demand for natural gas in China continues to increase, and the "coal-to-gas" conversion in some northern areas has resulted in a "gas shortage", exposing the problem of insufficient natural gas reserves in my country. The important role of underground gas storage in energy supply has been paid more and more attention (Wang et al., 2011).