Abstract: The construction and operation time of salt cavern gas storages is short in China; compared with gas storages in salt dome-type formations constructed with mature technology in foreign countries, most of them are in complex layered rock salt formations. Some problems exist, such as low grade of salt deposit, multiple interlayers, and formation of irregular caverns, and higher requirements are proposed for the stability of salt caverns and the safety evaluation of storage operation. Using the large-scale experiment equipment for physical simulation, based on the similarity principle of rock mechanics, similar materials and models were developed to conduct the cyclic injection-production simulation of salt cavern gas storages, so as to study the laws of injection and production of salt cavern gas storages, the stress-strain characteristics around salt cavern and the deformation characteristics of salt cavern. The results show that during the experiment, the response of stress and strain around the cavern laggs behind the change of air pressure in the salt cavern. The stress around the cavern increases and the strain also increases consequently during gas production and depressurization, and stress concentration is more likely to occur in the cavern top position than in other parts, and the deformation at the waist and the maximum diameter of cavern is relatively large. In combination with numerical simulation research and field production test, the paper studies the stress and deformation characteristics of salt cavern and salt plug of JT salt cavern gas storage. Studies have shown that compressive stress is distributed in all stages of operation, stress concentration mainly occurs at the top and the middle of salt cavern, but there is no tensile stress, and no tensile stress damage and failure occurs. When the internal pressure is the smallest, around the salt cavern, the safety factor is above 1.5, and the safety factor is above 3 when the pressure is maximum; no dilatation damage and failure occurs in either state. The research results have an important guiding role in the design of operation schemes, stability evaluation, cavern damage assessment and disaster prevention for similar salt cavern gas storages in China.

Key words: salt cavern gas storage, injection-production operation, salt cavern deformation, stability, physical simulation, damage

摘要： 中国盐穴储气库建设运行时间短，与国外具有成熟技术的盐丘型地层建库相比，多为复杂层状盐岩地层建库，存在盐层品位低、夹层多、形成的盐腔不规则等问题，对盐腔的稳定性和储库运行的安全性评价提出了更高的要求。利用大型物理模拟实验装置，根据岩石力学相似性原理，研制相似性材料和相似模型，对盐穴储气库的注采进行全周期模拟，用以研究盐穴储气库注采运行规律、盐腔周围应力—应变特征及盐腔变形特征。研究结果表明，实验过程中腔周应力和应变的反应较盐腔内气压变化滞后；采气降压时腔周应力增大，应变也随之增大，腔顶位置较其他部位更易出现应力集中的趋势，而腔腰和最大腔径处的变形相对较大。结合数值模拟研究和现场生产测试，对JT盐穴储气库的盐腔和盐柱受力与变形特征进行研究的结果表明，目前运行各阶段应力分布均为压应力，主要在盐腔顶部和盐腔中间位置发生应力集中，但无拉应力，未产生拉应力损伤破坏；内压最小时盐腔周围的安全系数都在1.5以上，压力最大时安全系数在3.0以上，这两种状态下均未发生扩容损伤破坏。研究成果对中国类似盐穴储气库运行方案的设计、稳定性评价及腔体损伤评估、灾害预防等具有重要的指导作用。

关键词: 盐穴储气库, 注采运行, 盐腔变形, 稳定性, 物理模拟, 损伤