层状盐岩溶腔储气库长期运行稳定性研究

针对我国盐岩矿床地质结构的典型特征:单层厚度薄、软弱夹层多,盐岩夹层对储气库的建造及稳定性具有很大影响,提出了层状盐岩溶腔储气库稳定性研究内容,并运用块裂介质固流耦合数值模拟方法对其影响作了进一步分析.主要结论如下:(1)层状盐岩矿床储气库建造中必然会受到高盐份泥岩夹层的影响.夹层的存在使腔体的稳定性减弱,延缓了腔体内流体的输运、对流扩散过程,增加了建腔的时间,盐岩与盐岩夹层由于蠕变率不同而造成损伤,形成裂隙气体渗漏.(2)高盐份泥岩夹层对储气库的稳定性影响很大,由弹塑性数值模拟可知,运行气压为8-24MPa,形状为椭球腔,且长短轴为7/4时结构最稳定.(3)盐岩夹层对储气库的渗透性具有一定影响.蠕变损伤在盐岩与夹层交接面处产生的裂隙是气体渗透的主通道,具有较强的导气能力,但渗透速度随着时间的延长而减小,最后达到稳定状态,且最外缘气体压力始终低于0.2MPa,从考虑气体渗透的角度,在层状盐岩矿床内建造储气库是可行的.所得结论可为我国薄盐岩矿床内建造储气库提供一定的参考依据.

Investigation on Stability of Gas Storage Caverns in Bedded Rock Salt

Because of the typical characters for the geological structure of rock salt deposit in our country, such as the thin thickness of monolayer and more weak intercalate layers, the salt - mudstone interlayer has an impact on building gas storage cavern and its stability. In this paper the content of building gas storage cavern and stability analysis in bedded rock salt is carried out, then its influence is analyzed by using numerical simulation of hydro - mechanical coupled mathematical model for rock matrix - fractured media . The following are revealed : (1)Building gas storage cavern in bedded rock salt is affected by salt - mudstone interlayer . The stability of the cavem is weakened by the interlayer with, the transportation of liquid and diffusion process postpone, and the time in cavity building increased. The creep rates is different between rock salt and interlayer, cranny will be come into being with gas leakage. (2)The stability of gas storage cavern is influenced by salt - mudstone interlayer, according to elasticity - plasticity model numerical simulation, the cavern is most stable when gas pressure is 8 - 15MPa and the shape is spheroid. (3) Gas permeation in gas storage cavern is influenced by salt - mudstone interlayer. The cranny at the surface of rock salt and interlayer is the main aisle of gas permeation, but the speed of gas permeation is diminishing with time and at last, it reaches invariableness. The gas pressure is less than 0.2MPa at the outer margin. From the view of gas permeation, the construction of gas storage cavern in bedded rock salt is viable. The results obtained can pro- vide some reference for building gas storage cavern in bedded rock salt.