双井水平盐腔恒定内压的天然气储库

Gas Storage Form of Horizontal Cavern with Two Wells Under Constant Internal Pressure

盐岩是国际公认的能源储存理想介质。中国盐岩呈层状分布并具有单层厚度薄、杂质含量高、含有众多不可溶夹层的特点,故地下能源储库更宜采用水平腔体形式。为保证水平盐腔的运营安全且实现整个候选场址能源储库总容积的最大化,提出双井水平盐腔恒定内压的储气库形式,即在水平腔体中对称均匀设置两口井,分别用于注采天然气和卤水,并保持运营过程中腔体内气压为恒定最大值。根据金坛盐岩实际地质构造及岩石力学参数,使用FLAC3D有限差分软件,建立双井水平盐腔恒定内压储气库模型进行数值模拟,从稳定性、密闭性、可使用性和井喷分析4个方面研究其长期运营的可行性和安全性;另设置对照组模拟传统腔体的工作状态,与其进行对比。结果表明:双井水平盐腔恒定内压储气库满足长期运营安全性等各方面的要求,且其性能明显优于传统储气库;此外,该储气库形式还具有经济、灵活、调峰能力强,能很好地应对井喷,相同容积造价低,能充分利用盐层密集建腔等诸多优点,是适合中国盐岩特点的储气库形式。

Rock salt is a globally recognized ideal medium for energy storage.Due to the special characteristics of Chinese rock salt,e.g.,thin depth,high impurity content and containing many insoluble interlayers,the horizontal cavern is more suitable for the underground energy storage in China.In order to ensure the safety of the cavern and to maximize the total storage volume,a new storage form of the horizontal cavern with two wells under constant internal pressure was proposed.The two wells,which were used to inject and extract brine and natural gas respectively,were evenly arranged in a rotating cavern.During natural gas extraction/injection,brine was injected into/extracted from the cavern,so that the internal pressure was maintained at its constant maximum level.Based on the actual geological structure and mechanical parameters of the salt rock in Jintan,a numerical model of the new horizontal cavern was established,and then a simulation was carried out with the finite difference software FLAC3D.The feasibility and safety of the storage form were studied from four aspects：stability,tightness,usability and blowout analysis.Besides,the operation of the traditional gas storage was also simulated for comparison.The results showed that,the new storage form could meet all aspects of safety requirements,and its performance was significantly better than that of the traditional gas storage.in addition,the new storage form had some other advantages,such as good economic efficiency,flexibility,strong ability of peak regulation,good ability to cope with blowout,low cost of the unit volume,making full use of salt layer and so on; thus,the new storage form is demonstrated to be quite suitable for China＇s rock salt.