Advanced natural gas storage system and verification tests of lined rock cavern - ANGAS project in Japan -

Technologies of an underground natural gas storage system, a Lined Rock Cavern (LRC) gas storage system called ANGAS (Advanced Natural GAs Storage), have been studied. The purpose of the project is to develop a suitable LRC system for Japan, and to contribute to expanding use of natural gas. It is necessary to study measures to shave off the daily peak load of natural gas through pipelines and it is expected that the ANGAS is one of key countermeasures for peak shaving. In the project, our goal is to ensure the design method of the LRC system under the Japanese geological conditions. One of the key technologies of the developed design method is based on plastic deformation of the steel liner considering the rock deformation appropriately. Using the developed design method and procedures, a small test cavern which is located at the Kamioka mine, the midland of Japan, was designed and constructed. The test cavern is surrounded by a sedimentary rock mass which consists of mainly sandstone and mudstone. The inner design pressure of the test cavern is 20MPa. In this paper, some results of the verification tests are presented and the validity of the LRC system for Japan is confirmed. Specifically, the steel liner was deformed up to its plastic zone, in order to be unified with the buffer material and the backfilled concrete as a hybrid structure. The displacements in the surrounding rock mass were stable under the inner design pressure 20MPa. Furthermore, the real crack intervals of the backfilled concrete are recognized to be less than the designed maximum interval and the real maximum crack width is inferred to be close to the designed one under 20 MPa pressure. Therefore, the design considering the crack properties of the back filled concrete has been verified.