The Japan Gas Association (JGA) has been studying technologies of an underground natural gas storage system, a Lined Rock Cavern (LRC) gas storage system called ANGAS (Advanced Natural GAs Storage). 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 we expect 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, we designed and constructed a small test cavern which is located at the Kamioka mine, the midland of Japan. The test cavern is surrounded by a sedimentary rock mass which consists of mainly sandstone and mudstone. The internal design pressure of the test cavern is 20MPa. We present some results of the verification tests and confirm the validity of the LRC system for Japan in this paper.
The ANGAS project was performed over 4 years, from 2004 to 2007. The purpose of the project is to develop a suitable LRC gas storage system for Japan, and to contribute to the expanding use of natural gas. For example, it is necessary to study measures to shave off the daily peak load of natural gas through pipelines because, as a special characteristic in Japan, there is a large daily fluctuation in gas supply and we expect ANGAS to be a key countermeasure in peak shaving. Furthermore, there is a possibility that LRC could be a novel storage system in inland areas.
In this project, our goal is to develop a design method for commercial LRC systems, under Japanese geological conditions of the limited hard rock distribution, referring to the results of the verification tests on the test cavern.
The concepts of LRC are as follows:
Gas pressure is transmitted to the surrounding rock mass through the backfilled concrete behind the steel liner and resisted by the rock mass;
Gas-tightness is ensured with a steel liner;
Groundwater around the storage cavern can be drained with a drainage system (composed of drainage pipes and other elements) while the storage cavern is being constructed or the inner gas pressure is released. The objective is to prevent extremely high external water pressure from acting on the steel liner.
(Figure in full paper)
In order to ensure the concepts of LRC under the above design conditions, the LRC system needs evaluation technologies for the surrounding rock mass and design technologies for the storage cavern, as key technologies. In particular, design technologies for the storage cavern have been developed in the project.