Position design of the casing shoe of an abandoned horizontal salt cavern to be used for gas storage

ABSTRACT

China’s salt mines have a typical bedded structure, composed of many interlayers and salt rock layers. If the conventional vertical single cavern leaching technology is used, the shape control of the caverns is difficult. Horizontal salt cavern gas storage (HSCGS) can be built in thicker pure salt sections. The internal pressure, casing shoe position and the range of plastic, dilatation, and failure zones are significant factors to be considered in the design. The yield behavior of rock salt can be described by the Tresca yield criterion. The second invariant of the plastic strain was used as the hardening parameter to analyze the hardening behavior. The dilatancy boundary is defined to determine the dilatation zone. Based on the Mohr-Coulomb criterion, a failure criterion of rock salt is established. The constitutive model was modified and the state parameters were self-defined in FLAC3D. Thus a Yield-Dilatancy-Failure (YDF) model is established. Based on the YDF model, the rock surrounding a HSCGS is divided into four zones: elastic, plastic, dilatation and failure zone. The casing shoe position should be outside the dilatation zones. When the dilatation zone of the HSCGS in the middle part is prevented from developing. The minimum pressure (9 MPa) is determined that prevents the formation of a dilatation zone around the middle part of the HSCGS. The research results can provide a reference for determining pressure and casing shoe position of an HSCGS.

KEYWORDS:

• Rock salt
• horizontal salt cavern gas storage (HSCGS)
• Yield-Dilatancy-Failure model
• stability
• casing shoe position

Acknowledgments

The authors wish to acknowledge the financial support of National Natural Science Foundation of China [Grant Nos. 51874274; 51774266; 51774266]. National key research and development plan [Grant Nos. 2018YFC0808401]. We thank Jaak J. K. Daemen for its linguistic assistance during the preparation of this manuscript. Moreover, the authors wish to thank the reviewers for constructive comments and suggestions that have helped us improve our manuscript.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51774266,51874274];National Key Research and Development Project [2018YFC0808401].

Notes on contributors

Yuhao Zhang

Yuhao ZhangA graduate student at the University of Chinese Academy of Sciences. Mainly engaged in the stability research work of underground salt cavern gas storage. The research interests is creep of rock salt and its application of underground Storage of Petroleum/Natural gas.

Hongling Ma

Hongling MaA researcher at institute of Rock and Soil Mechanics, Chinese Academy of Sciences. The interested research field is stability analysis and parameters optimization for underground mining and underground energy storage. The main job is to establish modeling ground stability analysis to assess stresses, displacement, plastic state for underground mining, open pit mining, and underground energy storage with FLAC^3D/ANSYS.

Xilin Shi

Xilin Shi A researcher at institute of Rock and Soil Mechanics, Chinese Academy of Sciences. The interested research field is strength theory of hard/soft rock and its applications on the stability of geotechnical engineering. The main job is to participate in field tests such as deformation monitoring, phreatic surface monitoring with borehole observation.

Hongwu Yin

Hongwu Yin A doctor at the University of Chinese Academy of Sciences. The interested research field is numerical modeling technology for geotechnical/mining engineering. The main job is to participate in laboratory tests such as uniaxial, triaxial compression test, creep test, tension test, and direct shear experiment on different rocks such as salt rock, marble, granite, limestone, et al.

Shengnan Zhang

Shengnan ZhangThe research direction is rock mechanical theory and application on deep drilling of natural gas and petroleum, geological disposal of radioactive wastes and underground storage of Energy (Petroleum and natural gas).