Experimental study on the gas tightness of a mined cavern with groundwater

Yoshinobu Nishimoto, Noboru Hasegawa, Makoto Nishigaki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The gas tightness of underground rock cavern tanks installed for the storage of gas and oil is preserved by sealing the rock joints around the cavern tanks with groundwater. This storage system is efficient and cost effective, because utilizing groundwater around the rock cavern tanks negates the need for expensive steel liner plates. However, the mechanisms and principles of this gas sealing method are not entirely clear. Two conditions are important for a groundwater sealing system. The first condition is that gas does not exude into the rock joints from the cavern surface. The second condition is that gas bubbles must be retained in the rock joints, even if exuding into the joints. Ensuring higher water pressure than gas pressure satisfies the first condition. The second condition is thought to be governed by bubble buoyancy, capillary pressure, and drag force, however the effect of these factors on the second condition is not clearly understood. Therefore, we performed laboratory experiments to elucidate the mechanisms of securing gas tightness in rock joints with groundwater. The experimental model was comprised parallel glass plates imitating an actual underground rock joint, and we observed the behavior of air bubbles injected into the gap filled with water. The width of the gap between the parallel glass plates and the hydraulic gradient were varied parametrically. This paper shows the methods and results of the experiments and theoretical speculations of the reliance of gas tightness on the buoyancy, surface tension, and drag force.

Original languageEnglish
Title of host publicationISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014
PublisherInternational Society for Rock Mechanics
Pages1591-1598
Number of pages8
ISBN (Print)9784907430030
Publication statusPublished - 2014
Event8th Asian Rock Mechanics Symposium, ARMS 2014 - Sapporo, Japan
Duration: Oct 14 2014Oct 16 2014

Other

Other8th Asian Rock Mechanics Symposium, ARMS 2014
CountryJapan
CitySapporo
Period10/14/1410/16/14

Keywords

  • Buoyancy
  • Capillary pressure
  • Cavern tank
  • Drag force
  • Gas tightness
  • Hydraulic gradient

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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  • Cite this

    Nishimoto, Y., Hasegawa, N., & Nishigaki, M. (2014). Experimental study on the gas tightness of a mined cavern with groundwater. In ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 (pp. 1591-1598). International Society for Rock Mechanics.