Control of water flow through a geothermal reservoir using hydrothermal processing of smectite clays

Shoji Higashi, Nobuo Hirano, Nakamichi Yamasaki, Kazuo Hayashi

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Recent progress in geothermal technology enables us to explore hot dry rock (HDR) as a promising energy source. Viscous gelation through hydrothermal processing of smectite clays has proven to facilitate control of flowing water and plugging in a fracture network. Utility of the hectorite and saponite agents comprising individual smectite raw components in a dilute slurry has been confirmed by a water control test with flow-type autoclave equipment. The flow paths between granite fragments in a reactor tube is successfully plugged with hectorite gel formed when a dilute slurry is injected into the reactor heated at 200 and 250°C. Effective plugging is sustained for more than 30 days when a more concentrated (6%) slurry is processed. The saponite agent also reveals sustained plugging for more than 10 days when a 3% slurry is processed at 300°C. A montmorillonite agent is not useful for effective plugging because of its reduced viscous gelation when hydrothermally processed. The hectorite agent is so functional in quality of plugging and endurance that it could facilitate the design of a HDR system, by preventing water leakage (e.g., temporary or permanent plugging of the minute fractures in the HDR reservoir), and therefore improve the recovery of circulating water.

Original languageEnglish
Pages (from-to)245-258
Number of pages14
JournalGeothermal Science and Technology
Issue number1-4
Publication statusPublished - 1999


  • Geothermal reservoir fracture
  • HDR
  • Hydrothermal processing
  • Smectite gel
  • Water control

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Management of Technology and Innovation


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