Evaluation on Solid - Liquid Interface Structure of Altered Rock Based on Hydrothermal Flow Experiments

Junko Hara, Noriyoshi Tsuchiya

Research output: Contribution to journalArticlepeer-review

Abstract

Fluid-rock interactions in geothermal fields are controlled by several chemical and physical conditions, such as temperature, hydraulic condition and mass transport properties of dissolved chemical species in geothermal fluids. Entire solution chemistry in the system is affected by mass transport phenomena in solid - liquid interface, not only depending on non-stoichiometric chemical reaction. Dynamic function and formation of leached surface layer in solid and boundary film in liquid were analytically defined using results of hydrothermal flow through experiments. Surface layer corresponds to leached layer of mineral surface where alkali is depleted and Si, Al are enriched. Specifically, the thickness of surface layer was described as a function of Reynolds number, reaction temperature and length from fluid input point. Based on the thickness of surface layer,. The mass transport factors in solid-liquid interface are evaluated to be 10-8 to 10-5 m/s under low temperature and low velocity condition (75°C, 0.33m/hour), and 10-6 to 103 m/s under high temperature and high velocity condition (250°C, 2.2 m/hour). These factors for rock forming elements are obviously different from each other and that range evaluated as 103 between alkali ions and Si or Al Zonal geothermal alteration is regulated by leaching and enrichment of specific ions in hydrothermal fluid characterized by this ion mobility on mineral surface besides chemical reaction.

Original languageEnglish
Pages (from-to)95-106
Number of pages12
Journaljournal of the geothermal research society of japan
Volume28
Issue number1
DOIs
Publication statusPublished - 2006 Jan

Keywords

  • flow through experiment
  • geothermal alteration
  • ion mobility
  • reaction rate

ASJC Scopus subject areas

  • Geophysics

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