Fluid Pocket Generation in Response to Heterogeneous Reactivity of a Rock Fracture Under Hydrothermal Conditions

A. Okamoto, H. Tanaka, N. Watanabe, H. Saishu, N. Tsuchiya

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Fractures are the location of various water-rock interactions within the Earth's crust; however, the impact of the chemical heterogeneity of fractures on hydraulic properties is poorly understood. We conducted flow-through experiments on the dissolution of granite with a tensile fracture at 350°C and fluid pressure of 20 MPa with confining pressure of 40 MPa. The aperture structures were evaluated by X-ray computed tomography before and after the experiments. Under the experimental conditions, quartz grains dissolve rapidly to produce grain-scale pockets on the fracture surface, whereas altered feldspar grains act as asperities to sustain the open cavities. The fracture contained gouge with large surface area. The feedback between fluid flow and the rapid dissolution of gouge material produced large fluid pockets, whereas permeability did not always increase significantly. Such intense hydrological-chemical interactions could strongly influence the porosity-permeability relationship of fractured reservoirs in the crust.

Original languageEnglish
Pages (from-to)10,306-10,315
JournalGeophysical Research Letters
Volume44
Issue number20
DOIs
Publication statusPublished - 2017 Oct 28

Keywords

  • X-ray CT
  • aperture structure
  • fracture permeability
  • gouge
  • hydrothermal experiment
  • mineral dissolution

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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