Rock Engineering

[PY2-73] IMPACT ON PERMEABILITY DUE TO AXIAL STRESS DISTURBANCES FOR CRETACEOUS SANDY SHALE

○Sophea BOEUT¹, Teppie OSHIMA¹, Yoshiaki FUJII¹, Junichi KODAMA¹, Daisoke FUKUDA¹, Hiroyuki MATSUMOTO², Kazumi UCHIDA² (1. Hokkaido University, 2. Kushiro Coal Mine)

Keywords:Axial stress disturbances, Enhanced methane gas recovery, Earthquakes, Induced stress, De-routing underground water flow

Seismic waves generated from earthquakes and artificial surface vibration might alter the water level in the wells and oil or gas production. These transient stress disturbances prospectively caused the permeability change due to new pathway occurring or existing pathway being cleared. The permeability change might encourage enhancing gas recovery, inducing small earthquakes preventing future large earthquakes, and de-routing underground water flow for various purposes. The prospective permeability increase by axial stress disturbances of Cretaceous sandy shale may effectively expand the capacity of methane gas recovery of Kushiro Coal Mine. The paper observes the permeability change of intact or triaxially fractured Kushiro Cretaceous sandy shale by axial stress disturbances. It will be shown that increasing and decreasing factors might work together on permeability.