Geophysical exploration in and around CTD Applied Method

Geophysical exploration in and around CTD

Applied Method • GPR • Electrical Resistivity Tomography (2 D, 3 D) • Elastic Velocity (3 D)

ERT Image (2 D) • Survey Area Line 2 End of CTD Line 1 Water conducting fracture CTD Plug 13 MI 40, 41 Borehole (pressure monitoring) • A~D Borehole for 3 D tomography (Resistivity, Elastic wave) • Conducted only on the same side as line 1 • Survey Date Before closure test July, 2014 After closure test (1 st ) October, 2017 After closure test (2 st ) February, 2018

Time lapse Resistivity Image(Line 1) Before closure test (July, 2014) B E A Pressure monitoring (13 MI 41) A, B, E Borehole for tomography Fracture Water Conducting Fracture After closure test (1 st, October, 2017) B E A Pressure monitoring (13 MI 41) After closure test (2 nd, February, 2018) B End of CTD Plug

Time lapse Resistivity Image(Line 2) Before closure test (July, 2014) Pressure monitoring (13 MI 40) A, B, E Borehole for tomography Fracture Water Conducting Fracture After closure test (1 st, October, 2017) After closure test (2 nd, February, 2018) End of CTD Pressure monitoring (13 MI 40) 水圧観測孔 Plug

Tomography Image (Resistivity, Elastic wave) • Survey Area Line 2 Water conducting fracture End of CTD Line 1 Target area CTD Plug • Survey Date Plug 13 MI 40, 41 Borehole (pressure monitoring) • Wall on only 1 side (13 MI 40 side) • 5 Boreholes • Length of each borehole: 2 m Before closure test July, 2014

Tomographic Image (Resistivity) • Scanned Volume: 1. 75[m]* 2. 0[m] C D C End of CTD D Plug A Depth Wall B End of CTD Plug B Depth Wall A

Tomographic Image (P wave velocity) • Scanned Volume: 1. 75[m]* 2. 0[m] Wall End of CTD Depth Plug

Tomographic Image (Elastic wave attenuation) • Scanned Volume: 1. 75[m]* 2. 0[m] Plug Wall End of CTD Depth Plug Depth Wall End of CTD

GPR Image (GPR Reflection) • Survey Area • Both in inclined drift and CTD. • Total length of measurement line: 505 m (Not all profiles are shown in this slide) • Survey Date Before closure test Several times before March, 2014

CTD (Wall) Configuration CMP Frequency 5～ 500 MHz Wall (Left side) Wall (End of CTD) Plug End of CTD

CTD (floor) End of CTD Configuration 0 offset Frequency 800 MHz End of CTD

CTD (Both floor and Wall) Configuration 0 offset Frequency 800 MHz Left wall Floor End of CTD Floor Right wall Wall of End of CTD Plug

Inclined (3 D like profile) Shaft • Floor (Inclined) • 5 Parallel survey lines Configuration 0 offset Frequency 800 MHz Plug

Inclined (Right wall) Configuration 0 offset Frequency 800 MHz Shaft Plug