Consistency evaluation of three advanced stress measurement techniques upon Dual Core-bit Coring, Compact Conical-ended Borehole Overcoring and High Stiffness Hydraulic Fracturing at Kamioka mine, Japan
Abstract
We are promoting the development of a new Dual Core-bit Coring technique as a method of measuring the crustal stress in the supercritical geothermal conditions. The field test of the Dual Core-bit Coring technique used in this method was conducted at Kamioka Mine in Japan. In the Dual Core-bit Coring technique, a rock core in the stress-released state and the initial stress state is continuously sampled in an one core barrel, it can be obtained that both the direction and the magnitude of the principal stress in a two-dimensional plane perpendicular to the borehole. The reliability of the Dual Core-bit Coring technique is evaluated by comparing the rock stresses obtained by this technique with the rock stresses obtained by other advanced stress measurement techniques. This time, as an advanced rock stress measurement method, we adopted the Compact Conical-ended Borehole Overcoring technique (CCBO) and the High Stiffness Hydraulic Fracturing technique (HSHF). The CCBO is a three-dimensional stress measurement technique categorized as a stress release method, and it is a highly reliable method that has been particularly proven in Japan. HSHF is a two-dimensional stress measurement method, but it is a technique that can determine the maximum stress value with high accuracy using a low-compliant water delivery system. The rock stress states measured by the three techniques are respectively well approximated. The measured rock stresses are unusual stress states in which the horizontal components indicate the maximum values respectively. The reason is considered to be that there is a large cavity for mining immediately below the measurement point. In this time, the practicability of the Dual Core-bit Coring technique is evaluated by comparing the stress value in the new technique with the stress state obtained by two advanced stress measurement techniques.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH11D0793Y
- Keywords:
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- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGY;
- 7294 Seismic instruments and networks;
- SEISMOLOGY;
- 8194 Instruments and techniques;
- TECTONOPHYSICS