ディトネータテストによる三軸AE計測系の校正
1987 年 103 巻 1195 号 p. 537-542
詳細
1987 年 103 巻 1195 号 p. 537-542
A simple technique to calibrate a downhole AE system to locate subsurface cracks is presented. Cross-hole detonation tests were employed for the calibration. In situ P-wave velocity in the formations is estimated from the P-wave arrival time. A simple formula associated with an appropriate filtering is proposed to equalize the difference of the frequency dependent coupling of tri-axial accelerometers set in a downhole AE sonde. Consideration ofthe ray path and the coupling compensation reduces the mapping error.
Data measured at Higashi Hachimantai Field supports the validity of this technique. The accuracy achieved in the mapping of the AE source lies within 10 degrees in all directions.
