Precise source location of AE doublets by spectral matrix analysis of triaxial hodogram

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Geophysics

DOI:https://doi.org/10.1190/1.1443532· OSTI ID:143786

Moriya, Hirokazu; Nagano, Koji; Niitsuma, Hiroaki ^[1]

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1. Tohoku Univ., Sendai (Japan). Faculty of Engineering

The authors have developed a precise relative source location technique using acoustic emission doublets (AE doublets) in the triaxial hodogram method to evaluate the direction and distance of subsurface extension cracks. An AE doublet is a pair of acoustic emissions with similar waveforms and adjacent locations on the same crack but which occur at different times. The relative source location is estimated by an analysis in the frequency domain. The relative distance between two AE sources is determined from the difference of P-S arrival time delays by cross-spectrum analysis. The relative direction is derived using a spectral matrix from the difference in P-wave polarization directions. They also propose a method to optimize the estimated relative location by using a group of AE doublets. The accuracy of the estimated source location was confirmed by performing field experiments. The relative locations of artificial wave sources about 150 m from a triaxial detector can be estimated with distance errors of less than 1 m, and direction errors of less than 3.8 degrees in both azimuth and inclination. Results of the application of this analysis on AE doublets in a geothermal field demonstrate its ability to evaluate deeper subsurface fractures.

• OSTI ID: 143786
• Journal Information: Geophysics, Journal Name: Geophysics Journal Issue: 1 Vol. 59; ISSN GPYSA7; ISSN 0016-8033
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
ACCURACY
DATA ANALYSIS
GEOTHERMAL WELLS
HOT-DRY-ROCK SYSTEMS
HYDRAULIC FRACTURES
MAPPING
SEISMIC SURVEYS