Subsurface AE Source Location with Simplified Velocity Model in Multi-Point Triaxial Measurement

Abstract

AE (Acoustic Emission) source location technique is essential to evaluate dynamic behavior of subsurface cracks in geothermal developments. The triaxial hodogram method has an advantage, especially in the evaluation of deeper geothermal reservoir, because it can determine AE source locations by single point obserbation. However, source locations estimated by the simple triaxial hodogram method are directly afected by subsurface velocity structure. This paper describes a modeling method of subsurface velocity structure to reduce the location error in the multi-point triaxial AE measurement. The model is optimized with a evaluating function in terms of the distances between the located sources at each detector. Feasibility of the proposed method has been confirmed in both simulation and field studies using an artificial seismic source. We also applied this technique to AE source locations in geothermal fields. The results have demonstrated the effectiveness of the technique for the precise evaluation of geothermal resevoir.