Energy transition

[ET-02] Detection of P-S travel time for Low SNR Event by particle motion analysis

*Sun Jingyi¹, Yusuke Mukuhira¹, Takayuki Nagata², Taku Nonomura², Hirokazu Moriya³, Takatoshi Ito¹ (1. Institute of Fluid Science,Tohoku University (Japan), 2. Department of Aerospace Engineering, Tohoku University (Japan), 3. School of Engineering, Tohoku University (Japan))

Detecting low signal-to-noise ratio (SNR) events provides a way to understand subsurface reservoirs. The results of detected events analysis allow us to map the location of microseismic sources. The direct S-wave particle motion depicts a flat shape in most cases. Therefore, we introduced 3D particle motion to measure the direct S-wave of low SNR events and used spectral matrix (SPM) analysis to characterize the 3D particle motion in the time-frequency domain. The SPM analysis can detect the arrival of coherent seismic waves but is not sufficient to measure S-wave arrivals. So, eigen-decomposition of S-wave arrivals in the time domain preserves the characteristics of the particle motion. We utilize the perpendicularity of the particle motion between P-wave and S-wave to confirm S-wave detection. We apply our approaches to field data recorded at the Groningen gas field in the Netherlands to detect known catalog events as well as buried events hidden in the noise. Thus, we can gain an insight into the formation of subsurface fractures and improve the efficiency of resource mining.