A Combined Denoising Method for Microseismic Signals from Coal Seam Hydraulic Fracturing: Multithreshold Wavelet Packet Transform and Improved Hilbert-Huang Transform

<div>Scatter and density source plots of the MS events with Hudson diagrams (<i>T</i>-<i>k</i> plot). (a, c) Scatter plot of MS events. (b, d) Density source plot of MTs from MS data (colored according to relative seismic event density). (a) Scatter plot (crack extension stage). (b) Density source plots (crack extension stage). (c) Scatter plot (crack open/close stage). (d) Density source plots (crack open/close stage).</div>

Shock and Vibration

fig11

Figure 11

Figure 11: A Combined Denoising Method for Microseismic Signals from Coal Seam Hydraulic Fracturing: Multithreshold Wavelet Packet Transform and Improved Hilbert-Huang Transform 

Figure 11 | A Combined Denoising Method for Microseismic Signals from Coal Seam Hydraulic Fracturing: Multithreshold Wavelet Packet Transform and Improved Hilbert-Huang Transform 