Characterizing anelastic attenuation using distributed acoustic sensing (DAS) data

The seismic quality factor, Q, is a critical parameter for seismic data processing and interpretation. Distributed acoustic sensing (DAS) provides a unique acquisition geometry that is ideal for estimating Q. We use a simple twolayer model to generate synthetic DAS data along a vertical well using typical velocity values representative of the end points of the observed well velocity range. We show that Q estimation with the spectral ratios method using DAS measurement, when performed without gauge length correction, results in significant errors. Properly correcting the DAS measurement for gauge length effects yields axial strain that permits accurate Q estimation. Gauge length corrections are shown to reduce Q estimation errors in synthetic data (Q=100) from 210% for DAS measurement to 1% for axial strain.