Aligning microseismic reflections for imaging

An Observation on ``popular" waveforms

Most microseismic sources in the Bonner sand are along the hydraulic fracture (Sharma et al., 2008). Many of them are expected to be very close in location and to have the same waveform (from the same fracking mechanism), while others further apart on the hydraulic fracture have rather different waveforms. This is reflected in the tight clustering of source locations of waveforms having high correlation with the master waveform. However, the clustering of locations does not necessarily imply any fixed distribution of event times. What we observe is a long-tailed distribution, with most appearing at the early stages of the treatment. This we attributed to such events being due mostly to the initial opening of the fracture, with some later slippage as pressures vary during later stages of the treatment.

Due to the high correlation values obtained in most cross-correlations, deciding what the threshold for what constituted a match/multiplet was not possible without visual inspection. We conservatively opted to only include in a given multiplet those records with nearly perfect correlation to the multiplet master.

Aligning microseismic reflections for imaging