Joint Arrival Time Optimization for Microseimic Events Recorded by Seismic Borehole Arrays

We cross- correlate microseismic borehole array data for similar events (multiplet events) in order to determine accurate P and S arrival times. The proposed method extends existing concepts by cross-linking waveforms of different events in a multiplet recorded by closely spaced receivers, and the augmented interconnectivity of waveforms increases the consistency of the arrival time data. The method is applied to microseismic data recorded by two inclined borehole arrays consisting of in total 30 receivers. It is shown that the picking accuracy is significantly improved compared to the original picks and also compared to the adjusted picks obtained from single receiver based processing. Relocation of the events using the new picks results in a reduction of the location RMS misfit by about 20%.