Detection and location for microseismic events recorded by single downhole acquisition with cross-correlation method

摘要

We develop a novel approach for detection and relative location of weak microseismic events based on waveform cross-correlation. We treat microseismic events with high signal to noise ratio (SNR) as master events and cross-correlate with continuous recording using both P- and S-waves to detect weak events (slave events). Subsequently, the detected weak events were located relatively to the master events, by stacking together the P- and S-waves cross-correlations along differential moveouts. Specifically, we add the azimuth restriction of P-wave to the cross-correlation stacking to improve the location accuracy in the case of single downhole acquisition. The utility of this technique is demonstrated with synthetic events. Then, we applied our method to real microseismic data from one stage of hydraulic fracturing operation. 1140 events were detected and located, which is approximately 4 times the number of events from conventional method.