A migration-based location method using improved waveform stacking for microseismic events in a borehole system
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RESEARCH ARTICLE-APPLIED GEOPHYSICS
A migration‑based location method using improved waveform stacking for microseismic events in a borehole system Qinghui Mao1,2 · Tahir Azeem3 · Xuliang Zhang4 · Yu Zhong5 · Yuan Fang6 · Yunxiao Zhang7 Received: 5 December 2019 / Accepted: 18 September 2020 © Institute of Geophysics, Polish Academy of Sciences & Polish Academy of Sciences 2020
Abstract The migration-based microseismic event location methods using waveform stacking algorithms are widely used for hydrofracturing monitoring. These methods have the advantage of not requiring the accurate first arrival time around a detected event, which is more suitable for noisy data than classical travel time-based methods. However, accuracy of these methods can be affected under the condition of relatively low signal-to-noise ratio (SNR). Therefore, in order to enhance the location accuracy of microseismic events in a borehole system, we have proposed a migration-based location method using improved waveform stacking with polarity correction based on a master-event technique, which optimizes the combination way of P- and S-wave waveform stacking. This method can enhance the convergence of the objective function and the location accuracy for microseismic events as compared to the conventional waveform stacking. The proposed method has been successfully tested by using synthetic data example and field data recorded from one downhole monitoring well. Our study clearly indicates that the presented method is more viable and stable under low SNR. Keywords Microseismic event · Migration-based location · Improved waveform stacking · Hydraulic fracturing · SNR
Introduction It is vital to accurately and automatically locate the microseismic events for estimating the stimulated reservoir volume. Migration-based source location methods are more * Qinghui Mao [email protected] 1
Key Laboratory of Exploration Technologies for Oil and Gas Resources (Yangtze University), Ministry of Education, Wuhan 430100, China
2
Hubei Cooperative Innovation Center of Unconventional Oil and Gas, Yangtze University, No. 111 Daxue Rd. Caidian District, Wuhan 430100, Hubei Province, China
3
Department of Earth Sciences, Quaid-I-Azam University, Islamabad 45320, Pakistan
4
Bureau of Geophysical Prospecting, Zhuozhou 072750, China
5
Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
6
Development and Research Center, China Geological Survey, Beijing 100037, China
7
Oil and Gas Survey, China Geological Survey, Beijing 100083, China
applicable to relatively low signal-to-noise ratio (SNR) microseismic data than traditional travel time-based source location methods, because the former methods are far less sensitive to the picking precision than the latter ones (Gharti et al. 2010). During the last two decades, a number of studies have been carried out about the migration-based location of microseismic events based on nonnegative waveform stacking in order to eliminate the influence of waveform pola
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