Microseismic first arrival picking based on least square curve fitting
LIU Tengjiao1, GAO Yang2, CHU Fangdong1, HE Jixiang2, LIU Rongjun2, ZHANG Shiqiang1
1. New Resources Geophysical Exploration Division, BGP Inc., CNPC, Zhuozhou, Hebei 072750, China; 2. Research Institute of Exploration and Development, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China
Abstract：Microseismic events are characterized by weak energy,variable signal-to-noise ratio (SNR),and complicated source interferences.So it is very difficult to do rapid and accurate microseismic first arrival picking in real-time monitoring to guide fracturing operation,and the energy ratio method has low accuracy and poor adaptability to different SNR events.To solve this problem,we propose a new microseismic first arrival picking method.First,an initial picking is carried out with the energy ratio method.Then the theoretical curve is fitted with the least square curve fitting.In the time window range before and after curve fit setting,the secondary optimized picking is conducted based on the initial picking.Real data tests verify the validity and feasibility of the proposed method.Comparing with the energy ratio method,the proposed method can quickly and accurately pick first arrivals from microseismic events with different waveform characteristics and different SNR,and effectively improve the accuracy of microseismic realtime positioning.
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