Low-frequency evaluation and recovery of conventional geophone data and applications in seismic imaging
Zou Zhihui1,4, Zhang Yimeng2, Bian Aifei3, Zhou Huawei1,4,5, Ni Yudong6, Li Peiming2
1. College of Marine Geosciences, Ocean University of China, Qingdao, Shandong 266100, China;
2. BGP International, BGP Inc., CNPC, Zhuozhou, Hebei 072751, China;
3. Institute of Geophysics and Geomatics, China University of Geosciences(Wuhan), Wuhan, Hubei 430074, China;
4. Key Laboratory of Submarine Geosciences and Prospecting Technology, Ministry of Education. Qingdao, Shandong 266100, China;
5. Department of Earth & Atmospheric Sciences, University of Houston, Houston, Texas 77004, USA;
6. Acquisition Technique Support Department, BGP Inc., CNPC, Zhuozhou, Hebei 072751, China
Abstract：Seismic low frequencies play an important role in increasing the resolution and fidelity of seismic imaging and/or inversion. Conventional seismic data often lacks useful low frequency components due to the limited frequency bandwidth of seismic source, geophone response and contamination of environmental noise. Estimating the useful low-frequency bandwidth of conventional seismic data is crucial step to compensate these signals before imaging process. Based on the signal-to-noise ratio of conventional seismic data and the natural frequency of geophone, data spectrum are divided into three non-overlap frequency bands called the conventional band, the low-frequency recoverable band, and the low-frequency unrecoverable band. The low-frequency recoverable and unrecoverable bands are defined as the lowest reliable frequency (fLR). According to the spectrum of real data acquired by different seismic recording systems, a low frequency recovery method is proposed to estimate the fLR and the low-frequency recovery parameters. A new seismic processing workflow is designed. Both broadband data and conventional data acquisition is simultaneously recorded for test. The field data tests show that the 4.5Hz geophone data still have acceptable signal-to-noise ratio after their down to 0.04Hz frequency is recovered while down to 2Hz can be recovered for conventional 10Hz-geophone data. Seismic imaging and velocity modeling with low-frequency-recovered data show obvious improvement in terms of fidelity and resolution.
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Zou Zhihui, Zhang Yimeng, Bian Aifei, Zhou Huawei, Ni Yudong, Li Peiming. Low-frequency evaluation and recovery of conventional geophone data and applications in seismic imaging. OGP, 2016, 51(5): 841-849.
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