Ghost elimination with extrapolation least square for seismic data acquired by over/under towed-streamers
He Jianwei1, Gu Hanming2, Wu Yaole3, Fang Zhongyu3, Li Tiancai3
1. Zhanjiang Branch, CNOOC, Zhanjiang, Guangdong 524057, China;
2. Institute of Geophysics and Geomatics/Hubei Subsurface Multi-scale Imaging Key Laboratory, China University of Geosciences, Wuhan, Hubei 430074, China;
3. Department & Prospecting Geophysical Institute, CNOOC EnerTech-Drilling & Production Co.,Zhanjiang, Guangdong 524057, China
Abstract:There is a notch on conventional marine towed-streamer data due to ghost effects of the sea surface. Considered as a new development in recent years, the over/under streamer acquisition can eliminate ghost. However,conventional processing for this kind of data neglects noise on it. So we propose in this paper an approach for removing both host and noise. First we use the wavefield extrapolation algorithm in the frequency-wavenumber domain to obtain the relationship between the total wavefield and the up-going/down-going waves on over/under streamer data, and then obtain the relationship between the total wavefield and the up-going wave, and ghost operators. Finally we eliminate ghosts with the least square method and minimize residual noise to optimize up-going waves from over/under streamer data. Test results on synthetic and real data show that the proposed approach preserves not only high-resolution and high-frequency information on shallow layers, but also strong low-frequency information on deep targets.
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