波场延拓最小二乘法去虚反射技术在上下缆采集数据处理中的应用

海上拖缆采集数据通常存在缘自海水面虚反射(鬼波)的陷波特性, 而近年推出的上下缆采集技术可有效压制虚反射, 但常规上下缆处理技术往往忽略了测量过程中的噪声影响。本文基于已有研究成果, 先利用频率-波数域波场延拓算子分别获得上下缆总波场与上行波和下行波的关系, 继而获得上下缆总波场与上行波和虚反射算子的关系, 然后采用最小二乘算法去除虚反射并将剩余噪声最小化, 从而实现上下缆数据中最优提取上行波。合成数据和实际海上数据处理测试结果表明, 上下缆数据处理结果既保留了浅层高频信息, 有较高分辨率, 又确保了深层低频信息, 目的层反射比浅缆数据能量强、信噪比高。

Ghost elimination with extrapolation least square for seismic data acquired by over/under towed-streamers

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.