分布式声波传感VSP数据中的光缆耦合噪声局部稀疏优化压制方法

分布式声学传感系统在采用光纤采集垂直地震剖面（Vertical Seismic Profile,VSP）时,受到光缆与井壁耦合不良等因素影响,地震数据会受到能量较强的光缆耦合噪声干扰.全局稀疏优化方法在压制光缆耦合噪声时未考虑有效信号和光缆耦合噪声的时变特性,影响了噪声压制效果.本文提出了一种基于局部稀疏优化的光缆耦合噪声自适应压制方法.该方法针对每道地震数据在时窗长度选择范围内综合计算每个时窗长度下的有效信号和光缆耦合噪声的稀疏度,进而选择稀疏度最优下的时窗长度,最终采用形态成分分析方法在最优时窗内实现VSP数据中光缆耦合噪声的稀疏优化压制.模型算例和实际算例的结果均表明本文所提方法优于全局稀疏优化方法.

Distributed acoustic sensing VSP coupling noise suppression based on local sparse optimization

The vertical seismic profile records collected by the distributed acoustic sensing system are affected by many factors, such as the poor coupling between the cable and the wellbore, thus the seismic data will be interfered by the optical cable coupling noise with strong energy. The global sparse optimization method does not consider the time-varying characteristics of the effective seismic signal and the optical cable coupling noise when suppressing the optical cable coupling noise, which affects the noise suppression effect. In this paper, an adaptive suppression method of optical fiber coupling noise based on local sparse optimization is proposed. Firstly, the sparsity of the effective signal and the optical cable coupling noise of each time window length is calculated for each seismic data within a series of time windows with preset length, and then the time window length with the optimal sparsity is selected. Finally, the morphological component analysis method is used to suppress the VSP optical cable coupling noise within the optimal window. The results of both synthetic data example and real data examples show that the proposed method is superior to the global sparse optimization.