时频分析技术在蓬莱气区深层高频噪声压制中的应用
Application of time-frequency analysis in the suppression of deep high-frequency noise in the Penglai gas area
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摘要: 地震波在地下传播过程中会发生能量衰减,尤以高频成分衰减最为明显,导致高频段信号的信噪降低,极大降低了深层油气地震勘探的准确度。为了更好地提高深层资料信噪比,本文基于地震信号的非平稳特征,采用时频分析技术描述信号频率随时间变化的关系,提出一种基于时频分析法压制深层高频噪声的方法。利用有效信号的时频特征具有稳定性和相似性、而高频干扰具有不确定性和随机性的原理,提出一种基于相关性分析的自适应阈值选择策略,从优势频段提取有效信号的时频特征,与高频段信号时频特征进行对比分析,对高频端时频谱进行特征约束衰减,从而达到压制高频噪声的目的。理论模型和实际资料处理结果表明,该方法能够较好地压制高频噪声,有效提高深层资料的信噪比。Abstract: Seismic waves, particularly their high-frequency components, will undergo energy attenuation during subsurface propagation. This results in a low signal-to-noise ratio (SNR) within the high-frequency band, significantly reducing the accuracy of seismic exploration for deep oil and gas. To enhance the SNR of deep seismic data, this study employed the time-frequency analysis technique to describe the time variations of signal frequency based on the non-stationary characteristics of seismic signals. Accordingly, this study proposed a method for suppressing deep high-frequency noise based on time-frequency analysis. Considering the stable and similar time-frequency characteristics of effective signals and the uncertain and random high-frequency interference, this study proposed an adaptive threshold selection strategy based on correlation analysis. This strategy involves extracting the time-frequency characteristics of effective signals from an advantageous frequency band and comparing them with the time-frequency characteristics within the high-frequency band. Subsequently, feature-constrained attenuation was applied to time-frequency spectra in the high-frequency band, thereby suppressing high-frequency noise. Theoretical models and actual data processing results demonstrate that the proposed method can effectively suppress high-frequency noise and significantly enhance the SNR of deep seismic data.
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