局部时频变换域地震波吸收衰减补偿方法

地震信号在地下传播时会受到地层吸收衰减的影响,从而降低了地震资料的分辨率。因此地震波吸收衰减补偿是地震资料处理中的一项重要环节。本文研究的地层吸收衰减补偿方法主要基于局部时频变换(LTFT),该方法能够调节选取谱分解的频率范围和频率采样间隔,解决了短时傅里叶变换固定时窗和小波系数无法提供波形频率的精确估计值问题,适用于非平稳地震信号的时频分析。在求取地层Q值的方法中,频谱比值法具有高效简单的特点,有着广泛的应用范围。本文假设地下介质为层状变Q模型,使用局部时频变换将信号转换为时频域,通过频谱比值法求出各层的Q值,最后根据Kolsky衰减模型来补偿地震信号。理论模型测试和实际资料处理的结果表明,本文提出的方法能够有效恢复衰减信号,提高地震资料的分辨率。

Attenuation Compensation Method of Seismic Wave in the Local Time-Frequency Transform Domain

Seismic signal will decay w hen spreading under the ground ,w hich will decrease the resolution ratio of seismic data .The attenuation compensation of seismic wave is an important step in seismic datum processing .The proposed attenuation compensation method is based on the local time‐frequency transform (LTFT ) which allows the user to choose a range or sample interval of the frequency .As a result ,it performs well in time‐frequency analysis and solves the problem of fixed‐windows STFT and the precise estimates of the frequency ,which cannot be provided by expansion coefficients in a wavelet frame . The spectrum ratio method is widely used for its convenience and effectivity .Besides we choose the earth filtering operator based on the Kolsky attenuation model .The result of theoretical model and real data trials show that the seismic wave compensation method based on LTFT can compensate the attenuation of seismic signal especially in a deep stratum and improve the resolution of seismic data efficiently .