基于匹配追踪的叠前道集吸收补偿和频散校正

Pre-stack seismic gather absorption compensation and dispersion correction based on matching pursuit

关键词:  地震勘探  叠前道集  吸收衰减  匹配追踪  振幅增益系数  频散校正

Key words:  seismic prospecting  pre-stack gather  absorption attenuation  matching pursuit  amplitude gain coefficient  dispersion correction

摘要:

基于匹配追踪算法,对地震道集吸收和频散进行补偿。首先,运用匹配追踪算法对叠前道集作匹配分解,以零偏移距匹配子波建立随子波中心时间和中心频率乘积值变化的振幅衰减曲线,进而得到不同匹配子波衰减振幅的增益系数;然后,基于射线路径获取零偏移距吸收衰减与非零偏移距吸收衰减间的关系,运用零偏移距振幅增益系数与道集角度计算各个角度地震道的匹配子波振幅增益系数;最后,用振幅增益系数对不同匹配子波衰减振幅分别进行吸收补偿,并重构地震信号;对于频散影响,通过匹配子波求取品质因子进行频散校正。数据资料测试发现,深部吸收衰减能量得到有效补偿,同时消除了吸收对振幅随偏移距变化特征的影响。

Abstract:

Pre-stack seismic gathers are firstly decomposed into a variety of matching wavelets by utilizing the matching pursuit algorithm. The amplitude attenuation curve, which changes with the products of wavelets central times and central frequencies, can be established by using zero-offset matching wavelets. Based on this, the gain coefficients that belong to different matching wavelets attenuation amplitude can be obtained. Then, according to the absorption differences between zero-offset event and non-zero offset event, the zero-offset amplitude gain coefficients and the gather angels are combined to calculate non-zero offset events amplitude gain coefficients. Lastly, different matching wavelets attenuation amplitudes can be compensated by utilizing amplitude gain coefficients accordingly to reconstruct the seismic signal. To correct the influence of dispersion, Q values are estimated by matching pursuit. The comparison between the synthetic seismic signal and the real data shows that this new algorithm is efficient in both compensating the deep part seismic attention energy, and eliminating the influence of absorption in offset direction.