四川中部大足地区高分辨率地震资料的处理及其效果

PROCESSING AND EFFECTIVENESS OF HIGH RESOLUTION SEISMIC DATA FROM DAZU REGION OF MIDDLE SICHUAN PROVINCE

地质矿产部石油物探研究所

Research Institute of Geophysical Prospecting for Petroleum,MGMR

本文简要地阐述了高分辨率地震资料处理的一般原理和方法;介绍了弥陀场工区两条正交高分辨率测线的处理情况,比较详细地分析了资料的处理效果。地震资料的分辨率主要取决于子波的频带宽度、振幅谱形态以及子波的相位特性。箱形谱、零相位、宽频子波的分辨率最高。高分辨地震资料处理的基本目标是把野外记录到的具有一定时变空变特点的子波尽可能转换成时不变的、空不变的、振幅谱为箱形的零相位子波。在弥陀场工区高分辨率地震资料的处理中,我们通过道编辑、叠加方式的选取以及高保真去噪声方法提高信噪比,拓宽有效频带宽度(我们把信噪比大于等于1的所有频率成分的集合定义为地震资料的有效频带);通过SCALCOMP消除了大部分与岩性无关的横向振幅变化;通过DESIG、QCOMP及TCOMP把振幅谱整形为时变作用较小的白色谱;通过NMP处理获得零相位子波。经过上述处理,资料的有效波频带宽度达到10～110Hz,相对频带宽度约为3个倍频程,子波近似为10～100Hz的零相位Sine子波;在高速的碳酸盐岩地区,薄层分辨力约为15～23m,与常规地震剖面相比分辨率有了明显提高。

In the paper,the general principle and method on the high resolution seismic data processing are concisely expounded ;how were the two othogonal H. R. lines of Mituochang prospecting area processed and their processed results turned out are in some detail elaborated.The resolution of seismic data depends largely on wavelet bandwidth and amplitude spectrum pattern,and wavelet phase characteristics. The most desirable resolution can be expected from the boxcar spectrum, zero phase and broadband wavelets. The major objective of performing the H. R. seismic data processing is to try as far as possible to turn the wavelet characterized (to certain degree) by time-variance and space-variance into boxcar spectrum zerophase wavelet with neither time-variance nor space-variance. While dealing with the processing of the H. R. seismic data collected from Mituochang,the approaches,trace editing,stack mode selection and Hi-Fi noise removal are used to enhance the S/N ratio and broaden the band width (all the gathered frequency components with S/N ratio≥1 are defined as the effective frequency band of seismic data) ;by applying SCALCOMP,most of the lithologic characters being independent of lateral amplitude variation are eliminated;by applying DES1G,QCOMP and TCOMP to have the amplitude shaped to be a less time-variant white spectrum and by performing NMP processing, the zerophase wavelet could be obtained. As a result of the above processing,the effective wave bandwidth of the data reaches to 10-110Hzjthe relative bandwidth is about 3 octaves and wavelets turned out approximate to 10-100Hz zerophase Sine wavelet. The resolution of high-velocity thin bed in the carbonate area is around 15-23m. It shows that its resolution is distinctively improved as compared with the conventional seismic section.