二维倾斜叠加速度分析

在传统的速度分析方法中,是将相邻几个 CDP 道集组合在一起制作速度谱,不考虑界面倾角引起的时差。实际上这种时差是随界面倾角的增大而增大的。此外,相邻 CDP 道集的叠加能量还随倾角的增大而衰减,因此出现丢层现象。近年来,随着倾斜叠加方法的出现和发展,一种适用于倾斜叠加的速度分析方法也应运而生,此法的关键是在制作倾斜叠加速度谱时,把倾斜动校正用于速度扫描,在扫描叠加时又利用地震波的相似性和能量准则进行加权叠加。此法不受界面倾角的影响,由此法求出的速度更接近实际介质的速度。本文提供的倾斜叠加速度模块既可作倾斜叠加速度谱,又可作水平叠加速度谱,既可提取可信度较高的速度信息,又可检测精度高的倾角信息,还可顺便完成一次静校正处理。

Velocity analysis using 2D slant-stack approach

In conventional velocity analysing, people use adjacent CDP gathers to make velocity spectrum, without dip moveout considered.With the increase of reflector dip, the dip moveout increases, but the stacking energy of adjacent CDP gathers decreases; therefore, the phenomenon of missing layer happens. In recent years, a velocity analysis method which is applicable to slant-stack follows the seismic slant-stack technique.This method has two key points: (1) DMO correction is used in velocity scanning in making velocity spectrum by slant-stack approach; (2) in scanning stacking, both waveform similarity and energy criterion are used in weighted stacking.This method is not affected by reflector dip; consequently, the velocity determined by this method is more approximate to true velocity in medium. The slant-stack velocity module presented in the paper can be used (1) to make velocity spectra by both slant-stack approach and horizontal-stack approach, (2) to extract quite reliable velocity information and quite accurate dip information, and (3)to perform static correction.