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低信噪比、绕射波干涉和与倾角有关的一些问题(即:反射点分散、与倾角有关的NMO以及反射角度)使得可靠的AVO分析成为一项困难的工作。叠前时间偏移(PSTM)使得绕射波收敛,提高了资料的信噪比,并减少了与倾角有关的一些问题。此外,在从地震数据中提取与偏移距有关的信息之前,通常需要进行叠前时间偏移,并且在真实地震数据和一维地下模型合成数据进行比较之前PSTM是必须的。我们提出了一种二维频率波数域共偏移距叠前时间偏移算法。为了能正确地完成振幅处理,在进行偏移之前需要进行三维数据到二维数据的转换,这种转换是通过对非平面几何扩散数据的校正来实现的,利用偏移的最大倾角随旅行时和偏移距的增大而减小的原理减少偏移假象。在进一步处理之前的最后一个处理步骤是对二维几何扩展进行校正,并且去除在偏移中隐含的NMO校正。两组海上数据的实例表明,数据的质量在叠前时间偏移之后得到了提高,并使得后续的振幅分析更加可靠。
Low signal-to-noise ratio, diffraction of diffraction waves, and problems related to dip (ie, reflection point dispersion, tilt-dependent NMO, and reflection angles) make reliable AVO analysis a difficult task. The prestack time shift (PSTM) converges the diffracted waves, improves the signal-to-noise ratio of the data and reduces some of the problems associated with dip. In addition, prestack time migration is usually required before extracting offset-related information from the seismic data and the PSTM is necessary before the real seismic data is compared with the one-dimensional substructure synthesized data. We propose a two-dimensional frequency wavenumber domain co-offset prestack time migration algorithm. In order to complete the amplitude processing correctly, the transformation from 3D data to 2D data is needed before the offset. This conversion is achieved by correcting the non-planar geometry diffusion data. The maximum tilt angle of the offset is used to calculate the travel time And offset the increase of the principle of reducing the offset to reduce the illusion. The last processing step before further processing is to correct the two-dimensional geometric extension and remove the NMO correction implicit in the offset. Examples of two sets of maritime data show that the quality of the data has been improved after the prestack time migration and has made subsequent amplitude analysis more reliable.