基于多方位相干属性的断裂预测技术

Fault prediction method based on multi-azimuth coherence attribute

地震相干属性是地震解释中识别大中尺度构造和地层异常的关键技术,目前常规属性技术基于叠后三维数据进行.宽方位地震采集和解释技术的发展为提高地下构造的地震识别精度提供了新思路,但如何利用丰富的宽方位地震数据开展地震几何属性研究仍具有挑战.因此,本文充分利用地质不连续面造成的地震异常在不同观测方位上的差异,以及垂直断裂构造走向的部分方位叠加数据对识别断裂有更好的效果,发展了一种基于方位地震数据提取多方位相干属性的方法.首先,在不同方位地震数据的三维分析窗中对地震道插值,沿不同方向构造方位分析窗,其次,在计算方位相干时,对方位分析窗内不同位置的地震道使用反距离加权算法计算权重,最后通过主成分分析技术实现多方位信息融合,并将归一化后的结果定义为最终多方位相干.实际应用验证了所提方法的有效性和稳定性,与常规方法相比,本文所提方法包含了地质构造不同方位的特征,在所有方向上突出了地质边缘,同时提供了局部和整体的不连续性,并且有效地提高了相干图像的信噪比.

Seismic coherence attribute is the key technology for identifying large and mesoscale structures and stratigraphic anomalies in seismic interpretation,while the current conventional attributes are based on post-stack seismic data.The development of wide-azimuth seismic acquisition and interpretation technology provides new ideas for improving the seismic identification accuracy of underground structures,but it is still challenging to use informative wide-azimuth seismic data to carry out seismic geometric attributes research.Therefore,this paper makes full use of the difference of seismic anomalies caused by geological discontinuities in different observation azimuths,and the azimuthal seismic data perpendicular to strikes of fault have a better effect on identifying the fault,we develop a method to extract multi-azimuth coherence attribute based on azimuthal seismic data.First of all,the seismic traces in the spatial analysis windows of the azimuthal seismic data are interpolated,and azimuthal analysis windows are constructed along different directions.Secondly,the traces at different positions in azimuthal analysis window are weighted by inverse distance weighting algorithm when calculating the azimuthal coherence.Finally,we fuse the information in different azimuthal coherence by principal component analysis,and the normalized result is defined as the multi-azimuth coherence.The effectiveness and stability of the method proposed in this paper have been verified in practical applications.Compared with the conventional methods,the proposed method contains the characteristics of the geological structure in different azimuth,highlights the geological edge in all directions,and provides local and global discontinuities,in addition,the signal-to-noise ratio of multi-azimuth coherent images has been improved effectively.