复杂地表低信噪比地震数据处理研究

焉耆盆地地质条件复杂,侏罗纪末燕山运动和第三纪喜山运动的挤压推覆作用在焉耆盆地南缘霍拉山前形成一系列推覆构造.由于地形起伏大,近地表结构复杂,采集的地震资料信噪比较低;以推覆构造为主体的地下地质复杂性给地震成像造成极大的困难.针对该复杂地区低信噪比地震资料,在偏移前资料预处理中,通过采取一系列旨在提高信噪比、重建反射信号的技术,为后续的复杂构造成像处理奠定基础.针对断裂交错的复杂推覆构造成像,采用增强高波数波场成像的半解析Fourier地震偏移方法,能很好地成像强速度对比下的陡倾角大断裂地质构造,有效突出推覆体构造的空间形态,改善推覆体下的成像效果.

Seismic processing of low-S/N ratio data from complex near surface areas in huola mountain

Geological conditions in Yanqi basin are very complex. The extrusion and overthrow processes by both Yanshanian movement in late Jurassic and Himalayan movement in Tertiary lead to a series of thrust nappe structures at the southern edge of the basin. Seismic data acquired in this area has a very low S/N ratio due to complex near-surface conditions. Seismic imaging becomes difficult because of complex subsurface conditions with overthrust structures and faults. Seismic processing for such data focused on both data preprocessing and seismic imaging techniques. The data preprocessing with some new methods enhanced the S/N ratio of the data and rebuilt weak reflections, which laid a foundation for velocity analysis and seismic imaging. A new Fourier migration method was used to enhance high-wavenumber components for imaging complex overthrust structures and faults. The resulting seismic migration sections show a significant improvement over old migration sections.