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横向各向同性介质中的速度随着深度的改变而发生变化。因此对该种介质做数据处理时,第一步也是最重要的步骤是参数估计。倾斜反射层的多层正常时差方程式提供了把Alkhalifah和Tsvankin的横向各向同性速度分析法推广到垂向非均匀介质的基础,该正常时差方程式是以NMO层速度的均方根平均值为基础的。这些NMO层速度对应于单个射线参数,即倾斜同相轴的射线参数。因此,正常时差层速度(包括水平同相轴的正常时差速度V_(nmo)(0))可通过Dix型的微分法从叠加速度求得。另一方面,与时间有关的处理所依赖的Thomsen参数的关键组合η,可通过在每层中使用均质反演,从正常时差层速度中提取。 在垂向非均匀介质中,时间偏移和倾角时差一样,依赖于两个随深度变化而变化的参数V_(nmo)(0)和η,所以通过P波时差速度的倾角依赖关系估计出的V_(nmo)(0)和η,可用于横向各向同性介质。 对非洲海上地震资料的各向异性处理表明,在处理中考虑各向异性,特别是在倾斜同相轴的聚焦和成像中考虑各向异性是非常重要的。
The velocity in a transversely isotropic medium varies with depth. Therefore, when dealing with this kind of media, the first and most important step is parameter estimation. The multi-layered normal time difference equation for the slanted reflector provides the basis for generalizing the transverse isotropic velocity analysis of Alkhalifah and Tsvankin to a vertically inhomogeneous medium based on a mean-squared average of the NMO layer velocities of. These NMO velocities correspond to a single ray parameter, that is, a ray parameter of a dip-dip event. Therefore, the normal time difference layer velocity (including the normal time difference velocity V nmo (0)) of the horizontal event can be obtained from the superposition velocity by the Dix-type differential method. On the other hand, the key combination of the Thomsen parameters on which time-dependent processes depend, η, can be extracted from normal transitory layer velocities by using a homogeneous inversion in each layer. In a vertical inhomogeneous medium, the time offset is the same as the dip time difference and depends on two parameters v_ (nmo) (0) and η that change with the depth. Therefore, from the tilt dependence of P wave transit time velocity V_ (nmo) (0) and η, can be used for transversely isotropic media. Anisotropy of offshore seismic data in Africa suggests that it is important to account for anisotropy in processing, especially considering anisotropy in the focusing and imaging of sloped events.