利用不同角度域P波资料反演纵、横波速度

基于反射P波垂直入射假设的常规地震道反演方法不能得到可靠的速度或其他岩性信息，而利用叠前地震资料按部分角度道集叠加后，可以获得多个具有AVO特性的地震剖面，信噪比也得到显著改善，因此角度部分叠加道集可以作为弹性阻抗反演或纵、横波速度同步反演的基础道集记录。对每个角度范围的部分叠加剖面进行反演处理都会得到该角度范围内的阻抗或纵、横波速度值，但是不同角度范围内反演结果之间的关系以及如何求取零入射角的纵、横波速度值仍然是难以解决的问题。为此本文提出利用地震波传播速度在各向异性介质中随入射角变化的理论，由各个角度范围的纵、横波速度反演结果求取地震波零入射角的纵、横波速度的方法，实现了利用叠前P波资料同步反演地震纵、横波速度，进而可以求得纵、横波速度比和泊松比剖面，为解释人员进行岩性及含油气性解释提供可靠的依据。

Using P-wave data in different angular domains for inversion of P- and S-wave velocities.

The ordinary seismic trace inversion based on the hypothesis of vertical incidence of reflected P-wave can't get reliable velocity or other lithologic information, but using prestack seismic data for stack by partial angular gathers can obtain many seismic sections with AVO characters, where the S/N ratio can also be greatly improved, so partial angular stack gathers can act as basic gathers of e-lastic impedance inversion or simultaneous inversion of P- and S-wave velocities. The inversion of partial stack sections in each angular scope can result in impedance or P- and S-wave velocities values in that angular scope,but relationship between the inverted results in different angular scopes and how to compute P- and S-wave velocities values in zero-incident angle are still difficult to be solved. For that reason,the paper presented the theory using variation of seismic propagating velocities with incident angles in anisotropic media and computation of P- and S-wave velocities values of seismic wave in zero-incident angle from inverted results of P- and S-wave velocities values in different angular scopes, which realized using prestack P-wave data for simultaneous inversion of P- and S-wave velocities and further can compute ratio of P- and S-wave velocities and Poison section that can provide reliable foundation for lithologic and oil-bearing interpretation conducted by the interprers.