VTI介质中的地层弹性参数反演

Seismic Inversion of Strata Parameters for VTI Media

在ＶＴＩ介质中,用非双曲线可以很好地近似Ｐ—Ｐ波中长排列情况下的旅行时;而对于Ｐ－ＳＶ波来说,应用非双曲线却不能很好地近似Ｐ－ＳＶ波的旅行时。对Ｐ－Ｐ波、Ｐ－ＳＶ波的旅行时进行三项泰勒展开时,它们的系数却包含了地震波的各向异性信息及其垂直速度信息,这为地震波的弹性参数反演提供了基础。实验分析表明,在中等排列长度下可以精确地得到Ｐ—Ｐ波、Ｐ—ＳＶ波旅行时的三项泰勒展式系数,从而可以精确地进行地层弹性参数反演。

In VTI media, P - P wave traveltime curve can be approximated by a nonhyperbola for a long or middle spread, as for P - SV wave, nonhyperbola is not accurate enough to fit traveltime curve. Three - term Taylor series for t2 - x2 curves of P - P and P - SV waves over layered vertically transverse isotropic media are related to dimensionless parameters and vertical velocities of P - and S - wave, which provide a basis for seismic elastic parameter inversion. Only in middle spread, three- term Taylor series for t2 - x2 curves of P - P and P - SV waves can precisely be obtained in modeling analysis, meanwhile seismic elastic parameter inversion can'be implemented precisely too.