用P-SV波叠加剖面合成横波层速度剖面

Deriving a S-wave interval-velocity section from P-SV wave stack section

本文从Zoeppritz方程的精确解出发，导出了P－SV波反射系数的高精度近似表达式，证明卜SV波的反射振幅正比于△Vs／Vs。这里，Vs为反财界面两侧横波层速度的平均值；△Vs为两侧横渡层速度的差值。文中将P－SV波共转换点水平叠加改进为共转换点拟合叠加，得到正比于△Vs／Vs的叠加振幅。仿照纵波勘探中的波阻抗技术，利用P－SV波拟会叠加剖面（或其偏移归位剖面）逐层向下递推反演，再加上适当的标定，便可获得横渡层速度剖面。

The desirable approximate expression of P-SV wave refIection coefficient is de-duced from the accurate solution of Zoeppritz's equation. Then,the reflection ampli-tude of P-SV wave is proved to be directly proportional to △Vs/Vs,where Vs is theaverage interval velocity of shear waves at the both sides of reflector,and △Vs is theinterval velocity difference of the shear waves. The horizontal stack of common con-version points of P-SV waves is changed into fitting stack of these comrnon conver-sion points to result in stacked amplitudes which are directly proportional to △Vs/Vs. People can obtain S-wave interval-velocity section by imitating wave impedancetechnique in P-wave exploration,namely,by rnaking downward layer by layer recur-sion inversion and calibration of fitting-stacked (or rnigrated) section of P-SVwaves.