共炮检距二维弹性波地震剖面的偏移方法

TWO DIMENSIONAL ELASTIC WAVE MIGRATION OF COMMON OFFSET SEISMIC SECTION

在均匀各向同性介质的分界面上入射纵波时，除产生纵波反射Ｐ－Ｐ波外，还会产生转换横波的反射Ｐ－ＳＶ波。同样，当入射波为ＳＶ横波时，在分界面上会同时产生ＳＶ－ＳＶ反射波和ＳＶ－Ｐ反射转换波，对这种二维弹性波地震记录如何进行偏移是正在探讨的问题。为了能够处理实际地震数据，本文提出在共炮检距剖面上进行二维弹性波记录的偏移方法。具体做法是，首先用弹性波方程将两分量的地震记录分解为Ｐ－Ｐ（或ＳＶ－ＳＶ）波和Ｐ－ＳＶ（或ＳＶ－Ｐ）波，然后用我们已导出的适合于处理共炮检距剖面的叠前偏移方法对它们进行处理。用模拟数据进行的试验说明方法正确，效果良好。

Upon the interface of homogenuous isotropic elastic media the incident longitudinal wave produces the reflected longitudinal (P-P) wave and upgoing converted shear (P-SV)wave.Similarly ,the incident shear wave produces the reflected shear (SV-SV) wave and upgoing converted longitudinal(SV-P) wave. Migration of these records acquired on the surface has been engaged in the research among geophysicists. To get successful application of real data processing I propose a method of prestack migration of wave equation for common offest sections. The method includes three steps.First,the two-component record is separated into P-P(or SV-SV) wave and P-SV(or SV-P) wave by a formula derived from elastic equation. Then, the P-P(or SV-SV) and P-SV(or SV-P) common offect sections are seParately migrated with the wave equation migration derived In this paper. Finally, the migrated diffrent common offset sections are stacked and we get two seismic sections for geologlcal interpretation. The test with synthetic data shows this migration method described is correct and the results are attractive.