The casing wave and formation compressional wave can be differentiated by the waveform difference between open hole and cased hole,and the formation compressional wave can be extracted by a STC(slowness-time coherence) method.

• 从下套管前后测得的全波波形的差异可区别套管波和地层纵波,采用慢度-时间相关STC(Slowness-Time Coherence)法可提取地层纵波。