| 摘要 |
A method for determining formation shear wave velocity or slowness comprises deploying a down hole tool in borehole, generating an acoustic wave using a transmitter on the tool, receiving an acoustic waveform at a receiver on the tool and measuring the tool standoff distance. The tool standoff measurement is used to indicate the absence or presence of leaky shear wave arrivals (evanescent shear wave arrivals) in the received waveform. If leaky shear wave arrivals are present they are processed to determine the shear wave velocity, possibly using a semblance algorithm or phase velocity algorithm. If leaky shear wave arrivals are absent the shear wave velocity is estimated from a borehole guided wave velocity instead. The method may provide direct determination of shear wave formation velocity in acoustically slow formations. |
