Research and Application of Reflected Acoustic Wave Data Processing Methods for Remote Detection Acoustic LWD

To extract formation-interface information from reflected acoustic-wave data during boundary detection using remote detection acoustic logging while drilling (LWD), a reflected acoustic-wave data processing method (RAPM) was investigated. Remote detection acoustic LWD employs reflected acoustic waves to detect the formation interface, and the received waveforms contain strong direct waves propagating along the borehole, weak reflected acoustic waves, and drillstring vibration noise. To this end, a wavefield separation method based on slowness-time coherence and median filtering was constructed to filter out the direct waves from the received waveforms. By adopting scanning migration stack imaging technology, the remaining reflected acoustic waves after filtering were imaged to obtain information about the reflecting interface. Numerical simulation results for borehole models containing formation interface demonstrate that the proposed method can separate various direct waves including P-wave, S-wave and Stoneley wave and filter out direct waves from received waveforms. A pool experiment on acoustic remote detection was conducted, in which reflected acoustic-wave data was successfully acquired and imaged, and a reflecting interface at a radial distance of approximately 8.00 m was identified. RAPM enabled reflected wave extraction and formation interface imaging, which provided technical support for the application of remote detection acoustic LWD to geosteering.