Acoustic Wave Time Difference Acquisition and Extraction Method in Oversized Wellbore and Unconsolidated Stratum
In the ultra-deep oil and gas exploration in the southern margin of Junggar basin,the P-wave time difference cannot be obtained effectively,because the acoustic energy is affected by the attenuation of oversized wellbore and unconsolidated stratum in the surface.In order to solve this problem,the acquisition and extraction methods of correlation acoustic wave lag logging are studied.Aiming at the acquisition of oversized wellbore acoustic logging,a logging method of acoustic eccentric instrument is proposed.The dipole array acoustic logging is selected as the unconsolidated stratum acoustic logging series.Based on the slower-time correlation method,the frequency window technique is used to lock the frequency range of the leakage P-wave excited by the dipole sound source is 2.6～3.6 kHz.Through the frequency filtering of shear wave signal and direct wave signal,the processing parameters of waveform window,time difference search window length and time difference search offset are determined to make the P-wave signal the strongest,and the leakage P-wave is separated from the original dipole S-wave waveform,so as to extract the acoustic time difference of the unconsolidated stratum.Using this method,dipole acoustic wave data of 12 wells in super-large and unconsolidated stratum in the southern margin of Junggar basin are successfully collected,and the P-wave time difference is extracted.The extracted P-wave time difference is applied to well seismic imaging,which significantly improves the quality of seismic processing data,and provides an important basis for understanding the ultra-deep structure and well location in front of mountains.
万方数据
维普
