超大井眼疏松地层声波时差采集与提取方法

Acoustic Wave Time Difference Acquisition and Extraction Method in Oversized Wellbore and Unconsolidated Stratum

在准噶尔盆地南缘山前超深层油气勘探中,由于声波能量受表层超大井眼、疏松地层衰减的影响,无法有效获取纵波时差。为解决此难题,对相关声波时差测井采集与提取方法进行了研究。针对超大井眼声波测井采集,提出了一种声波偏心仪器的测井方法,并选取偶极子阵列声波测井作为疏松地层声波测井系列。基于慢度-时间相关法提取声波时差的原理,利用频率开窗技术,锁定了区域偶极子声源激发的漏能纵波的频率为2.6~3.6 kHz;通过对横波信号与直达波信号进行频率过滤,确定了波形窗口、时差搜寻窗长和时差搜索偏移量处理参数,使得纵波信号最强,并将漏能纵波从偶极横波原始波形中分离出来,从而提取疏松地层的声波时差。应用该方法成功采集了准噶尔盆地南缘山前表层超大井眼、疏松地层12口井的偶极子声波资料,并提取了纵波时差。将提取的纵波时差应用于井震成像,显著提高了地震处理资料品质,为认识山前超深层构造和井位部署提供了重要依据。

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.