基于超级混合虚折射干涉法的阵列声波处理方法及其在套管井中的应用

摘要

在声学测井勘探时,复杂多变的测井条件(如胶结不好的套管井和随钻测井等)下的强直达干扰信号会导致地层信号的信噪比降低,使得地层有用信号的提取十分困难.本文在超级虚折射法的基础上,利用声源与接收器的互易原理,对原始波场信号进行互相关和褶积重建,并对所有可能的位形产生的信号进行叠加,将该叠加波场与超级虚折射波场进行叠加,重构出超级混合虚折射波场,使不同接收器上的折射波信噪比在超级虚折射的基础上进一步得到提高,显著提高了有用信号的信噪比,同时解决了超级虚折射近场能量不足的问题.套管井测井的理论模拟及实际处理表明,该方法可以很好地压制套管波信号、提高地层信号的信噪比.%During acoustic logging using an array acoustic tool,the signal-to-noise (S/N) ratio of formation signals are often contaminated by the background noise and by the interference of the strong unwanted direct signals (e.g.,casing waves in cased hole logging and collar waves in logging while drilling conditions),making it different to extract the formation acoustic signal from the data.In this paper,we present a super mixing virtual (SMV) interferometry based on the super-virtual (SV) interferometric method.Based on the principle of reciprocity,we reconstruct a new wavefield,which is called the super-reverse-virtual (SRV),by processing the raw wavefield using cross correlation and deconvolution over all receivers positioned at stationary-phase points.We finally reconstruct the super-mixing-virtual (SMV) by averaging the SRV and SV results over all receiver positions in the array.The S/N ratio of formation signals can be significantly enhanced.At the same time,it can significantly improve the near-field performance of the existing SV method.The new technique was tested on synthetic waveform data and the cased hole acoustic logging data.The results show that the new technique effectively suppresses the coherence of the casing waves and significantly enhances the S/N ratio and the coherence of the formation acoustic signal.