| 基于波干涉原理的套管井阵列声波处理方法及其应用 |
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| 引用本文： | 唐晓明,祁晓,张博,李盛清,苏远大.基于波干涉原理的套管井阵列声波处理方法及其应用[J].地球物理学报,2015,58(4):1447-1457. |
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| 作者姓名： | 唐晓明 祁晓 张博 李盛清 苏远大 |
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| 作者单位： | 中国石油大学(华东)地球科学与技术学院, COSL-UPC声学测井联合实验室, 青岛 266580 |
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| 基金项目： | 国家重点基础研究发展计划(2014CB239006)资助. |
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| 摘 要： | 在套管井测井中,沿着钢管产生的拉伸波(即管波)在声波数据中产生很强的干扰,使得地层声速的提取十分困难.基于管波与地层声波的干涉原理,本文提出了一种声波处理方法.管波的传播特征是已知的,且管波和地层波都由同一声源激发,因此,可以用管波来改造测井声波数据.对改造后数据采用希尔伯特变换作进一步处理,得到与地层信息相关的解析信号,从该信号中即可提取出地层声速.通过对理论模拟数据的处理和现场测井数据的应用,验证了新方法的正确性和有效性.
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| 关 键 词： | 套管井测井 管波 波干涉 希尔伯特变换 |
| 收稿时间： | 2014-08-20 |
An interference-based array signal processing technique for cased-hole acoustic logging and applications |
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| TANG Xiao-Ming,QI Xiao,ZHANG Bo,LI Sheng-Qing,SU Yuan-Da.An interference-based array signal processing technique for cased-hole acoustic logging and applications[J].Chinese Journal of Geophysics,2015,58(4):1447-1457. |
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| Authors: | TANG Xiao-Ming QI Xiao ZHANG Bo LI Sheng-Qing SU Yuan-Da |
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| Institution: | COSL-UPC Allied Borehole Acoustic Laboratory, School of Geosciences & Technology, China University of Petroleum, Qingdao 266580, China |
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| Abstract: | In cased boreholes, acoustic logging waveforms are often contaminated by casing waves, making it difficult to extract formation acoustic velocity from the acoustic data, especially when the casing is poorly bonded with formation. Various methods have been tested to solve the problem with only limited success, due to the weak signal amplitude and poor coherence compared to the dominant casing waves. The new technique of this paper utilizes the modulation of wave power spectrum caused by the interference of casing and formation waves. The advantage of the technique is its ability to suppress the coherence of the casing wave and significantly enhance the coherence of the formation wave, allowing for determining the formation acoustic velocity from the latter wave signal. For an acoustic logging instrument composed of an array of equally spaced receivers, the waveform data containing casing and formation waves are windowed and transformed into frequency domain to obtain the power spectrum for each receiver in array. The average power spectrum of the array is calculated and subtracted from the power spectrum of each receiver, yielding a residue power spectrum. The residue spectrum and its Hilbert transform form the real and imaginary parts of an analytical signal, which, after transformation into time domain, results in a new waveform array data whose phase moveout across array is entirely controlled by the velocity of the formation wave. Processing the new array data using an array velocity analysis method, e.g., the slowness-time-coherence (STC) method, yields the formation slowness behind the steel casing.The new technique was tested on synthetic waveform data calculated for a poorly bonded casing. The synthetic data processing example shows that the technique effectively cancels the coherence of the casing signal and significantly enhances the coherence of the desired formation signal. The technique has also been applied to processing field acoustic logging data acquired in cased boreholes. In depth intervals with poor bonding conditions, the STC result of the new technique shows that the casing wave coherence almost disappears and the formation wave coherence is significantly enhanced. Further, the validity of the velocity curve is verified by comparing it with its counterpart from the raw data. The much improved result in the poorly bonded section indicates the ability of the new technique to extract and enhance weak formation signals in the presence of strong casing wave interference. |
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| Keywords: | Cased-hole logging Casing wave Wave interference Hilbert transform |
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