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在分析声波测井信号时,单纯的时间域与频率域方法不能同时了解信号在时间和频率这两方面的信息,而采用单一的一种时频分析方法时又会遇到一些困难,因此,也就会影响声波测井信号分析的可行性。为了解决这些问题,本文将分数阶Fourier变换及平滑伪Wigner-Ville(SPWD)分布的方法相结合,并运用于阵列声波测井信号的分析之中,得到信号的时频分布随分数阶Fourier变换阶数变化的规律,从而总结出不同性质储集层在不同阶数下的时频分布特点。由于分数阶Fourier变换具有旋转特性,而交叉项旋转速度较纵波、横波、斯通利波、伪瑞利波要快,因此,对于不同性质的储集层,根据实际情况选择不同的阶数,交叉项同4种分波会相互分离。通过研究各组分波的性质,就能达到提取储集层信息的目的。结合实际测井数据,表明,此方法极大地削弱了交叉项的干扰,增强了对信号中各组分波的识别能力。
In the analysis of acoustic logging signals, simple time domain and frequency domain methods can not simultaneously understand the signal in both time and frequency information, and when using a single time-frequency analysis method will encounter some difficulties, therefore, It will affect the feasibility of acoustic logging signal analysis. In order to solve these problems, this paper combines fractional Fourier transform with the method of smoothing pseudo Wigner-Ville (SPWD) distribution and applies it to the analysis of array acoustic logging signals. The time-frequency distribution of the signal is obtained with fractional Fourier transform Order changes in order to sum up the different nature of the reservoir at different orders of time-frequency distribution characteristics. Because the fractional Fourier transform has the characteristics of rotation, and the cross term rotation speed is faster than the longitudinal wave, transverse wave, Stoneley wave and pseudo Rayleigh wave, so for different reservoirs, different orders are chosen according to the actual situation, The crossover terms will be separated from each other by four kinds of wave splitting. By studying the properties of wave components, we can achieve the purpose of extracting reservoir information. Combined with the actual logging data, it shows that this method greatly weakens the interference of the crossover term and enhances the ability of identifying each component wave in the signal.