一种提取声波测井频散波相慢度的方法

在声波测井中，单极子声源激发的斯通利波和偶极子声源激发的弯曲波都是频散波。严格来讲，传统的相似法只适于处理非频散波，不适于处理频散波。只有从频散的斯通利波和弯曲波中提取出相慢度，才有可能进一步求准地层渗透率和横波慢度等参数。提出一种简便、快捷的方法从声波测井的频散波中提取相慢度。该方法从离散傅立叶变换的圆周时移性质出发，分别将2道频散波在幅度最大位置劈开做圆周时移，对圆周时移后的波形做快速傅立叶变换进而得到2道连续的相位谱，再由2道波形的相位差和接收探头间距可以计算出相慢度。给出了用该方法处理理论计算的偶极子波和现场声波测井资料的例子。

A Method to Extract Phase Slowness of Dispersive Wave from Sonic Logging Data

In sonic well logging, Stoneley wave generated by a monopole source and flexural wave generated by a dipole source are both dispersive waves. Strictly speaking, conventional semblance method is not adaptable to dispersive waves processing but only to nondispersive waves processing.Only when phase slowness is extracted from the Stoneley wave and the flexural wave, can the parameters of formation be obtained exactly, such as permeability and shear slowness. This paper presents a simple and quick processing method to extract the phase showness from dispersive waves provided by sonic logging. According to the circularly-shifting character of DFT, two dispersive waveforms are split at the position of maximal amplitude and shifted circularly,thus two continuous phase spectrums are gained by doing FFT of the shifted waveforms, then the phase slowness can be calculated with the phase difference and the transceiver spacing. As examples, the method is employed to process both theoretical dipole wave and field sonic logging data in this paper.