基于振幅相位估计法的频散校正方法研究

Dispersion Correction Based on Amplitude Phase Estimation Algorithm

偶极子声波测井采用偶极子激发,在井筒中激发挠曲波沿井内流体传播,偶极子波形具有明显的频散效应,低频截止值处横波速度为地层的横波速度.有效的频散校正方法是偶极子声波测井有效应用的关键技术.对振幅相位估计法进行了研究,设计指定波数的滤波器建立目标函数,通过滤波器的权函数进行拟合函数的求取,得到偶极子波形的频散曲线,可以获得较高分辨率的频散曲线.求得频散曲线后,采用直方图和拟合函数法进行了频散校正方法的研究.通过对模拟数据的对比,得出拟合函数的频散校正方法能获得较高的频散校正结果.实际数据处理验证了该频散校正方法的有效性.

Dipole acoustic logging uses dipole sources to shoot flexural wave which then propagates in the fluid in the borehole.The dipole waveform is obviously disperse.The velocity of the shear wave at low cut-off frequency is equal to that of the shear wave of formation.An effective dispersion correction method is important for the effective application of dipole acoustic logging.This paper studies the amplitude phase estimation algorithm and establishes the objective function by designing a filter with specific wave number.The dispersion curve with high resolution can be obtained by getting the fitting function from the weight function of the filter.Then histogram and fitting function methods are used to study dispersion correction.By comparing simulated data,it is concluded that the dispersion correction method based on the fitting function can provide dispersion correction results with higher precision.The validity of the dispersion correction method has been verified by actual data.