| This is the research regarding with the partial wave acquisition method for the crossed dipole array sound waves equipment.Normally,the acquisition method can be classified into 2 kinds: frequency domain processing method and time-domain data processing method.As for frequency domain processing method,there are Prony anticipation method and spectral weight method.But this method is time-consuming,so normally it used as the analytical tool for the research,but not for the massive data processing.So the time-domain data processing is mainly used for the partial wave acquisition method,for example,the similarity correlation method and waveform forecast method.It mainly studies Slowness-time correlation method(STC method)and N-th root method.The design and development of the crossed dipole array sound waves equipment serves for the Soft formation shear wave information.Dipole source provoke the bending mode wave in the medium around the wellbore,and when this wave transmitted at the cut-off frequency,and the transmission speed in the direction of the well axis is the transverse wave of the medium.Thus flexural wave speed can be used to replace shear wave velocity.But under the influence of the feature of frequency dispersion,there is deviation between the flexural wave velocity and transverse wave velocity.Thus,the transverse wave velocity acquired(actually the flexural wave)shall be applied with dispersion correction.This essay utilized the computer numerical simulation technique to simulate and calculate data of the well hole diameter,Fluid density,velocity of sound,formation density,compressional and shear velocity of formation.And how these data influence the dispersion characteristic curve in the soft and hard formation.Make the analysis of the cut-off frequency of bending mode wave and change rule of Dispersion curve.Besides,use select the sensitivity parameter to make the dispersion calibration to increase the accuracy of the Shear wave interval transit time logging acquisition. |
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