岩石声波主频漂移现象及其应用探讨

岩石超声测量分析结果表明，不同岩石具有不同的纵波或横波频率特性，岩石声衰减越大，其频率主值越低。纵波主频随孔隙流体性质变化较显著表明，不同岩石具有不同的纵波或横波频率特性。井孔模型中的声波全波列观测实验也指出，随着地层孔隙度及渗透率的增大，不仅各组分波的衰闰增大、速度减小，而且其主频也有不同程度的降低。特别是斯通利波的主频明显向低频方向漂移，高频组分波比低频组分波衰减更大。上述实验现象得到了实际声

Effects of Center Frequency Shift on Acoustic Spectrum of Rock and Its Application

The experimental results of rock ultrasonic measurement show that the center frequency of acoustic waves may vary with the properties of rocks. The larger the acoustic amplitude attenuation is, the lower is the acoustic center frequency. A relationship of U shape is shown between the center frequency of Pwave and gas (or water) saturation of sandstone. Investigation on the acoustic full wavetrain in a scaled model borehole also show that, with the increase of porosity and permeability of the formation, the wave attenuation becomes larger, the velocities become slower, and the center frequencies become lower. Especially the center frequency of the Stoneley waves obviously shifts low. These results can be used to evaluate the complex reservoirs and to improve the acoustic logging tool.