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目前,关于岩石中孔隙流体含量对超声波衰减影响的实验数据还很少。本文介绍的由瞬态波形存贮器和微机控制系统组成的超声波信号采集与数字处理系统,适于实验室内测量超声衰减与流体含量的变化关系。作者以砂岩试件作了实验并取得一些有价值的数据。 实验研究结果,表明砂岩中横波衰减随饱和度增加而增加,纵波衰减随饱和度增加有一个明显的峰值出现。砂岩中声波衰减的品质因数Q值比声波速度v值反映岩石的物理力学性质更灵敏。从所得数据看,同一岩石的Q值随含水量变化量为速度变化量的五倍以上。
At present, experimental data on the effect of pore fluid content in rock on ultrasonic attenuation are still scarce. This article describes the transient waveform memory and microcomputer control system composed of ultrasonic signal acquisition and digital processing system for laboratory measurement of ultrasonic attenuation and fluid content changes. The author experimented with sandstone specimens and obtained some valuable data. The experimental results show that the attenuation of transverse shear in sandstone increases with the increase of saturation, and there is a clear peak in the attenuation of longitudinal wave with increasing saturation. The quality factor Q of acoustic attenuation in sandstone is more sensitive than the value of acoustic velocity v reflecting the physical and mechanical properties of rock. From the data obtained, the Q value of the same rock varies with the amount of water as more than five times the speed of change.