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为了尽可能在宽频范围内确定岩石的弹性性质,在帝国学院的井下试验基地对饱和的沉积岩岩石系列进行了一系列的实验。这些实验分成四类:频率范围在30～280Hz之间的垂直地震剖面(VSP),井间勘探(0.2～2.3KHz),声波测井(8～24KHz)和实验室测试(300～900KHz)。在这些实验中尽量测试了岩石的纵波和横波的本征衰减和速度。观察了纵波和横波的速度频散。在声波频段,纵波的本征衰减有一个与频率有关的衰减峰。模拟数据认为衰减是由于在小的纵横比孔隙中局部流体流动引起。这个模拟表明本征衰减主要由纵横比约为10~(-3)到10~(-4)的裂隙控制。
In order to determine the elastic properties of rocks as broadly as possible, a series of experiments were performed on the saturated sedimentary rock series at Imperial College’s downhole test site. These experiments are divided into four categories: Vertical Seismic Profile (VSP), Crosswell Exploration (0.2-2.3 KHz), Sonic Logging (8-24 KHz) and Laboratory Testing (300-900 KHz) in the frequency range of 30-280 Hz. In these experiments, we tried to test the intrinsic attenuation and velocity of the compressional and shear waves of rocks. The velocity dispersion of longitudinal and transverse waves was observed. In the sonic band, the intrinsic attenuation of the longitudinal wave has a frequency dependent attenuation peak. The simulation data suggests that the attenuation is due to the local fluid flow in the small aspect ratio pores. This simulation shows that the intrinsic attenuation is mainly controlled by a crack with an aspect ratio of about 10 -3 to 10 -4.