酸化作用下页岩超声波透射试验研究

为了探索碳酸（H2CO3）对页岩酸化作用引起的声学特性变化特征，以修武盆地海相页岩为研究对象，通过超声波透射试验方法研究了页岩试样被H2CO3处置后的时域信号、频域信号、波速、衰减系数等特征。研究结果表明，页岩试样被H2CO3处置后，超声波纵波和横波在页岩中的传播时间延长，纵波与横波幅值均呈现明显的下降特征；超声波频域内最大振幅下降，主频向低频方向发生偏移，部分页岩试样主频发生畸变；超声波纵波与横波波速均下降，纵波与横波衰减系数均增大。页岩试样被H2CO3处置后呈现的声波特性变化特征，反映出H2CO3酸化作用导致页岩孔隙度增大或者产生了破坏裂隙。

Research on Ultrasonic Transmission Test of Shale effected by Carbonic Acid

In order to explore the acoustic characteristics of shale affected by carbonic acid (H2CO3), taking the marine shale in Xiuwu basin as the study object, the ultrasonic transmission test was used to study the characteristics of time domain signal, wave velocity, frequency domain signal, and attenuation coefficient of H2CO3-treated shale. The results show that, compared with dry shale, the propagation time of P- and S-wave of aqueous shale is prolonged, and the amplitudes of P- and S-wave present obvious decline. Under the same conditions, the amplitude of first P-wave is stronger than that of the first S-wave, namely, the transmissibility of P-wave in shale is stronger than that of S-wave; the maximum amplitude in frequency domain decreases, the dominant frequency shifts to low frequency, and the dominant frequency of some samples is distorted; the velocity of P- and S-wave decreased, and the attenuation coefficients of P-wave and S-wave increased. It is concluded that shale porosity increased or fracture produced induced by acidification.