Experimental Research of Seismoelectric Interface Response in Rock Sample with Cavity

The characteristics of seismoelectric interface response measured at different interfaces on rock sample are studied by seismoelectric experiments. The rock sample is water-saturated sandstone with a cavity drilled on the left side. The receiving electrodes set at different position to acquire the seismoelectric signal. The signals received by electrodes are compared with each other. The analysis of the traveltime and the phase of the seismoelectric interface response shows that the receiving position has much influence on the signal to be obtained. The amplitude comparison of each arrival suggests that the seismoelectric signal which is generated by the wave reflected from lower interface and is received at the upper interface of cavity turns out to be stronger than the signal directly generated at the lower interface, which means that seismoelectric signal induced by the reflected wave is easier to be received by electrode than the seismoelectric signal directly from the lower interface. The difference of signal strength may cause misjudgment of interface position in seismoelectric record. This phenomenon may form a new viewpoint on the application of the interface response in providing the subsurface information. In addition, the interfical signals induced by multiple waves should be noted.