Active source seismic imaging on near-surface granite body: case study of siting a geological disposal repository for high-level radioactive nuclear waste

摘要

In order to research whether it is suitable to set a geological disposal repository for high-level radioactive nuclear waste into one target granite body, two active source seismic profiles were arranged near a small town named Tamusu, Western China. The study area is with complex surface conditions, thus the seismic exploration encountered a variettraveltimey of technical difficulties such as crossing obstacles, de-noising harmful scattered waves, and building complex near-surface velocity models. In order to address those problems, techniques including cross-obstacle seismic geometry design, angle-domain harmful scattered noise removal, and an acoustic wave equation-based inversion method jointly utilizing both the and waveform of first arrival waves were adopted. The final seismic images clearly exhibit the target rock’s unconformable contact boundary and its top interface beneath the sedimentary and weathered layers. On this basis, it could be confirmed that the target rock is not thin or has been transported by geological process from somewhere else, but a native and massive rock. There are a few small size fractures whose space distribution could be revealed by seismic images within the rock. The fractures should be kept away. Based on current research, it could be considered that active source seismic exploration is demanded during the sitting process of the geological disposal repository for nuclear waste. The seismic acquisition and processing techniques proposed in the present paper would offer a good reference value for similar researches in the future.