Numerical Simulation of the Binchuan Airgun Source Affected by Water Body

The numerical simulation of the influence of a reservoir water body on the Binchuan airgun source could provide a theoretical basis to analyze the data obtained from the active source detection and inversion of regional interior medium structures. Based on a medium model containing limited water body, we use the finite different method to simulate the effect of the water level, excitation energy and focal depth. The results show that the influence on the waveform amplitude caused by the water level changing is very large near the water body, and that a high water level or large amplitude change can have a larger effect. However, for stations beyond a certain epicentral distance, the influence will be weakened and kept stable. As for the Binchuan airgun source, amplitude fluctuation caused by the water level changing becomes very small (±0.05 times) after propagating a certain distance, so we can remove the influence of the water level changing by referring to the numerical simulation result. Wave amplitude increases linearly with the excitation energy and focal depth, therefore, the greater the energy and the deeper the focal depth, the better the effect of the excitation, and is more conducive in detecting remote and deep penetration underground structures.