Integration and sea test of single-channel seismic system mounted on unmanned surface vehicle
Unmanned operation is a major trend in the development of marine survey technology.Multiple survey equipment,such as single/multi-beam bathymetry,side-scan sonar,sub-bottom profiler and CTD,have achieved Unmanned Surface Vehicle(USV)carrying and automated operation.However,seismic exploration has not yet realized full-system unmanned autonomy.This paper introduces the key technologies of the USV integrated with a single-channel seismic system and verifies the feasibility of unmanned seismic exploration operations through offshore tests.The USV in this work is a commercial catamaran,model L25 C,designed for hydrographic surveying.The seismic source used is a homemade boomer,which is designed and integrated into the bottom of the USV to keep flexibility during exploration.A short-arranged and narrow-spaced hydrophone streamer is selected to reduce the influence of the hydrophone array length on the detection effect of shallow strata.The streamer is towed behind the USV with a short offset to keep flexibility.Meanwhile,the towing distance of the hydrophone streamer must also consider the influence of the propeller wake on the receiving signal.We determined the source-receiver offset through the try-and-error method.The sea test results show that when the source-receiver offset distance is 10 m,the seismic imaging result can be more satisfactory in the water depth between 10～15 m.The strata reflection event is continuously and traceable,and the longitudinal resolution is about 1 m.
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