Plasma spark sources are widely used in high-resolution seismic exploration.However,research on the excitation mechanism and propagation characteristics of plasma spark sources is very limited.In this study,we elabora...Plasma spark sources are widely used in high-resolution seismic exploration.However,research on the excitation mechanism and propagation characteristics of plasma spark sources is very limited.In this study,we elaborated on the excitation process of corona discharge plasma spark source based on indoor experimental data.The electrode spacing has a direct impact on the movement of bubbles.As the spacing between bubbles decreases,they collapsed and fused,thereby suppressing the secondary pulse process.Based on the premise of linear arrangement and equal energy synchronous excitation,the motion equation of multiple bubbles under these conditions was derived,and a calculation method for the near-field wavelet model of plasma spark source was established.We simulated the source signals received in different directions and constructed a spatial wavelet face spectrum.Compared with traditional far-field wavelets,the spatial wavelet facial feature representation method provides a more comprehensive display of the variation characteristics and propagation properties of source wavelets in three-dimensional space.The spatial wavelet variation process of the plasma spark source was analyzed,and the source depth and the virtual reflection path are the main factors affecting the wavelet.The high-frequency properties of plasma electric spark source wavelets lead to their sensitivity to factors such as wave fluctuations,position changes,and environmental noise.Minor changes in collection parameters may result in significant changes in the recorded waveform and final data resolution.So,the facial feature method provides more effective technical support for wavelet evaluation.展开更多
The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark sour...The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark source(source level:216 dB,main frequency:750 Hz,frequency bandwidth:150-1200 Hz)and a towed hydrophone streamer with 48 channels.Because the source and the towed hydrophone streamer are constantly moving according to the towing configuration,the accurate positioning of the towing hydrophone array and the moveout correction of deep-towed multichannel seismic data processing before imaging are challenging.Initially,according to the characteristics of the system and the towing streamer shape in deep water,travel-time positioning method was used to construct the hydrophone streamer shape,and the results were corrected by using the polynomial curve fitting method.Then,a new data-processing workflow for Kuiyang-ST2000 system data was introduced,mainly including float datum setting,residual static correction,phase-based moveout correction,which allows the imaging algorithms of conventional marine seismic data processing to extend to deep-towed seismic data.We successfully applied the Kuiyang-ST2000 system and methodology of data processing to a gas hydrate survey of the Qiongdongnan and Shenhu areas in the South China Sea,and the results show that the profile has very high vertical and lateral resolutions(0.5 m and 8 m,respectively),which can provide full and accurate details of gas hydrate-related and geohazard sedimentary and structural features in the South China Sea.展开更多
基金supported by the Key Laboratory of Marine Mineral Resources,Ministry of Natural and Resources,Guangzhou(No.KLMMR-20220K02)the Marine Geological Survey Program of China Geological Survey(No.DD20191003)。
文摘Plasma spark sources are widely used in high-resolution seismic exploration.However,research on the excitation mechanism and propagation characteristics of plasma spark sources is very limited.In this study,we elaborated on the excitation process of corona discharge plasma spark source based on indoor experimental data.The electrode spacing has a direct impact on the movement of bubbles.As the spacing between bubbles decreases,they collapsed and fused,thereby suppressing the secondary pulse process.Based on the premise of linear arrangement and equal energy synchronous excitation,the motion equation of multiple bubbles under these conditions was derived,and a calculation method for the near-field wavelet model of plasma spark source was established.We simulated the source signals received in different directions and constructed a spatial wavelet face spectrum.Compared with traditional far-field wavelets,the spatial wavelet facial feature representation method provides a more comprehensive display of the variation characteristics and propagation properties of source wavelets in three-dimensional space.The spatial wavelet variation process of the plasma spark source was analyzed,and the source depth and the virtual reflection path are the main factors affecting the wavelet.The high-frequency properties of plasma electric spark source wavelets lead to their sensitivity to factors such as wave fluctuations,position changes,and environmental noise.Minor changes in collection parameters may result in significant changes in the recorded waveform and final data resolution.So,the facial feature method provides more effective technical support for wavelet evaluation.
基金Supported by the National Key R&D Program of China(No.2016YFC0303900)the Laoshan Laboratory(Nos.MGQNLM-KF201807,LSKJ202203604)the National Natural Science Foundation of China(No.42106072)。
文摘The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark source(source level:216 dB,main frequency:750 Hz,frequency bandwidth:150-1200 Hz)and a towed hydrophone streamer with 48 channels.Because the source and the towed hydrophone streamer are constantly moving according to the towing configuration,the accurate positioning of the towing hydrophone array and the moveout correction of deep-towed multichannel seismic data processing before imaging are challenging.Initially,according to the characteristics of the system and the towing streamer shape in deep water,travel-time positioning method was used to construct the hydrophone streamer shape,and the results were corrected by using the polynomial curve fitting method.Then,a new data-processing workflow for Kuiyang-ST2000 system data was introduced,mainly including float datum setting,residual static correction,phase-based moveout correction,which allows the imaging algorithms of conventional marine seismic data processing to extend to deep-towed seismic data.We successfully applied the Kuiyang-ST2000 system and methodology of data processing to a gas hydrate survey of the Qiongdongnan and Shenhu areas in the South China Sea,and the results show that the profile has very high vertical and lateral resolutions(0.5 m and 8 m,respectively),which can provide full and accurate details of gas hydrate-related and geohazard sedimentary and structural features in the South China Sea.
