基于振幅加权的拖缆与海底地震资料联合波形反演方法  

Joint full-waveform inversion of towed-streamer and ocean-bottom seismic data with amplitude weighting

作　　者：杨华臣[1] 张建中[1,2] 吴志强 YANG HuaChen;ZHANG JianZhong;WU ZhiQiang(Key Laboratory of Submarine Geosciences and Prospecting Techniques,Ministry of Education of the People's Republic of China,College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;Functional Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,China;Key Laboratory of Marine Environmental Geology,Ministry of Natural Resources,Qingdao Institute of Marine Geology,Qingdao 266071,China)

机构地区：[1]海底科学与探测技术教育部重点实验室,中国海洋大学海洋地球科学学院,青岛266100 [2]青岛海洋科学与技术国家实验室,海洋矿产资源评价与探测技术功能实验室,青岛266237 [3]自然资源部海洋环境地质重点实验室,青岛海洋地质研究所,青岛266071

出　　处：《地球物理学报》2023年第3期1180-1191,共12页Chinese Journal of Geophysics

基　　金：山东省自然科学基金(ZR2019MD001);国家自然科学基金(42174154)联合资助。

摘　　要：南黄海新近系沉积层与其下方中-古生代海相地层之间速度差异大,存在强波阻抗界面,导致接收的浅部和中深部地层的反射波振幅差异极大.一般全波形反演方法未考虑不同界面反射波振幅的差异,对南黄海浅部沉积层速度的反演效果好,而对中深部地层速度的反演效果差.为此,本文提出一种基于振幅加权的拖缆与海底地震资料联合波形反演方法.该方法对中深部弱反射波数据施加较大的权重,对浅部强反射波数据施加较小的权重,从而均衡浅、中和深部地层反射波的振幅,使得自浅至深所有地层速度均能得到较好反演效果.同时,该方法利用海底地震资料和拖缆地震记录积分的低频成分反演低波数背景速度场,利用拖缆资料的高频成分提高反演模型的分辨率,充分发挥了拖缆和海底地震资料的优势互补作用,获得了比仅使用单一资料更好的反演结果.根据地震剖面和钻井资料,建立了南黄海中部隆起的速度模型.利用该理论模型的合成地震记录对本文方法进行了测试和分析,验证了本文方法的正确性和有效性.The large velocity differences between the Neogene sediments and Mesozoic-Paleozoic marine strata form a strong wave-impedance interface, leading to huge amplitude differences between the observed reflections from shallow and deep layers. The conventional Full-Waveform Inversion(FWI) methods ignore the large amplitude differences of observed reflections from different layers. Therefore, only the velocities of the shallow sediments in South Yellow Sea(SYS) basin can be correctly inverted using the conventional FWI while ones of the middle-deep layers are unsatisfactory. In this paper, we propose a joint FWI of towed-streamer and ocean-bottom seismic data based on amplitude weighting. In the proposed method, large weights are applied to the middle-deep weak reflections while small weights are applied to the shallow strong reflections, so as to balance the amplitudes of the reflections from shallow-deep strata and help the FWI correctly invert the velocities of all layers. Meanwhile, this method uses the low-frequency components of ocean-bottom seismic data and integrated towed-streamer seismic data to modify the low-wavenumber background velocity models, and the high-frequency components of the towed-streamer data to improve the resolution of the inverted models. The proposed method gives full play to the advantages of towed-streamer and ocean-bottom seismic data, and obtains better velocity models than only using either of them. Based on the stack sections of the observed seismic data and the drilling data obtained in the SYS, a theoretical velocity model is established. The synthetic seismic data of the theoretical model are used to test and analyze the proposed method. The numerical tests demonstrate the correctness and effectiveness of the proposed method.

关 键 词：南黄海 波形反演 联合反演 海底地震资料 振幅加权 速度模型 强波阻抗界面 

分 类 号：P631[天文地球—地质矿产勘探] P738[天文地球—地质学]