| 基于相邻虚拟道叠加的超虚折射干涉法及其在广角OBS折射波增强中的应用 |
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| 引用本文： | 宋龙龙,邹志辉,黄忠来.基于相邻虚拟道叠加的超虚折射干涉法及其在广角OBS折射波增强中的应用[J].地球物理学报,2019,62(3):993-1006. |
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| 作者姓名： | 宋龙龙 邹志辉 黄忠来 |
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| 作者单位： | 1. 中国海洋大学海洋地球科学学院海底科学与探测技术教育部重点实验室, 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 266061;3. 中交天航(大连)浚航工程有限公司, 大连 116039 |
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| 基金项目： | 国家重点研发计划（2018YFC0603604）、国家科技重大专项（2016ZX05006002-001）、山东省自然科学基金（ZR2014DM006）、中国海洋大学专项基金（201564006）、教育部留学回国人员科研启动项目（教外司留1098号）和国家自然科学基金重点项目（41230318）联合资助. |
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| 摘 要： | 广角地震的远偏移距折射初至含有地下深层的信息,提高远偏移距折射波信噪比能够有效提高初至拾取精度,对于深部结构的层析速度建模十分有利.超虚折射干涉法基于干涉原理对远道折射波进行增强,它在炮点和检波点都非常密集的情况下效果较好.然而,在应用于台站间距较大且环境噪声较强的广角海底地震仪(OBS)观测时,该方法对折射波的增强能力不足,而且容易产生虚假波形,造成增强后的折射波信噪比仍然较低.针对这种情况,本文提出基于相邻虚拟道叠加的超虚折射干涉法,通过叠加相邻虚拟道来提高远道与近道互相关的准确度,以达到稳定增强远道折射波信噪比的目的.理论实验和实际资料测试均显示,基于相邻虚拟道叠加的超虚折射干涉法在台站间距较大和信噪比较低的情况下能够准确构建虚拟道,且增强后的波形同相轴连续程度和信噪比均较高,有利于拾取高精度的折射初至到时.本文方法也可用于增强陆上炮间距较大的广角地震数据折射波.
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| 关 键 词： | 超虚折射干涉法 广角OBS 折射波 相邻虚拟道叠加 远偏移距 |
| 收稿时间： | 2018-05-02 |
Supervirtual refraction interferometry based on stacking of neighboring virtual-traces and its application to enhancing wide-angle OBS refraction waves |
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| SONG LongLong,ZOU ZhiHui,HUANG ZhongLai.Supervirtual refraction interferometry based on stacking of neighboring virtual-traces and its application to enhancing wide-angle OBS refraction waves[J].Chinese Journal of Geophysics,2019,62(3):993-1006. |
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| Authors: | SONG LongLong ZOU ZhiHui HUANG ZhongLai |
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| Institution: | 1. College of Marine Geosciences, Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Ocean University of China, Qingdao 266100, China;2. Evaluation and Detection Technology Laboratory of Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China;3. CCCC-TDC(DaLian) Channel Dredging Engineering Co., Ltd., Dalian 116039, China |
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| Abstract: | The first-arrival of far-offset refraction waves of wide-angle seismic data carries the information of structure in the deep subsurface. Enhancing the signal-to-noise ratio (SNR) of these waves can effectively improve the accuracy of first-arrival picking up, and would be very helpful for the tomographic velocity modeling of deep structures. The Supervirtual Refraction Interferometry (SRI) method can enhance refraction waves based on the principle of interference. It works well when the shots and receivers are densely distributed. However, when the SRI method is applied to the wide-angle Ocean Bottom Seismometer (OBS) observation with large station space and under high environmental noise, it cannot sufficiently enhance the refraction waves and could create artifacts in resulted waveforms, leading to low SNR of refraction waves. To cope with this problem, we propose a supervirtual refraction interferometry based on the stacking of neighboring virtual-traces (SRI-SNV). By stacking neighboring virtual-traces, our method can stably increase the accuracy of cross-correlation between the far-and near-offset traces, and achieve the high SNR of refraction waves. The synthetic tests and field-data applications both indicate that SRI-SNV can accurately construct virtual-traces under the situation of large station spacing and low SNR, and the resulted refraction waveforms have better continuity and higher SNR than the SRI method. Using the waveforms enhanced by the SRI-SNV, the first-arrival picking up can achieve higher accuracy than using the SRI method. The SRI-SNV method can also be used to enhance the seismic refraction waves of the wide-angle seismic data on land, which has large shot interval. |
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| Keywords: | Supervirtual refraction interferometry Wide-angle OBS Refraction wave Stacking of neighboring virtual-traces Far-offset |
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