WANG Zhongcheng1, ZHOU Huawei1,2, TONG Si-you1,3, FANG Yunfeng4, CAO Guobin5
1. Key Lab of Submarine Geosciences and Prospecting Techniques, MOE, Ocean University of China, Qingdao, Shandong 266100, China; 2. Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204, USA; 3. Functional Laboratory for Marine Mineral Resources Assessment and Prospecting, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266061, China; 4. R&D Center, BGP, CNPC, Zhouzhou, Hebei 072751, China; 5. Sinopec Geophysical Corporation, Dongying, Shandong 257100, China
Abstract:Due to the influence of bottom topography,ocean current,et al.,OBNs may deviate from their original positions in the process of data acquisition.To guarantee imaging quality,it is necessary to perform secondary positioning.Current velocity,which is an important parameter in secondary positioning,is usually given as a constant or fitted as the function of offset.But actually,current velocity often changes with depth and almost remains unchanged within a specific range of offset.This means that above velocity definitions are both incorrect.We use model tests to investigate the accuracy of secondary positioning for different velocity definitions,and then we propose to substitute depth-varying velocity in the vertical direction with equivalent velocity,which is derived from the inversion of receiver coordinates.Model tests show that this equivalent velocity is better than constant velocity and fitted velocity in higher accuracy of secondary positioning; such improvement facilitates subsequent NMO correction and imaging.
韩立强,常稳.海底电缆初至波二次定位技术的应用[J].石油物探,2003,42(4):501-504.HAN Liqiang and CHANG Wen.Application of first break second positioning technique in OBC[J].Geophysical Prospecting for Petroleum,2003,42(4):501-504.
[3]
Morvan P Y,Pelletier H,Blomme R.Positioning for ocean bottom systems(OBS) applications:A case study[C].Acoustics in Underwater Geosciences Symposium,IEEE/OES,2016,doi:10.1109/RIOAcoustics.2015.7473646.
[4]
刘慧敏,王振杰,吴绍玉,等.顾及声线弯曲的浅海多目标水声定位算法[J].石油地球物理勘探,2019,54(1):9-15.LIU Huimin,WANG Zhenjie,WU Shaoyu,et al.A positioning determination of multi-transponders with sound ray bending in shallow waters[J].Oil Geophy-sical Prospecting,2019,54(1):9-15.
[5]
杨正华,张慧静.海底电缆地震勘探中近正四面体法二次定位技术[J].石油地球物理勘探,2013,48(2):163-170.YANG Zhenghua and ZHANG Huijing.An approximate tetrahedron method for the secondary position-ing in OBC seismic survey[J].Oil Geophysical Prospecting,2013,48(2):163-170.
[6]
倪成洲,全海燕,陈刚,等.一种高精度初至波二次定位新方法——搜索法[J].石油地球物理勘探,2008,43(2):131-133,157.NI Chengzhou,QUAN Haiyan,CHEN Gang,et al.A new method for high-precision first break secondary positioning:search method[J].Oil Geophysical Prospecting,2008,43(2):131-133,157.
[7]
肖永新,杨海申,蒋先艺,等.OBC勘探中扫描拟合二次定位方法[J].石油地球物理勘探,2012,47(3):366-370.XIAO Yongxin,YANG Haishen,JIANG Xianyi,et al.A secondary positioning method by grid scanning and curved-surface fitting in OBC survey[J].Oil Geophysical Prospecting,2012,47(3):366-370.
[8]
葛晓丹.浅海地震勘探海底电缆初至波二次定位方法研究[D].山东青岛:中国海洋大学,2011.GE Xiaodan.A Study on the Second Positioning Technique for the First Break in OBC Seismic Exploration of Shallow Sea[D].Ocean University of China,Qingdao,Shandong,2011.
[9]
刘伯胜,雷佳煜.水声学原理[M].黑龙江哈尔滨:哈尔滨工程大学出版社,1997,138-145.
[10]
Asakawa E,Kawanaka T.Seismic ray tracing using linear traveltime interpolation[J].Geophysical Prospecting,1993,41(1):99-111.
[11]
韩复兴,孙建国,王坤.深海声道对波场传播的影响[J].石油地球物理勘探,2014,49(3):444-450.HAN Fuxing,SUN Jianguo and WANG Kun.Deep sea channel influence on wave field energy propagation[J].Oil Geophysical Prospecting,2014,49(3):444-450.
[12]
马德堂,赵会兵,伍忠良.基于直达波旅行时的OBS混合定位方法[J].石油地球物理勘探,2013,48(5):677-681.MA Detang,ZHAO Huibing and WU Zhongliang.An OBS positioning mixed method based on travel-time of direct wave[J].Oil Geophysical Prospecting,2013,48(5):677-681.
[13]
徐萃薇,孙绳武.计算方法引论[M].北京:高等教育出版社,2007,221-228.
[14]
敖威,赵明辉,丘学林,等.西南印度洋中脊三维地震探测中炮点与海底地震仪的位置校正[J].地球物理学报,2010,53(12):2982-2991.AO Wei,ZHAO Minghui,QIU Xuelin,et al.The correction of shot and OBS position in the 3D seismic experiment of the SW Indian Ocean ridge[J].Chinese Journal of Geophysics,2010,53(12):2891-2991.
[15]
张莉,赵明辉,王建,等.南海中央次海盆OBS位置校正及三维地震探测新进展[J].地球科学——中国地质大学学报,2013,38(1):33-42.ZHANG Li,ZHAO Minghui,WANG Jian,et al.Correction of OBS position and recent advanced of 3D seismic exploration in the Central Sub-basin of South China Sea[J].Earth Science-Journal of China University of Geoscience,2013,38(1):33-42.
[16]
刘斌.海底地震仪重新定位:以东沙群岛海域为例[J].热带海洋学报,2015,34(2):66-70.LIU Bin.Ocean bottom seismometer relocation:Using Dongsha sea area as an example[J].Journal of Tropical Oceanography,2015,34(2):66-70.