DEPTH MEASUREMENT ANALYSIS FOR SHORT ARRAY HIGH RESOLUTION SEISMIC TOWING STREAMERS AT SEA
-
摘要:
海洋短排列、小道距、高分辨率地震勘探具有分辨率、信噪比高和施工便捷的特点,是浅部高分辨率地震勘探的重要手段。由于拖缆整体拖曳长度较短,受作业环境和设备等限制,通常采用加配重物代替水鸟来调节拖缆沉放深度。施工采集状态下的实际监测发现,受潮流、船速、配重量等多种因素影响,电缆和地震震源沉放深度变化较大,有较强的规律性变化。笔者对震源、电缆沉放深度测试结果进行了分析总结,认为地震采集船速控制宜采用稳定对水速度,能在地震资料采集过程中合理地保证较稳定的震源、电缆沉放深度控制,针对高分辨率地震调查目的,地震电缆沉放深度越小越好。该认识对优化海洋短排列、小道距、高分辨率多道地震采集参数,地震精确处理提供了准确、高精度的数据和保障。
Abstract:The short array high resolution seismic survey is an important survey method commonly used at sea because of its advantages of high resolution, high signal to noise ratio and easy operation. However, since the length of the towing streamers is too short, the sinking depth of the towing streamers is always limited by the operating conditions and the equipment itself. Generally, waterbird control is not used, and the towing streamers sinking depth is usually adjusted by weight. The source depth and the depth of the towing streamers depend upon many factors such as the tidal current, the speed and weight of survey vessel and the conditions of data acquisition. As the results, the sink depths of the source and streamers change greatly and regularly. In this paper, we summarized our experiences from offshore survey and recognized that for the purpose of high resolution seismic survey, when the data acquisition of seismic data is going on, the relative water velocity should be as stable as possible and smaller seismic cable sinking depth is preferred.
-
Key words:
- multiple-channel seismic /
- high-resolution /
- short array /
- sinking depth /
- notch
-
-
表 1 地震数据采集系统参数表
Table 1. The main parameters of the seismic acquisition system
道间距/m 能量/J 炮间距/m 最小偏移距/m 道数 覆盖次数 采样率/ms 记录/s 震源沉深/m 震源放长/m 电缆沉深/m 电缆放长/m 船速/kn 3.125 5000 12.5 12.5 64 8 0.25 2.5 1 50、38 1 50 5 表 2 电缆沉放深度测试结果表
Table 2. The information related to seismic cable sinking depth
是否
配重潮流 前端/m 陷波频率/Hz 中部/m 陷波频率/Hz 尾端/m 陷波频率/Hz 配重 顶流 2.8~2.9 250 7.1~7.3 107 9~10 75 顺流 3.7~4.3 187 7.5~8.5 93 10~11 68 无配重 顶流 1.0~2.1 375 7.6~8.5 93 7.9~8.5 93 顺流 2.0~2.9 250 8.8~9.8 83 8.6~9.5 83 -
[1] 张勇,田双风,周建平,等. 小排列高分辨率多道地震系统在岱山岛大桥工程中的应用[J]. 海洋学研究,2008,26(4):105-110. doi: 10.3969/j.issn.1001-909X.2008.04.016
[2] NISSEN S E,COMBES J M,NEKUT A G. Acquisition,processing,and analysis of shallow,high-resolution seismic data from the outer continental shelf and upperslope,offshore Louisiana[J]. Journal of Sedimentary Research,1999,69(2):300-316. doi: 10.2110/jsr.69.300
[3] BELLEFLEUR G, DUCHESNE M J, HUNTER J, et al. Comparison of single- and multichannel high-resolution seismic data for shallow stratigraphy mapping in St. Lawrence River estuary, Quebec [J]. Current Research , 2006: 1-10.
[4] LEE H Y,PARK K P,KOO N H,et al. High-resolution shallow marine seismic surveys off Busan and Pohang,Korea,using a small-scale multichannel system[J]. Journal of Applied Geophysics,2004,56(1):1-15. doi: 10.1016/j.jappgeo.2004.03.003
[5] MOSHER D C,SIMPKIN P G. Status and trends of marine high-resolution seismic reflection profiling:data acquisition[J]. Geoscience Canada,1999,26:174-187.
[6] 史慧杰,赵铁虎,褚宏宪,等. 海域高分辨率24道地震采集技术在渤海海峡跨海通道项目中的应用[J]. 海洋地质前沿,2015,31(10):47-56.
[7] 吴志强,祁江豪,张训华,等. 大陆架科学钻探CSDP-2 井的垂直地震剖面测量[J]. 地球物理学报,2019,62(9):3492-3506. doi: 10.6038/cjg2019M0353
[8] 唐进,杨凯,顾汉明,等. 海上变深度缆地震采集宽频机理分析[J]. 地球物理学进展,2015,30(5):2386-2391. doi: 10.6038/pg20150555
[9] 褚宏宪,孙运宝,秦轲,等. 小道距高分辨率多道地震对天然气水合物勘查的适用性[J]. 海洋地质前沿,2015,31(6):50-54.
[10] 陈金海,王桂华,徐新南. 海上地震虚反射探讨[J]. 海洋石油,2000,20(1):22-27.
[11] 金明霞,宋鑫,易淑昌,等. 海洋地震变深度电缆采集数据的频谱分析及消除鬼波研究[J]. 物探与化探,2018,42(3):529-530.
[12] 李军峰,肖都,孔广胜,等. 单道海上反射地震在海上物探工程中的应用[J]. 物探与化探,2004,28(4):365-368.
[13] 钟明睿,朱江梅,杨薇,等. 震源及电缆沉放深度对海上地震资料的影响[J]. 物探与化探,2012,36(1):78-83.
[14] 骆迪,蔡峰,吴志强,等. 海洋短排列高分辨率多道地震高精度成像关键技术[J]. 地球物理学报,2019,62(2):730-741. doi: 10.6038/cjg2019M0178
[15] 祁江豪,吴志强,郭兴伟,等. 大容量气枪震源在南黄海海相高速屏蔽层下VSP资料采集中的应用:以大陆架科学钻探CSDP-2井为例[J]. 地球物理学进展,2019,34(4):1661-1670. doi: 10.6038/pg2019CC0559
[16] 吴志强,郝天珧,唐松华,等. 立体气枪阵列延迟激发震源特性及在浅海区OBS探测中的应用[J]. 地球物理学报,2016,59(7):2573-2586.
[17] 王桂华. 海上地震数据采集主要参数选取方法[J]. 海洋石油,2004,24(3):35-39. doi: 10.3969/j.issn.1008-2336.2004.03.007
-