南黄海中部隆起带折射波层析成像  

Refraction tomography of the central uplift in the South Yellow Sea

作　　者：胡雪莹 龚锐 高顺莉 张建明 刘玉柱[1,2] 耿建华[1,2] HU XueYing;GONG Rui;GAO ShunLi;ZHANG JianMing;LIU YuZhu;GENG JianHua(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;School of Ocean and Earth Science,Tongji University,Shanghai 200092,China;Shanghai Branch of CNOOC Ltd.,Shanghai 200335,China)

机构地区：[1]海洋地质国家重点实验室,同济大学,上海200092 [2]海洋与地球科学科学学院,同济大学,上海200092 [3]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《地球物理学进展》2023年第2期803-813,共11页Progress in Geophysics

基　　金：国家自然科学基金项目(41630964)资助。

摘　　要：南黄海中部隆起带中、古生界地层具有良好的油气勘探潜力.但是,由于该区处于水深10~100 m的浅水环境,地震记录上多次波十分发育;且上覆新生界低速地层与下伏中、古生界高速地层速度反差可达2~3倍,形成了地震波能量屏蔽界面,下伏地层反射波能量弱,严重影响了地震反射波速度建模质量.而新生界地层与下伏中、古生界地层之间的速度大反差界面在地震记录上产生了稳定的、易于拾取的折射波,因此,我们将改进的散射积分走时层析成像方法结合多偏移距反演策略应用到南黄海中部隆起带折射波速度建模中.结果表明,折射波层析成像可重建2.5~3.0 km深度的高质量速度模型.对比该速度模型与叠加速度转换得到的速度模型逆时偏移成像的结果,发现用折射波速度模型偏移的地震剖面揭示中生界盆地轮廓、内部构造和断层更清晰,地震同相轴连续性强,且古生界陡倾角地层成像质量也显著提高.证明折射波走时层析成像在南黄海中部隆起带速度建模中是有效的,为南黄海浅、中层地震速度建模提供了一种可靠的解决方案.The Mesozoic and Paleozoic formations of the central uplift in the South Yellow Sea have good oil and gas exploration potential. However, due to the shallow water with a depth of 10 m to 100 m, multiples strongly develop in the seismic records, and the velocity-contrast between the overlying Cenozoic formation with low-velocity and the underlying Mesozoic-Paleozoic formations with high-velocity reaches 2~3 times in this area, forming a shielding interface of seismic wave energy, the reflection wave energy of the underlying formations is weak, which seriously degrade the quality of seismic velocity model building by reflection wave. However, the large velocity-contrast interface generates stable refraction waves which are easy to pick up in seismic records. Therefore, we use these refraction waves to build velocity model by the preconditioned improved scattering-integral refraction travel time tomography combined with multi-offset ranges strategy. The results show that the refraction tomography can build a better velocity model from surface to 2.5 km or 3 km depth than traditional velocity analysis methods. We apply the velocity models obtained from refraction tomography and converted from root-mean-square velocity to reverse-time depth-migration. Compared with the migrated profile using the velocity model converted from root-mean-square velocity, the migrated profile using refraction tomography clearly shows the Cenozoic fault, the outline and internal structures of the Mesozoic basin.The continuity of the seismic events and the quality of the Paleozoic steep dip strata are improved. The preconditioned improved scattering-integral refraction travel time tomography method is effective in building velocity model of the central uplift in the South Yellow Sea,which provides a reliable solution for building seismic velocity model at shallow and middle depth of the South Yellow Sea.

关 键 词：速度建模 折射波层析成像 反射波速度分析 偏移成像 南黄海盆地中部隆起带 

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