应用散射时距关系的三维三分量VSP成像  

3D3C VSP imaging technology based on scattering time-distance relationship

作　　者：闫媛媛 秦俐 罗坤 芦俊 王赟[1] YAN Yuanyuan;QIN Li;LUO Kun;LU Jun;WANG Yun(School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China;Southwest Branch,BGP Inc.,CNPC,Chengdu,Sichuan 610213,China)

机构地区：[1]中国地质大学(北京)地球物理与信息技术学院,北京100083 [2]东方地球物理公司西南物探分公司,四川成都610213

出　　处：《石油地球物理勘探》2021年第1期118-126,I0012,共10页Oil Geophysical Prospecting

基　　金：中国地质大学(北京)2020年度本科教育质量提升计划建设项目“地震波传播虚拟仿真实验”(XNFZ202011);国家自然科学基金项目“六分量地震波场的模拟与观测”(U1839208)、“沁水盆地高煤阶煤层气井产能控制因素与增产机理研究”(U1910205)联合资助。

摘　　要：由于观测系统的特殊性,无法采用地面地震技术处理三维三分量(3D3C)VSP数据。现有的VSP成像技术中,可借鉴的高精度成像方法较少,缺乏相匹配的处理软件,成像速度分析多需要迭代,成像难度大。为此,提出一种适用于3D3C-VSP数据的无需迭代的速度建模与基于散射时距关系的成像方法。首先,建立了适用于3D3C-VSP观测系统的散射时距曲线方程,将地震道上各时刻的振幅分别搬至对应的反射面上,通过干涉叠加,抽取共成像点道集;然后,针对上、下行波射线路径不对称以及偏移速度不一致的情形,把共成像点道集中消除正常时差的上行波波场校正至具有双曲时差特性的虚拟炮检距道集中;最后,对虚拟炮检距道集进行精细速度分析、动校正和叠加,获得高精度的PP波与PS波成像剖面。该方法用于四川盆地A井3D3C-VSP地震数据的偏移,获得了优于常规VSP-CDP叠加的成像效果。Acquired by special recording geometry,3D3C(three-dimensional and three-component)VSP data can’t be processed by conventional processing methods for surface seismic data.In addition,there are less applicable 3D3C-VSP imaging technologies with high precision,and there is less processing software for 3D3C-VSP data.To process3D3C-VSP data,many iterations should be run for velocity analysis,and it is very difficult to get 3 D imaging results.In this paper,we propose a method for velocity analysis and migration for 3D3CVSP data.It is based on wave scattering theory and without iterating.First,we set up the timedistance curve equation of reflected wave in VSP data.Based on this equation,we move the amplitude at each time sample of the seismic trace to the corresponding reflective surface and extract the common-imaging-point gathers by interference stacking.Then,for the asymmetric ray-paths and inconsistent migration velocities of up-going and down-going waves,we convert the NMO corrected up-going waves in common-imaging-point gathers to virtual offset gathers with the characteristics of hyperbolic time difference.Eventually,through velocity analysis and NMO correction for the virtual offset gathers,we obtain high-precision PP and PS wave imaging profiles.This method was applied to the 3D3C-VSP seismic data of Well A in Sichuan Basin,and produced better imaging results than the conventional VSP-CDP stacking method.

关 键 词：3D3C-VSP 共成像点道集 虚拟炮检距 偏移 PS波 

分 类 号：P631[天文地球—地质矿产勘探]