山前带地震勘探策略与成像处理方法  

Seismic exploration strategy and image processing in mountain areas

作　　者：王华忠[1] 刘少勇[1] 杨勤勇[2] 方伍宝[2] 徐兆涛[2] 蔡杰雄[1,2] 张兵[1,2] 

机构地区：[1]同济大学海洋与地球科学学院波现象与反演成像研究组,上海200092 [2]中国石化物探技术研究院,江苏南京211103

出　　处：《石油地球物理勘探》2013年第1期151-159,1,共9页Oil Geophysical Prospecting

基　　金："973"项目(2006CB202402);国家科技重大专项项目(2011ZX05005-005-008HZ)联合资助

摘　　要：山前带地震资料信噪比低和道间时差剧变是引起此类地区成像困难的主要原因。本文从宏观速度估计的角度,分析了山前带勘探中野外数据采集、资料低信噪比和道间时差剧变等因素与后续成像处理的关系,认为速度建模是山前带成像处理的关键问题,山前带地震数据采集要以有利于近地表浅层速度建模和中深层宏观速度估计为目标。为此,本文提出了一套以宏观速度建模为核心的成像处理流程。在该流程中首先利用基于叠前深度偏移(PSDM)的扫描速度分析方法得到初始宏观速度场;再利用非水平地表射线束PSDM技术高效生成深度域成像道集;最后进行角度道集层析速度估计,为射线束PSDM提供更精细速度模型。压噪和消除道间时差是该流程的两个关键环节。本文强调尽可能用同相叠加方法压制噪声,通过选取合适成像基准面以消除或减弱高波数道间时差对叠前成像的影响;中低波数道间时差由后续速度分析及成像消除,将静校正问题置于速度建模过程中加以解决。理论模型和实际资料成像结果验证了本文思路的正确性及方法的有效性。The main challenges of pre-stack seismic data imaging in mountain areas are move-out differences among traces and low signal to noise ratio(SNR).Based on velocity estimation,this paper analyzes imaging problems with data acquisition,data low SNR and move-out differences in mountain areas.We find out that building an appropriate velocity model is the key of data imaging in mountain areas.A good velocity model is dependent on seismic data quality and seismic processing working flow.The acquisition geometry design should be benefit of velocity model building for shallow,middle and deep layers.An effective seismic data imaging procedure is presented on velocity estimation in mountain areas.Firstly,scanning velocity analysis is carried out to obtain an initial velocity model.Then,common image point gathers(CIGs)is generated by Beam-Ray Kirchhoff PSDM.Finally,the velocity model is iteratively updated by velocity tomography based on CIGs until obtain a satisfied velocity model.Noise suppression and move-out deduction among traces are also very important.We achieve these two tasks by in-phase stacking and suitable imaging datum choosing to remove high wave number move-out.The low wave number move-out will be deducted during PSDM procedure.In other words,the traditional statics is replaced by PSDM and migration velocity analysis(MVA).Both synthetic and field data examples demonstrate that the procedure is quite effective.

关 键 词：山前带 地震勘探 低信噪比 速度估计 复杂地表 叠前深度偏移 

分 类 号：P631[天文地球—地质矿产勘探]