二维Offset平面波有限差分法叠前时间偏移  

Finite-difference pre-stack time migration of 2D offset plane wave

作　　者：王华忠[1] 冯波[1] 任浩然[1] 

机构地区：[1]同济大学海洋与地球科学学院海洋地质国家重点实验室,上海200092

出　　处：《石油物探》2009年第1期11-19,共9页Geophysical Prospecting For Petroleum

基　　金：国家高技术研究发展计划(863)项目(2006AA092323);国家重点基础研究发展计划(973)项目(2006CB202402)共同资助;胜利油田物探研究院和中国石化集团公司科技部的资助

摘　　要：在岩性油气藏勘探中,保振幅或保波形成像是进行储层特征分析和参数估计的基础。由于Kirchhoff积分叠前时间偏移、F-K域波动方程叠前时间偏移不适应弱横向变速介质情形,因此,基于偏移距(Offset)域平面波偏移思想,提出了Offset平面波有限差分法叠前时间偏移方法。讨论了CMP道集平面波分解原理,推导了Off- set平面波方程及其有限差分解法,给出了角度道集生成方法。利用大庆油田的一个横向缓变的速度模型,对Offset平面波有限差分法叠前时间偏移方法的有效性进行了验证。结果表明,该方法适应缓横向变速介质情形,波场外推算子保幅,计算效率高,可以为AVP/AVA分析提供较好的基础数据。Amplitude-preserving or waveform-preserving imaging results are the basis for reservoir characterizing and parameter estimating in lithologic reservoir exploration.Kirchhoff integral pre-staek time migration and F-K domain wave equation pre-stack time migration is not suitable for the medium with gradual transverse change in ve- locity.Therefore,an offset plane wave finite-difference pre-staek time migration method was proposed.The CMP gather plane wave decomposition was discussed.Offset plane wave equation was de- rived and its finite-difference solution was given.Then,an ap- proach for generating angle imaging gather is deduced.A velocity model with gradual transverse change from Daqing oilfield was used to verify the fidelity of the method.The results show that the method is suitable for the medium with gradual transverse change in velocity,can preserve amplitude of field extrapolation operator and provide better basic data for sequent AVP/AVA analysis.

关 键 词：Offset平面波 有限差分偏移 叠前时间偏移 横向缓变介质 

分 类 号：P631.4[天文地球—地质矿产勘探]