双复杂条件下非倾斜叠加精确束偏移方法及应用Ⅰ——声波方程  

The accurate beam migration method without slant stack under dual-complexity conditions and its application(Ⅰ):Acoustic equation

作　　者：黄建平[1] 袁茂林 李振春[1] 岳玉波 

机构地区：[1]中国石油大学(华东)地球科学与技术学院地球物理系,青岛266555 [2]中石油东方地球物理公司物探技术研究中心,河北涿州072750

出　　处：《地球物理学报》2015年第1期267-276,共10页Chinese Journal of Geophysics

基　　金：国家重点基础研究发展计划(973计划)项目(2014CB239006;2011CB202402);国家自然科学基金(41104069;41274124);山东省自然科学基金(ZR2011DQ016);中央高校基本科研业务费专项基金(R1401005A;R1401038A);骨干教师人才支持计划联合资助

摘　　要：近年来,油气勘探的重心正转向具有复杂地表和复杂地质体的双复杂区域.本文发展了一种精确的双复杂条件下基于地表倾角信息的非倾斜叠加束偏移方法,相对于传统束成像方法无需进行三方面处理:(1)高程静校正;(2)相位校正;(3)束中心与接收点之间关于速度和束出射角的近似替换,因而具有更高的成像精度.通过加拿大逆掩断层模型、中原油田断层模型及实际资料的偏移试算,并与传统束偏移及波动方程偏移成像结果对比可知:本文非近似束偏移方法在近地表、高陡倾等构造处的成像精度、反射界面成像振幅等方面优于传统的偏移方法,以此验证了本文非倾斜叠加精确束偏移方法的正确性、优越性及适应性.Recent trends in seismic exploration have transferred to lands where both topography and subsurface targets are complex,leading to challenges for both acquisition and processing methods.Compared with one-way or two-way wave-equation migration,ray-based migration is an efficient and flexible method,especially for complex topography.In general,Gaussian beam migration（GBM）is more accurate than single-arrival Kirchhoff migration,although there are some issues resulting in dissatisfactory GBM images.For example,static correction will lead to the distortion of wavefields when near-surface elevation and velocity vary drastically.Worse still,unbalanced amplitude will emerge in migrated images when receivers are not placed within some neighborhood of the beam center,that is,GBM is slightly inflexible for the irregular acquisitionsystem.For the irregular surface,both near-surface velocity and takeoff angle of an individual beam at the beam center are different from those at each receiver,so GBM usually produces nonignorable migration artifacts.In order to improve the flexibility and accuracy of GBM,we propose an accurate beam migration method without slant stack based on acoustic wave equation.An accurate acoustic beam migration algorithm based on surface dip angle information for complex topography is presented.Unlike the conventional GBM migration method,the proposed method shoots beams directly from receivers without elevation static correction,phase correction,as well as approximate velocity and takeoff angle of an individual beam.Based on acoustic wave equation,we first derive the acoustic backward-continued wavefields from receivers by using surface dip angle information and then derive the acoustic beam migration formula by using the deconvolution imaging condition.Finally,we use a real data and two synthetic datasets separately from the 2D Canadian Foothills model and the Zhongyuan oilfield fault model to verify the proposed algorithm.In the example of 2D Canadian Foothills model,our method suppresses the near-

关 键 词：双复杂 倾角信息 非倾斜叠加 束偏移 波动方程偏移 

分 类 号：P631[天文地球—地质矿产勘探]