井间地震有限角度叠加方法研究与应用
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摘要
在胜利油田垦71区块的井间地震资料采集中,所采用的压电晶体可控震源的能量辐射主要集中在水平方向,导致井间地震反射波中既有小于临界角的正常反射,也存在超过临界角的广角反射。为了消除这些广角反射对上行反射波成像结果的影响,本文利用VSP-CDP方法对上行反射波进行Z-T域到Z-X域的映射,在CDP道集内按照入射角度抽取形成CDP角度道集,再依据Snell定律计算临界角大小。最后参考实际资料的角度道集,最终确定叠加成像角度范围,此区最大临界角为70°。因此本文方法可克服广角反射对成像的影响。
In cross-hole seismic data acquisition on Ken-71 block of Shengli Oilfield, the radiation energy of piezocrystal used for vibroseis mainly concentrated into horizontal direction, leading seismic reflections to have both normal reflections less than critical angle and wide-angle reflections greater than critical angle. In order to remove the influence of these wide-angle reflections on imaging of up-going reflections, the paper uses VSP-CDP approach to map the reflections from Z-T domain to Z-X domain; then sorts and forms CDP angle gathers according to incident angles on CDP gathers; and again computes the size of critical angle based on Snell law; finally, defines the angle range of stack imaging by reference to angle gathers of real data. The maximum critical angle in the region is 70°. The approach presented in the paper can overcome the influence of wide-angle reflections on imaging.
In cross-hole seismic data acquisition on Ken-71 block of Shengli Oilfield, the radiation energy of piezocrystal used for vibroseis mainly concentrated into horizontal direction, leading seismic reflections to have both normal reflections less than critical angle and wide-angle reflections greater than critical angle. In order to remove the influence of these wide-angle reflections on imaging of up-going reflections, the paper uses VSP-CDP approach to map the reflections from Z-T domain to Z-X domain; then sorts and forms CDP angle gathers according to incident angles on CDP gathers; and again computes the size of critical angle based on Snell law; finally, defines the angle range of stack imaging by reference to angle gathers of real data. The maximum critical angle in the region is 70°. The approach presented in the paper can overcome the influence of wide-angle reflections on imaging.
引文
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[7]陆基孟.地震勘探原理.山东东营:石油大学出版社,1993
[2]陈世军等.井间地震技术在樊124井区的应用.石油物探,2003,42(3):369~373
[3]曹辉等.井间地震反射波场分离及应用研究.石油物探,2004,43(6):518~522
[4]郭全仕等.井间地震反射波成像技术探讨.石油物探,2005,44(5):439~444
[5]左建军等.波动方程法井间地震成像.勘探地球物理进展,2005,28(3):212~214
[6]李庆忠.井间地震勘探的误区及出路.石油地球物理勘探,2004,39(1):1~11
[7]陆基孟.地震勘探原理.山东东营:石油大学出版社,1993
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