起伏地表条件下的合成平面波偏移及其并行实现  

Synthetic plane wave migration in relief surface condition and implementation in parallel way

作　　者：叶月明[1] 李振春[1] 仝兆岐[1] 安琪[1] 

机构地区：[1]中国石油大学(华东)地球资源与信息学院

出　　处：《石油地球物理勘探》2007年第6期622-628,共7页Oil Geophysical Prospecting

基　　金：国家自然科学基金(40474011);国家863专题(2006AA06Z206);CNPC中青年创新基金(04E7040);中原油田;江苏油田博士后科研工作站和CNPC物探重点实验室中国石油大学(华东)研究室等的资助

摘　　要：基于波动方程的延拓方法保持了波场的动力学和运动学特征,能很好地克服时移静校正法(使波场产生畸变)的不足,消除地表起伏的影响,将非水平观测界面记录改造为水平观测界面(新基准面)记录。在重建的水平基准面上进行平面波源和平面波源记录的合成,可克服以往由于地形起伏而无法进行平面波源和平面波源记录合成的问题,完成起伏地表条件下的平面波偏移。为了进一步提高运算效率,可按照将平面波的不同入射角、不同频率范围分配到各个节点的原则,进行MPI并行计算,可成倍地提高计算效率。具体步骤如下:①将共炮集数据延拓至最低起伏面以下的新基准面;②从延拓后的共炮集数据中抽出共接收点道集;③将共接收点道集延拓至最低起伏面以下的新基准面;④从延拓至新基准面的接收点道集中抽出共炮集数据。上述整个过程相当于将观测系统下移至新的基准面。模型试算及实际资料处理结果表明,基准面重建后的并行平面波深度偏移结果与基于原始炮记录应用波场直接下延法得到的深度偏移数据的效果相当,但是前者的计算效率随着应用节点数的增多而成倍地提高。Wave equation-based continuation approach keeps the feature of dynamics and kinematics of wavefield,can better overcome the shortcomings of time-shift static correction approach that distorts wavefield and eliminate the influence of relief surface,and reforms records in non-horizontal surveying interface to that in horizontal surveying interface (new datum).Synthesis of plane wave source and its records in reconstructive horizontal datum can overcome the issues that is incapable to synthesize the plane wave source and its records because of relief geomorphology,finishing plane wave migration in relief surface condition.In order to further improve operation efficiency,and according to the principle distributing the plane waves in different incident angles and frequency range to separate nodes,the MPI parallel computation was implemented,which doubled and redoubled the computational efficiency.The concrete steps are as follows: continuing the CSP gathers to new datum that is below the lowest relief plane; ②sorting CRP gathers from continued CSP gathers data; ③continuing the CRP gathers to new datum that is below the lowest relief plane; ④sorting CSP gathers from CRP gathers continued to new datum.The total abovementioned process corresponds to downshift the geometry to new datum.The results of model tests and practical data processing showed that the results of parallel plane wave depth migration after reconstruction of datum are same as that of depth migration data by directly down-continuing wavefield based on raw shot records,but the former computational efficiency doubled and redoubled along with increasing the number of applied nodes.

关 键 词：起伏地表 叠前深度偏移 基准面重建 平面波偏移 合成炮记录 MPI并行 

分 类 号：P631.443[天文地球—地质矿产勘探]