摘要
程玖兵 ,王华忠 ,于富文 ,马在田 .波动方程共炮检距道集叠前深度偏移 .石油地球物理勘探 ,2 0 0 1,36 (5 ) :5 2 6～ 5 32 目前所用的几种波场外推算法 (分步傅里叶、傅里叶有限差分、广义屏和频率—空间域有限差分 )可以在共炮道集上获得较好的成像效果。在上述算法中 ,共炮道集为了兼顾各种波传播角 ,每炮偏移都要考虑相当多的边道 ,并且炮点和检波点要分别向下外推 ,因而计算量很大。针对上述问题 ,本文提出了基于双平方根算子的波动方程共炮检距道集的深度偏移方法 ,它适用于二维和三维叠前深度成像 ,其步骤为 :1在高频假设条件下 ,把共炮检距道集波场延拓公式中的积分运算进行稳相近似 ,得到波场延拓的相移公式 ;2把速度场分裂为层内常速背景和变速扰动 ,可求得整个均匀层波场深度延拓的偏移时移量、各层的偏移时移量及振幅校正系数 ,进而可得到最终波场延拓值。脉冲响应测试和理论模型试算表明 ,该方法具有较高的计算效率和成像精度 。
Several common used wavefield extrapolating method up to now(such as split step Fourier method,Fourier finite difference method,generalized screen method and finite difference method in frequency space domain) can obtain a good imaging result in common shot gathers,but in order to take account of transmitting angle of different waves,quite a number of side traces need to be added when making migration for each shot,and shot points and receiver points need to be extrapolated downward separately,so there are considerable amount of computation.Aimed at above problems,the paper presented a wave equation pre stack depth migration for common offset gathers based on double square roots operator which can be used for 2 D and 3 D wave equation pre stack depth imaging,the steps are:①the phase shift formulae for wave field continuation can be obtained by stationary phase approach forintegration of wave field continuation on common offset gathers in a condition of high frequency hypothesis;②time shift quantity of migration for wave field depth continuation in total uniform bed,time shift quantity of migration in each bed and amplitude correction factor can be calculated by splitting velocity field into constant velocity background and variable velocity disturbance and then final wave field continuation value can be obtained. Pulse response test and theoretic model migration test show that the migration method has a higher computational efficiency and better imaging quality and suitable for imaging of complex geologic body.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2001年第5期526-532,共7页
Oil Geophysical Prospecting
基金
国家自然科学基金资助项目 (代号 :4 9894 1 90 -2 4 )
关键词
波动方程
叠前深度偏移
共炮检距道集
双平方根算子
稳相近似
地震勘探
wave equation,pre stack depth migration,common offset gather,double square root operator,stationary phase approach
