摘要
在速度横向剧烈变化且地质断层的断距甚大的复杂地球介质中要完成反射地震波的正确偏移成象,常规的时间偏移是无能为力的,这时,采用深度偏移方法。但是,已有的深度偏移技术对此特殊地质条件也不能得出满意的结果。本文使用高阶方程深度偏移方法,并且在计算中采用了一种与差分运算等价的时移法解决了计算中出现的频散和振幅失真问题。采用高阶方程是为了解决陡倾角地层的正确偏移复位,而折射效应的校正采用了时移法,从而解决了波形畸变和地震波能量损失问题。试验结果表明,本方法可以解决速度比值达2倍的横向突变和断距3km的断层、地层倾斜高达60°的复杂地质体的正确成象问题。
The image reconstruction of complex geological structures using the seismic reflection data can＇t be carrid out by conventional time migration when the velocity is severely varied laterally and the big fault exists in the earth media. In this case, the depth migration must be used. But the existing depth migration techniques don＇t adapt to special geological conditions. The depth migration with higher-order approximation by time-shift algorithm eliminates the frequency dispersion and amplitude distortion in the calculation process. Image of the dip structure is based on the higher-order equation, and the correction of the refraction effect depends on the time shift algorithm. As a result, the problems of waveform distortion and energy loss presented in other depth migration methods have been solved. The tests demonstrate that our method can be used to image complex geological structures correctly with the lateral velocity variation ratio in two times, big fault with 3km throw and 60 degrees dip layer.
出处
《同济大学学报（自然科学版）》
EI
CAS
CSCD
1992年第4期361-369,共9页
Journal of Tongji University:Natural Science
基金
国家自然科学基金会资助课题
关键词
深度
偏移
高阶方程
时移法
地震波
Depth migration
Higher-order approximation
Time-shift algorithm
Refraction correction
