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深度偏移方程
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  “45°深度偏移方程”译为未确定词的双语例句
     Starting from the 45° depth migration cquation, we introduce a parameter called Mirectional derivativeu and incorporate tht refraction effect term caused by lateral velocity variation into the directional derivative so as to make the depth migration be formally consistent with the corresponding time migration.
     作者从45°深度偏移方程出发,引出方向导数,并将速度横向变化所引起的折射效应项纳入此方向导数内,使所构造的深度偏移方法在形式上与相应的时间偏移方法一致。
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  相似匹配句对
     Directional derivative method for 45°acoustic equation poststack depth migration
     45°方程叠后深度偏移的方向导数法
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     Wave Equation Plane-wave Depth Migration
     波动方程平面波深度偏移
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     Implementation of 45° difference migration
     45°差分偏移的实现
短句来源
     A new algorithm for stolt 45°up-going wave equation migration
     Stolt 45°上行波方程偏移的一种新算法
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     Pseudospectral wave equation depth migration.
     虚谱法波动方程深度偏移
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By Fourier transform, scalar wave equation, can be transformed into single square root equation, which is a basic equation for post-stack migration. The radical expression in the equation may be approximated in different ways; consequently, there are different migration methods. The finite difference depth migration equation in space-frequency domain can be derived when the radical expression is approximated by continued fraction. In practice, this equation is solved by split- ting into two ones (called thin...

By Fourier transform, scalar wave equation, can be transformed into single square root equation, which is a basic equation for post-stack migration. The radical expression in the equation may be approximated in different ways; consequently, there are different migration methods. The finite difference depth migration equation in space-frequency domain can be derived when the radical expression is approximated by continued fraction. In practice, this equation is solved by split- ting into two ones (called thin lens and diffraction term equations), which are solved alternately. Crank-Nicolson scheme is used in secondorder difference so that both the high accuracy and the stability of wave field extrapolation can be ensured. Furthermore, "one sixth knack" of approximation is taken for higher accuracy. In summary, this migration process is composed of the following steps: first, by Fourier transform, a seismic section is transformed from time domain to frequency domain; then, for each frequency, the wave field is extrapolated from known depth Z to unknown depth Z+△Z by making use of the thin lens term equation and the diffraction term equation; finally, the component extrapolated results for all frequencies are summed up to form a resultant migration result at depth Z+△Z. summation process is also migration image process. Two theoretical models illustrated in the paper all bring good migration result.

从标量波动方程出发,利用傅里叶变换,可导出单均方根方程(single radical equation),它是叠后偏移的基础方程。此方程中的根式可采用不同的近似方法,因而有不同的偏移方法。采用连分式近似,可以得到空间频率域的有限差分深度偏移方程。在具体实现时应用分裂算法,即分裂成薄透镜项及绕射项,然后进行差分运算。对于二阶差分,采用了Crank-Nicolson差分格式,这不仅保证较高的计算精度,而且保证在波场外推过程中的稳定性。为了得到更高的计算精度,还采用了一种叫做1/6的近似技巧。上述的这种偏移方法过程可以归结为:首先对地震剖面作傅里叶变换,由时间域转换到频率域,然后对每一固定频率,利用薄透镜项和绕射项偏移方程进行外推,即把已知深度Z的波场外推到未知深度Z+ΔZ的波场,最后把Z+ΔZ处所有频率成分外推的结果累加求和,得到最终的偏移结果。累加的过程,即是偏移成像的过程。文中给出两个理论模型的例子,都能得到较好的偏移结果。

Without taking aceount of the lateral variation of velocities, time migration may cause stratigraphie images to deviate from their correct underground positions. Starting from the 45° depth migration cquation, we introduce a parameter called Mirectional derivativeu and incorporate tht refraction effect term caused by lateral velocity variation into the directional derivative so as to make the depth migration be formally consistent with the corresponding time migration. In this way,depth migration is achicvable...

Without taking aceount of the lateral variation of velocities, time migration may cause stratigraphie images to deviate from their correct underground positions. Starting from the 45° depth migration cquation, we introduce a parameter called Mirectional derivativeu and incorporate tht refraction effect term caused by lateral velocity variation into the directional derivative so as to make the depth migration be formally consistent with the corresponding time migration. In this way,depth migration is achicvable with the current application module after a slight modification,i. e. increasing the part of non-integer nodes for interpolation. The efficiency in both computation and programming is thus improved. The results frorn numerical trial show that this method is reliable and effective.

时间偏移由于忽略了速度的横向变化而导致成像偏离正确位置。作者从45°深度偏移方程出发,引出方向导数,并将速度横向变化所引起的折射效应项纳入此方向导数内,使所构造的深度偏移方法在形式上与相应的时间偏移方法一致。因此,只需对目前生产中应用的时间偏移模块略作修改,即增加非整数节点插值部分,就可实现深度偏移。这样不仅节省了计算工作量,提高了计算效率,而且也缩短了编程的时间。数值试验结果表明,方法是可靠有效的。

In this paper the fast-speed migration methods of 3-D structure are studied. These methods are available for the cases that the propagation velocity in the media is laterally variable and the angle that the reflecting interfase makes with the horizontal is less than 30 degrees. We derived 30 degrees depth migration equation and proposed some numerical methods solving this class of migration equation. They are direct and explicit method, factorization method and splitting-factorization method. Furthermore, the...

In this paper the fast-speed migration methods of 3-D structure are studied. These methods are available for the cases that the propagation velocity in the media is laterally variable and the angle that the reflecting interfase makes with the horizontal is less than 30 degrees. We derived 30 degrees depth migration equation and proposed some numerical methods solving this class of migration equation. They are direct and explicit method, factorization method and splitting-factorization method. Furthermore, the factorization method for me frequency-space domain is discussed. The later is very available for parallel algorithm of 3-D migration. In comparison with some other methods, the methods presented in this paper possess higher difference accuracy and reductive computational efforts. The method is tested with impulse response. Both the numerical results and the theoretical analyses show the effectiveness of the methods.

研究了地下反射界面倾角不超过30°,具有横向速度变化的三维构造的深度偏移问题.文中导出了30°倾角深度偏移方程,提出了在时间-空间域中求解这种偏移方程的直接显式方法、因式分解方法及分裂-分解方法,并讨论了频率-空间域中的因式分解方法,后者适合于三维偏移的并行计算.对于三维深度偏移而言,以上方法具有差分精度高、计算工作量较少的优点.

 
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