An efficient computer program for wavefront calculation by the finite-difference method

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• 作者：Ping ; Zhao
• 关键词：Eikonal solution ; Finite-difference method ; Fermat's principle ; Huygens' principle ; Ray tracing ; FORTRAN
• 刊名：Computers and Geosciences
• 出版年：1996
• 出版时间：April, 1996
• 年：1996
• 卷：22
• 期：3
• 页码：239-251
• 全文大小：571 K

文摘

Traveltime calculation by the finite-difference method offers a powerful tool for numerical modeling, Kirchhoff migration and VSP or crosshole tomography. This technique shows a significant advantage in first traveltime calculations as compared with ray tracing when concerned with shadow zones, high contrasts in velocity, and sharp boundaries. It eliminates the inconvenience in complicated model construction faced by ray tracing. In this paper, a FORTRAN 77 computer program is presented for wavefront propagation by the finite-difference method. It is based on the idea of Eikonal solution, Fermat's principle, Huygens' principle, and the curved wavefront assumption. This computer program successfully handles arbitrarily changing velocity, high velocity contrasts, sharp boundaries, and arbitrary survey layouts. Four examples are given (high velocity gradients in the horizontal and vertical, high velocity contrasts, and high velocity boundaries where head waves are created). The results show that the computer code is accurate in traveltime calculation, stable with model varieties, efficient in computer time consumption, and friendly to use.