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3D地震波走时计算是偏移、反偏移、层析等诸多地震勘探技术中的重要中间步骤。快速推进法计算3D地震波走时具有高效率、稳定性及适应能力强的特点,但快速推进法在震源附近区域的计算精度不高,降低了整个走时算法的计算精度。本文提出了一种联合3D走时计算方法来解决这一问题。该方法在震源附近小范围内使用计算精度较高的波前构建法计算走时,在剩余区域使用快速推进法计算走时,由于模型中绝大多数网格节点走时是通过快速推进法计算的,故新方法保留了快速推进法高效的特点,同时由于震源附近网格节点走时精度的提高,整个新算法的计算精度相对于快速推进法而言有了较大的改善。文中通过数值分析对上述结论进行了验证并使用三维岩丘模型验证了新方法的稳定性和适应能力。
3D seismic traveltime calculation is an important intermediate step in many seismic exploration techniques such as migration, de-migration, tomography and so on. The rapid propulsion method has the characteristics of high efficiency, stability and adaptability when calculating 3D seismic wave travel time. However, the fast propulsion method has low computational accuracy in the vicinity of the seismic source and reduces the calculation accuracy of the entire travel time algorithm. This paper presents a joint 3D travel time calculation method to solve this problem. The method uses the wave front construction method with high accuracy of calculation to calculate the travel time in a small area near the seismic source and the fast forward method to calculate the travel time in the remaining area. Because the travel time of most mesh nodes in the model is calculated by the fast propulsion method, The new method retains the characteristics of rapid propulsion method and the accuracy of the new algorithm has been greatly improved compared with the rapid propulsion method due to the improved accuracy of travel time of grid nodes around the source. In the paper, the above conclusions are verified by numerical analysis and the stability and adaptability of the new method are verified by using 3D mound model.