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基于扰动理论的混合域波动方程波场外推算子,具有一定介质横向速度变化适应能力,是反射地震学中研究较多的成像方法。此类波场外推算子沿深度层进行波场外推,都存在参考速度选择问题。单参考速度波场外推算子,适应地下介质弱横向变速,而多参考速度波场外推算子可以提高横向变速的适应能力和成像精度,但要以大量计算为代价。本文提出的自适应多参考速度选择策略,根据外推层地质构造的复杂度和给定的速度门槛值自动选择参考速度个数,利用该策略构造混合域SSF、FFD、WXFD和GSP等多参考速度波场外推成像算法。盐丘模型理论数据测试结果表明,自适应多参考速度波场外推算法具有强横向变速适应能力和较高成像精度。
Based on the perturbation theory, the wavefield extrapolation operator of the mixed-domain wave equation has some adaptability to lateral velocity variation of medium, and is an imaging method that has been widely studied in reflection seismology. Such wave field extrapolation operator wave field extrapolation along the depth layer, there is a reference speed selection problem. The single-reference velocity wavefield extrapolation operator can adapt to the weak lateral velocity change of underground medium, while the extra-reference velocity wavefield extrapolation operator can improve the adaptability and imaging precision of lateral velocity transformation, but at the expense of a large number of calculations. In this paper, adaptive multi-reference speed selection strategy is proposed. According to the complexity of geophysical structure of extrapolation layer and the given speed threshold, the number of reference speed is automatically selected. By using this strategy, multiple references such as SSF, FFD, WXFD and GSP are constructed. Speed wavefield extrapolation imaging algorithm. Salt dome model theoretical data test results show that the adaptive multi-reference velocity wavefield extrapolation algorithm has the ability of strong transverse speed adaptation and high imaging accuracy.