声波各向异性时间域高斯束叠前深度偏移

作为一种改进的射线类偏移方法，高斯束偏移不仅具备射线类偏移灵活、高效的特性，而且还拥有接近波动类偏移的成像精度。与传统频率域高斯束偏移相比，时间域高斯束偏移通过调整成像公式，把频率域积分转换为成像时刻的函数，提升了计算效率。随着地震采集方位角的变宽和观测排列的加长，各向异性对地震偏移成像的影响变得不容忽略。文中将基于相速度的各向异性射线追踪算法应用于时间域高斯束偏移，并对动力学射线追踪相关系数进行优化，形成一种更高效的各向异性声波时间域高斯束偏移方法。模型试算表明，相比于其他各向异性算法，在保证成像精度前提下，所提方法具有更高计算效率和更强适用性，尤其适用于各向异性复杂构造成像。

Time-domain Gaussian beam prestack depth migration for acoustic anisotropic media

As an improved ray migration method,Gaussian beam migration not only inherits the efficiency and flexibility of ray methods,but also has the imaging accuracy close to wave equation migration methods. Compared with traditional Gaussian beam migration in frequency domain,the method in time domain greatly improves computational efficiency by adjusting the imaging formula and converting frequency integral into the function of imaging time. As seismic azimuth becomes larger and recording spread becomes longer,the influence of anisotropy on seismic migration can't be ignored any longer. This paper introduces the anisotropic ray tracing algorithm based on phase velocity to time-domain Gaussian beam migration and optimizes the dynamic ray tracing correlation coefficient,and finally proposes a more efficient method for acoustic anisotropic media. Model tests have demonstrated that the method proposed has higher computational efficiency and better applicability while maintaining higher imaging accuracy than similar anisotropic algorithms,especially it can be used for imaging complex anisotropic structures.