The seismic data of foothill areas is characterized by low S/N and large moveout between gathers; therefore,conventional imaging technical workflow is not effective. First of all, we gave a review of imaging methods in foothill areas and analyzed the characteristics of these methods. Then,it was concluded that beam-ray based method is the first choice for irregular and low S/N data, rugged surface area and anisotropic media. Thirdly,we summarized several ray theory based methods and give two prestack depth migration (PSDM) scheme from rugged topography,which are Kirchhoff PSDM based on 3D dynamic programming traveltime computation approach and Gaussian beam PSDM based on Gaussian Beam dynamic ray tracing. The traveltime computation method based on Fermat's principle has no limitation on large velocity contrast and can adapt anisotropic media, which has no problem for ray interpolation and shadow areas. The intrinsic character of Gaussian beam is propagate wave in ray-centered coordinate, which get a ray path by conventional ray tracing and calculate the energy attribution around the central ray by dynamic ray tracing. As a typical beam method, the Gaussian beam method balance the advantages of ray tracing algorithm and wave equation propagation methods. Numerical tests on synthetic data and real data shows that this technologies and schemes are quite effective.%以低信噪比和剧变的道间时差为特征的山前带地震数据使得常规成像技术流程在该类探区不再有效.回顾了针对山前带地震数据处理的主要成像方法,分析了主流山前带成像方法的特点,指出基于射线(束)理论的成像方法在适应不规则数据体、低信噪比、各向异性介质及非水平地表等方面有很好的优势,是山前带地震数据成像方法的首选.总结了基于射线理论的典型成像方法,给出了作为山前带速度分析主要工具的非水平地表Kirchhoff积分叠前深度偏移(PSDM)和非水平地表高斯束PSDM的实现方案.将三维动态规划旅行时计算发展到适应非水平地表各向异性介质情况,进一步完善了山前带成像方法流程.理论模型和实际资料测试结果证明,山前带地震数据射线(束)叠前成像方法在处理低信噪比数据上有很大的优势,考虑各向异性后进一步提高了成像精度.
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