共反射角叠前偏移成像研究及应用

共偏移距道集已被广泛地应用于地震速度建模及振幅随偏移距变化(AVO)的研究中,但复杂构造及射线多路径产生的共偏移距道集不保幅性等一系列缺陷给AVO研究带来很大的困难.共反射角道集包含有能反映地下速度和岩性变化的信息,更有利于速度模型优化、地震振幅属性分析及地下岩性和断裂的研究.本文通过研究共反射角深度偏移方法和理论,完善了基于目标的共反射角深度偏移技术,提出了获得相对保幅共反射角道集方法.该方法克服了共偏移距域道集在复杂介质中遇到的困难,更能有效地反映波场和地质结构方面的信息.通过理论模型数据进行了试算,并采用实际地震数据对此方法进行了验证,在陡倾角成像方面取得较好效果.

Research and application of common reflection angle domain pre-stack migration

Because there are multi-paths during the process of seismic wave propagation in complex media, the common offset gather will bring on the problem that the location of underground reflector can not be given accurately. The common reflection angle gather(CRA) can solve the problem, it is the main method of imaging accurately, AVA analysis and amplitude preserving migration imaging in complex area. Especially in complex structural area with wide reflection angles, even with multiple wave arrivals, the amplitude and phase of reflection event can be effectively preserved. This article is based on the common reflection angle migration of object body, to research how to get common reflection angle gather, calculate traveling time, geometric diffusion factor and the impact of migration stretching on CRA gather. We have calculated with theoretical models, at the same time validated the method with 2D real data, and achieved good effect in the steep dip imaging. We think that the CRA gather in angle domains is better for optimizing velocity model and doing AVA analysis, it can be a new direction of pre-stacked inversion and lithologic prediction in future.