三维地震资料叠前时间偏移应用研究

Application of prestack time migration for three dimensional seismic data

本文通过选取合适的叠前时间偏移软件,对两块三维地震资料进行偏移成像试验,验证叠前时间偏移中影响偏移成像效果的几个主要因素.该软件偏移算法的核心技术是弯曲射线偏移处理,这不同于工业界常用的直射线假设.偏移速度是偏移成像好坏的主要因素,通过迭代进行偏移、速度分析,使共成像点道集拉平,从而实现构造的准确成像;偏移孔径也是影响偏移成像的一个关键参数,其选取与成像目标层的倾斜角、深度、速度等有关;反假频参数对偏移成像效果有一定影响,是偏移中需要考虑的因素之一.

By using a suitable prestack time migration application software, two 3D seismic data set from the different area were migrated to show the parameter effects on the imaging quality. The key technology of this prestack time Kirchhoff migration is ray-bending travel-time calculation. Obtaining an accurate migration velocity model is fundamental to successfully do PSTM. By iterating for the ray-bending migration and velocity analysis, all reflection events are made as flat as possible. Migration aperture is another key factor for PSTM imaging. It＇s related to the structure＇ s dip, depth and velocity. Parameter of anti-aliasing filter has some effects for the migration section, thus it＇s one of the factors we should pay attention to.