川东北复杂山地三维静校正应用及实例分析

A statics solution in CBD hilly areas

川东北复杂山地由于地表高程变化大、风化层厚度不均匀、低降速带速度横向变化大、高速层底界不稳定等因素,得到的地震资料具有严重的静校正问题,因此,如何解决山地静校正问题是后续地震资料处理的关键之一,本文首先分析高程静校正、折射静校正、层析静校正的基本原理和适用条件,结合实际复杂山地三维地震资料的特点,进行试验对比,提出了进行山地静校正的基本思路,即:首先进行高程静校正,这样可以利用高程静校正更容易拾取初至时间,然后利用折射静校正结合微测井等资料建立近地表速度-深度模型,以此速度-深度模型作为层析静校正的初始模型进行迭代处理,最后得到最终的近地表速度-深度模型和静校正值.根据以上处理流程,我们建立了适合于川东北山地三维复杂地表地震资料的静校处理正方法,并在实际生产过程中取得了良好的效果.

Because of sharp variations in elevation,weathering layer thickness and the near-surface velocity in CDB hilly areas,seismic imaging always suffers from great statics problems.We first analyze the theories and conditions of some typical solutions,such as the elevation static correction,refraction static correction,and tomography static correction.Comparing different resuhs of CDB data,a new flow of static correction in mountain areas is proposed.As the first step,elevation statics correction is applied;and the first-breaks on the elevation-corrected shots are picked interactively.The original velocity-depth model for tomography is established by means of refraction static correction.The optimum velocity-depth model and static correction are achieved sucessfully.