复杂近地表区综合长波长静校正方法

An integrated long-wavelength static correction method for complex near-surface area

复杂近地表区长波长静校正问题一直是地震资料处理难点之一,其原因不是野外数据密度不够,就是方法假设条件不能满足。在复杂近地表情况下,精确求解风化层速度、厚度和高速层速度是严重的非线性问题。本文通过非线性问题线性化、模型参数替代方法解决长波长静校正问题。野外表层调查和地震数据中含有丰富长波长信息,解决长波长静校正问题应该综合考虑这两方面因素。本文在表层调查和初至折射波速度的共同约束下,建立初始速度场,利用层析静校正进行近地表速度场反演获得近地表模型,再运用初至波旅行时拟合迭代技术,在地震数据共炮点、共检波点和共炮检距道集上综合解决长波长静校正问题。中国西部黄土塬地区野外实际资料的应用结果表明,本文方法在复杂近地表条件下能够很好地解决长波长静校正问题。

Long-wavelength static corrections in complex near-surface area are always one of the difficulties in seismic data processing.A single statics method cannot presently obtain high-quality gathers because of data sparse coverage or/and unmet hypothesis.In complex near-surface terrains,to obtain accurate weathering velocity and thickness,and refraction velocity is severe nonlinear problem.In this paper,we propose an approach to solve long-wavelength static corrections by linearization of nonlinear problem and model replacement.Both LVL data and seismic data contain rich long-wavelength information,therefore two types of data should be comprehensively taken in account for solving the problem.We first build initial velocity field with the constrain of LVL data and first breaks,then obtain near-surface model by invert velocity with tomostatics,and finally use first break traveltime fitting on common shot gathers,common receiver gathers,and common offset gathers.Applications in complex near-surface area,western China show the validity of this integrated method.