基于近地表相分析的全局约束近地表建模方法

Global constrained near-surface modeling based on a near-surface seismic facies analysis

针对复杂地表地区近地表地质、地球物理条件变化剧烈、结构复杂等特点,提出近地表相和近地表相分析的概念和理论方法,在完成近地表相分析的基础上,充分利用可控震源地震采集、近地表调查等所得到的多种地学数据,进行了近地表黏弹性参数反演并提出了拟微测井的概念,进而建立了高精度的极浅近地表层模型,最后结合地震波初至层析反演实现了各种地学数据及多种近地表建模方法之间宏观与微观的全局约束,建立了具有明确地质、地球物理意义的近地表模型。微测井和VSP数据标定结果表明:该模型精度较高,实际资料处理应用中较好地解决了中长波长静校正问题。该方法代表了目前近地表模型研究的一个方向,为复杂地表地区近地表建模提供了一种新的思路与方法。

The concept and relevant analysis methods of near-surface seismic facies are proposed to solve the problems of near-surface modeling under complicated surface conditions in areas with radical changes in near-surface geologic and geophysical conditions and complexity in geological structures.Based on a near-surface seismic facies analysis,various data from vibroseis-based seismic acquisition and from near-surface survey are used to perform near-surface viscoelastic parameter inversion.Moreover,a concept of pseudo-microlog is presented and an extremely shallow near-surface layer model with high resolution is built.In combination with tomographic inversion of the first arrival signals,macroscopic and microscopic global constraint is achieved between various subsurface data and diverse near-surface modeling methods,and near-surface models are successfully build with definite geologic and geophysical meanings.Calibration results of microlog and VSP data show that these built models have relatively high resolution and can solve the problem of static correction of medium-to long-wavelength.This study provides a new idea and a methodology for near-surface modeling under complicated surface conditions.