【作者】 李可恩；

【导师】 贺振华； 黄德济；

【作者基本信息】 成都理工大学 ， 应用地球物理， 2007， 硕士

【摘要】 高速层与围岩之间波阻抗差异大，反射系数也大，形成强反射界面，若采用常规的勘探方法，纵波向下入射遇到高速层时，临界角比较小，很小的入射角就产生全反射，地震波难以透射下去达到勘探所要求达到的目的层，所以高速层会对下传的地震波的能量产生_定的屏蔽作用。而且透射不下去的那部分能量会产生了各种干扰波，使得折射波及多次反射波的能量特别强。本文根据Snell定理和Zoeppritz方程，通过射线追踪进行正演模拟，对含高速屏蔽层地区的地震数据采集工作做了一定的研究。首先，在不同地层参数条件下，较为系统的分析了P波和SV波反射透射系数随入射角变化的规律。从而得出可针对高速层反射透射的特点，相应对其采集方法和采集技术进行改进。其次，对广角纵波反射勘探作了一定的研究，当地下存在高速层时，采用长排列接收到广角反射波时可以获得较强的能量。但长排列时若用常规的动校正方法就不能满足勘探的精度要求，所以要采用高阶的非双曲时距方程。本文通过理论公式的推导还得出不能准确进行动校正的原因是因为地震波沿射线路径的平均速度和均方根速度都随炮检距的增加而变大。再次，根据地震波的反射和透射特点知道在一定的地质条件下可以获得相对较强的反射SV波，即在含高速屏蔽层的地质条件下可进行PS转换波勘探。本文通过对一元四次方程和一元三次方程的求解推导出对均匀水平界面可以准确求出共转换点的位置，并对单参数、双参数和三参数时距方程进行了分析和对比，还对PS转换波的AVO特点进行了一定的分析。更多还原

【Abstract】 The discrepancy of high velocity layer and wall rock in wave impedance or in reflectivity is palpable, so it will come into being a strong reflector. If we adopt a normal method of seismic exploration, the high velocity will shield the energy of down wave, because the critical angle is very small and the full reverberation is easy, also it is difficulty for seismic wave strike the interface which we will explore. Moreover, the energy of the interference wave, such as multiple wave and refractive wave, are very strong. Based on Snell law and Zoeppritz equation and used the forward modeling in ray theory, this master’s thesis have do some research on gathering the seismic data in the high velocity shielded layer area.Firstly we analysis the reflection coefficient and transmission coefficient of P-wave or SV-wave vary with the incidence angle under different condition. So we can ameliorate ways and means in seismic exploration according to the peculiarity of the high velocity shielded layer.Secondly this thesis study the wide-angel reflection, we can receive stronger energy with a long layout in the high velocity layer area. In this condition, it is inapplicable to NMO correction with normal method, so non-hyperbolic time-distance equation is required. In addition, this thesis also deduce the V_av or V_r will be accelerate along with the off-set.Finally based on the peculiarity of reflection and transmission we can receive comparatively stronger reflected SV wave, so it is feasible to explore with PS converted wave in the high velocity shielded layer area. This thesis has sought exactly the converted point in homogeneous medium by solving the cubic equation and quartic equation, it also analysis and compare one-parameter, two-parameter and three-parameter time-distance equation of PS converted wave. Moreover, it analysis the peculiarity of AVO.更多还原