HTI煤层AVO响应特征及其影响因素

针对两地层均为HTI介质的界面,根据位移理论,推导出地震纵波、横波分别从界面上方和下方入射情况下的反射纵波、反射横波、透射纵波和透射横波等发散系数精确表达式。推导公式可以解决地层物性差异大和大偏移距造成系数不够准确的问题。利用所推导的公式,得到HTI煤层AVO的发散系数曲线。通过分析发现,HTI煤层AVO响应特征,除了受背景介质物性参数影响外,还与裂隙密度、裂隙开度和裂隙填充物有关。在裂隙填充物为流体时,裂隙密度是影响AVO的最主要因素。

AVO response characteristics and its influencing factors in HTI coalbed

According to the displacement theory，authors derived the exact scattering coefficients of reflected P wave，reflected S wave，transverse P wave and transverse S wave when P and S waves travel up and down through the boundary between the two HTI media.This expression can solve the problem of the inaccurate coefficient caused by the formation with great physical differences and the large offset.Through the derived formula，drew the AVO scattering curves of HTI coalbed.Crack density，aspect aperture and crack filling have effects on AVO response characteristics of HTI coalbed in addition to the physical parameters of the background medium.When the crack filling is fluid，crack density is the most important factor.