基于球面波的地震记录合成方法及AVO分析

Seismogram synthesis method based on spherical wave and AVO analysis

在子波具有Rayleigh形式假设基础上,利用Laplace变换对基于球面波理论的地震AVO(振幅随偏移距变化)方程进行积分变换,通过半解析的方法,使得计算球面波反射系数得到有效简化,并对球面扩散、近场影响补偿及权函数进行分析,最后进行理论模型的计算与分析。结果表明,球面波反射系数不仅与入射角度有关,还受地震子波频率和储层埋藏深度影响。在临界角附近,基于球面波理论反射系数计算结果较基于平面波理论更为合理。

The amplitude versus offset （AVO） seismic equation based on spherical wave theory was transformed via Laplace transform by assuming a wavelet to be of Rayleigh form. In this process, the computaion of spherical wave reflection coefficients was simplified by the semi-analytical method. The spherical divergence and near-field effects were corrected, and the weighting function was analyzed. At last, the theoretical model was calculated and analyzed. The results show that spherical wave reflection coefficients not only have relation with incidence angle, but also are influenced by seismic frequency and reservoir depth. The computation of reflection coefficients based on spherical wave is more reasonable than that based on plane wave near the critical angle.