动校拉伸及调谐效应对AVO反演的影响

Influence of NMO stretch and tuning effect on AVO parameters in- version

采用大炮检距地震数据进行AVO反演可以提高反演的精度及稳定性,但大炮检距地震数据存在动校拉伸和随炮检距变化的调谐效应,这会使AVO反演产生误差。基于Dong的近似公式推导出梯度的相对误差表达式,从理论上分析了动校拉伸和调谐效应对4类含气砂岩模型AVO反演的影响。制作了4类含气砂岩模型的合成地震记录,基于贝叶斯理论进行了AVO截距和梯度反演,并将反演结果与理论曲线进行了对比分析。从分析结果看,动校拉伸和调谐效应影响梯度反演的精度,对截距反演的影响较小。

The accuracy and stability of AVO inversion can be improved by adapting large offset seismic data.However,NMO stretch and offset-dependent tuning existing in large offset seismic data,which causes error of AVO inversion.Based on the Dong's approximate formula,the relative error formula of the AVO gradient was deduced, then the influence of NMO stretch and offset-dependent tuning on four AVO models was theoretically analyzed.Synthetic seismogram of four types of gas-bearing sand model was made.Based on Bayesian theorem,the AVO intercept and gradient was inversed, the inversion results were compared to the theoretical curves.From the analysis result,the NMO stretch and tuning effect impacts the accuracy of AVO gradient inversion,has smaller influence on AVO intercept inversion.