【摘要】 为克服常规方位AVO梯度提取方法各方位截距项难以一致,以及井的方位AVO梯度先验约束不易获取的问题,提出了稳定方位AVO梯度无约束反演方法。该反演方法分为两步:第一步认为地震数据是反射系数序列,据此消除导致最小二乘反演方程不稳定的子波项,得到自激自收地震记录和方位AVO梯度地震记录;第二步基于最少反射层假设搜索准确的地下界面位置,以降低方位AVO梯度地震记录反褶积方程维数。模型试算结果表明,该方法能够提高方位AVO梯度反演方程稳定性,并且所得方位AVO梯度的椭圆分析可以较好地指示裂缝密度和裂缝走向。实际工区的应用结果表明,稳定方位AVO梯度无约束反演结果的方位AVO梯度椭圆分析可以较为准确地预测地层裂缝发育带,为裂缝型储层预测提供了有利的技术支撑。更多还原

【Abstract】 In order to overcome the inconsistency of intercepts in different azimuths with conventional azimuth AVO gradient extracting method and the difficulty in obtaining azimuth AVO gradient as priori constraint from wells,we developed a steady azimuth AVO gradient unconstrained inversion method.The inversion method is divided into two steps:the first step is to assume that seismic data is reflection coefficient sequence for eliminating wavelet term which could result in instability in the least squares inversion equation,and obtain the self-exciting and self-receiving seismograms and seismic azimuth AVO gradient records;the second step is to search reflection interface locations exactly based on the least reflection layer assumptions in order to reduce the dimensions of deconvolution equation for seismic azimuth AVO gradient records.The model test shows that the method can improve the stability of the inversion equation and the ellipse analysis of azimuth AVO gradient is a good indication of fracture density and fracture strike.The application results of the actual exploration area show that the ellipse analysis of azimuth AVO gradients from above inversion method can more accurately predict the formation fracture zone and provide a favorable technical support for fractured reservoir prediction.更多还原