四川盆地焦石坝地区页岩气储层地震定量预测方法

针对四川盆地东南部焦石坝地区五峰组-龙马溪组页岩气储层,提出了一种地震定量预测方法。首先在分析页岩储层地震响应特征的基础上,以波阻抗反演技术实现页岩层段的精细预测;接着进行页岩的总有机碳(total organic carbon,TOC)敏感参数分析,发现研究区页岩储层的密度参数与测井解释的TOC含量(C_TOC)具有很好的相关性,由两者的拟合关系得到基于密度的TOC计算模型;然后在波阻抗反演页岩层段的空间约束下,采用叠前同时反演方法获得叠前密度反演数据体;最后将密度反演数据体转换为TOC数据体,精确预测出研究区页岩气储层(C_TOC≥1%)的空间展布。与测井解释结果的对比表明,地震定量预测的精度较高,研究区内多个井点处页岩气储层厚度预测结果的相对误差小于2%。

 Aiming at the shale gas reservoirs of the Wufeng-Longmaxi Formation,Jiaoshiba Area,Southeastern Sichuan Basin,a quantitative seismic prediction method is proposed.First of all,based on the analysis of seismic response characteristics of shale reservoirs,impedance inversion is used to realize fine prediction of the shale section.Secondly,different parameters are analyzed in order to find out the parameters that are sensitive to TOC(C_TOC).As a result,density is revealed to have good correlation to TOC,and a template for calculating TOC is generated based on the correlation.Thirdly,constrained by the distribution of the shale section,density is obtained by using pre-stack simultaneous inversion.Finally,TOC data volume is transferred from the density data volume to finely delineate the spatial distribution of the shale gas reservoirs (C_TOC≥1%) within this region.Comparing to the interpretation of well logs,it is showed that the seismic prediction of shale gas reservoir thickness has a higher accuracy,since the relative error are less than 2% according to the drilling results in this region.

中国地质调查局油气资源调查中心油气专项(12120114020201)资助。