元坝西部地区须二下亚段致密砂岩储层预测研究

川北元坝西部地区须家河组二段下亚段主要发育辫状河三角洲前缘沉积,水下分流河道砂体发育,但由于埋深大,压实强烈,岩石致密,有效储层预测难度大。针对上述难点,采用了“相控储层预测”研究思路:首先通过岩石物理分析优选出预测岩性的敏感地震属性,应用地震沉积学研究方法获得叠前S属性表征的目的层地震地貌图,预测河道砂岩分布；然后借助地震物相研究方法,通过坐标旋转由叠前近、远角度射线弹性阻抗反演结果得到地震物相体,预测须二下亚段致密砂岩有效储层分布。建议井位的钻探结果表明,储层预测精度高,预测方法行之有效。

Braided river delta front facies mainly develop in lower subsection of Xu_2 member in western Yuanba area,where sand bodies develop in subaqueous distributary channels.Deep buried depth,strong compaction and compact rocks would increase difficulty in reservoir prediction.To solve the problems mentioned above,“facies-controlled reservoir prediction” research ideas are adopted.First of all,the seismic attributes that are sensitive to lithological prediction are optimally selected by petrophysics analysis,and by utilizing seismic sedimentology research method,the seismic geomorphologic maps represented by prestack S attribute is obtained to predict the distribution of channel sands.And then the data bodies of seismic reservoir property facies are derived by coordinate rotation from prestack near,far angle elastic impedance inversion results,which is used to predict the distribution of effective reservoirs in lower subsection of Xu_2 member.Drilling results of recommended well locations show that the reservoir prediction accuracy is high and the method is effective.