海安凹陷曲塘次洼阜三段薄层砂岩预测

Thin sandstone prediction of Fu 3 member in Qutang sub sag of Hai'an Sag

海安凹陷曲塘次洼阜三段地层埋藏深、砂岩薄(1.3～3.0 m),岩性主要为泥质粉砂岩、粉砂质泥岩,阻抗叠置严重,常规的波阻抗反演不能满足实际生产的需求。为此,用自然伽马重构波阻抗曲线,预测砂岩平面变化趋势,再利用砂地比与波阻抗的分布关系,描述有效砂岩储层数据体,刻画了曲塘次洼阜三段隐蔽油气藏储层空间展布规律,结果显示,该区波阻抗重构反演结果与井震符合较好,储层预测误差小,为岩性、构造–岩性油藏预测提供了有效技术手段。

Fu 3 member in Qutang sub sag of Hai’an sag has characteristics of deep buried depth,small sandstone thickness(1.3~3.0 m),the lithology is mainly of argillaceous siltstone and silty mudstone,and the wave impedance is overlapped.As conventional wave impedance inversion cannot meet the demand of actual production,the impedance curve of natural gamma wave was reconstructed to predict the trend of sandstone plane.By using the relationship between sand-ground ratio and wave impedance distribution,the effective sandstone reservoir data body was described,and the spatial distribution regularity of hidden oil and gas reservoirs in Fu 3 member of Qutang sub sag was described.The results showed that the inversion results of wave impedance reconstruction in this area were in good agreement with the well seismic data and the reservoir prediction error was small,which provided an effective technique for reservoir prediction of lithologic reservoirs and structural-lithologic reservoirs.