海拉尔盆地贝西南地区南屯组断层-砂体组合类型及油气差异富集机理

Fault-sandbody assemblage types and differential enrichment mechanism of hydrocarbon in Nantun Formation in Beixinan area,Hailar Basin

贝西南地区南屯组断层-砂体组合对油气富集有显著的控制作用,为了查明不同构造单元的断层-砂体组合类型,以及不同类型控制油气富集的差异机理,综合考虑地层倾向、断层走向和砂体走向三者之间的匹配关系,利用断层和砂体平面、剖面组合分析及走向玫瑰花图统计相结合的方法,确定出了研究区断层-砂体组合类型,在此基础上开展油藏解剖,分析了油气富集的差异性。结果表明:斜坡区断层-砂体组合类型一般有6种,研究区主要有3种,分别是d型(地层倾向∥砂体走向⊥同向断层走向)、e型(地层倾向⊥砂体走向∥反向断层走向)和f型(地层倾向∥砂体走向⊥反向断层走向);e型和f型是富油类型,且f型优于e型,d型多出现失利井;油气富集机理的差异是由断裂带内部结构的不对称性造成的,d型最有利于油气向高部位“阶梯状”调整,e型多沿断层走向形成油气富集条带,f型最有利于侧向遮挡,多在下盘一侧聚集成藏。研究成果可为类似地区的断层-砂体组合控藏分析提供理论参考。

Fault-sandbody assemblages of Nantun Formation in Beixinan area have significant control effect on hydrocarbon enrichment.In order to find out the fault-sandbody assemblage types of different structural units and the difference mechanism of different types controlling hydrocarbon enrichment,comprehensively considering the matching relationship among strata dip,fault strike and sandbody orientation,the method combining analysis of fault-sandbody plane and section assemblages and statistics of strike rose diagram is used to determine fault-sandbody assemblage types in studied area.On this basis,reservoir is dissected to analyze hydrocarbon enrichment difference.The results show that:There are generally 6 types of fault-sandbody assemblage in slope area,with mainly 3 types in studied area,including Type d(strata dip parallel to sandbody strike and perpendicular to syntropic fault strike),Type e(strata dip perpendicular to sandbody strike and parallel to reverse fault strike)and Type f(strata dip parallel to sandbody strike and perpendicular to reverse fault strike).Type e and Type f are oil-rich,and Type f is better than Type e,while Type d is mostly in failed wells.The difference of hydrocarbon enrichment mechanism is caused by asymmetry of internal structure of fault zone.Type d is most conducive to“stepped”adjustment of hydrocarbon to high part,and Type e mostly forms hydrocarbon enrichment bands along fault strike.Type f is most conducive to lateral sheltering,and mostly form reservoirs on footwall side.The research provides reference for theoretical reservoir control analysis of fault-sandbody assemblages in similar slope areas.