高邮凹陷阜三段隐蔽油藏主控因素及成藏特征

Main controlling factors and reservoir formation characteristics of the subtle reservoir of the third member of the Funing Formation of Gaoyou Sag

随着高邮凹陷阜三段勘探程度不断提高,构造油藏勘探空间越来越小,迫切需要探索潜力较大的隐蔽油藏。从油气成藏基本条件入手,结合油藏分布特征,对高邮凹陷阜三段隐蔽油藏的主控因素及油藏类型进行了分析和总结。结果表明:三角洲前缘前端发育的水下分流河道及河口坝、滩坝等是形成隐蔽油藏的有利砂体类型,控制着岩性圈闭的分布;断层输导和封闭性控制油气分布层系及富集程度;构造背景与砂体展布配置关系控制油气运移趋势。在此基础上,总结了断层-岩性复合油藏和岩性油藏两大类阜三段隐蔽油藏类型,并细分为断层-河道或河口坝岩性、断层-滩坝岩性、岩性上倾尖灭、滩坝砂岩透镜体等4种类型;总结了阜三段具有“断岩、翘倾、独滩坝”的隐蔽油藏成藏特征,明确了隐蔽油藏勘探有利区在三角洲前缘前端,为高邮凹陷阜三段隐蔽油藏勘探指明了方向。

With the increasing exploration degree of the third member of the Funing Formation in Gaoyou Sag,the exploration space of structural oil reservoirs is getting smaller and smaller,and it is urgent to explore hidden oil reservoirs with high potential.Based on the basic conditions of oil and gas accumulation and reservoir distribution characteristics,the main controlling factors and reservoir types of the concealed reservoirs in the third member of the Funing Formation in Gaoyou Sag are analyzed and summarized.The results show that the underwater distributary channels,estuarine bars,and beach bars developed at the front of the delta front are the favorable sand body types for forming concealed reservoirs,which control the distribution of lithological traps.Fault transport and closure control hydrocarbon distribution and the degree of enrichment.The relationship between the tectonic background and the sand body spreading configuration controls the trend of oil and gas transportation.On this basis,two types of concealed reservoirs in the third member of the Funing Formation,namely fault-rock composite reservoirs and rocky reservoirs,were summarized,and subdivided into four types,namely,fault-channel or estuarine bar lithology,fault-beach bar lithology,lithology up-dip pinout,and beach bar sandstone lens.The third member of the Funing Formation was summarized to have the hidden reservoir formation characteristics of“fractured rock,warped dipping,and single beach bar”,and it was clarified that the favorable area for exploration of hidden reservoirs is at the front of the delta front,which points out the direction for the exploration of hidden reservoirs in the third member of the Funing Formation.