松辽盆地四五家子油田下白垩统泉头组沉积相

SEDIMENTARY FACIES OF THE QUANTOU FORMATION OF LOWER CRETACEOUS AT SIWUJIAZI OILFIELD OF SONGLIAO BASIN

松辽盆地四五家子油田位于吉林省公主岭市内 ,在构造上是松辽盆地东南隆起区杨大城子背斜的一部分。油田的储层主要由下白垩统泉头组组成 ,它是在晚白垩世干旱和氧化环境中沉积的。其物源来自东北部的中央古隆起。本区储层岩性以岩屑长石砂岩为主 ,部分为岩屑质长石砂岩和长石质岩屑砂岩。通过单井相分析 ,主要相标志为具有牵引流沉积机制为主的沉积构造和粒度分布特征。根据相标志分析 ,储层为曲流河相沉积 ,发育曲流河点坝、决口扇、天然堤及泛滥平原四种沉积微相类型。曲流河相自下而上为河床滞留沉积 -点坝 -天然堤 -决口扇 -泛滥平原的正韵律组合。在建立各沉积微相测井相模式的基础上 ,对全区 136口非取芯井进行了沉积微相识别 ,而应用顺序指示模拟实现了沉积微相的平面展布 ,恢复其古地理面貌 :主要发育两条自北北东向南南西方向延伸的曲流河床 ,具有曲流河点坝特征的泉头组小层 6、小层 7是主要的储集层。这个研究成果为下一步油田开发奠定了基础。

Siwujiazi Oilfield,located in Gongzhuling City,Jilin Province,is a part of the of Yangdachengzi anticline at Southeast Upwelling Area of the Songliao Basin. The reservoir of the oilfield is mainly composed of Quantou Formation of the Lower Cretaceous,which was deposited in dry and oxidizing environment in the Late Cretaceous. Its source provenance area is the central ancient-uplift in northeastern part of the basin. The reservoir is mainly composed of lithic arkoses, some lithic feldspathic sandstones,and feldspathic litharenite sandstones. Based on the analysis of single well facies,the main facies marker includes sedimentary structure and granularity distribution reflecting the traction current sedimentary mechanism. Through the analysis of facies marker,the reservoir is meandering river facies. The facies are classified into four microfacies,i.e. meandering point bars,crevasse splays,natural levees and flood plains. The vertical combination of the river is Lag deposit-point bars-natural levees-crevasse splays-flood plains from bottom to top. Based on the model of the logging facies,the microfacies of 136 non-sampling wells were identified,and the inter-well sedimentary microfacies were forecasted by applying sequential indicator simulation. The research shows that there are two meandering rivers stretching from NNE to SSW and the layers 6 and 7 in Quantou Formation have the character of point bars. This study is an important foundation for next oilfield development.