松辽盆地肇源—太平川地区白垩系姚家组一段沉积特征及演化

Sedimentary characteristics and evolution of member 1 of Yaojia Formation of cretaceous in Zhaoyuan-Taipingchuan area of Songliao Basin

以高精度层序地层学理论为指导,通过对岩心、地震、测井、录井以及分析化验等资料的综合研究,建立松辽盆地肇源—太平川地区白垩系姚家组一段层序地层格架。将姚家组一段划分为3个层序,每一层序发育完整,分别由低位、水进和高位3个体系域构成;并在层序格架内进行沉积微相类型及沉积相展布特征研究,确定姚家组一段主要为浅水三角洲沉积体系,识别出三角洲平原、三角洲前缘、前三角洲3种亚相,以及分流河道、天然堤、决口扇、分流河道间、泛滥平原、水下分流河道、水下分流间湾、水下决口扇、河口坝、远砂坝和席状砂11种微相;三角洲平原、三角洲前缘广泛发育,前三角洲发育较差;三角洲平原分流河道通过填积和频繁的分叉改道,向湖盆中心方向长距离推进,在三角洲前缘的浅水区域发育了大量水下分流河道,分流河道与水下分流河道砂体相互切割、叠加,形成了树枝状砂体,(水下)分流河道砂体构成了油气富集的主要储集体。该区沉积相的精细研究为该区下一步油气的勘探与开发奠定了基础。

According to the theory of high-resolution sequence stratigraphy,the sequence stratigraphic framework in Member 1 of Yaojia Formation of Zhaoyuan-Taipingchuan area was built up through the comprehensive research on core,seismic,log and analysis assay.Member 1 of Yaojia Formation was divided into three completely-developed sequences which were constituted by three system tracts： low stand systems tract,transgressive systems tract and high stratigraphic framework were also discussed,confirming the shallow water delta sedimentary system in member 1 of stand systems tract.The characteristics of sedimentary micro-facie and distribution were ascertained in the sequence Yaojia Formation in cretaceous.Three sub facies（delta plain,delta front and prodelta）,and eleven sedimentary micro-facies（branch channel,natural levee,crevasse splay,distributary interchannel,flood plain,underwater distributary channel and interbay,subaqueous crevasse splay,mouth bar,distal bar and sheet sand） were identified.The delta plain and delta front are widely developed,but the prodelta is poor.By depositing and frequent bifurcation,the branch channels in delta plain are advanced toward the basin center with long-distance,and developed abundant underwater distributary channels in the shallow water area of delta front.Dendrites sand body is formed through the cutting and stacking between distributary channels and sandstone in the underwater distributary channel sand body.In this way,underwater distributary channel sand body constitute the reservoir body of hydrocarbon enrichment.Precise research on the sedimentary facie in this area will establish the foundation for further petroleum exploration and development.