乌尔逊凹陷下白垩统层序地层研究  

Sequence Stratigraphy of Low Cretaceous in the Wuerxun Depression

作　　者：秦雁群[1] 邓宏文[2] 侯秀林[1] 郭佳[2] 梁旭[2] 魏海鹏[2] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国地质大学能源学院,北京100083

出　　处：《沉积学报》2011年第6期1130-1137,共8页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(编号:2009ZX05009-002)资助

摘　　要：以构造层序地层学分析为主线,从断陷盆地结构和古地貌的区域变化分析着手,利用地质、地球物理数据对乌尔逊凹陷下白垩统主要含油层段铜钵庙组、南屯组、大一段进行了层序地层研究。在识别了5个等时层序界面及区域钻井剖面对比基础之上,建立了该区目的层段层序地层格架。研究结果表明:凹陷沉积充填以及层序形成与构造演化相对应,具有阶段性。凹陷结构控制地层充填样式以及层序地层构型:西部陡坡带沉积粗粒冲积扇—扇三角洲体系,东部缓坡带沉积细粒河流三角洲和滨浅湖体系。其中,单断断阶型结构发育加积型层序组叠置样式;单断断槽型结构发育加积或进积层序组叠置样式;单断断超型结构发育类似被动大陆边缘缓坡型层序。根据乌北地区构造古地貌及对沉积层序类型控制分析认为,该区主要储集体是位于大一段层序低位滑塌浊积岩,油藏类型为岩性—构造油藏,而非前人认为南二段顶部构造油藏。Taking the structural sequence stratigraphic analysis as the thread,through the study of architecture of faulted basin and regional paleogeomorphology change analysis,based on the geological and geophysical data,this paper analyses sequence stratigraphy of the main oil formation K1t,K1n and K1d1 of Low Cretaceous in Wuerxun Depression.Five isochronous sequence boundaries are identified by which regional well profiles are correlated,then the purpose layer sequence stratigraphic framework has been established.This study suggests that the sedimentary history of Wuerxun Depression includes a few stages corresponding with structural evolution.The pattern of strata filling and the structural of sequence are controlled by sag structure.Western steep slope of the depression,alluvial fan and fan delta are developed.But fine depositional system of fluvial delta and coastal shallow lake are developed in the eastern gentle slope of the depression.Among them,single fault bench type is developed as aggradational sequence sets pattern,single fault trough type is developed as aggradational or progradational sequence sets pattern,and single fault overlap type is similar developed as passive continental margin slope type sequences.Based on the tectonic paleogeomorphology and the sequence constitute analysis.Slump turbidities rock located in lowstand system tract of SQd1 is the main reservoir of northern Wuerxun Depression.It is lithologic-structural oil reservoir,rather than structural oil reservoir which at the top of K1n2 of predecessors.

关 键 词：乌尔逊凹陷 层序地层 盆地结构 构造古地貌 

分 类 号：P539.2[天文地球—古生物学与地层学]