Provenance, Sedimentary System and Beach Bar Distribution of the Upper Es4 in Qingnan Area, Dongying Depression

滩坝砂岩是近年来东营凹陷沙四上亚段油气勘探活跃且成效显著的一类隐蔽岩性地层油气藏,但在青南地区,由于缺乏对物源沉积体系的系统研究,对滩坝的分布范围和规模认识不足,制约了该区的精细勘探和储量升级.通过砂岩重矿物组合和泥岩特征元素比值分布模式的综合物源分析认为,北部物源主要供应方向为西南方向,南部物源主要供应方向为西北方向和正北方向,且南部物源影响范围显著大于北部物源,并将南北物源的混合区域限定在X7井-Wx583井-W58井-W126井-L74井-Wx119井-L108井-L2井-L64井-Lx63井连线一带;通过岩石学和测井研究在研究区划分出冲积扇、三角洲、湖泊、重力流4种沉积体系和近岸水下扇、扇三角洲、河流三角洲、湖泊和深水浊积扇5种沉积相类型;通过物源控制下的沉积相连井对比和不同砂组时期沉积相的平面分布研究,厘清了物源沉积体系的演化特征和各类砂体,特别是滩坝的分布范围和规模,为油田的精细勘探提供依据.青南地区沙四上亚段滩坝主要来自南部物源,其发育规模仅次于河流三角洲,发育层位遍及整个沙四上亚段,单个砂组的发育规模受同时期河流三角洲发育规模的影响较大,受扇三角洲发育规模的影响较小:河流三角洲发育规模较大但扇三角洲不发育的纯下3砂组-纯上4砂组时期,滩坝发育规模较大;河流三角洲发育规模逐渐缩小但扇三角洲发育规模逐渐增大的纯上3砂组-纯上1砂组时期,滩坝发育规模也逐渐减小.The provenance and sedimentary facies of the upper Es4 of Qingnan area, Dongying Depression lack systematic research, especially the distribution and scale of lacustrine beach-bar sediment, which restrict the precise exploration and reserves promotion in this area.This paper determines the types of sedimentary facies through petrological study, clarifies the sedimentary evolution by using logging methods, cleares the provenance direction and influence range using heavy mineral assemblage and the distribution of characteristic element ratio, and thus restricts the distribution of different sedimentary facies controlled by different provenance, especially the precise distribution of each sand-body, which can provide references for precise exploration of the oilfield.According to the research, there are four sedimentary systems(alluvial fan, delta, lake and gravity flow)and five sedimentary facies(coastal subsea apron, delta, fan delta, lake and deep water turbidity fan)in the study area;The boundary of southern and northern provenances lies along the line X7-Wx583-W58-W126-L74-Wx119-L108-L2-L64-Lx63, the southern Guangrao Heave provides a massive provenance to the north and northwest, nevertheless, the northern Qingtuozi Heave provides a limited provenance to the southwest;Delta sand-body exists through the whole Es4 and widely spreads from Guangrao Heave to northwest, deep water turbidity fan sand-body exists at the middle period of Es4 and distributes contiguously at the semi-deep and deep lake evironment in the northwest, fan delta sand-body exists at the late period of Es4 and has a limited distribution from Qingtuozi Heave to the southwest, beach bar sand-body exsits at the whole time of Es4 and has a wide range at the shore-shallow lake evironment, which has a range only smaller than delta sand-body and provides abundant potential reservoirs for lacustrine tight oil and gas.国家重点基础研究发展计划(973计划)项目(2012CB214801)[National Key Basic Research Program of China; No.2012CB214801]中国科学引文数据库(CSCD)3561-5763