摘要
滩坝作为发育于滨岸带非常重要的沉积储集层类型之一,已成为隐蔽油气藏勘探的目标。为进一步明确峡山湖东岸滨浅湖滩坝沉积模式,以现代沉积考察为基础,结合探地雷达技术和粒度分析资料,对东岸研究区滩坝砂体的沉积特征以及控制因素进行详细分析。结果表明:峡山湖东岸主要发育风成沙丘及滩坝2种沉积体系。早期风成沉积物以发育连续性好的大型板状交错层理细砂为主,分选较好,粒度概率曲线以两段式为特征;滩坝沉积物以发育连续性差的板状交错层理、平行层理中砂为主,主要为反粒序或者复合粒序,具冲刷构造,岩性较混杂并以砂泥薄互层为特征,发育大量植物根系,粒度概率曲线以三段式为主,跳跃组分分为2段,分选较好。探地雷达资料表明研究区下部主要以厚层层状反射结构砂体为主,与风成沙丘沉积反射特征较为一致,环境敏感粒度组分对滩坝沉积较强的水动力作用有较好的指示。总体上,风力作用控制了风成砂体的沉积发育并且改变了古地貌条件,风浪作用冲刷改造了早期砂体,为滩坝的发育提供了物源,控制了滩坝发育的规模和地理位置,可概括为"风运-湖改"滩坝沉积模式,可为滩坝体系的识别和有利储集层预测提供指导。
Beach-bars,one of the important hydrocarbon reservoirs formed in the coastal zone,become the exploration target in terms of subtle reservoirs. In order to figure out the sedimentary model of beach bars deposited in the east coast of Xiashan Lake,a detailed study on sedimentary characteristics and controlling factors of beach-bars was carried out by using ground penetrating radar( GPR) and grain size analysis. The results show that,the east coast of Xiashan Lake has developed two types of sedimentary systems including beach bars and eolian dunes. The eolian sediments in the early stage are well-sorted finegrained sandstones,which are characterized by large tabular cross-bedding and two-segment pattern on grain size cumulative frequency plot. The beach bars sediments are reverse graded medium-grained sandstone and feature the low-continuity tabular cross-bedding. Plant roots,scouring structure,interbedding of sand and mud and three-segment pattern on on grain size cumulative frequency plot arethe typical characteristics of beach-bar deposits. The saltation proportion is divided into two different parts indicating high energy hydrodynamic condition. Layered reflecting structures can be confirmed through GPR which implies the eolian sediments depositional pattern. The analyses of environmentally sensitive components of the grain size of eolian sediments suggest two different hydrodynamic environment. In conclusion,eolian sediments and the change of paleogeomorphy environment depend on wind action. The coastal erosion plays an important role in the early stage of the position and sand supply for beach bars. According to the sedimentary model as well as its formation mechanism,we propose a ‘wind transporting-wave modifying’ sedimentary system,which will be helpful for identification of beach bars and the prediction of favorable reservoir.
作者
白立科
邱隆伟
杨勇强
杜双虎
杨保良
韩晓彤
Bai Li-Ke;Qiu Long-Wei;Yang Yong-Qiang;Du Shuang-Hu;Yang Bao-Liang;Han Xiao-Tong(School of Geosciences,China University of Petroleum(East China),Shandong Qingdao 266580,China;Key Laboratory of Deep Oil and Gas,Shandong Qingdao 266580,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Shandong Qingdao 266237,China)
出处
《古地理学报》
CAS
CSCD
北大核心
2020年第2期278-294,共17页
Journal of Palaeogeography：Chinese Edition
基金
国家科技重大专项(编号:2017ZX05009-002,2017ZX05072-002)
国家自然科学基金项目(编号:41972099)联合资助。
关键词
峡山湖
滩坝
风成沙丘
沉积模式
控制因素
Xiashan Lake
beach-bar
eolian dune
sedimentary model
controlling factor
