浅水三角洲沉积体系与储层岩石学特征——以鄂尔多斯盆地西部地区山1—盒8段为例  

Sedimentary system and sandstone reservoir petrology of a shallow water delta:Case study of the Shan-1 and He-8 members in the western Ordos Basin

作　　者：朱世发[1,2] 崔航 陈嘉豪 骆高俊 王文禹 杨祎 施翌 ZHU ShiFa;CUI Hang;CHEN JiaHao;LUO GaoJun;WANG WenYu;YANG Yi;SHI Yi(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Faculty of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;The Eighth Oil Production Plant of Changqing Oilfield Company,Xi’an 710200,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249 [3]中国地质大学(武汉)资源学院,武汉430074 [4]长庆油田公司第八采油厂,西安710200

出　　处：《沉积学报》2021年第1期126-139,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41872102,41202107)。

摘　　要：浅水三角洲已经成为当前沉积学研究和油气勘探的重点领域,浅水三角洲常规和非常规砂岩储层中发现了丰富的油气资源。鄂尔多斯盆地中—古生界发育大型浅水三角洲沉积,结合岩芯、测井、分析化验等资料,对盆地西部地区山1—盒8段浅水三角洲的母岩特征、沉积充填、砂体展布与储层岩石学特征进行研究,为研究区常规砂岩储层和致密砂岩油气勘探提供地质依据。分析表明,研究区南部和北部砂岩重矿物组合相似,以锆石和白钛矿为主。综合La/Yb-REE与Dickinson三角图解、稀土元素配分模式和碎屑锆石定年分析认为,北部物源主要来自盆地西北部阿拉善古陆太古界和元古界花岗岩、片麻岩、石英砂岩,向南影响到陇东地区北部;南部物源主要来自盆地南部北秦岭地区太古界、元古界花岗岩、片麻岩和片岩,向北影响陇东地区中南部。山1段发育曲流河三角洲,盒8段发育辫状河三角洲,孤立型与垂向叠置型水下分支河道砂体是主要的砂体类型。盒8段沉积时期,古湖泊可能萎缩;南北物源形成的三角洲在研究区中部环县东南一带交汇混合。砂岩类型主要为岩屑质石英砂岩、石英砂岩和岩屑砂岩,结构成熟度中等—较差。砂岩成岩改造强烈,水—岩反应复杂,压实作用是储层致密化的主因,多期胶结作用使砂岩的孔喉结构变得十分复杂。孔隙类型以微米—纳米级的岩屑溶蚀孔、剩余粒间孔和高岭石晶间孔为主,整体上属于非常规致密砂岩储层。砂体分布与“甜点”预测是研究区致密油气勘探的关键。The shallow water delta has become the focus of sedimentology research and oil and gas exploration.Abundant oil and gas resources have been found in conventional and unconventional sandstone reservoirs within shallow water deltas.Large scale shallow water delta deposits were developed during the Mesozoic to Paleozoic in the Ordos Basin.Based on the core,well logging,and geochemical data,the parent rock,sedimentary filling,sand body distribution,and reservoir characteristics of the shallow water deltas from the Shan-1 and He-8 Members in the western part of the basin are studied in this paper,which provides a geological basis for conventional sandstone reservoirs and tight oil-gas exploration in the study area.The results show that the heavy mineral assemblages of sandstone in the south and north regions of the study area are similar,mainly composed of zircon and white titanium.Using LA/Yb rare earth elements(REEs),Dickinson triangle diagrams,REE distribution models,and the analysis of detrital zircon dating,we find that the provenance in the north is mainly from Archean and Proterozoic granites,gneisses,and quartz sandstone of the Alashan ancient land in the northwest part of the basin and affects the northern part of the Longdong area southward.The provenance in the south part of the basin mainly comes from Archean and Proterozoic granites,gneisses,and schists in the North Qinling area and affects the central and southern Longdong area northward.Meandering river delta was developed in the Shan-1 Member,braided river delta was developed in the He-8 Member.Isolated,and vertical superimposed underwater branch channel sand bodies are the main sand body types.During the depositional period of the He-8 Member,the ancient lakes have shrunk;the delta lobes formed by the North-South provenance converged and mixed in the southeast part of Huanxian County in the central part of the study area.Sandstone types are mainly lithic quartz sandstone,quartz sandstone,and lithic sandstone,with medium to poor textural maturity.Sands

关 键 词：浅水三角洲 致密砂岩 源—汇体系 山1—盒8段 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]