东营凹陷沙四上亚段陆相页岩岩相特征、成因及演化  

Characteristics,Depositional Processes,and Evolution of Shale Lithofaceis of the Upper Submember of Es_4 in the Dongying Depression

作　　者：马义权 杜学斌[1,3] 刘惠民[4] 陆永潮[1,2] 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国地质大学资源学院,湖北武汉430074 [3]中国地质大学海洋学院,湖北武汉430074 [4]中国石化胜利油田分公司地质科学研究院,山东东营257000

出　　处：《地球科学（中国地质大学学报）》2017年第7期1195-1208,共14页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究发展计划("973"计划)项目(No.SQ2013CB021013);国家十三五科技重大专项<中国典型盆地陆相页岩油勘探开发选区与目标评价>子课题四<济阳坳陷页岩油勘探开发目标评价>(No.2017ZX05049004);"构造与油气资源"教育部重点实验室开放研究基金课题(No.TPR-2016-09)

摘　　要：我国陆相湖盆页岩具有较大的生烃潜力,但是对其研究起步较晚,目前存在诸多不足,尤其对富生烃页岩岩相特征及其沉积作用过程、成因演化等方面的研究工作均处于探索阶段.综合岩心、薄片、XRD矿物含量分析、主微量元素和测井等数据,在沉积学、元素地球化学以及T-R(湖进-湖退)层序理论的指导下,详细研究了东营凹陷沙四上亚段页岩的岩相特征及其沉积过程、岩相发育与层序耦合关系以及古气候和湖泊的演化过程.结果表明,沙四上亚段页岩自下而上主要由硬石膏薄夹层页岩相、含粉砂富粘土质页岩相、块状灰质页岩相和纹层状灰质页岩相组成,分别沉积于盐湖环境、前三角洲环境、浅湖环境和深湖-半深湖环境.页岩岩相组合的垂向演化与体系域的纵向分布具有明显的耦合关系,揭示了古气候由干旱转为潮湿、湖盆由小型湖泊演化为大型湖泊,并推断古气候的变化和控盆正断层的活动是控制研究区古湖泊演化的两个重要因素.Organic-rich lacustrine shales have high hydrocarbon potential,but relevant studies did not start until recently,suffering from many deficiencies including relatively few studies on lithofaceis,depositional process and origin and evolution of lacustrine shales.The lacustrine shale succession of the upper submember of Es_4 in the Dongying depression,Bohai Bay basin,eastern China,is the most important hydrocarbon source rock and an unconventional reservoir.In this study,we conduct detailed lithofacies characterization to the upper submember of Es_4 shale succession in the NY1 drilling core by combining core descriptions,microscopic observations,mineralogy,major and minor elements and log data.Based on the theories of petrography,sedimentology,element geochemistry and T-R sequence stratigraphy,lithofacies features,depositional process of lithofacies,coupling relationship between lithofacies and sequence stratigraphy,and evolutions of paleoclimate and paleolake are investigated in detail.Four major lithofacies associations are identified,including the interbedded evaporite and shale lithofacies association,silt-bearing clay-rich shale lithofacies association,the massive calcareous shale lithofacies association,and the laminated calcareous shale lithofacies association from bottom to top.These lithofacies associations are interpreted to be depositedin small salt lake,apro-delta environment,shallow lacustrine environment and deep,stratified,anoxic lake,respectively.By contrast,there is coupling between dominant lithofacies and system tracts through time.The changes of dominant lithofacies in the upper submember of Es_4 shale succession through time suggest that paleoclimate changed from arid to humid and paleolake changed from small and shallow lake to large and deep lake,and it is inferred that paleolake evolution was controlled by paleoclimate changes and the tectonic subsidence associated with the development of depression-bounding faults.

关 键 词：陆相盆地 页岩 岩相 东营凹陷 沙河街组 石油地质 

分 类 号：P586[天文地球—岩石学]