摘要
以鄂尔多斯盆地陇东地区三叠系延长组长7油层组为例,在岩心描述与测井解释的基础上,应用岩石热解、同位素测定、显微组分分析、气相色谱、色谱—质谱等技术方法,深入剖析湖相富有机质细粒沉积岩的地质、地球化学特征,研究细粒沉积岩的展布情况,并探讨其对致密油成藏的作用。结果表明:湖相富有机质细粒沉积岩按照岩性及结构的不同可分为富有机质页岩及富有机质泥岩,富有机质页岩沉积于水体安静缺氧的深湖环境中,水体分层明显,有机质丰度高,主要来源于浮游生物和底栖藻类生物;富有机质泥岩主要沉积于水体相对略浅的半深湖环境中,水体盐度相对较低,有机质丰度低,为浮游生物和陆源碎屑物质的混合来源。陇东地区富有机质细粒沉积岩发育最厚的区域位于八珠—马岭—庆城—华池一带,其中富有机质页岩主要发育于长73亚段,富有机质泥岩在长7段各个亚段均有所发育。陇东地区致密油在长7浊积砂体中广泛分布,其油源主要为长73亚段富有机质页岩,油层的展布受控于富有机质细粒沉积岩的发育程度。
In order to clarify the distribution characteristics of lacustrine organic-rich fine-grained sedimentary rocks and its effects on tight oil accumulation,the Chang 7 member of Triassic Yanchang Formation in Longdong area of Ordos Basin was taken as an example to study the geological and geochemical characteristics by rock pyrolysis,isotopic determination,maceral analysis,gas chromatography(GC),gas chromatography-mass spectrometry(GC-MS),core description and log interpretation.Lacustrine organic-rich finegrained sedimentary rocks were divided into organic-rich shale and organic-rich mudstone according to their lithology and texture.The results show that organic-rich shale deposited in the quiet and anoxic deep lake environment,the stratification of water was obvious,the abundance of organic matter is high,and the organic matter mainly came from plankton and benthic algae(type Ⅰ-Ⅱ1).Organic-rich mudstone mainly deposited in the semi-deep lake environment,where the water was relatively shallow,the salinity of water was relatively low,and the abundance of organic matter was low,and the organic matter was derived from the mixed source of plankton and terrestrial clastic(typeⅡ1-Ⅱ2).The organic-rich fine-grained sedimentary rock in the area of Bazhu-Maling-Qingcheng-Huachi is the thickest in Longdong area.The organic-rich shale is mainly developed in Chang 73 sub-member,while the organic-rich mudstone is developed in each sub-member of Chang 7 member.In Longdong area,tight oil is widely distributed in the Chang 7 turbidite sand bodies,and it was mainly derived from the Chang 73 organic-rich shale.The distribution of reservoir is controlled by the development of organic-rich fine-grained sedimentary rocks.
作者
高永亮
文志刚
李威
Gao Yong-liang;Wen Zhi-gang;Li Wei(College of Resources and Environment,Key Laboratory of Technology for Oil and Gas Resources,Ministry of Education,Yangtze University,Wuhan 430100,China;CNOOC Research Institute Co.Ltd.,Beijing 100028,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2019年第5期729-739,共11页
Natural Gas Geoscience
基金
中国地质调查局"中国西部大型盆地海相碳酸盐岩油气地质调查评价"项目(编号:1212011220762)资助
关键词
富有机质细粒沉积岩
致密油
地球化学特征
陇东地区
长7油层组
Organic-rich fine-grained sedimentary rocks
Tight oil
Geochemical characteristics
Longdong area
Chang 7reservoir
