鄂尔多斯盆地甘泉-富县地区延长组长9-长7段烃源岩地球化学特征及长8致密油源对比  

Geochemical characteristics of source rocks in the Chang 9-Chang 7 members and their correlation with the tight oil sources of Chang 8 member in the Ganquan-Fuxian area,Ordos Basin

作　　者：蒋杨 弓虎军[1] 蒲仁海[1] JIANG Yang;GONG Hujun;PU Renhai(Department of Geology,Northwest University,Xi'an 710069,China)

机构地区：[1]西北大学地质学系,陕西西安710069

出　　处：《沉积与特提斯地质》2024年第3期656-670,共15页Sedimentary Geology and Tethyan Geology

基　　金：国家科技重大专项(2016ZX05050001)。

摘　　要：为评价鄂尔多斯盆地甘泉—富县地区长9—长7段烃源岩品质,探讨长8致密油油气来源问题,通过TOC、氯仿沥青“A”、岩石热解参数、镜质体反射率、有机质显微组分、生物标记化合物、单体碳同位素等技术方法,研究该区长9—长7段烃源岩生烃潜力、母质来源及沉积环境,并对长8段原油样品进行地球化学分析及油源对比。结果表明:(1)研究区主要发育长9、长8、长7三套暗色泥岩,长9—长7段暗色泥岩有机质类型为Ⅱ1~Ⅱ2型;其TOC含量为3.25%~7.92%,生烃潜量为3.06~38.13 mg/g,氯仿沥青“A”含量为0.18%~0.69%,为最好烃源岩,且均处于高成熟演化阶段。(2)长9—长7段暗色泥岩样品形成于典型的淡水湖泊环境,长9沉积期为氧化—亚氧化沉积环境,长8沉积期为弱还原沉积环境,长7沉积期为强还原沉积环境,长9—长7段烃源岩母质来源为低等水生生物和陆源高等植物混源。(3)研究区长81与长82原油为同一类原油,长9—长7段烃源岩对长8致密油均有贡献,其中以长7烃源岩为主。In order to evaluate the quality of the source rocks in the Chang 9–Chang 7 members in the Ganquan-Fuxian area of the Ordos Basin and explore the hydrocarbon sources of the Chang 8 tight oil.The technical methods of TOC,chloroform asphalt"A",rock pyrolysis parameters,specular mass reflectance,organic matter microfraction,biomarker compounds,and monomeric carbon isotopes were used to study the hydrocarbon generation potential,parent material source,and sedimentary environment of the Chang 9–Chang 7 source rocks in this area.Geochemical analysis and oil-source correlation were performed on the Chang 8 crude oil samples.The results show that:(1)Three sets of dark mudstone mainly developed in the study area,specifically the Chang 9,Chang 8,and Chang 7.The organic matter types of the dark mudstone in the Chang 9–Chang 7 are TypeⅡ1-Ⅱ2;the TOC content ranges from 3.25%to 7.92%,the hydrocarbon generation potential from 3.06 to 38.13 mg/g,and the chloroform asphalt"A"content from 0.18%to 0.69%,identifying them as the best source rocks,all in a high mature evolution stage.(2)The Chang 9-Chang 7 dark mudstone samples formed in a typical freshwater lake environment:the Chang 9 deposits under oxidation-suboxic conditions,the Chang 8 deposits under weak reduction conditions,and the Chang 7 deposits under strong reduction conditions,indicating that the organic matter of the Chang 9-Chang 7 source rocks is derived from a mixed source of lower aquatic organisms and terrestrial higher plants.(3)The Chang 81 and Chang 82 crude oils in the study area belong to the same type.The source rocks of the Chang 9-Chang 7 contribute significantly to the production of the Chang 8 tight oil,with the Chang 7 source rocks being the primary contributors.

关 键 词：鄂尔多斯盆地 烃源岩评价 生物标志化合物 油源对比 

分 类 号：P618.13[天文地球—矿床学]