烃类包裹体赋存碳酸盐矿物U-Pb定年及其在油气成藏期次研究中的应用——以川中震旦系灯影组为例  

U-Pb dating and trapped hydrocarbon inclusions in carbonate for petroleum accumulation:Case study from the Sinian Dengying Formation in the central Sichuan Basin

作　　者：邓宾[1,2] 吴娟[1,2] 李文正 鲁鹏达 田腾振 姜华[3] 杨荣军[3] 王恒 刘树根[1,2,4] DENG Bin;WU Juan;LI Wenzheng;LU Pengda;TIAN Tengzhen;JIANG Hua;YANG Rongjun;WANG Heng;LIU Shugen(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China;PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China;Xihua University,Chengdu 610039,China)

机构地区：[1]成都理工大学“油气藏地质及开发工程”国家重点实验室,四川成都610059 [2]成都理工大学能源学院,四川成都610059 [3]中国石油勘探开发研究院,北京100083 [4]西华大学,四川成都610039

出　　处：《天然气地球科学》2023年第11期1887-1898,共12页Natural Gas Geoscience

基　　金：国家自然科学基金项目“海相深层油气富集机理与关键工程技术基础研究”(编号:U19B6003)资助.

摘　　要：中国西部叠合盆地古老深层碳酸盐岩成岩演化特征复杂,有效定量研究其油气成藏过程是一项关键性技术难题。碳酸盐矿物激光原位U—Pb定年受矿物低放射性元素丰度制约的同时,普遍存在微量元素分馏、质量歧视、普通铅校正等缺点,基于高质量标样、^(207)Pb-和^(208)Pb-校正方法等能有效降低其U—Pb年龄误差值。为有效进行古老碳酸盐岩油气成藏期次年代学研究,采取烃类包裹体赋存碳酸盐矿物U—Pb定年“五步法”分析过程,包括岩心观察、同位制片、显微无损观测分析、原位主—微量元素测试和激光U—Pb定年,能够有效指导定量成藏年代学过程中点位选取,最大限度降低矿物微量元素非均一性等缺陷对测试结果的影响。川中地区震旦系灯影组成藏期次定量化研究表明:灯影组储层流体活动可分为粉晶白云岩/栉壳状白云石(509±38 Ma)→第一期沥青→中—粗晶白云石(453±52 Ma)→鞍形白云石/萤石(240±34 Ma)→第二期沥青→石英多期充注过程。进一步综合研究表明,川中地区筇竹寺组烃源岩历经早寒武世—中奥陶世、早二叠世—三叠纪多期生烃过程,灯影组储层内油气历经早寒武世—中奥陶世、早二叠世—三叠纪幕式油气充注过程,以及侏罗纪—白垩纪原油原位裂解生气成藏过程。The diagenetic evolution of ancient deep carbonate rocks in the western superposition basin of China is complex,and it is a key technical challenge to effectively quantitatively study their hydrocarbon formation and reservoir processes.While laser in situ U-Pb dating of carbonate minerals is constrained by the abundance of low radioactive elements in the minerals,there are common shortcomings such as trace element fractionation,mass discrimination,and common lead correction,etc.Based on high-quality standard samples,the ^(207)Pb-and ^(208)Pb-corrected methods can effectively reduce the error value of their U-Pb ages.In order to effectively carry out the geochronology study of the oil and gas formation period in ancient carbonate rocks,by the“five-step”analysis of U-Pb dating of carbonate minerals which trapped hydrocarbon inclusions,including core observation,cutting in the same place,microscopic nondestructive observation and analysis,in-situ main-trace element testing and laser ablation U-Pb dating,which can effectively guide the quantitative formation geochronology process.It can effectively guide the selection of points in the process of quantitative diagenesis and minimize the influence of defects such as non-uniformity of mineral trace elements on the test results.The quantitative study on the storage period of the Sinian Dengying Formation in the central Sichuan Basin shows that the reservoirs fluid activity of the Dengying Formation can be divided into the process of dolomicritem or silt crystalline dolomite(509±38 Ma)→bitumen-Ⅰ→medium-coarse crystal dolomite(453±52 Ma)→saddle dolomite/fluorite(240±34 Ma)→bitumen-Ⅱ→quartz multi-phase infilling process.Further comprehensive studies show that the hydrocarbon source rocks of the Qiongzhusi Formation in the central Sichuan Basin have gone through the Early Cambrian-Middle Ordovician and Early Permian-Triassic multi-phase hydrocarbon generation processes,and the hydrocarbons in the reservoirs of the Dengying Formation have gone through the

关 键 词：灯影组 成藏期次 U-PB年代学 烃类包裹体 川中地区 

分 类 号：TE121.12[石油与天然气工程—油气勘探]