塔里木盆地轮探1井寒武系轻质油成藏地球化学特征  

Geochemical characteristics of the Cambrian light crude oil accumulation in Luntan 1 well, Tarim Basin, NW China

作　　者：邓倩 张海祖 王浩哲 于双[1,2] 邓晗宇 韦志伟 李诗达 王云鹏 程斌[1,2] 廖泽文[1,2] DENG Qian;ZHANG Haizu;WANG Haozhe;YU Shuang;DENG Hanyu;WEI Zhiwei;LI Shida;WANG Yunpeng;CHENG Bin;LIAO Zewen(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute ofPetroleum Exploration and Development,PetroChina Tarim Oilfield Company,Korla 841000,Xinjiang,China)

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049 [4]中国石油塔里木油田分公司石油勘探开发研究院,新疆库尔勒841000

出　　处：《地球化学》2023年第1期20-28,共9页Geochimica

基　　金：中国科学院A类战略性先导科技专项(XDA14010103)资助。

摘　　要：轮探1(LT-1)井在8000 m以下的寒武系中获得轻质油,是塔里木盆地超深层油气勘探的重大突破。对LT-1井寒武系轻质油的δ13C、生物标志物地球化学特征开展分析,对LT-1井寒武系玉尔吐斯组干酪根开展催化加氢热解实验,以探讨寒武系轻质油与玉尔吐斯组烃源岩之间的油源关系。结果显示:LT-1井轻质油的δ13C为-32.5‰;低碳数正构烷烃占优势,Pr/Ph值低,反映了其生烃母质还原的沉积环境;三环萜烷(TT)相对含量高,C19~31TT分布完整,以C23TT为主峰,C24四环萜烷丰度低;C27-C28-C29规则甾烷的分布为C29>C27>C28。干酪根催化加氢产物、干酪根抽提物、烃源岩抽提物和原油的成熟度依次增加,体现了不同赋存状态有机质的演化差异,其中干酪根催化加氢产物由于受到干酪根大分子的保护作用而受到热演化的影响最小。综合分析LT-1井的地质背景、δ13C对比关系、生物标志物分布特征及成熟度匹配关系等地质地球化学特征,推测LT-1井轻质油与玉尔吐斯组烃源岩具有亲缘关系,LT-1井8000 m以下轻质油藏的发现表明塔里木盆地超深层仍具有良好的油气勘探前景。Light crude oil was discovered at the Cambrian reservoirs in the 8000 m deep Luntan 1 (LT-1) well,which is a breakthrough in ultra-deep oil and gas exploration in the Tarim Basin.To explore the oil-source relationship between the light oil and Yuertusi source rocks in well LT-1,the carbon isotope composition and biomarker distribution of the light oil were analyzed,and catalytic hydropyrolysis on the kerogens extracted from the Yuertusi source rocks was performed.The results showed that the stable carbon isotope of the light oil from well LT-1 was-32.5‰.The lower carbon numbered n-alkanes were dominant in the light oil,and the low pristane/phytane ratio reflected a reduced depositional environment of its parental source rocks.The biomarkers were characterized by a considerably abundant and complete distribution of C19–31tricyclic terpanes,with C23as the main peak,and the regular steranes as C29>C27>C28.Moreover,the biomarker maturity parameters from the kerogen catalytic hydrogenation pyrolysates,namely the kerogen extract,rock extract,and crude oil showed a tendency to increase.Among them,the catalytic hydrogenation product is the least affected by thermal evolution due to the protection of kerogen macromolecules.A comprehensive investigation of the geological background and correlations of the organic carbon isotope,biomarker distribution,and maturity suggested that the light oil from well LT-1 was related to the underlying Yuertusi formation.The discovery of light oil reservoirs deeper than 8000 m in well LT-1 indicates a good prospect for hydrocarbon exploration at ultra-deep depths in the Tarim Basin.

关 键 词：轮探1井 生物标志物 催化加氢热解 寒武系 塔里木盆地 

分 类 号：P618.13[天文地球—矿床学]