鄂尔多斯盆地富县古生界天然气成因及气源综合识别  

Comprehensive evaluation on origin and source of natural gas in the Paleozoic in Fuxian area,Ordos Basin

作　　者：王杰[1,2] 贾会冲[3] 孙晓[3] 陶成[1,2] 张毅[1,2] 马亮帮 王付斌[3] 姜海健[1,2] WANG Jie;JIA Huichong;SUN Xiao;TAO Cheng;ZHANG Yi;MA Liangbang;WANG Fubin;JIANG Haijian(SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi 214126,China;Wuxi Research Institute of Petroleum Geology,SINOPEC,Wuxi 214126,China;Research Institute of Exploration and Development,Huabei Company,SINOPEC,Zhengzhou 450006,China)

机构地区：[1]中国石油化工集团公司油气成藏重点实验室,江苏无锡214126 [2]中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡214126 [3]中国石化华北油气分公司勘探开发研究院,河南郑州450006

出　　处：《天然气地球科学》2022年第9期1476-1484,共9页Natural Gas Geoscience

基　　金：国家自然科学基金“海相深层不同类型有机质Re—Os赋存形式及年龄地质意义”(编号:42072154);中国石化股份公司科技部鄂尔多斯项目群“鄂尔多斯盆地古生界资源潜力评价”(编号:P17009-2);“鄂尔多斯盆地元古—下古生界目标评价与关键技术”(编号:P20043)联合资助

摘　　要：近年来,鄂尔多斯盆地南部(简称鄂南)古生界天然气勘探取得重要进展,展示了良好的勘探前景,但鄂南古生界天然气成因及气源研究相对薄弱,直接制约了下一步的勘探部署。为此通过系统开展富县古生界天然气组分、烷烃气碳氢同位素、稀有气体组分和同位素等地球化学分析,查明了鄂南富县古生界天然气中甲烷占绝对优势,含有一定量的重烃,非烃气CO_(2)、N_(2)含量相对较高,显示其为过成熟阶段生成的干气。鄂南富县古生界天然气以典型油型气为主,煤型气为辅,甲烷和乙烷的碳同位素组成存在倒转现象可能为油型气与煤型气的混合造成,上古生界天然气烷烃气碳同位素组成普遍比下古生界天然气偏重,可能混有相对较多的煤型气。综合运用烃源岩干酪根碳同位素—岩石脱附气碳同位素—天然气乙烷碳同位素、天然气甲烷氢同位素、稀有气体Ar同位素定年等综合地球化学手段,推断出鄂南富县古生界天然气可能主要来源于下古生界马家沟组烃源岩。In recent years,important progress has been acquired in the exploration of natural gas in the Paleozoic in the southern part of the Ordos Basin,which has shown a good exploration prospect.However,the study on the origin and source of natural gas in the Paleozoic in the area is relatively weak,which directly restricts the next exploration project in the Paleozoic in the southern part of the Ordos Basin.By means of systematic analysis of gas components,carbon and hydrogen isotopes,noble gas components and isotopes in the Paleozoic natural gas in Fuxian area,it is found that methane is the absolute dominant component in the natural gas with a certain amount of heavy hydrocarbons,and the carbon dioxide and nitrogen content is relatively high.The above characteristics show that the Paleozoic natural gases in Fuxian area are dry gases generated in over mature evolution.According to isotopic characteristics,it is concluded that the Paleozoic natural gases in Fuxian area are dominated by typical oil-type gas,supplemented by coal-type gas.The inversion of carbon isotopic composition of methane and ethane may be caused by the mixing of oil-type gas and coal-type gas,and the oil-type gas is predominant in the natural gas.The carbon isotopes of the Upper Paleozoic hydrocarbon gas are relatively heavier than that of the Lower Paleozoic,which shows that the Upper Paleozoic gas may be mixed with more coal type gas.By means of comprehensive geochemistry such as the carbon isotope of source rocks desorption gas and natural gas and kerogen,methane hydrogen isotope and argon isotopic dating method,it demonstrates that the Paleozoic natural gas in Fuxian area in the southern part of Ordos Basin mainly originated from the source rocks of the Majiagou Formation in the Lower Paleozoic.

关 键 词：天然气成因 气源判识 富县 古生界 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]