同源常规-非常规天然气组分与同位素分馏差异及控制因素——以四川盆地石炭系黄龙组与志留系龙马溪组为例  

Differences and control factors of chemic and isotopic fractionation of conventional-unconventional natural gas of the same source:Take the Carboniferous HuanglongFormation gas and Silurian Longmaxi Formation shale gas in Sichuan Basin as example

作　　者：黄士鹏[1] 冯子齐 姜华[1] 唐友军[3] 江青春[1] 吴伟 戴金星[1] HUANG Shipeng;FENG Ziqi;JIANG Hua;TANG Youjun;JIANG Qingchun;WU Wei;DAI Jinxing(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083;School of Geosciences,China University of Petroleum(East China),Qingdao 266580,Shandong;Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education(Yangtze University),Wuhan 430100,Hubei;Shale gas Research Institute,PetroChina Southwest Oil&Gasfield,Chengdu 610051,Sichuan)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]油气资源与勘探技术教育部重点实验室(长江大学),湖北武汉430100 [4]中国石油西南油气田公司页岩气研究院,四川成都610051

出　　处：《长江大学学报（自然科学版）》2023年第5期34-46,共13页Journal of Yangtze University(Natural Science Edition)

基　　金：中国石油天然气股份有限公司科学研究与技术开发项目“海相碳酸盐岩成藏理论与勘探技术研究”(2021DJ05);“重点盆地综合地质研究与勘探潜力评价”(2022KT0405)。

摘　　要：当前中国已经进入常规-非常规油气并举勘探时代。四川盆地是我国最重要的天然气产区之一,常规、非常规气资源有序聚集。前人对相同烃源来源的石炭系黄龙组常规天然气(以下简称黄龙组天然气)和龙马溪组非常规页岩气(以下简称龙马溪组页岩气)地球化学组成差异及控制因素的研究较薄弱,为此通过大量的常规、非常规天然气组分、同位素和稀有气体组成分析,结合实际地质条件,对黄龙组天然气和龙马溪组页岩气地球化学组成差异进行了详细分析,并探讨了形成差异的控制因素,取得以下认识:①受成熟度、储层岩性、参与裂解物质等因素影响,同源的黄龙组天然气和龙马溪组页岩气组分和同位素组成差异明显;②黄龙组天然气CH_(4)含量一般低于龙马溪组,而前者重烃气含量稍高,主要是由于成熟度差异导致;③龙马溪组页岩气中有机质热降解生成的H_(2)S易与金属反应而被消耗掉,导致页岩气中不含H_(2)S,黄龙组天然气中H_(2)S应来源于有机质热降解;④黄龙组天然气CO_(2)含量明显高于龙马溪组页岩气,与碳酸盐岩矿物高温分解关系密切,页岩中的N_(2)含量低,是由于N_(2)快速的运移扩散速率所导致;⑤成熟度越高,同源常规气与非常规气CH_(4)碳同位素分馏程度越大,重烃气碳同位素也有类似特征,但是分馏程度没有CH_(4)明显;⑥封闭体系内不同母质来源(干酪根、滞留油和湿气)裂解生成天然气的混合导致高-过成熟页岩气出现负碳同位素系列(δ^(13) C_(1)>δ^(13)C_(2)>δ^(13)C_(3)),而先期形成的伴生气与后期形成的原油裂解气混合是造成黄龙组天然气倒转(δ^(13)C_(1)>δ^(13)C_(2)<δ^(13)C_(3))的主要原因。At present,China has entered the era of conventional and unconventional oil and gas exploration.Sichuan Basin is one of the most important natural gas producing basins in China,with orderly accumulation of conventional and unconventional gas resources.Previous studies on the differences in geochemical compositions and controlling factors of conventional gas in the Carboniferous Huanglong Formation(Fm)and Silurian Longmaxi Fm shale gas with the same source rock are relatively weak.Based on a large number of conventional and unconventional natural gas components,isotopes and rare gas composition analysis,combined with geological conditions,the differences in the geochemical composition of conventional gas in Huanglong Fm and shale gas in Longmaxi Fm are analyzed in detail,and the controlling factors for the differences are also discussed.The following understandings are obtained:①Affected by maturity,reservoir lithology,substances involved in cracking and other factors,the chemical and isotopic compositions of conventional gas in Huanglong Fm and shale gas in Longmaxi Fm are obviously different;②The methane content of conventional gas in Huanglong Fm is generally lower than that in Longmaxi Fm,while the content of heavy alkane gases in the former is slightly higher,which is mainly due to the difference in maturity;③Hydrogen sulfide generated by thermal degradation of organic matter in Longmaxi Fm shale gas is easily consumed by reaction with metals,resulting in no hydrogen sulfide in shale gas.Hydrogen sulfide in conventional gas of Huanglong Fm should come from thermal degradation of organic matter;④The carbon dioxide content of conventional gas in Huanglong Fm is obviously higher than that of shale gas in Longmaxi Fm,which is closely related to the high-temperature decomposition of carbonate minerals;The low content of N_(2) in shale is due to the rapid migration and diffusion rate of it;⑤The higher the maturity,the greater the fractionation degree of methane carbon isotope of conventional and unconvent

关 键 词：常规天然气 页岩气 地球化学特征 控制因素 黄龙组 龙马溪组 四川盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探]