松辽盆地天然气中稀有气体地球化学特征及其地质意义

Geochemical characteristics and geological significance of noble gases in natural gas from Songliao Basin, China

李伟 陈践发 王杰 王晓波 何大祥 王东良 刘凯旋 尤兵 陈聪 付娆 唐帅旗 张佳琦

LI Wei CHEN Jianfa WANG Jie WANG Xiaobo HE Daxiang WANG Dongliang LIU Kaixuan YOU Bing CHEN Cong FU Rao TANG Shuaiqi ZHANG Jiaqi

1. 中国石油大学(北京) 地球科学学院 油气资源与工程全国重点实验室, 北京 102249; 2. 天水师范学院 资源与环境工程学院, 甘肃 天水 741000; 3. 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; 4. 中国石油天然气股份有限公司 勘探开发研究院, 北京 100089; 5. 长江大学 湖北省油气地球化学与环境重点实验室, 武汉 430100

1. National Key Laboratory of Petroleum Resources and Engineering, College of Geosciences, China University of Petroleum (Beijing), Beijing 102249, China; 2. School of Resources and Environmental Engineering, Tianshui Normal University, Tianshui, Gansu 741000, China; 3. Wuxi Research Institute of Petroleum Geology, SNOPEC, Wuxi, Jiangsu 214126, China; 4. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100089, China; 5. Hubei Key Laboratory of Oil & Gas Geochemistry and Environment, Yangtze University, Wuhan, Hubei 430100, China

稀有气体地球化学已运用于地球深部物质及天体陨石研究，随着测量技术的进步，在天然气研究中也开始得到越来越多的应用。使用目前最先进的稀有气体质谱仪，对中国东部松辽盆地中深部天然气的稀有气体全组分丰度及同位素进行了系统的分析，明确了断陷盆地稀有气体的组成特征。研究表明，天然气中稀有气体的丰度从轻稀有气体到重稀有气体具有逐渐减小的反“厂”字形趋势。稀有气体的同位素比值3He/4He为2.64×10-6、20Ne/22Ne为9.94、21Ne/22Ne为0.029 22、40Ar/36Ar为743.7，均高于大气值，80Kr、84Kr、86Kr、131-136Xe均表现出相对大气过剩的特征，显示天然气中有幔源气体的混入。综合稀有气体的组成特征，说明松辽盆地中深部天然气均为壳幔混源的无机成因，而且不同构造区块、不同类别天然气的幔源组分贡献存在一定差异。对比稀有气体组成与天然气类型发现，轻稀有气体可以较好地区分天然气的类型，而重稀有气体的组成在各种天然气中没有明显差别。稀有气体同位素除了可以示踪天然气来源外，还可以应用在判别天然气成因、区分天然气类型、表征大地构造等方面。

Geochemistry of noble gases has been applied to the study of deep Earth materials and celestial meteorites. With advancements in measurement technology, it is also increasingly being used in natural gas research. Using the most advanced noble gas mass spectrometer, a systematic analysis was conducted on the abundance and isotopes of noble gas samples collected from the middle and deep Songliao Basin in eastern China to elucidate the compositional characteristics of noble gases in a faulted basin. The findings reveal that the abundance of noble gases in natural gas decreases from light noble gases to heavy noble gases in a left-to-right reversed L-shaped pattern. Specifically, the isotopic ratios of noble gases are: 3He/4He at 2.64×10-6, 20Ne/22Ne at 9.94, 21Ne/22Ne at 0.029 22, and 40Ar/36Ar at 743.7, all of which are higher than atmospheric values. The isotopes 80Kr, 84Kr, 86Kr, and 131-136Xe show relative excess compared to atmospheric levels, indicating the mixing of mantle-derived gases in the natural gas. Based on the compositional characteristics of noble gases, this study suggests that the natural gas in the middle and deep Songliao Basin originated from inorganic crust and mantle mixing. Additionally, certain differences exist in the contribution of mantle-derived components across different tectonic blocks and categories of natural gas within the basin. Comparison between noble gas compositions and the types of natural gas demonstrates that light noble gases distinguish effectively between different types of natural gas, whereas the composition of heavy noble gases shows no significant differences among various types of natural gas. Noble gas isotopes, in addition to tracing the source of natural gas, can also be used to determine natural gas genesis, distinguish natural gas types and characterize tectonic settings.

国家重点研发计划项目(2021YFA071900)、“十三五”国家科技重大专项(2016ZX05007003-004)、甘肃省教育科技项目(2022QB-146)和天水师范学院基金项目(CXJ2020-27)联合资助。

https://doi.org/10.11781/sysydz202403576