氦气富集理论及富氦资源勘探思路  

Helium enrichment theory and exploration ideas for helium-rich gas reservoirs

作　　者：秦胜飞[1] 窦立荣[1] 陶刚 李济远 齐雯[2] 李晓斌 郭彬程[1] 赵姿卓 王佳美 QIN Shengfei;DOU Lirong;TAO Gang;LI Jiyuan;QI Wen;LI Xiaobin;GUO Bincheng;ZHAO Zizhuo;WANG Jiamei(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China;Northwest Institute of Eco-Environmental Resources,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油勘探开发研究院西北分院,兰州730020 [3]中国科学院西北生态环境资源研究院,兰州730000

出　　处：《石油勘探与开发》2024年第5期1160-1174,共15页Petroleum Exploration and Development

基　　金：国家自然科学基金专项项目“中西部叠合盆地氦气富集机理与资源潜力”(42141022);国家自然科学基金面上项目“富氦煤层气和页岩气藏氦气富集机理”(42272189);国家自然资源部项目“中石油矿业权区及周边空白区油气资源评价”(QGYQZYPJ2022-1);中国石油天然气集团关键核心攻关项目(2021ZG13)。

摘　　要：基于国内外重要含油气盆地天然气样品和岩石样品,进行氦气含量、组分、同位素及岩石样品中U、Th含量分析,对氦气富集机理、富集模式、分布规律和勘探思路等进行研究。研究认为,能否形成富氦气藏取决于气藏中氦气的供给量和天然气对氦气的稀释程度,其富集成藏特征可以概括为“多源供氦、主源富氦;氦氮伴生、同溶共聚”。氦气主要来自岩石中U和Th的放射性衰变,所有岩石都含有微量的U和Th,都可为气藏提供一定的氦源,但以花岗岩或变质岩为主的大型古老基底往往是富氦气藏的主力氦源。古老基底中的U和Th经历漫长地质历史时期的衰变生成的氦气连同基底岩石中无机含氮化合物裂解生成的氮气溶解在水中,随构造抬升,地层水沿断裂往上运移至气藏并释放出氦和氮气,使气藏同时富集氦和氮气,氦氮的伴生关系十分明显。在东部拉张型盆地,构造活动强烈,天然气中混有一定比例的幔源氦气。富氦气藏大多发育于有断裂沟通的古老基底之上、后期经历大幅度构造抬升、盖层封盖能力适中、天然气充注强度中等、地下水比较活跃的常压或低压区。氦气勘探须放弃以寻找天然气甜点和高产大气田的传统“兼探”思路,根据氦气富集特点,寻找有断裂并与古老基底沟通、晚期构造抬升幅度较大、盖层封盖能力相对较弱、天然气充注强度不高、古老地层水较丰富的气藏。Using gas and rock samples from major petroliferous basins in the world,the helium content,composition,isotopic compositions and the U and Th contents in rocks are analyzed to clarify the helium enrichment mechanism and distribution pattern and the exploration ideas for helium-rich gas reservoirs.It is believed that the formation of helium-rich gas reservoirs depends on the amount of helium supplied to the reservoir and the degree of helium dilution by natural gas,and that the reservoir-forming process can be summarized as"multi-source helium supply,main-source helium enrichment,helium-nitrogen coupling,and homogeneous symbiosis".Helium mainly comes from the radioactive decay of U and Th in rocks.All rocks contain trace amounts of U and Th,so they are effective helium sources.Especially,large-scale ancient basement dominated by granite or metamorphic rocks is the main helium source.The helium generated by the decay of U and Th in the ancient basement in a long geologic history,together with the nitrogen generated by the cracking of the inorganic nitrogenous compounds in the basement rocks,is dissolved in the water and preserved.With the tectonic uplift,the ground water is transported upward along the fracture to the gas reservoirs,with helium and nitrogen released.Thus,the reservoirs are enriched with both helium and nitrogen,which present a clear concomitant and coupling relationship.In tensional basins in eastern China,where tectonic activities are strong,a certain proportion of mantle-derived helium is mixed in the natural gas.The helium-rich gas reservoirs are mostly located in normal or low-pressure zones above ancient basement with fracture communication,which later experience substantial tectonic uplift and present relatively weak seal,low intensity of natural gas charging,and active groundwater.Helium exploration should focus on gas reservoirs with fractures connecting ancient basement, large tectonic uplift, relatively weak sealing capacity, insufficient natural gas charging intensity, and rich ancient f

关 键 词：氦气 富氦气藏 富集理论 分布规律 主控因素 勘探思路 

分 类 号：TE122.2[石油与天然气工程—油气勘探]