【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。更多还原

【Abstract】 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 formation water, depending on the characteristics of helium enrichment, beyond the traditional idea of searching for natural gas sweetspots and high-yield giant gas fields simultaneously.更多还原