有效氦源岩类型及氦气释放机理  

Characteristics of effective helium source rocks and releasing mechanism of helium

作　　者：王晓锋 赵栋[1] 张东东[1] 李孝甫 陈科羽 刘文汇 WANG Xiaofeng;ZHAO Dong;ZHANG Dongdong;LI Xiaofu;CHEN Keyu;LIU Wenhui(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China)

机构地区：[1]西北大学地质学系,大陆动力学国家重点实验室,陕西西安710069

出　　处：《天然气地球科学》2025年第3期381-389,共9页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:42472187);国家重点研发计划项目(编号:2021YFA0719002)联合资助.

摘　　要：不同类型氦源岩特征各异、母体元素(U、Th)含量和赋存状态差异显著。沉积岩中的原生U、Th主要以有机质和黏土矿物吸附、络合的形式赋存。由于缺乏矿物晶体的束缚,沉积岩中生成He的初次运移比较容易。为气藏作出贡献的有效烃源岩和气藏的储集层是沉积岩中最主要的有效He源岩,除此之外的其他类型沉积岩,由于高的孔隙度造成He溶解饱和时间较长,氦的脱溶与二次运移受限。岩浆岩中U、Th主要以类质同象形式富集于硅酸盐和磷酸盐矿物中,温度是影响其初次运移的主要控制因素。花岗岩孔隙度小,溶氦能力低,体积巨大,地层抬升和异常高温可造成He的大规模释放,是壳源富氦天然气的重要源岩类型。变质岩中U、Th存在多种赋存形式,岩石孔隙度一般高于花岗岩,地层水溶He能力较强,He较难释放。虽然天然气藏的直接烃源岩和储集层是有效He源岩,但是由于烃类稀释作用的影响,很难形成富He天然气。充足的盆地基底或者地幔来源的He是天然气藏富He的关键条件。Different helium source rocks are characterized by varying characteristics,precursor element(U,Th)contents and occurrence states.U and Th in sediments primarily exist in the forms of adsorption and/or complexation with organic matter and clay minerals.The primary migration of helium generated in sediments is more likely to occur due to the absence of mineral crystal restraints.Therefore,the source rocks and reservoir rocks of gas pools act as the primary effective helium source rocks in sediments,while other sediments are not effective helium source rocks due to the fact that high porosity causes long saturation time of helium dissolution,thereby restraining the desolubilization and secondary migration of helium.Isomorphous U and Th were mainly enriched in silicate and phosphate minerals in magmatic rocks,and temperature acts as the main controlling fac⁃tor affecting their primary migration.Granite is characterized by low porosity and low dissolution of helium,large-scale release of helium can happen under uplift movement and abnormal high temperature,acting as the he⁃lium source rock of helium-rich natural gases.Various forms of U and Th can exist in metamorphic rocks,which have higher porosity and higher soluble helium contents than granite,but this results in greater difficulty in heli⁃um release.Although the direct source rocks and reservoirs of natural gas reservoirs are effective helium source rocks,it is difficult to form He-rich natural gas due to the influence of hydrocarbon dilution.Sufficient He supply from basin basement or mantle-derived sources is a key condition for natural gas reservoirs to be rich in He.

关 键 词：有效氦源岩 富氦天然气 氦溶解饱和时间 氦初次运移 氦脱溶与二次运移 

分 类 号：TE132.1[石油与天然气工程—油气勘探]