柴达木盆地天然气的碳同位素地球化学特征及成因分析  

Characteristics of Carbon Isotope and Origin of Natural Gas in Qaidam Basin

作　　者：赵东升[1] 李文厚[1] 吴清雅 甘贵元 杨乾政 李元奎 郝小梅 杨武玲 

机构地区：[1]西北大学地质系,西安710069 [2]中国石油青海油田分公司,甘肃敦煌736202

出　　处：《沉积学报》2006年第1期135-140,共6页Acta Sedimentologica Sinica

摘　　要：依据天然气碳同位素中δ13C1、δ13C2、δ13C3的组成与划分标准,将柴达木盆地天然气划分为煤型气、裂解气、油型气与生物气四种类型,通过对天然气同位素中的1δ3C1、1δ3C2-1δ3C1、δ13C3-1δ3C2值的差异分析以及与对应的烃源岩干酪根碳同位素进行对比分析,探讨了柴达木盆地不同地区天然气的成因以及影响因素,这对于探索柴达木盆地的成气规律以及在不同地区天然气勘探的目标选择都有着现实意义。δ^13C1,δ^13C2,δ^13C3,δ^13C4of natural gas isotopic composition are various in different parts of Qaidam Basin. The average of them are - 23.1‰, - 24.1‰, - 22.7‰ and - 23.6‰ in Sanhu area around ; - 29.8‰, - 24.7‰, - 23.1‰ and - 22.9‰ in Chaibeiyuan area; - 39.2‰, - 26.8‰, - 23‰ and - 23‰ in Chaixi area; -67.8‰, -39.2‰, -32.3‰ and lack of -δ^13C4 in Sanhu area. -δ^13C4 〉 -δ^13C3 〉 -δ^13C2 〉 -δ^133C1 exist between component of most natural gas isotope, and reversion of minor heavy carbon isotopic composition exist. Reginally,-δ^13C1,-δ^13C2,-δ^13C3,-δ^13C4 of natural gas isotopic composition decrease gradually from Sanhu area around, Chaibeiyuan area and Chaixi area to Sanhu area. -δ^13C2 --δ^13C1 and -δ^13C3 --δ^13C2 of natural gas isotopic composition increase gradually from Sanhu area around, Chaibeiyuan area and Chaixi area to Sanhu area, the average of them are - 0.8%0 and - 0.9‰ in Sanhu area around, 5.1‰ and 1.3‰ in Chaibeiyuan area, 14.5‰ and 2.3‰ in Chaixi area, 27.9‰ and 12.5‰ in Sanhu area. δ^13C4 〉 δ^13C3 〉 δ^13C2 〉 δ^13C1 Clexist between component of most natural gas isotope because natural gas of or- ganic geneses are derived from the similar process of thermodynamic action, anti reversion of minor heavy carbon isotopic composition exist because of the mixed action of natural gas from the different derivation or the difference of duration, temperatures and pressures in developing hydrocarbon process from the same source rock. The difference between δ^13C2 -δ^13C1 and δ^13C3 -δ^13C2 in different area depend on duration, temperatures and pressures of source rock evolution, the higher temperatures and pressures and the longer duration of source rock evolution, the more uni- form δ^13C distribution between natural gas component, In the meantime, bacteria and types of kerogen have an effect on δ^132 -δ^13C1 and δ^133 -δ^13C2 to some extent. The study on carbon isotope geochemical characteristic, can not only divide types

关 键 词：天然气 碳同位素 成因 柴达木盆地 

分 类 号：P593[天文地球—地球化学]