松辽盆地北部昌德东气藏CO成因的地球化学判据

Geochemical Criterion of CO Origin of Changdedong Gas Deposit in North of Songliao Basin

谈迎 张长木 刘德良

TAN Ying ZHANG Chang-mu LIU De-liang

中国科学技术大学 地球与空间科学院, 安徽 合肥 230026; 中科院 南京紫金山天文台 天体化学和行星科学实验室, 江苏 南京 210008; 中国石化 江苏油田 勘探开发研究院, 江苏 扬州, 225009

The Earth and Space Science Department, University of Science and Technology of China, Hefei 230026, China; The Cosmochemical and Geochemical Center, The Purple Mountain Observatory, Nanjing 210008, China; Jiangsu Oil Exploration Corp., Yangzhou 225009, China

CO2气藏中CO2的百分含量、CO2伴生的烃类气体含量、稀有气体的含量及同位素、CO2产出的地质背景、δ13CCO2以及伴生甲烷同系物的碳同位素系列等特征都可以用来对CO2成因进行判别。昌德东气藏天然气中的CO2含量最高(89%~90%), CO2的碳同位素值为-4.06‰~-6.61‰, 落在无机成因区, 3He/4He值为3.9×10-6和4.5×10-6, 介于幔源与壳源之间, 伴生甲烷同系物的碳同位素都呈倒序排列, 具有无机成因气负碳同位素系列的特征。对其更具体的母源区的判别有赖于对松辽盆地北部深部地质结构的研究及CO2/3He等新的CO2成因判据的探索。

Several characters of CO2 deposits can be used to judge the origin of CO2, such as the percent of CO2, the percent of companion hydrocarbon, the percent of inert gases and their isotopes, geology background of CO2 generation, δ13CCO2 and carbon isotopes of companion methane homologous series. The percent of CO2 in Changdedong gas deposit is 89%~90%, δ13CCO2 is-4.06 ‰~-6.61 ‰, which is belong to the area of inorganic origin, 3He/4He is 3.9 ×10-6 and 4.5 ×10-6, which is between the mantle origin and crust origin. Carbon isotopes of companion methane homologous series reverse order, which have the character of inorganic origin. The judgement of more detail origin of this CO2 deposit is dependent on the researching of deep geology structure of northern Songliao basin and exploring new geochemical criterions such as CO2/3He, etc.

本文系"九五"国家攻关重点项目(99-110-01-03);国家基金资助项目(40472074)中的部分内容