中国东部幔源CO2气藏的CO2／^3He比率及形成机制  

CO_2/~3He RATIO OF MANTLE-DERIVED CO_2 GAS POOLS AND ITS FORMATION MECHANISM IN EAST CHINA

作　　者：许多[1] 周瑶琪[1] 朱岳年 查明[1] 

机构地区：[1]石油大学油气资源与环境地质研究所,山东东营257062

出　　处：《石油与天然气地质》1999年第4期290-294,共5页Oil & Gas Geology

基　　金：石油大学重点科研基金

摘　　要：我国东部含油气盆地幔源CO2气藏的CO2／3He比率在107－1013之间，与幔源气体脱离玄武岩浆时恒定的CO2／3He比率（2×109～7×109）相比较发生了很大的变化。其中形成于中生代的万金塔CO2气藏，具有109～1013的高CO2／3He比率，而新生代以来形成的黄骅、济阳、苏北、三水等地的幔源CO2气藏，均以107－109的低CO2／3He比率为特征。研究表明，幔源气藏CO2／3He比率的形成受到了幔源气体的释放机制的控制。在玄武岩浆喷溢、侵入为幔源气藏的形成提供大量气源的同时，岩浆房中的幔源气体通过深切岩浆房的断裂通道直接释放，对幔源气藏的形成、幔源气体的补给以及气藏CO2／3He比率等地球化学特征的塑造具有重要作用。同时，我国东部含油气盆地中无机成因CO2气藏的CO2／3He比率特征为气藏的幔源成因提供了新的证据。CO_2/3He ratio of the mantle-derived CO2 gas pools ranges from 107 to 1013 in petroliferous basins in East China.This differs greatly from the constant CO_2/3He ratio of 2×109 ~ 7×109 of the manile-derived CO2 gas whileSeparatng from the basalt magma. The CO2/3He ratio of Wanjingta CO2 gas pool formed in Mesozoic in Sogliao Basinranges from 109~ 1013, but that of the mantle-derived CO2 gas pools formed since Cenozoic in Huangha, Jiyang, Subeiand Shanshui Basins is as low as 107 ~ 109. This indicates that CO2/3He ratio of the mande-derived gas pools is controlled by release mechanism of the gases.The eruption and intrusion of the basalt magma provided a large number ofgas sources for the formation of the mantle-derired gas pools; the CO2 gas in the magma chamber would release directlyalong fault-passages which cut the chamber deeply. This played an important role in the formaion, the gas source supplies, the CO2/3He ratio and geochemical properties of the pools. Meantime, characters of CO2/3He ratio of the inomanic origin CO2 gas pools provide a new evidence for its mantle-derived origin.

关 键 词：CO2/^3He比率 幔源气 断裂 气藏形成 二氧化碳 

分 类 号：P618.130.1[天文地球—矿床学] P593[天文地球—地质学]