南海盆地及邻区CO_2天然气成因类型及特征综述

An overview of characteristics and origin types of CO_2 gas in South China Sea and the adjacent region

利用目前公开发表的资料,对南海盆地CO2天然气的成因类型及特征进行了综合分析和归纳。根据CO2气体的δ13C和伴生的稀有He同位素特征,将CO2分为2大类4种类型,即有机类和无机类,无机类又进一步分为壳源、幔源和壳-幔混合3种类型。研究表明,南海莺歌海盆地-琼东南盆地西部CO2气藏以无机类壳源型为主,可有少量有机类以及无机类幔源型和壳-幔混合型;南海琼东南盆地东部-珠江口盆地和中国东部等地区CO2气藏以无机类幔源型为主,可有少量有机类以及无机类壳源型和壳-幔混合型;而北部湾盆地以有机类为主。

According to the published data,the origin type and characteristics of carbon dioxide are analyzed and concluded comprehensively.Two groups and four types of carbon dioxide are classified as per(13C of carbon dioxide and the characteristics of rare isotope He existing in it.They are organic and inorganic group,the latter includes earth crust type,mantle type and earth crust-mantle mixed type.Studies show that carbon dioxide pools in Yinggehai Basin——the west of Qiongdongnan Basin in South China Sea mainly belong to earth crust type,inorganic group,but sometimes with a little carbon dioxide of organic group,mantle type or earth crust-mantle mixed type of inorganic group existing in them;carbon dioxide pools in the east of Qiongdongnan-Pearl River Mouth Basin and in eastern China are mainly mantle type of inorganic group,but sometimes with a little carbon dioxide of organic group,earth crust type or earth crust-mantle mixed type of inorganic group existing in them;carbon dioxide pools in Beibuwan Basin are mainly organic group.