中国东部天然气分布特征

Distribution Characteristics of Natural Gas in Eastern China

中国东部天然气成因类型多,主要为有机成因的烷烃气、无机成因的烷烃气和无机成因的CO23种类型。目前发现的有机成因烷烃气大气田主要分布在大陆架上的莺琼盆地(崖13-1气田、乐东22-1气田和东方1-1气田)、珠江口盆地(番禺30-1气田)、东海盆地(春晓气田)和台西盆地(铁砧山气田),天然气乙烷碳同位素较重,δ13C2值大于-28‰,成因类型为煤成气;无机成因的烷烃大气田分布在松辽盆地的深层(如兴城气田等),天然气具有甲烷碳同位素较重(δ13C1值大于-30‰)、负碳同位素系列和R/Ra>0.5等特征;CO2气田(藏)分布较广,从北部的松辽盆地至南部的莺琼盆地均有分布,共发现有35个CO2气田(藏),这些气田(藏)具有CO2含量均大于60%,δ13CCO2值大于-8‰的分布特征。

There are various genetic types of natural gas in eastern China, which are mainly biogenic hydrocarbon gas, abiogenic hydrocarbon gas and inorganic CO2. Large biogenic hydrocarbon gas fields discovered at present are mainly distributed in the Ying-Qiong basin （Ya 13-1 gas field, Ledong 22-1 gas field, Dongfang 1-1 gas field）, Pearl River Mouth basin （Panyu 30-1）, Eastern China Sea basin （Chunxiao gas field） and Taixi basin （Tiezhanshan gas field） in the Continental Shelf, and ethane carbon isotope is heavier than -28‰, which shows that the gas is coal derived. Large abiogenic hydrocarbon gas fields are distributed in the deep part of Songliao basin （Xingcheng gas field, etc）, and the natural gas is characterized by heavy methane carbon isotope （δ^13C1〉-30‰）, negative carbon isotope series and R/Ra〉0.5. The distribution of CO2 gas fields （gas reservoirs） is wide from the Songliao basin in north to the Ying-Qiong basin in south, and total 35 CO2 gas fields （gas reservoirs） have been discovered in these areas with CO2 content more than 60% and δ^13CCO2 heavier than -28‰.