辽河盆地东部凹陷南部地区天然气的同位素特征及成因

Gas isotope characteristics analysis in the south of eastern sag in Liaohe Basin

为了确定辽河盆地东部凹陷南部地区天然气的气源、类型、成熟度及沉积环境特征,对该区天然气中氦、氩、碳和氢同位素测定数据进行了系统的分析。结果表明,该区为构造活动区,区内的天然气主要为有机成因,偶有无机气混入;该区天然气存在多个气源,既有“自生自储”的原生气藏,又有运移而来的次生气藏;区内发育生物气、低成熟-成熟油型气、高成熟油型气、过成熟油型气及煤型气5种类型的天然气,且以低成熟-成熟的油型气和高成熟油型气为主;该区天然气源岩主要形成于淡水—半咸水的河流及湖泊环境。

In order to make gas sources, types, maturity and sedimentary environment clear in the south of eastern sag of Liaohe Basin,i sotope assay data of helium,argon,carbon and hydrogen of the natural gas in this area are analyzed. The result is that this area was a structurally active zone. Gases in this area were mainly organic origin with occasional invasion of inorganic gas. There were many gas sources in this area,including both 'source and resefvoir in the same bed' primary gas reservoir and secondary gas reservoir formed by migration. Five types of gas developed in the area,which are biogas,less mature and mature petroliferous gas,highly mature petroliferous gas,over - mature petroliferous gas and coal - related gas, with less mature and mature petroliferous gas and highly mature petroliferous gas as the main. The gas source rocks in this area were mainly formed in fresh - brackish fluvial and lake environment.