英台断陷深层天然气成因分析及气源对比

松辽盆地南部深层天然气资源丰富,但其烃类气既存在有机成因气(包括油型气和煤型气),亦存在无机成因,还存在混合成因,在同位素序列上常表现为部分倒转和完全倒转。为了明确英台断陷天然气的成因及来源,根据烃源岩的地化指标、天然气组分、碳同位素以及轻烃指纹对研究区的天然气成因类型加以分析,并进行气源对比。研究表明,英台断陷烃类气为凝析油伴生气和煤型气的混合,其中南部洼槽天然气主要来自于沙河子组,而北部则来自于营城组。通过判定天然气成因的类型和识别气源方向,有利于加深对英台断陷深层天然气成藏条件和成藏模式的认识,从而为研究天然气藏的分布规律,以及下一步的天然气勘探指引方向。

Causes Analysis of Deep Natural Gas and Correlation of Gas Soure in Yingtai Fault Depression

The southern Songliao Basin have abundant natural gas source. But the genetic type of hydrocarbon gas are organic, abiogenetic and mixed. The organic type includes coal-formed gas and oil-formed gas. It perform as part-inversion and complete- inversion. To definite the source and origin of natural gas in Yingtai fault depression, according to geochemistry index, natural gas component, carbon isotopic and light hydrocarbon fingerprints of hydrocarbon source rocks, we analyze the genetic type of natural gas in the area of interest and correlate the source of natural gas. It can be concluded that the hydrocarbon gas in Yingtai fault depression contains the composition of condensate-associated gas and coal-formed gas. The natural gas in the southern sag mainly origins from Sahezi Group, and the northern are from Yingcheng Group. It affiliates to enhance the cognition of the hydrocarbon accumulation condition and accumulation model, in order to direct the research for the accumulation and distribution principle of natural gas and the further natural gas exploration.