辽河东部凹陷天然气地球化学特征及深层天然气勘探潜力

Gas geochemistry and deep gas exploration potential in Eastern Liaohe Depression

对辽河东部凹陷天然气地球化学特征及其判识标志、不同类型烃源岩生成气态烃的地球化学特征、气源岩进行研究,分析认为:目前发现的天然气以低成熟的煤型气为主,局部为成熟煤型气;经气源对比,煤型气源岩以s3为主;除煤型气外,局部存在油型气、原生生物气和原油菌解气等类型。利用δ13C-Ro关系,结合东部凹陷成熟度-深度关系进行研究,结果表明:目前发现的天然气主要为深度在4 300 m以上、Ro<1.0%的浅源岩层;深源岩层(4 300～7 000m)生成的高成熟天然气探明量较少,仅在红星地区深层少量分布。由此推测,深层天然气勘探潜力较大。

The research on gas geochemistry,identification marker and gas source rock in Eastern Liaohe Depression indicates that currently discovered natural gas is mainly coal related gas of low maturity,with some local mature coal related gas;gas-source correlation shows that s3 is the dominant coal related gas source rock;except coal related gas,there are locally oil related gas,biogas and bacterial degradation gas,etc.Based onδ13C-Ro and the relationship of maturity and depth in this depression,the result shows that most of the gas currently discovered so far is deeper than 4 300 m,generated from shallow source with Ro less than 1.0%;highly mature gas generated from deep source rock(4 300～7 000 m) is only discovered in the deep Hongxing area with limited proved reserves,therefore it is presumed that there is big potential in deep gas exploration.