临南地区煤成气藏成因分析

济阳坳陷广泛分布石炭系和二叠系 ,但是此地层煤成气的成藏问题一直没有获得突破。临南地区曲古 1井产出的天然气证明是源自石炭系和二叠系煤岩。对该地区煤系地层的地球化学特征进行了研究 ,结果表明 ,该煤系具有较大的生烃潜力 ,并经历了 4次生烃过程 ,燕山期和喜山期是主要生烃期。对煤系烃源岩生、排烃期次、构造活动以及煤成气成藏期次的研究认为 ,曲古 1井煤成气藏有两种成因 :①原生气藏在喜山期被破坏后再次聚集而成 ;②埋藏较深的石炭系和二叠系烃源岩在新近纪再次生烃。因此 ,临南地区在燕山期和喜山期形成的圈闭是有利的煤成气勘探目标区。

Genetic analysis of coal-bed methane reservoir in Linnan area

The Carboniferous-Permian System is abroad distributed in Jiyang Depression, but there hasn't found accumulation of coal-bed methane. The gas produced from Qugu-1 Well in Linnan area proved that the main gas source rock was the coal bed of the Carboniferous-Permian System. The geochemistry study showed that the hydrocarbon source rock in coal bed had a great potential for generating hydrocarbon, and there was four periods of hydrocarbon generation. Yanshan period and Xishan period were the main hydrocarbon generation periods. The interrelation of generation-expulsion periods of hydrocarbon source rock in coal bed, structural activity and accumulation period of coal-bed methane was studied. There were two causes for generating gas pool. One was the secondary gas pool formed after primary pool destroyed in Xishan period. The other was the gas pool formed by secondary hydrocarbon generation of the deep Carboniferous-Permian system resource rock in the Later Tertiary system. The traps formed in Xishan and Yanshan periods are the favorable exploration target of coal-bed methane in the future.