阜新盆地白垩系阜新组煤层气系统

Cretaceous Fuxin Formation coalbed methane system in Fuxin Basin

运用非常规含油气系统的理论和方法研究阜新盆地煤层气系统地质特征。阜新组孙家湾煤层组、中间煤层组和太平煤层组是煤层气的生储层。阜新组上部砂质泥岩、泥质粉砂岩、粉砂岩为阜新组煤层气的盖层,盖层条件中等。上覆岩层是阜新组上部及孙家湾组。阜新组煤层的第一次生气高峰出现在孙家湾期末,此时镜质体反射率最大达到0.67%;后来喜马拉雅期辉绿岩的侵入导致煤层到达第二次生气高峰,在靠近岩浆侵入位置的局部地区镜质体反射率最大达到4.95%;另外,地表降水下渗带入细菌导致煤层产生大量次生生物气,而后进入煤层气保存期。煤层气系统的关键时刻是古近纪晚期。阜新组煤层气系统的特征表明,盆地阜新组煤层气具备进一步勘探开发的前景。

The Fuxin Formation coalbed methane system is studied using the theory and method of non-conventional petroleum system. The source and reservoirs are Sunjiawan, Zhongjian and Taiping coal seams of the Fuxin Formation. The coalbed methane is sealed by the roof comprised by mudstone, siltstone, and bauxite of the upper Fuxin Formation. The overburden is the upper Fuxin Formation and the Sunjiawan Formation deposits. The hydrocarbon generation of the source rocks reaches its first peak in the late Sunjiawan period, and the highest maturity is about Ro =0.67%. The dolerite intrusion during the Himalayan orogeny enhances the coal maturity and causes a second peak of hydrocarbon generation with the highest maturity up to 4.95 % at local areas. The underwater brings many bacteria generating second biogenic methane. Then the coalbed methane is reserved and the critical moment of the coalbed methane system is at the end of the Late Paleogene Period. The Fuxin Formation coal seams are favorable for coalbed methane exploration.