四川盆地东北部飞仙关组高效气藏形成机理

Formation Mechanism of Highly Effective Gas Pools in the Feixianguan Formation in the NE Sichuan Basin

最近10年,四川盆地东北地区发现了一批飞仙关组鲕滩高效气藏。本文通过对大量实验测试数据的分析整理以及成藏过程的模拟研究,提出了高效气藏形成机理。指出古油藏及分散液态烃在燕山中期快速升温条件下,形成高效气源灶,为高效气藏的形成提供了丰富的气源;优质鲕粒白云岩储集层经历6个阶段的演化历史,受控于沉积相带、烃类充注、深埋藏条件下强烈溶蚀以及多期断层活动;二叠系烃源岩与飞仙关组储集层存在强大的剩余压力差,为油气沿断层发生优势输导提供强大动力;燕山晚期—喜马拉雅期的构造作用,使得气藏发生调整与改造。

Several highly effective gas pools have been explored in the Feixianguan Formation in the NE Sichuan Basin for nearly 10 years. Based on geological analysis of data and modeling, the mechanism of highly effective gas pools is pointed out in this paper. In the mid--late Jurassic, high rate of tectonic subsidence and huge thickness overburden rock resulted in high temperature that is an advantageous condition for secondary cracking gas to occur. High-quality reservoir rocks of oolitic dolomite evolved in 6 stages, and led to the key factors, facies, hydrocarbon charge, corrosin in deep burial, and multistage faulting. High residual pressures difference between Permian source and reservoirs in the Feixianguan Formation occurred that is a driving force for hydrocarbon migration along faults. In the late Yanshanian to Himalayan, strong structural deformation resulted in adjusting and altering of gas reservoirs.