川东北地区海相碳酸盐岩油气成藏作用及其差异性——以普光、毛坝气藏为例

对普光气藏与毛坝气藏的成藏要素、天然气和沥青特征、气源、成藏演化和成藏机制等进行对比分析,研究川东北地区海相碳酸盐岩油气成藏作用的差异性及其原因.普光飞仙关组、长兴组气藏与毛坝长兴组气藏的成藏作用具有较大的相似性,但毛坝飞仙关组气藏成藏作用在时间、空间和天然气成分上却有明显差异.川东北地区气藏具有多层系源和多转化源,表现为各气藏具有明显的来源差异.海相碳酸盐岩地层中受特殊沉积相带控制的特殊储集层的发育对油气藏分布具有重要的影响;多旋回叠合盆地复杂的构造演化背景在宏观上控制油气成藏要素,从根本上制约成藏规律和成藏机制,是导致海相碳酸盐岩差异成藏的根本原因.

Characteristics and differences of hydrocarbon accumulations in marine carbonate rocks, northeast Sichuan Basin: A case study from Puguang and Maoba gas fields

The comparison of the accumulation elements, natural gas and bitumen characteristics, gas sources, accumulation evolution and mechanisms between the Puguang and Maoba gas reservoirs indicates that the Feixianguan Formation and Changxing Formation gas reservoirs in Puguang and the Changxing Formation gas reservoir in Maoba are similar in hydrocarbon accumulation. But the Feixianguan Formation hydrocarbon accumulation in Maoba is obviously different in terms of time, space and gas composition. The gas reseruoirs include gases generated by multilayer source rocks and by multi-transformation sources in northeast Sichuan Basin, and the gas reservoirs present different sources. Special reservoir beds controlled by special sedimentary facies are very important to hydrocarbon accumulations. The complex structural evolution of the polycyclic superimposed basin macroscopcially controlled the hydrocarbon accumulation elements and restricted the regularity and mechanism of the hydrocarbon accumulations. It is the ultimate reason for the differences.