裂谷盆地侵入岩区油气成藏系统研究——以济阳坳陷罗家地区为例

Study on Oil Gas Reservoir Forming System in Intrusive Rocks Region of Rift Basins——a Case of Luojia Area,Jiyang Depression

裂谷盆地侵入岩区往往油气分布复杂,成为油气勘探的重要领域。为了深入探讨这类油气藏的地质特征,从成藏系统角度出发,运用地质和地球化学等方法,分析了济阳坳陷罗家侵入岩区油气藏的成藏要素和成藏过程。结果发现,侵入岩的高温高压不仅显著促进了附近源岩生烃,而且使之生成大量裂缝和孔隙;再者侵入岩形成的高压场大大提高了地层对油气的吸附力(量);而侵入岩在成岩过程中也形成许多裂缝和孔隙。综合评价认为,侵入岩的边缘亚相和变质岩的角岩亚相是最有利储层,外侧未变质的暗色泥岩为良好盖层或遮挡;油气运移通道主要为断层、裂缝和晶间孔隙,且具有距离短、运聚效率高之特征。最后指出,侵入岩区往往发育以侵入岩体为中心的高压、高产、复杂的油气成藏系统。

There was great volume oil-gas complicated in distribution regularity in rift basins with strong magmatic activities. In order to find out feature and mechanism,the reservoir accumulation factors and accumulation effecting of Luojia intrusion rocks area were studied by the way of geology and geochemistry on the basis of accumulation system theory,and found high temperature and high pressure magma not only promoted notably hydrocarbon generation of source rocks,and also made them produce a lot of cracks and organic pores. At the same time,many cracks and pores generated in the intrusion rocks. Through evaluating,edge subfacies of the intrusion rocks and hornstone subfacies were thought the most favorable reservoir,and outboard dark mudstone was good cap rock,oil gas migration channels had mainly fault,crack which were shorter in distance and higher in efficiency. In the end,there were often a high pressure,high efficiency and complicated reservoir forming system around the intrusion rocks in rift basin.