迈陈凹陷陆区油气运聚条件研究

Hydrocarbon migration and accumulation condition in land area of Maichen Sag

油气输导及汇聚条件是迈陈凹陷油气成藏的重要控制因素。以北部湾盆地迈陈凹陷东部陆区为重点,从骨架砂体、油源断裂、不整合面等入手开展输导条件研究,指出区内发育三种油源断裂,建立了斜坡带、断裂带五种输导模式,同时认为涠洲组三段下部油气输导较中上部更为有利;在此基础上,通过刻画断层与盖层匹配关系、主断层断面形态及古今构造叠置关系等方面的研究,指出平面上斜坡带发育2~3个北西-南东向构造脊,断裂带发育1~2个构造脊,构造脊所处位置与断层凸断面叠合,是有利的油气指向区;纵向上,具有“下凸”构造背景及发育油源断层的地区最有利于油气向涠洲组汇聚,但对于涠洲组底部,“下凹上凸”型叠置关系同样可以汇聚成藏。结合输导和汇聚条件的综合研究,指出了不同构造带有利的勘探层系和类型,为迈陈凹陷下步油气勘探提供有力指导。

The condition of hydrocarbon migration and accumulation is one of main control factors of forming reservoir in Maichen Sag. Focusing on the eastern land area of Maichen Sag,we carried out migration condition study from the sand-body framework, source fault and unconformity surface, etc.It is pointed out that there are three types of source fault.Five types of conduit system are set up in slope zone and fault zone.It is considered that the lower part of E 2 w 3 has more better migration ability than that of the middle and upper part. According to studies on matching relationship between fault and cap, section morphology of main fault,and superimposition relationship between paleo structure and current structure, it is pointed out that in the plane, 2 or 3 structure ridges in NW-SE direction are developed in slope zone, 1 or 2 structure ridges are developed in fault zone, and the superimposition between the position of structure ridge and the convex fault plane is favorable for oil and gas accumulation;in the vertical direction, the developed source fault and paleo-high structure area beneath E 2 w 3 is the most favorable area of E 2 w 3;but for the bottom of E 2 w 3, even if there is no paleo-high structure , it can also accumulates gas and oil. Based on the research of migration and accumulation, it is pointed out the favorable exploratory formation and trap type of different structural zone, guiding the next hydrocarbon exploration of Maichen Sag.