典型逆掩断裂带油气富集规律与准噶尔盆地西北缘勘探思路

THE REGULARITY OF HYDROCARBON-RICH IN TYPICAL OVERTHRUST FAULT ZONE AND IDEA FOR EXPLORATION OF NORTHWESTEN MARGIN OF JUNGGAR BASIN

通过系列调研资料总结得出,世界典型逆掩断裂带的油气具有在沿断裂带应力集中部位、次级构造、基岩断块风化壳以及靠生油凹陷一侧的斜坡区、断裂下盘的有利圈闭中富集的规律.在此基础上,指出准噶尔盆地西北缘的勘探潜力非常巨大,还有约13?08 m3的油气地质储量有待发现;在勘探思路上要系统查明西北缘断裂带,圈定探明程度较低的有利勘探区域和层位以及目前还未进行勘探的有利区块或构造;勘探重点应放在勘探程度较低的有利区块斜坡区和主断裂下盘,并进行深入细致的探测和综合研究工作,以期找到新的储量增长点.

The regularities of hydrocarbon-rich in typical overthrust fault zones in the world are summarized systematically in this article. It is considered that the fields in the overthrust belt distribute principally at the margin of stable depression basin (i.e. foreland basin) and near the side of active belt; the hydrocarbon is accumulated generally at the position of stress concentration; the hydrocarbon is closely related to substructures distributed along fault zone, the extensive clinothem zone to the side of basin of the overthrust is favorable to form reservoir and lithologic hydrocarbon reservoir; the hydrocarbon reservoir can also be formed in the traps of reverse fault and secondary fault footwall . On the basis of the experiences from exploration of typical overthrust fault zone in the world, it is pointed out that it is foundation of improving understanding on the geological study of overthrust fault to renew exploration technique, accumulate data and study further synthetically, which is the key of making correct exploration plan and realizing exploration breakthrough. On the basis of comparative analysis, and the evaluation criterion of 79.2% of mean proved resources of hydrocarbon in the world, in combination with exploration experiences of abroad overthrust fault zone and exploration practice of overthrust fault zone of northwestern margin of Junggar basin,it is pointed out that it has great potential for exploration in this margin, and additional 13?08m3 of OOIP will be discovered. It is suggested that Xinjiang Oilfield Company should carry out synthetic study in petroleum geology and the synthetic exploration of hydrocarbon again in northwestern margin of Junggar basin. In the train of thought ,the proved degree of northwestern fault zone should be verified systematically and the potential region and horizons with less proved degree , as well as favorable and unexplorated blocks and structures should be trapped. The favorable blocks with less proved degree (climothem zone and the footwall of main fault) should be focused by detailed exploration and comprehensive study to increase new reserves. In the exploration strategy, the strong professional team with multidiscipline should be organized. The advanced and suitable techniques should be applied for describing the seismotectonic profile and sedimentary facies, and for hydrocarbon detection. The effective methods of identifying subtle trap and low-amplitude structural trap should be established. This is the key whether the exploration breakthough could be realized and could be brilliant again in northwestern margin of Junggar basin.