塔里木盆地塔中北斜坡奥陶系鹰山组三段—四段油气富集主控因素及有利区带

塔里木盆地塔中隆起下奥陶统鹰山组三段—四段高产油气的发现揭开了塔中地区2套新的含油气层系,预示广阔的勘探前景,但成功井与失利井的共存是明确该区油气富集规律,划分有利区带,实现高效勘探不可回避的核心问题。借助钻测井、野外露头剖面、高品质三维地震数据资料,结合相应的物探技术手段对油气富集主控因素进行研究,并据此对成藏有利区带进行了预测。结果表明:满加尔凹陷寒武系烃源岩是塔中隆起油气的主要来源,研究区从位置上更靠近满加尔生烃凹陷,近源是该区油气成藏的物质基础;Ⅰ、Ⅱ级北东向油源走滑断裂贯穿研究区南北,有效沟通深层寒武系烃源岩,成为油气横向疏导、纵向调整的有效路径,又因其活动期次、强度不同,平面上分段性明显,造成走滑断裂断穿层位,构造样式存在差异性,羽状破碎带是油气成藏的优势区;鹰一段—鹰二段致密灰岩与数百米厚的桑塔木组泥岩阻止了油气的向上逸散,是区域上的有效盖层。基于上述认识,运用模型正演分析缝洞体储层地震反射特征,与实钻井能够很好地吻合,并以此确定塔中隆起塔中Ⅰ号断裂带附近的基底古构造宽缓斜坡区鹰三段—鹰四段羽状断裂与强串珠共同发育区为有利勘探区带。

Main controlling factors of oil and gas enrichment and favorable zones:Case study of 3rd and 4th members of Ordovician Yingshan Formation,northern slope of Tazhong Uplift,Tarim Basin

In the Tazhong Uplift of Tarim Basin,the discovery of high yield oil of 3 rdand 4 thmembers of Ordovician Yingshan Formation reveals two new hydrocarbon reservoirs,which indicate broad prospect for exploration.But the coexistence of successful and unsuccessful drillings makes it difficult to determine the pattern of hydrocarbon accumulation,and how to find favorable zones becomes the core problem of efficient exploration.In this paper,the major controlling factors of hydrocarbon accumulation is studied by drillings,high quality 3 D seismic data and the field outcrop with corresponding geophysical techniques.According to this,the favorable zone of accumulation was predicted.The research results show that,Cambrian source rocks are the main source of oil in the area,adjacent hydrocarbon generation depression is the most favorable material basis for hydrocarbon accumulation.GrandⅠandⅡnortheast trending slide faults break through the whole area,which communicate deep cold warfare hydrocarbon source rock effectively.And the slides play an effective path for lateral dredging and vertical adjustment of hydrocarbon.Because of the segmented activity intensity,the pinnate fracture zone is the dominant area for hydrocarbon accumulation.The tight limestone of the 1 stand 2 ndmembers of Yingshan Formation and the several hundred meters mudstone of the Sangtamu Formation prevented the upward escape of oil and gas,which is another guarantee for oil and gas accumulation.Based on the above understanding,the forward modeling is used to analyze the seismic emission characteristics of fracture-body reservoir,which is in good agreement with the drilling,so as to determine the favorable exploration zone and provide the technical support for the exploration.