台南凹陷二叠系油成藏主控因素及模式

MAIN COTROLLING FACTORS AND MODES OF PERMIAN OIL ACCUMULATION IN TAINAN SAG

为了研究吐哈盆地台南凹陷二叠系油成藏规律,在二叠系油藏类型及分布特征研究的基础上,通过油分布与其侧向运移成藏条件之间关系,对台南凹陷二叠系油侧向运移成藏主控因素及模式进行了研究。结果表明:台南凹陷二叠系油成藏与分布主要受到3个因素的控制。(1)油运移路径控制着油平面分布部位,二叠系油主要分布在凹陷西部火焰山断阶带和东部火焰山断垒带油运移路径上;(2)断—盖配置控制着油分布层位,上梧桐沟组泥岩盖层封闭区油仅分布在其下二叠系,不封闭区油上调至其上三叠系,少量分布在其下二叠系;(3)封闭断层和不整合控制着油聚集部位,凹陷西部油聚集主要是因鲁北断裂侧向封闭,而凹陷东部油聚集除了库北断裂侧向封闭外,上二叠统底不整合遮挡也起了重要作用。二叠系油侧向运聚成藏存在断层遮挡和断层—不整合遮挡2种侧向运聚成藏模式,断层遮挡油侧向运聚成藏模式主要分布在凹陷西部火焰山断阶带和鲁克沁断垒带,少数分布在火焰山断垒带,断层—不整合遮挡油侧向运聚成藏模式主要分布在火焰山断垒带。

In order to study the Permian oil accumulation laws in Tainan Sag of Tuha Basin,on the basis of the researches on Permian reservoir types and distribution characteristics,through analyzing the relationships between the oil distributions and accumulation conditions of the lateral migration,the oil main controlling factors and accumulation patterns were figured out,the achievements show that: the three main factors are shown as follows: 1 the oil migration paths control the oil horizontal distribution locations,Permian oil is mainly distributed in Huoyanshan Fault Terrace Belt of the western sag and on the paths of East Huoyanshan Fault Horst Zone; 2 matching between the faults and caprocks controls the positions of the oil distribution,the oil is only distributed in sealed Upper Wutonggou-Formation oil region,while in the unsealed oil region,the oil rises to Triassic system and a small amount of it distributes in the Permian; 3 sealed faults and unconformity control the oil accumulated parts,the enriched oil in the western sag mainly due to the lateral sealing of Lubei Fracture,while the oil in the east resulted from the important role of the unconformity in Permian Upper Series besides the lateral seal of Kubei Fault. Two modes of thelateral-migration oil accumulation exist for the corresponding enrichment of Permian oil: fault block type and faultunconformity block one. The former is mainly distributed in Huoyanshan Fault Terrace Belt of the western sag and Lukeqin Fault Horst Zone,beside a small amount of the oil is located Huoyanshan Fault Horst Zone; the latter is generally distributed in the Huoyanshan Fault Horst Zone.