周口坳陷石炭—二叠系油气成藏条件与富集控制因素

Hydrocarbon accumulation conditions and enrichment controlling factors of Permo-Carboniferous system in Zhoukou Depression

周口坳陷石炭—二叠系保存较好,面积较大,油气显示普遍。通过对研究区石炭—二叠系的分布特征、圈闭条件、油气成藏期次、油气聚集类型及其成藏控制因素等方面的综合研究,深入探讨了石炭—二叠系的油气成藏条件及其富集控制因素。结果表明,"古生新储"型是倪丘集地区重要的油气聚集类型;周口坳陷多期构造活动形成了多类型的构造圈闭;下古生界碳酸盐岩顶部风化壳为岩溶地貌圈闭的形成创造了良好条件;上古生界海陆交互相煤系地层为地层-岩性圈闭的形成打下了基础;印支期和喜马拉雅期是石炭—二叠系最重要的油气生成和运聚期,并存在"自生自储"、"下生上储"和古潜山型3种油气聚集类型;石炭—二叠系油气成藏的控制因素主要有效烃源岩的分布、输导体系的输导能力、圈闭定型期和油气运聚期的有效配置以及古近纪构造格局。研究区石炭—二叠系资源潜力较大,成藏条件有利,富集规律明显,是寻找大中型油气田的有利地区。

In Zhoukou Depression,Permo-Carboniferous system is well preserved and widespread with ubiquitous hydrocarbon shows.This paper synthetically researched the Permo-Carboniferous distribution,trap condition,and hydrocarbon accumulating stages,accumulation types,and controlling factors and so on.The hydrocarbon reservoir forming conditions and enrichment controlling factors of the Permo-Carboniferous were discussed thoroughly.The research result indicates that ' old source in young reservoir' is the important hydrocarbon accumulation type in Niqiuji area.The tectonic movement with multiple phases in Zhoukou Depression created all kinds of structural traps.The weathered crust at the top of the lower-Palaeozoic carbonatite produces good conditions to form karst topography traps,and the coal-bearing formation with marine-continental facies of the upper-Palaeozoic is the basis of forming stratigraphic-lithological traps.The Indo-Chinese epoch and Himalayan epoch were the most important periods of hydrocarbon formation,migration and accumulation in the Permo-Carboniferous,and there are three hydrocarbon accumulating types including the source and reservoir in the same bed,lower-generation and upper-accumulation,and the buried hill one.The hydrocarbon enrichment controlling factors mainly include the distribution of valid hydrocarbon source rock,capacity of transportation system,effective matching between structural traps forming stage and hydrocarbon migration-accumulation stage,and the palaeotectonic style in Paleogene.Permo-Carboniferous system in the interesting region has enormous resources potential and favorable hydrocarbon accumulating conditions,and is a favorable area for searching large-medium size hydrocarbon reservoirs with obvious enrichment rule.