叠合盆地老烃源岩系油气勘探前景评价方法——以南华北周口坳陷上古生界为例

Evaluation method for petroleum exploration prospect of hydrocarbon-generation paleo-strata in superimposed basins——A case study of the Upper Paleozoic strata of Zhoukou Depression in the southern North China

丰富有效的烃源岩、超晚期的"二次生烃"过程、相对较好的储集条件、继承性隆起的构造部位和有效的封盖层是形成上古生界自生自储油气藏必备的条件。石炭-二叠系原型盆地解体后,在周口坳陷中部坳陷带和北部坳陷带的中、新生代深凹区不同程度地残存有石炭-二叠系。其中倪丘集凹陷和谭庄—沈丘(东部)凹陷的上古生界烃源岩在中三叠世末(一次生烃)时的有机质热演化程度低,因而在喜山期再次深埋中保持了较强的"二次生烃"潜力,为成藏创造了条件。立足于超晚期成藏及充分考虑烃源岩"二次生烃迟滞效应",提出了叠合盆地老烃源岩系油气勘探前景评价方法。根据二次生烃潜力和成藏条件,在周口坳陷上古生界评价出3个较有利勘探区和3个远景勘探区。

The controlling factors of the Paleozoic Erathem inner oil pool formation include abundant source rocks, aftermost quadric hydrocarbon generation processes, relatively better reservoir conditions, and successive uplifts and effective caprock. The remaining Carboniferous-Permian system only occurred in the Mesozoic and Cenozoic sags in the center of the northern depression section of Zhoukou Basin. The Paleozoic source rocks in Niqiuji and Tanzhuang-Sbenqiu （east part） sags had relatively strong potentials of the quadric hydrocarbon generation in the Himalayan period, because of their lower evolution rank in the late stage of the middle Triassic age（the first hydrocarbon generation period）. The method of exploration prospect evaluations for the Paleozoic source rocks in view of aftermost refilling and lag-effect of quadric hydrocarbon generations was presented. Three favorable exploration districts and three prospective areas were determined, according to the quadric hydrocarbon generation in the Upper Paleozoic of Zhoukou Depression.