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黄骅坳陷歧口断陷湖盆沉积岩厚度大,地层分布范围广,由于盆内、盆外物源十分发育,构造活动频繁,使其沉积环境和沉积体类型丰富多样,烃源岩除湖相泥岩外,还发育较大范围的油页岩,且在油页岩主要发育期,在一定程度上因受海水影响而具有藻类勃发的条件,在油页岩和钙质页岩中发育一定的颗石藻;针对歧口凹陷烃源岩,以“富烃源岩生烃理论”为指导,对烃源岩进行分级评价,认为歧口凹陷具有烃源岩厚度大、有机质类型丰富、有机质丰度高、优质烃源岩发育的特点;同时,由于异常超压的发育,烃源岩的成熟门限偏深,有效生油井段长,与一般的烃源岩相比生油下限明显向深部偏移,因而也使得大量生气门限较深,有效生气期作用时间短,具有“持续生油、集中生气”的特点,歧口凹陷的这种生烃热演化特征对中深层油气的分布具有明显的控制作用。
The sedimentary rocks in the Qikou fault basin of the Huanghua Depression are large in thickness and have a wide range of strata. Due to the abundant development of the sedimentary environment and sedimentary bodies in the basin and the outer basin, In addition to the mudstone, a large range of oil shale is also developed. In the main developmental stages of oil shale, due to the algal blooms affected by seawater to a certain extent, a certain amount of oil shale and calcareous shale According to the theory of “hydrocarbon generation from hydrocarbon-rich source rocks”, we classify the source rocks according to the source rocks in the Qikou Sag. The authors believe that the Qikou Sag has the features of large source rock thickness, rich organic matter types, High abundance and high quality source rocks. At the same time, due to the development of abnormal overpressure, the mature threshold of source rocks is deeper and the length of active oil wells is longer. Compared with common source rocks, the lower limit of oil generation is obviously deeper Migration, so that a large number of biologically-induced thresholds are deep, and the effective gas-generating period has a short acting time with the characteristics of “sustained oil generation and concentrated gas generation”. The evolution of hydrocarbon generation in Qikou sag affects the distribution of middle-deep oil and gas Has obvious control effect.