针对渤海海域莱州湾凹陷钻井少、有机地球化学资料不够丰富的特点,基于KL6D构造区烃源岩评价与油源对比,提出了一种根据原油甾烷异构化成熟度参数C29 ααα20S/(20S+20R)确定排烃门限的新方法.根据KL6D构造区烃源岩和已发现原油的C29 ααα20S/(20S+ 20R)成熟度参数与深度拟合的线性公式,确定该构造及围区的排烃门限深度为3320 m,该深度以下烃源岩对研究区油气成藏有显著贡献.本文方法确定的排烃门限能直观地刻画研究区有效烃源岩,特别适用于少井和浅井地区.%There are less drilled wells and organic ge-ochemical data in Laizhou Bay sag, and a new method to determine hydrocarbon-expulsion threshold by an oil maturity parameter of sterane isomerization, C29aaa20S/(20S + 20R) , was developed on a basis of the source rock evaluation and oil-source correlation in KL6D structure. According to the linear e-quation of C29 aaa20S/( 20S + 20R) fitted with depth for the source rock and discovered oil in the structure, it can be determined that the depth of hydrocarbon-expulsion threshold of KL6D structure is about 3 320 m in the structure and its surrounding areas, and that the source rock below this depth may has significantly contribute to hydrocarbon accumulation there. The hydrocarbon-expulsion threshold determined by this new method can intuitively describe the effective source rocks, and is especially suitable for the areas with less wells or shallow wells.
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