Tracing secondary oil migration pathways is critical for understanding petroleum system evolution histories. Traditional tools (e.g., molecular indicators and numerical modeling) utilized for evaluating oil migration processes either lead to ambiguous interpretations or only provide qualitative estimates. We quantitatively constrain secondary oil migration processes under an absolute time frame by integrating oil-inclusion fluorescence and in situ calcite U-Pb dating on calcite veins and cements hosting primary oil inclusions. Fluorescence spectra of oil inclusions and U-Pb ages were obtained on samples from ultra-deep Ordovician reservoirs along two major faults in the Halahatang oilfield, Tarim Basin (northwestern China). Absolute U-Pb ages suggest two main oil charge events during 475–433 Ma and 294–262 Ma, respectively, and revealed a northward-decreasing trend for oil maturity during single charge events. Vertical migration of oil from in situ source rock through active (or reactivated) faults is believed to be the key process inducing the spatial maturity variation in charged oils and considered as the main mechanism of secondary migration, with brecciated fault zones and dilatant fractures along faults acting as major vertical oil-migration pathways. The successful application of this approach has wider implications for elucidating petroleum migration processes in tectonic complex basins worldwide.

中文翻译：

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方解石 U-Pb 年龄限制了构造复杂盆地的石油运移路径

追踪次生石油运移路径对于了解石油系统演化历史至关重要。用于评估石油运移过程的传统工具（例如，分子指标和数值模型）要么导致解释不明确，要么仅提供定性估计。我们通过将油包裹体荧光和原位方解石 U-Pb 测年对含有原生油包裹体的方解石脉和胶结物进行整合，在绝对时间范围内定量限制二次油运移过程。对塔里木盆地哈拉哈塘油田两大断裂沿奥陶系超深层油藏样品进行了油包裹体荧光光谱和U-Pb年龄分析。绝对 U-Pb 年龄表明分别在 475-433 Ma 和 294-262 Ma 期间发生了两次主要的石油充注事件，并揭示了单次充电事件中石油成熟度向北下降的趋势。原位烃源岩通过活动（或重新活动）断层的垂直运移被认为是导致带电油空间成熟度变化的关键过程，被认为是二次运移的主要机制，具有角砾状断层带和沿断层的膨胀裂缝作为主要的垂直石油运移通道。该方法的成功应用对于阐明全球构造复杂盆地的石油运移过程具有更广泛的意义。原位烃源岩通过活动（或重新活动）断层的垂直运移被认为是导致带电油空间成熟度变化的关键过程，被认为是二次运移的主要机制，具有角砾状断层带和沿断层的膨胀裂缝作为主要的垂直石油运移通道。该方法的成功应用对于阐明全球构造复杂盆地的石油运移过程具有更广泛的意义。原位烃源岩通过活动（或重新活动）断层的垂直运移被认为是导致带电油空间成熟度变化的关键过程，被认为是二次运移的主要机制，具有角砾状断层带和沿断层的膨胀裂缝作为主要的垂直石油运移通道。该方法的成功应用对于阐明全球构造复杂盆地的石油运移过程具有更广泛的意义。