Unconventional hybrid petroleum systems are partially to entirely self-sourced. Their hydrocarbons are generated within internal (intraformational) organic-rich mudstone source rocks and subsequently migrate into adjacent organic-lean reservoir beds composed of sandstone, siltstone or carbonate. Hybrid systems with volumetrically dominant reservoir-quality rocks can additionally receive hydrocarbon charge by longer-range migration from external source rocks. However, few previous studies of hybrid systems have focused on the migration and mixing of hydrocarbons from both internal and external sources. To address this shortfall, this study presents an integrated organic geochemistry and stable carbon isotope investigation of drill-core and produced hydrocarbon liquid samples from two wells in a major unconventional hybrid petroleum system in the Montney Formation of western Canada. The results reveal distinct geochemical trends with increasing depth through the upper part of the Montney Formation including decreased C biomarker compounds, increased depletion of saturate compared to aromatic δC values, and increased proportions of saturates and mobile oil. These trends indicate that oil from external source rocks of the overlying Doig Formation migrated into the upper part of the Montney Formation. Downward migration of externally sourced Doig oil resulted in a broad transition zone where Doig-sourced oil mixed with locally migrated lighter oil generated within internal Montney source rocks of slightly higher thermal maturity. This study sheds new light on the migration and mixing of disparate oil charges in the Montney Formation, and likely has widespread applicability to other similar unconventional hybrid petroleum systems that had hydrocarbon contributions from both internal and external source rocks.

中文翻译：

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加拿大西部蒙特尼组非常规混合石油系统中内部和外部烃源岩的石油运移

非常规混合石油系统部分或完全自产。它们的碳氢化合物在内部（层内）富含有机质的泥岩烃源岩中生成，随后运移到邻近的由砂岩、粉砂岩或碳酸盐组成的贫有机质储层中。具有体积占主导地位的储层质量岩石的混合系统还可以通过来自外部烃源岩的长距离运移来接收碳氢化合物充注。然而，之前的混合系统研究很少关注内部和外部来源的碳氢化合物的迁移和混合。为了解决这一不足，本研究对加拿大西部蒙特尼组一个主要非常规混合石油系统的两口井的钻芯和产出的烃液体样品进行了综合有机地球化学和稳定碳同位素研究。结果揭示了随着 Montney 地层上部深度的增加，出现了明显的地球化学趋势，包括 C 生物标志物化合物减少、与芳香族 δ13C 值相比饱和烃消耗增加以及饱和烃和流动油的比例增加。这些趋势表明来自上覆 Doig 组外部烃源岩的石油迁移到 Montney 组的上部。外部来源的多伊格石油的向下运移导致了一个广泛的过渡带，其中多伊格来源的石油与热成熟度稍高的内部蒙特尼烃源岩中产生的局部运移的轻质油混合。这项研究为蒙特尼组中不同石油充注的迁移和混合提供了新的线索，并且可能广泛适用于其他类似的非常规混合石油系统，这些系统具有来自内部和外部烃源岩的碳氢化合物贡献。