Summary Magnetic minerals form or alter in the presence of hydrocarbons, making them a potential magnetic proxy for identifying hydrocarbon migration pathways. In this paper we test this idea by magnetically measuring core samples from the Tay Fan in the Western Central Graben in the Central North Sea. In a companion paper, 3D petroleum systems modelling has been carried out to forward model migration pathways within the Tay Fan. Rock magnetic experiments identified a range of magnetite, maghemite, iron sulphides, siderite, goethite and titanohematite, some of which are part of the background signal, and some due to the presence of hydrocarbons. Typical concentrations of the magnetic minerals were ∼10–200 ppm. Importantly, we have identified an increasing presence of authigenic iron sulphides (likely pyrite and greigite) along the identified lateral hydrocarbon migration pathway (east to west). This is likely caused by biodegradation resulting in the precipitation of iron sulphides, however, though less likely, it could alternatively be caused by mature oil generation, which subsequently travelled with the migrating oil to the traps in the west. These observations suggest mineral magnetic techniques could be a rapid alternative method for identifying the severity of biodegradation or oil maturity in core sample, which can then be used to calibrate petroleum systems models.

中文翻译：

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使用磁技术校准石油系统建模中的碳氢化合物迁移：来自英国中北海下第三纪的案例研究

总结 磁性矿物在碳氢化合物存在的情况下形成或变化，使其成为识别碳氢化合物迁移路径的潜在磁性代表。在本文中，我们通过磁性测量北海中部中西部地堑的 Tay Fan 岩心样本来验证这一想法。在一篇配套论文中，已经进行了 3D 石油系统建模，以对 Tay Fan 内的迁移路径进行建模。岩石磁性实验确定了一系列磁铁矿、磁赤铁矿、硫化铁、菱铁矿、针铁矿和钛赤铁矿，其中一些是背景信号的一部分，还有一些是由于碳氢化合物的存在。磁性矿物的典型浓度为~10-200 ppm。重要的，我们已经确定沿着已确定的横向油气运移路径（从东到西）存在越来越多的自生硫化铁（可能是黄铁矿和灰铁矿）。这很可能是由生物降解导致硫化铁沉淀引起的，然而，虽然不太可能，但也可能是由于成熟的石油生成，随后随着运移的石油进入西部的圈闭。这些观察结果表明，矿物磁技术可能是一种快速的替代方法，用于识别岩心样品中生物降解或石油成熟度的严重程度，然后可用于校准石油系统模型。它也可能是由于成熟的石油产生，随后随着运移的石油进入西部的圈闭。这些观察结果表明，矿物磁技术可能是一种快速的替代方法，用于识别岩心样品中生物降解或石油成熟度的严重程度，然后可用于校准石油系统模型。它也可能是由于成熟的石油产生，随后随着运移的石油进入西部的圈闭。这些观察结果表明，矿物磁技术可能是一种快速的替代方法，用于识别岩心样品中生物降解或石油成熟度的严重程度，然后可用于校准石油系统模型。