In comparison to genetically related crude oils, oil bearing fluid inclusions are often relatively enriched in polar compounds. Phenolic, carbazolic and benzocarbazolic compounds, which are part of the polar fraction, are characterised by elevated solubilities in water, rendering them potentially useful indicators for oil migration and entrapment, as well as water-washing of oil-bearing fluid inclusions. These compounds were investigated in a set of crude oils and fluid inclusions, and methods were modified to allow for the direct and simultaneous analysis of phenolic and carbazolic compounds. By avoiding chromatographic column fractionation, this new analytical approach allows for faster analyses and higher throughput. Phenolic and carbazolic compounds were found to be present in all investigated crude oil samples, yet they represent only minor constituents of oil-bearing fluid inclusions. A newly described phenol–cresol index (PCI) is systematically elevated (> 0.7) in oil-bearing fluid inclusions, while crude oils are characterised by significantly lower values (< 0.5). Supported by observations of increasing PCI during progressive water-washing experiments, our data suggest oil-water interaction as a possible reason for the elevated PCI in oil-bearing fluid inclusions. Moreover, some of the phenolic compounds detected in oil-bearing fluid inclusion samples may derive from co-occurring aqueous fluid inclusions, whose simultaneous co-extraction cannot be avoided on this spatial scale. Our study highlights the importance of oil-water interaction in the subsurface and offers new techniques to aid understanding of this commercially relevant phenomenon.

与遗传相关的原油相比，含油流体包裹体通常相对富含极性化合物。酚类，咔唑类和苯并咔唑类化合物是极性组分的一部分，其特征是在水中的溶解度提高，使其成为潜在的指示油运移和截留以及对含油流体包裹体进行水洗的指标。在一组原油和流体包裹体中研究了这些化合物，并对方法进行了修改，以便可以直接和同时分析酚类和咔唑类化合物。通过避免色谱柱分级分离，这种新的分析方法可实现更快的分析和更高的通量。发现所有调查的原油样品中均存在酚类和咔唑类化合物，但是它们仅代表含油流体包裹体的次要成分。新近描述的含酚液体夹杂物中的苯酚-甲酚指数（PCI）会系统地升高（> 0.7），而原油的特征在于其值明显较低（<0.5）。在渐进式水洗实验中观察到PCI增加的观察结果支持，我们的数据表明油水相互作用是含油流体包裹体中PCI升高的可能原因。此外，在含油流体包裹体样品中检测到的某些酚类化合物可能来自共同存在的含水流体包裹体，在这种空间规模上，它们的同时共萃取是无法避免的。我们的研究突出了地下油水相互作用的重要性，并提供了新技术来帮助理解这种与商业相关的现象。