Identifying the dominating oil-producing layer(s) within a shaly system, typically characterized by multiple layers with similar properties, is always a critical yet formidable task, as the oil component disparities among these closely adjacent layers are too minor to be resolved by the traditional geochemical fingerprints. This challenge is now likely addressed by high-resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), which can resolve thousands of non-hydrocarbons that could serve as new fingerprints. Taking a typical shaly system in the Ordos Basin in China as an example, the specific proportions of non-hydrocarbon compounds from the retained petroleum of different source rock layers (rock extracts) and the produced oil at the wellhead were identified by FT-ICR MS. Their compositional similarity was calculated using a multidimensional scaling (MDS) method, and the layers hosting the retained petroleum with higher compositional similarity to the produced oils are considered to be the main contributors to oil production. The results show that the main producing layers identified by FT-ICR MS differ from those proposed based on traditional fingerprints like the Rock-Eval parameters. A typical example is that the thick low-TOC shales, conventionally proposed to be unessential to oil production, seem to have a similar contribution, if not higher, to their thick silty counterparts. This divergence may be attributed to the fact that the conventional fingerprints primarily rely on the rock extracts from a vertical well section, which may only represent a limited lateral area, while the non-hydrocarbon similarity approach involving the produced oil appears to be more realistic, as it can consider the engineering processes, like the horizontal well track and the hydraulic fracturing effects. The current approach provides a novel route for identifying the dominating producing layer(s) in a shale oil system, which may have extensive potential for optimizing the production strategy of shale oil wells.

中文翻译：

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基于 FT-ICR MS 非烃分析对湖相页岩油系统中各层的石油贡献进行排序


识别页岩系统中的主要产油层（通常以具有相似性质的多个层为特征）始终是一项关键但艰巨的任务，因为这些紧密相邻的层之间的石油成分差异太小而无法通过传统的地球化学指纹。现在，高分辨率傅里叶变换离子回旋共振质谱（FT-ICR MS）可能可以解决这一挑战，它可以解析数千种可作为新指纹的非碳氢化合物。以我国鄂尔多斯盆地典型页岩体系为例，利用FT-ICR MS识别了不同烃源岩层（岩石提取物）滞留石油和井口产出油中非烃化合物的具体比例。采用多维标度（MDS）方法计算其成分相似度，与产出油成分相似度较高的滞留石油层被认为是石油产量的主要贡献者。结果表明，FT-ICR MS 识别的主产层与基于 Rock-Eval 参数等传统指纹提出的主产层不同。一个典型的例子是，传统上认为对石油生产不重要的厚层低 TOC 页岩，似乎对其厚层粉质页岩具有相似的贡献，甚至更高。 这种分歧可能归因于这样一个事实，即传统的指纹主要依赖于垂直井段的岩石提取物，这可能仅代表有限的横向区域，而涉及产出油的非烃相似性方法似乎更现实，因为它可以考虑工程过程，如水平井轨迹和水力压裂效应。目前的方法为识别页岩油系统中的主要生产层提供了一种新的途径，这对于优化页岩油井的生产策略可能具有广泛的潜力。