Abstract Natural nuclear radiation-induced alteration of subsurface fluid composition hasbeen recently proposed as a geochemical tool for petroleum system analysis. This paper describes of how gamma radiation (doses up to 4000 kGy) affects the composition of crude oil based on ultrahigh-resolution mass spectrometry and nuclear magnetic resonance (NMR). Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) with electrospray (ESI) and atmospheric pressure photoionization (APPI) ion sources are used to target polar, high molecular-weight and/or heteroatom-containing species, whereas NMR analysis targets carbon-carbon double bonds generated by radiolysis. Oils with lower density and higher saturated hydrocarbon content are more susceptible to radiolysis, and the presence of water is confirmed to cause formation of O-bearing organic compounds. Preliminary evidence indicates radiolysis-induced polymerization reactions, as well as the decreased amounts of S- and N-bearing species with increased radiation dose. Hydrocarbon species with no or low aromaticity form within the oil matrix. Carbon-carbon double bonds likely facilitate the detection of such compounds in ESI and APPI modes. Oxygenated species with low aromaticity arising from the reaction of oil matrix compounds with water-derived, radiolysis-generated reactive oxygen species are also suitable candidates for future radiolysis proxies. NMR confirms the occurrence of carbon-carbon double bonds produced during radiolysis and was used to calibrate their concentration vs. the radiation dose. Preliminary FTICR-MS-based radiation proxies have been proposed, and their implications assessed. However, we acknowledge further analytical development is needed.

中文翻译：

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地下储层中石油流体停留时间的测年。第二部分：通过综合分子分析追踪辐解对原油的影响

摘要 自然核辐射引起的地下流体成分的改变最近被提出作为石油系统分析的地球化学工具。本文基于超高分辨率质谱和核磁共振 (NMR) 描述了伽马辐射（剂量高达 4000 kGy）如何影响原油的成分。带有电喷雾 (ESI) 和大气压光电离 (APPI) 离子源的傅里叶变换离子回旋共振质谱 (FTICR-MS) 用于靶向极性、高分子量和/或含杂原子的物质，而 NMR 分析则靶向碳-由辐射分解产生的碳双键。密度较低和饱和烃含量较高的油更容易受到辐射分解，并且确认水的存在会导致含氧有机化合物的形成。初步证据表明辐射引起的聚合反应，以及随着辐射剂量的增加，含硫和含氮物质的数量减少。在油基质中形成无芳香性或低芳香性的烃类物质。碳-碳双键可能有助于在 ESI 和 APPI 模式下检测此类化合物。由油基质化合物与水衍生的、辐射分解产生的活性氧物质反应产生的具有低芳香性的含氧物质也是未来辐射分解代理的合适候选者。核磁共振证实了在辐射分解过程中产生的碳-碳双键的出现，并用于校准它们的浓度与辐射剂量的关系。已经提出了基于 FTICR-MS 的初步辐射代理，并对其影响进行了评估。然而，我们承认需要进一步的分析发展。