Abstract Forty-seven heavy oil samples of three genetic types and similar maturity levels (early oil window) reflect that oils in the southeastern Mexico Basin have experienced complex oil biodegradation, charging and mixing processes. Strong oil fingerprinting signatures from the non- to slightly biodegraded, later charged oils discourage effective determination of biodegradation levels using the existing biodegradation scales. The later charges are recognized by accumulation of n-alkanes, peak/hump ratios and abundant diamondoids. Bicyclic sesquiterpanes show systematic changes caused by biodegradation, whereas very similar hopane and sterane distribution patterns indicate no microbial alteration of hopanes and steranes. Distributions of 2–5 ring aromatic hydrocarbons display regular trends caused by biodegradation, based on which a biodegradation parameter was derived. It shows a higher resolution than an adapted Manco score (Larter, S.R., Huang, H., Adams, J., Bennett, B., Snowdon, L.R., 2012. A practical biodegradation scale for use in reservoir geochemical studies of biodegraded oils. Organic Geochemistry 45, 66–76.). Biodegradation parameters were also derived based on systematic changes in NSO compound distributions. However, deconvolution of oil biodegradation, charging and mixing history is not achievable from a univariate or bivariate perspective. Hence, a multivariate method, exploratory factor analysis (EFA) was applied, incorporating biodegradation ratios and concentrations of compounds chiefly from the fresh charges. The EFA results categorize the studied oils into three broad biodegradation level ranges along with different amounts of the later fresh charge. Our study highlights that chemometric methods might be used to unravel complex oil biodegradation, charging and mixing history of petroleum systems worldwide.

中文翻译：

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探索性因子分析在墨西哥东南部稠油生物降解、充注和混合历史解卷积中的应用

摘要 47 个具有相似成熟度（早期油窗）的三种成因类型的稠油样品反映了墨西哥盆地东南部的石油经历了复杂的石油生物降解、充注和混合过程。来自非生物降解到轻微生物降解、后来带电的油的强油指纹特征阻碍了使用现有生物降解尺度有效确定生物降解水平。后面的电荷是通过正烷烃的积累、峰/峰比和丰富的金刚石来识别的。双环倍半萜烷表现出由生物降解引起的系统性变化，而非常相似的藿烷和甾烷分布模式表明没有微生物改变藿烷和甾烷。2-5 环芳烃的分布显示出由生物降解引起的规律趋势，据此推导出生物降解参数。它显示出比适应的 Manco 分数更高的分辨率（Larter, SR, Huang, H., Adams, J., Bennett, B., Snowdon, LR, 2012. 用于生物降解油的储层地球化学研究的实用生物降解标度。有机地球化学 45, 66–76.)。生物降解参数也是根据 NSO 化合物分布的系统变化推导出来的。然而，从单变量或双变量的角度无法实现石油生物降解、充电和混合历史的解卷积。因此，应用了一种多变量方法，探索性因素分析 (EFA)，结合了生物降解率和主要来自新鲜进料的化合物浓度。EFA 结果将所研究的油分为三个广泛的生物降解水平范围以及不同数量的后期新鲜进料。我们的研究强调，化学计量学方法可用于解开全球石油系统复杂的石油生物降解、充电和混合历史。