Department of Mining, Mechanical, Energetic and Civil Engineering, University of Huelva, 21819 Huelva, Spain.
Department of Geochemistry, Petrology and Geological Exploration, University of Barcelona, 08028 Barcelona, Spain.
Int J Environ Res Public Health. 2020 Oct 1;17(19):7204. doi: 10.3390/ijerph17197204.
The organic geochemistry of six oil samples from the offshore Block 17 (Lower Congo Basin, northwestern Angola) was studied by a combination of classical biomarker and extended diamondoid analyses to elucidate source rock facies, the extent of biodegradation, and thermal maturity. Based on molecular data, oils are interpreted as depicting a mixture of two pulses of hydrocarbon generation probably from the Bucomazi and Malembo formations. Geochemical results also gave evidence of mixing of a lacustrine siliciclastic-sourced oil charge and a second more terrestrially derived oil type in the samples analyzed. A single genetic oil family was identified through hierarchical cluster analysis; however, two groups of oils were identified on the basis of their biodegradation levels using the Peters/Moldowan scale. Lower and upper Malembo oils have a slight depletion and a notable absence of -alkanes, suggesting PM levels of 1 and 2, respectively. Most molecular maturity parameters of the oil samples suggest a maturity level equivalent to the onset of the peak of the oil generative window.
对来自近海 17 区块（安哥拉西北部下刚果盆地）的六份油样的有机地球化学进行了研究，综合使用了经典生物标志物和扩展的金刚烷分析方法，以阐明烃源岩相、生物降解程度和热成熟度。基于分子数据，这些油被解释为可能来自布科马齐和马勒姆博地层的两批烃生成混合。地球化学结果还表明，在所分析的样品中存在湖相硅质碎屑源油和第二种更源于陆地的油类型的混合。通过层次聚类分析确定了单一的遗传油族；然而，根据彼得斯/莫尔道烷规模对生物降解水平的分析，确定了两组油。下马勒姆博油和上马勒姆博油略有亏损，并且明显缺乏 -链烷烃，分别表明 PM 值为 1 和 2。大多数油样的分子成熟度参数表明成熟度水平相当于生油窗高峰期的开始。
