Crude-oil biodegradation via methanogenesis in subsurface petroleum reservoirs
Crude-oil biodegradation via methanogenesis in subsurface petroleum reservoirs
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DOI：
10.1038/nature06484
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发表时间：
2008-01-10
期刊：
影响因子：
64.8
通讯作者：
Larter, S. R.
中科院分区：
文献类型：
--
作者：
Jones, D. M.;Head, I. M.;Larter, S. R.
地下石油储层中原油的生物降解对世界上大多数石油产生了不利影响，使石油的回收和精炼成本更高（1）。浅层地下石油储层中普遍发生的生物降解（2、3）归因于受含氧大气沃茨（2）的地表补给刺激的需氧细菌烃类降解。这一假设得到了经验上的支持，即在地表附近的储层中遇到生物降解石油的可能性较高（4、5）。然而，最近的研究结果表明，厌氧降解过程在地下沉积环境中占主导地位（6），尽管反应动力学缓慢，而且油藏中发生的实际降解途径不确定。在这里，我们使用实验室实验在微观世界监测的烃类组成的降解油和生成的气体，以及在井口和瑞利同位素分馏盒模型的天然气和石油样品的碳同位素组成，以阐明可能的机制，烃类降解储层。我们发现，在实验室条件下产甲烷的原油烃类降解模拟了储层降解石油中所见的化合物类的特征性顺序去除。正构烷烃的初始优先去除产生接近化学计量量的甲烷，主要是通过氢营养甲烷生成。我们的数据意味着一个共同的产甲烷生物降解机制，在地下退化的油藏，导致一致的模式的烃蚀变，和常见的协会干气与严重退化的石油在世界范围内观察。基于加速天然产甲烷生物降解的甲烷形式的油田能量回收可以提供从油田经济地生产难以回收的能量的途径。
Biodegradation of crude oil in subsurface petroleum reservoirs has adversely affected the majority of the world's oil, making recovery and refining of that oil more costly(1). The prevalent occurrence of biodegradation in shallow subsurface petroleum reservoirs(2,3) has been attributed to aerobic bacterial hydrocarbon degradation stimulated by surface recharge of oxygen- bearing meteoric waters(2). This hypothesis is empirically supported by the likelihood of encountering biodegraded oils at higher levels of degradation in reservoirs near the surface(4,5). More recent findings, however, suggest that anaerobic degradation processes dominate subsurface sedimentary environments(6), despite slow reaction kinetics and uncertainty as to the actual degradation pathways occurring in oil reservoirs. Here we use laboratory experiments in microcosms monitoring the hydrocarbon composition of degraded oils and generated gases, together with the carbon isotopic compositions of gas and oil samples taken at wellheads and a Rayleigh isotope fractionation box model, to elucidate the probable mechanisms of hydrocarbon degradation in reservoirs. We find that crude- oil hydrocarbon degradation under methanogenic conditions in the laboratory mimics the characteristic sequential removal of compound classes seen in reservoir- degraded petroleum. The initial preferential removal of n-alkanes generates close to stoichiometric amounts of methane, principally by hydrogenotrophic methanogenesis. Our data imply a common methanogenic biodegradation mechanism in subsurface degraded oil reservoirs, resulting in consistent patterns of hydrocarbon alteration, and the common association of dry gas with severely degraded oils observed worldwide. Energy recovery from oilfields in the form of methane, based on accelerating natural methanogenic biodegradation, may offer a route to economic production of difficult- to- recover energy from oilfields.