Formation temperatures of thermogenic and biogenic methane
Formation temperatures of thermogenic and biogenic methane
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DOI：
10.1126/science.1254509
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发表时间：
2014-06
期刊：
影响因子：
56.9
通讯作者：
D. Stolper;M. Lawson;C. Davis;Alexandre A. Ferreira;E. Neto;Geoffrey S. Ellis;M. Lewan;A. Martini-A.-Mart
中科院分区：
文献类型：
--
作者：
D. Stolper;M. Lawson;C. Davis;Alexandre A. Ferreira;E. Neto;Geoffrey S. Ellis;M. Lewan;A. Martini-A.-Mart
水力压裂等技术现在可以从地下储层中提取天然气。在这种气体中，某些同位素的比例为它的起源提供了线索。Stolper等人分析了各种天然气，包括来自美国一些最活跃的水力压裂现场的样本。使用“聚集同位素”技术，作者可以估计甲烷在地下深处形成的高温，以及古代微生物产生甲烷的低温。该方法可以帮助区分来自两个源的气体的混合程度。《科学》，本期第1500页，甲烷的同位素分析表明了天然环境中碳氢化合物气体形成的时间和位置。甲烷是一种重要的温室气体和能源，主要由产甲烷菌在低温下和通过有机分子在高温下的分解产生。然而，甲烷形成温度在自然界中往往受到很差的限制。我们测量了形成温度的热成因和生物成因的甲烷使用的“聚集同位素”技术。热成因气的地层温度在157° C和221°C之间，在标称气体窗口内，生物成因气的地层温度与其相对较低的地层环境（<50°C）一致。在系统中，气体已经迁移和其他代理的气体生成温度产生模糊的结果，甲烷聚集同位素温度之间的区别，并允许独立的测试可能的气体形成模型。
Making of methane deep underground Technologies such as hydraulic fracturing, or “fracking,” can now extract natural gas from underground reservoirs. Within the gas, the ratio of certain isotopes holds clues to its origins. Stolper et al. analyzed a wide range of natural gas, including samples from some of the most active fracking sites in the United States. Using a “clumped isotope” technique, the authors could estimate the high temperatures at which methane formed deep underground, as well as the lower temperatures at which ancient microbes produced methane. The approach can help to distinguish the degree of mixing of gas from both sources. Science, this issue p. 1500 Isotopic analysis of methane indicates the timing and location of hydrocarbon gas formation in natural settings. Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a “clumped isotope” technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.