The Barents Sea basin is an oil and gas province containing more than 760 million tons of oil equivalents. The reservoir geology of the Barents Sea is complex due to multiple episodes of subsidence, uplift and erosion, which opened a network of extensional and wrench related faults allowing for fluid migration. The multifaceted geological history complicates efforts to describe the source and characteristics of natural gas in the subsurface Barents Sea. Here we apply stable isotopes, including methane clumped isotope measurements, to thirteen natural gases from five (Skrugard Appraisal, Havis, Alta, Filicudi, and Svanefjell) reservoirs in the Loppa High area in the southwestern Barents Sea to estimate the origins of methane. We compare estimates of methane formation temperature based on clumped isotopes to thermal evolution models for the region. We find that the methane has diverse origins including microbial and thermogenic sources forming and equilibrating at temperatures ranging from 34–238°C. Our clumped isotope temperature estimates are consistent with thermal evolution models for the area. These temperatures can be explained by gas generation and expulsion in the oil and gas window followed by isotopic re-equilibration in some reservoirs due to microbial methanogenesis and/or anaerobic oxidation of methane. Gases from the Skrugard Appraisal, Havis and Alta have methane equilibration temperatures consistent with maximum burial temperatures, while gases from Svanefjell have methane equilibration temperatures consistent with current reservoir temperature, suggesting isotope re-equilibration in the shallow reservoir. Gases from Filicudi on the other hand are consistent with generation over multiple points over its thermal history.

巴伦支海盆地是一个石油和天然气省，蕴含超过 7.6 亿吨石油当量。由于多次沉降、隆起和侵蚀，巴伦支海的储层地质复杂，这开辟了一个允许流体运移的伸展和扳手相关断层网络。多方面的地质历史使描述巴伦支海地下天然气来源和特征的努力变得复杂。在这里，我们对来自巴伦支海西南部 Loppa High 地区的五个（Skrugard Appraisal、Havis、Alta、Filicudi 和 Svanefjell）储层的 13 种天然气应用稳定同位素，包括甲烷聚集同位素测量，以估计甲烷的来源。我们将基于聚集同位素的甲烷形成温度估计值与该地区的热演化模型进行比较。我们发现甲烷有多种来源，包括在 34-238°C 的温度范围内形成和平衡的微生物和热源。我们的成簇同位素温度估计与该地区的热演化模型一致。这些温度可以通过油气窗口中的气体生成和排出来解释，随后由于微生物产甲烷和/或甲烷的厌氧氧化，在一些储层中同位素重新平衡。Skrugard Appraisal、Havis 和 Alta 的气体具有与最高埋藏温度一致的甲烷平衡温度，而来自 Svanefjell 的气体具有与当前储层温度一致的甲烷平衡温度，表明浅层储层中的同位素重新平衡。