Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage
Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage
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DOI：
10.1016/s0012-821x(99)00021-7
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发表时间：
1999-04
影响因子：
5.3
通讯作者：
T. Torgersen;B. Kennedy
中科院分区：
文献类型：
--
作者：
T. Torgersen;B. Kennedy
来自Elk Hills海军石油储备（NPR#1）（贝克斯菲尔德，加利福尼亚州）的碳氢化合物富含重惰性气体。132 Xe/36 Ar比值是空气中的1.576倍，代表了在陆地流体中观测到的最大相对Xe富集。同位素组成与空气无法区分。我们表明，这些样品不能解释通过平衡的油与空气饱和的水和二次富集通过瑞利蒸馏气提过程。基于对其他具有潜在石油源岩的实验室研究，我们认为这种富集的重惰性气体组分的来源是最初被捕获在源岩中/上的吸附空气，该吸附空气在排出和初次运移期间被排出并与烃混合。Kr和Ar的富集度随~（36）Ar浓度的增加而降低。我们提出了一个模型，在该模型中，初始的Kr-Kr-富烃在排出、迁移和储存过程中被从空气饱和的地下水中提取的惰性气体稀释。该模型生成的综合水/烃比的生产流体，这表明在烃的排出和迁移的水的作用最小。解释的结果提供的机制，烃类可以作为一个单独的阶段迁移的时间/几何约束。
Hydrocarbons from the Elk Hills Naval Petroleum Reserve (NPR#1), Bakersfield, CA, are enriched in heavy noble gases. The132Xe/36Ar ratios are as high as ∼576 times the ratio in air and represent the largest relative Xe-enrichments ever observed in terrestrial fluids. The Xe isotopic composition is indistinguishable from air. We show that these samples cannot be explained by equilibration of oil with air saturated water and secondary enrichment via a Rayleigh distillation gas stripping process. Based on laboratory studies of others with potential petroleum source rocks, we believe the source of this enriched heavy noble gas component was adsorbed air initially trapped in/on the source rocks that was expelled and mixed with the hydrocarbons during expulsion and primary migration. Kr and Xe enrichments decrease with increasing36Ar concentration. We propose a model in which an initial Kr–Xe-enriched hydrocarbon becomes diluted with noble gases extracted from air saturated groundwater during expulsion, migration, and storage. The model generates an integrated water/hydrocarbon ratio for the production fluid which indicates a minimal role for water in hydrocarbon expulsion and migration. The results are interpreted to provide time/geometrical constraints on the mechanisms by which hydrocarbons can migrate as a separate phase.