The noble gas geochemistry of natural CO2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA
The noble gas geochemistry of natural CO2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA
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DOI：
10.1016/j.gca.2007.10.009
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发表时间：
2008-02-15
影响因子：
5
通讯作者：
Cassidy, Martin
中科院分区：
文献类型：
--
作者：
Gilfillan, Stuart Mn.;Ballentine, Chris J.;Cassidy, Martin
确定天然储层中二氧化碳的来源和开发物理模型来解释二氧化碳与地下水的迁移和相互作用，对于定量了解CO在地下的长期储存潜力至关重要。本文介绍了美国科罗拉多高原隆起省（Bravo Dome， NM）东部3个天然储层中富含二氧化碳（>82%）的57种稀有气体的测定结果。（Sheep Mountain， CO.和McCallum Dome， CO.），以及隆起区域内的两个储层（St. John's Dome， AZ和McElmo Dome， CO.）。结果表明，所有油田的CO2/(3) He比值与主要岩浆源一致。该省最近的火山活动可追溯到8至10 ka，与Bravo Dome油田有关。最古老的岩浆活动可追溯到42至70 Ma，与位于科罗拉多高原构造稳定中心的McElmo Dome油田有关：二氧化碳可以在地下储存一千年。二氧化碳相与地下水系统接触的方式和程度是利用这些系统作为人为二氧化碳地质储存的自然类似物的关键参数。研究表明，地下水Ne-20/Ar-36与地壳放射性稀有气体（He-4, Ne-2, Ar-40）的相干分馏可以用两阶段再溶解模型来解释：第一阶段：岩浆CO2注入地下水系统，通过CO2/水相分配将溶解的气源惰性气体（ASW）和积累的地壳/放射性稀有气体分离。含有地下水剥离气体的二氧化碳提供了第一次储层流体充注。随后的CO2充注，不再提供更多的ASW或地壳稀有气体，只起到稀释原来的ASW和富含地壳稀有气体的CO2的作用。储层尺度上asw衍生稀有气体的浓度梯度保存为CO2的充注方向提供了依据。这是在布拉沃圆顶球场和圣约翰圆顶球场看到的。第二阶段：惰性气体重新溶解到任何可用的含气剥离地下水中。这被建模为瑞利蒸馏过程，使我们能够量化每个样本：(1)水库填充时最初“剥离”的地下水体积；(2)参与后续相互作用的地下水体积。在Bravo Dome样品中，天然气剥离的原始水量低至0.0005 cm(3)地下水/cm(3)气体（STP），而在St. John's Dome样品中，则为2.56 cm(3)地下水/cm(3)气体（STP）。随后的天然气/地下水平衡在所有油田中都有所不同，每个油田都显示出相似的范围，从0到接近100厘米(3)水/ 100厘米(3)气（在储层压力和温度下）。(c) 2007 Elsevier Ltd.版权所有。
Identification of the source Of CO2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO, in the subsurface. We present the results of 57 noble gas determinations in CO2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John's Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO2/(3) He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO2 can be stored within the subsurface on a millennia timescale.The manner and extent of contact of the CO2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO2. We show that coherent fractionation of groundwater Ne-20/Ar-36 with crustal radiogenic noble gases (He-4, Ne-2, Ar-40) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO2/water phase partitioning. The CO2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO2, provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO2 filling direction. This is seen in the Bravo Dome and St. John's Dome fields. Stage 2: The noble gases re-dissolve into any available gas stripped groundwater. This is modeled as a Rayleigh distillation process and enables us to quantify for each sample: (1) the volume of groundwater originally 'stripped' on reservoir filling; and (2) the volume of groundwater involved in subsequent interaction. The original water volume that is gas stripped varies from as low as 0.0005 cm(3) groundwater/cm(3) gas (STP) in one Bravo Dome sample, to 2.56 cm(3) groundwater/cm(3) gas (STP) in a St. John's Dome sample. Subsequent gas/groundwater equilibration varies within all fields, each showing a similar range, from zero to similar to 100 cm(3) water/cm(3) gas (at reservoir pressure and temperature). (c) 2007 Elsevier Ltd. All rights reserved.