Isotopic analysis of sulfur cycling and gypsum vein formation in a natural CO2 reservoir
Isotopic analysis of sulfur cycling and gypsum vein formation in a natural CO2 reservoir
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天然 CO2 储层中硫循环和石膏脉形成的同位素分析
DOI：
10.1016/j.chemgeo.2016.04.015
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Chen F
中科院分区：
文献类型：
--
作者：
Chen F
为了评估地质碳储存的长期安全性，研究储存CO2的储层中硫的地球化学行为至关重要。化石燃料燃烧可能产生二氧化碳和含硫气体的混合物，而硫-CO2协同封存的地球化学效应还知之甚少。本研究探讨硫矿化从一个堆叠序列的天然CO2水库附近的绿色河，犹他州镇钻取的核心。这些储层包括Entrada和Navajo砂岩，它们被卡梅尔组盖层隔开，并被一个CO2脱气正断层系统横切，含CO2盐水通过该系统排出。我们在这项研究中的目的是评估的机制和次生矿物形成的时间，特别是石膏形成，在CO2油藏和中间盖层。卡梅尔组含有断层带内的石膏层。石膏的次生脉存在于整个恩特拉达砂岩和卡梅尔组。本文报道了石膏和黄铁矿的硫、氧同位素（δ 34 SSO 4和δ 18 OSO 4）和水化水的氧、氢同位素（δ 18 O和δD）。多种同位素方法使我们能够追踪储层中硫的来源，并结合构造和岩石学证据，追踪流体-岩石反应的进展和脉状矿化的相对时间。卡梅尔组中的次生石膏脉来自于流体与两种同位素不同的硫酸盐来源的混合：来自卡梅尔组内石膏层的硫酸盐和来自下伏石炭纪Paramerite组中的碳酸盐岩的富硫酸盐卤水。Entrada砂岩中的石膏脉具有相对宽的δ 18 OSO 4范围，比原生石膏源更富集18 O和更贫化18 O。我们认为，在恩特拉达砂岩中的一些含水硫酸盐可能通过多价态循环，因为它经历还原和再氧化，导致其氧原子的取代，并允许偶尔形成具有异常低δ 18 OSO 4的石膏。我们的石膏水化水数据表明，石膏脉群在两个不同的时间形成。Entrada砂岩中的石膏脉和卡梅尔组中的一些脉可能是在第四纪充CO2的盐水排放事件期间形成的，而位于卡梅尔组中石膏床附近的其他脉形成较早，可能是在与Laramide年龄（40 Mya）断层相关的脱水和再水化循环期间形成的。我们的结论是，硫酸钙矿物形成盐水填充的裂缝可能发挥重要作用，抑制流体运移的地质油藏，含有CO2。
In order to assess the long-term security of geologic carbon storage, it is crucial to study the geochemical behavior of sulfur in reservoirs that store CO2. Fossil fuel combustion may produce mixtures of carbon dioxide and sulfur gases, and the geochemical effects of sulfur–CO2cosequestration are poorly understood. This study examines sulfur mineralization from a core drilled in a stacked sequence of natural CO2reservoirs near the town of Green River, Utah. These reservoirs include the Entrada and Navajo Sandstone, which are separated by the Carmel Formation caprock and transected by a system of CO2-degassing normal faults, through which saline CO2-charged brines discharge. Our objective in this study is to evaluate the mechanisms and timing of secondary mineral formation, particularly gypsum formation, in the CO2reservoirs and intervening caprock. The Carmel Formation contains beds of gypsum within a fault zone. Secondary veins of gypsum exist throughout the Entrada Sandstone and Carmel Formation. We report sulfur and oxygen isotope data (δ34SSO4and δ18OSO4, respectively) measured in gypsum and δ34S measured in pyrite, and the oxygen and hydrogen isotope composition (δ18O and δD, respectively) of gypsum hydration water. The multiple isotope approach allows us to trace the sources of sulfur in the reservoirs and, when combined with structural and petrological evidence, the progress of fluid-rock reactions and relative timing of vein mineralization.The secondary gypsum veins in the Carmel Formation derive from mixing of fluids with two isotopically distinct sulfate sources: sulfate from the gypsum beds within the Carmel Formation and sulfate-rich brines that originate from evaporites in the underlying Carboniferous Paradox Formation. The gypsum veins in the Entrada Sandstone have a relatively wide range of δ18OSO4, both isotopically more enriched in18O and more depleted in18O than the primary gypsum sources. We suggest that some aqueous sulfate in the Entrada Sandstone may cycle through multiple valence states as it undergoes reduction and reoxidation, resulting in the replacement of its oxygen atoms and allowing the occasional formation of gypsum with anomalous low δ18OSO4. Our data from gypsum hydration water indicates that groups of gypsum veins formed at two different times. Gypsum veins in the Entrada Sandstone and some veins in the Carmel Formation likely formed during Quaternary CO2-charged brine discharge events, while other veins located close to the gypsum beds in the Carmel Formation formed earlier, likely during cycles of dehydration and rehydration associated with the Laramide-age (40 Mya) faulting. We conclude that calcium-sulfate mineral formation in brine-filled fractures may play an important role in inhibiting fluid migration in geologic reservoirs that contain CO2.
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影响因子：
5
作者：
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通讯作者：
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影响因子：
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作者：
Victor N. Balashov;George D. Guthrie;J. Hakala;C. Lopano;J. Rimstidt;S. Brantley
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Victor N. Balashov;George D. Guthrie;J. Hakala;C. Lopano;J. Rimstidt;S. Brantley
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通讯作者：
SOFER, Z
纳瓦霍砂岩
DOI：
--
发表时间：
1995
期刊：
影响因子：
--
作者：
Jonathan E. Verlander
通讯作者：
Jonathan E. Verlander
影响因子：
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作者：
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通讯作者：
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