Unique Environmental Conditions Required for Dawsonite Formation: Implications from Dawsonite Synthesis Experiments under Alkaline Conditions,ACS Earth and Space Chemistry

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Unique Environmental Conditions Required for Dawsonite Formation: Implications from Dawsonite Synthesis Experiments under Alkaline Conditions
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2019-01-16 00:00:00 , DOI: 10.1021/acsearthspacechem.8b00121
Yutaro Takaya _{1,

2,

3,

4} , Miao Wu ₁ , Yasuhiro Kato _{2,

3,

4}

Affiliation

Although many numerical simulation studies suggest the formation of dawsonite in CO₂ reservoirs and its resulting contribution to secure geological carbon storage, dawsonite formation is not observed in experimental studies. In addition, the natural occurrence of dawsonite is scarce. The lack of certainty in “whether dawsonite forms in CO₂ reservoirs” is a major concern for evaluating the security of geological carbon storage and has been discussed for decades. This study performed dawsonite synthesis experiments with co-existing elements (K, Ca, and Mg) and investigated the unique formation conditions of dawsonite. Our experiments clearly show that co-existing magnesium (MgCl₂) inhibits dawsonite formation to form hydrotalcite and/or manasseite instead of dawsonite under alkaline conditions. Because magnesium is widespread in the Earth’s crust, dawsonite could be formed only under extremely restricted conditions (Mg-poor conditions) and is unlikely to form in CO₂ reservoirs during the post-injection period. We also indicate that the discrepancy between numerical simulations and experiments arises from the incompleteness of thermodynamic databases. Our results significantly contribute to resolving the long-running controversy regarding the formation of dawsonite in CO₂ reservoirs.

中文翻译：

片钠铝石形成所需的独特环境条件：碱性条件下片钠铝石合成实验的意义

尽管许多数值模拟研究表明在CO ₂储层中形成钠铝榴石及其对确保地质碳储存的贡献，但在实验研究中未观察到钠铝榴石的形成。另外，片钠铝石的天然存在是稀缺的。“ CO ₂储层中的片钠铝石形式”缺乏确定性是评估地质碳储量安全性的主要问题，并且已经讨论了数十年。这项研究进行了钠钙铝石与钾，钙和镁共存元素的合成实验，并研究了钠钙铝石的独特形成条件。我们的实验清楚地表明，镁（MgCl ₂）在碱性条件下抑制了片钠铝石的形成，以形成水滑石和/或菱镁矿而不是片钠铝石。由于镁在地壳中分布广泛，因此钠钠铝石只能在极为受限的条件下（贫镁条件下）形成，并且在注入后阶段不太可能在CO ₂储层中形成。我们还指出，数值模拟和实验之间的差异是由于热力学数据库的不完整引起的。我们的结果极大地有助于解决有关CO ₂储层中片钠铝石形成长期存在的争议。

更新日期：2019-01-16

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