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Flow-through reactor experiments on basalt-(sea)water-CO2 reactions at 90 °C and neutral pH. What happens to the basalt pore space under post-injection conditions?
International Journal of Greenhouse Gas Control ( IF 3.9 ) Pub Date : 2017-11-24 , DOI: 10.1016/j.ijggc.2017.11.013
D. Wolff-Boenisch , I.M. Galeczka

Recent publications on the successful mineralisation of carbon dioxide in basalts in Iceland and Washington State, USA, have shown that mineral storage can be a serious alternative to more mainstream geologic carbon storage efforts to lock away permanently carbon dioxide. In this study we look at the pore solution chemistry and mineralogy of basaltic glass and crystalline basalt under post-injection conditions, i.e. after rise of the pH via matrix dissolution and the first phase of carbonate formation. Experimental findings indicate that further precipitation of carbonates under more alkaline conditions is highly dependent on the availability of divalent cations. If the pore water is deficient in divalent cations, smectites and/or zeolites will dominate the secondary mineralogy of the pore space, depending on the basalt matrix. At low carbonate alkalinity no additional secondary carbonates are expected to form meaning the remaining pore space is lost to secondary silicates, irrespective of the basalt matrix. At high carbonate alkalinity, some of this limited storage volume may additionally be occupied by dawsonite −if the Na concentration in the percolating groundwater (brine) is high. Using synthetic seawater as a proxy for the groundwater composition and thus furnishing considerable amounts of divalent cations to the carbonated solution, results in massive precipitation of calcite, magnesite, and other Ca/Mg-carbonates under already moderate carbonate alkalinity. More efficient use of the basaltic storage volume can thus be attained by promoting formation of secondary carbonates compared to the inevitable formation of secondary silicate phases at higher pH. This can be done by ensuring that the pore water does not become depleted in divalent cations, even after carbonate formation. Using seawater as carbonating fluid or injection of CO2 into the basaltic oceanic crust, where saline fluids percolate, can reach this goal. However, such an approach needs sophisticated reactive transport modelling to adjust CO2 injection rates in order to avoid too rapid carbonate deposition and clogging of the pore space too close to the injection well.



中文翻译:

在90°C和中性pH下对玄武岩-(海水)-CO 2反应进行流式反应器实验。注入后的条件下玄武岩孔隙空间会发生什么变化?

关于在冰岛和美国华盛顿州的玄武岩中二氧化碳成功矿化的最新出版物表明,矿物存储可以替代更主流的地质碳存储以永久性地锁定二氧化碳,这是一种严重的替代方法。在这项研究中,我们研究了在注入后的条件下,即在通过基质溶解和形成碳酸盐的第一阶段使pH升高之后,玄武岩玻璃和结晶玄武岩的孔溶液化学和矿物学。实验结果表明,在更碱性的条件下碳酸盐的进一步沉淀高度依赖于二价阳离子的可用性。如果孔隙水中缺乏二价阳离子,则取决于玄武岩基质,蒙脱石和/或沸石将主导孔隙空间的次生矿物学。在低碳酸盐碱度下,预计不会形成额外的仲碳酸盐,这意味着剩余的孔隙空间将损失给仲硅酸盐,而与玄武岩基质无关。在高碳酸盐碱度下,如果渗滤地下水(盐水)中的Na浓度很高,则钠铝矾石可能会额外占用一部分有限的存储量。用合成海水代替地下水成分,从而向碳酸盐溶液中提供大量的二价阳离子,导致在已经中等的碳酸盐碱度下方解石,菱镁矿和其他Ca / Mg碳酸盐大量沉淀。因此,与在较高pH下不可避免地形成第二硅酸盐相相比,可以通过促进第二碳酸盐的形成来实现对玄武质储存体积的更有效利用。这可以通过确保即使在形成碳酸盐之后,孔隙水也不会耗尽二价阳离子来完成。使用海水作为碳酸化液或注入一氧化碳2进入玄武岩大洋地壳,在那里盐水流过,可以达到这个目的。然而,这种方法需要复杂的反应性传输模型来调节CO 2注入速率,以避免碳酸盐沉积过快以及堵塞过于靠近注入井的孔隙空间。

更新日期:2017-11-24
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