Institute for Sustainable Energy, and Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G8.
Lab Chip. 2013 Jul 7;13(13):2508-18. doi: 10.1039/c3lc00031a. Epub 2013 Mar 22.
In this study, we develop a lab-on-a-chip approach to study pore-scale salt precipitation dynamics during CO2 sequestration in saline aquifers-a challenge with this carbon management strategy. Three distinct phases-CO2 (gas), brine (liquid), and salt (solid)-are tracked through microfluidic networks matched to the native geological formations. The resulting salt formation dynamics indicate porosity decreases of ~20% in keeping with large scale core studies. At the network scale, the salt precipitation front moves at a constant velocity, ~2% that of the superficial CO2 velocity in this case. At the pore-scale, we observe two dominant types of salt formation: (1) large bulk crystals, on the order of the pore size (20-50 μm), forming early within trapped brine phases; and (2) polycrystalline aggregated structures, ranging over broad length scales, forming late in the evaporation process and collecting/projecting from the CO2-brine interface. Together, these two salt formation mechanisms show particular propensity for pore blockage and reduced carbon storage capacity.
在这项研究中，我们开发了一种芯片实验室方法来研究 CO2 在咸水含水层中封存过程中的孔隙尺度盐沉淀动力学——这是该碳管理策略面临的挑战。通过与天然地质构造相匹配的微流控网络来跟踪三种截然不同的相态——CO2（气体）、盐水（液体）和盐（固体）。所得盐形成动力学表明，孔隙度降低了约 20%，与大规模岩心研究一致。在网络尺度上，盐沉淀前沿以 ~2%的 CO2 表面速度的恒定速度移动。在孔隙尺度上，我们观察到两种主要的盐形成类型：(1) 大的块状晶体，尺寸与孔径相当（20-50 μm），在被困的盐水相中早期形成；(2) 多晶聚合结构，在蒸发过程的后期形成，并在 CO2-盐水界面处收集/突出，跨越广泛的长度尺度。这两种盐形成机制都显示出特别容易堵塞孔隙和降低碳存储能力的倾向。
