The Rayleigh convection induced by dissolved CO₂ in saline aquifers is significant for CO₂ permanent storage. In this paper, the lattice Boltzmann method (LBM) with external forces was established to simulate such the convection in NaCl, KCl, MgCl₂ and CaCl₂ solutions. The simulation was performed in two kinds of conditions, the one was the same concentration of salt, and another was the same concentration of Cl^-, at 298.15 K, 1.00 atm. The results showed that the order of convection appearance in four salt solutions was: KCl＞NaCl > MgCl₂>CaCl₂ in 1 mol·kg^-1 (M) salt solution. However, it was a little different in the condition of the same concentration of Cl^-, the order was: KCl > MgCl₂>CaCl₂>NaCl. This was mainly because a bigger density difference between brine and CO₂-saturated solution could enhance convective instability. The magnitude of convective velocity and mass transfer rate was 10^-5 and 10^-6 m∙s^-1, respectively. Furthermore, the mean dissolution rate was around 2 times larger than that at the onset of convection. In addition, we found that the onset convection would be delayed as salt concentration increased. Our results have a practical guidance for a further experimental design and industrial application on CO₂ geological separation in saline aquifers.

盐水层中溶解的CO ₂引起的瑞利对流对CO ₂永久储存具有重要意义。本文建立了带有外力的格子玻尔兹曼方法（LBM），以模拟在NaCl，KCl，MgCl ₂和CaCl ₂溶液中的对流。模拟是在两种情况进行的，所述一个是盐的相同浓度下，和另一个是氯的相同浓度^-，298.15 K，1.00个大气压。结果表明，四种盐溶液的对流出现顺序为：1 mol·kg ^-1的KCl＞ NaCl＞ MgCl ₂＞ CaCl ₂。（M）盐溶液。然而，它是在氯的浓度相同的条件稍有不同^- ，顺序为：氯化钾>的MgCl ₂ >的CaCl ₂ > NaCl中。这主要是因为盐水和CO ₂饱和溶液之间更大的密度差会增强对流不稳定性。对流速度和传质速率分别为10 ^-5和10 ^-6 m∙s ^-1， 分别。此外，平均溶出速率大约是对流开始时的2倍。此外，我们发现随着盐浓度的增加，对流的开始时间会延迟。我们的结果为盐水层中CO ₂地质分离的进一步实验设计和工业应用提供了实用指导。