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Pore-Scale Modeling of Nucleation and Growth in Porous Media
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2020-01-13 , DOI: 10.1021/acsearthspacechem.9b00290
Hossein Fazeli 1 , Mohammad Masoudi 1 , Ravi A. Patel 2 , Per Aagaard 1 , Helge Hellevang 1, 3
Affiliation  

During the chemical interactions between fluid and minerals in different geological processes, it is of high importance to predict where secondary precipitates form in the porous rocks as it helps correctly predict the hydrodynamic properties of the porous media. The reactive transport models developed for this purpose need to account for the nucleation process which is probabilistic by nature. To our knowledge, the probabilistic nature of nucleation based on the classical nucleation theory has not been accounted for previously in reactive transport models. In this study, we develop a new probabilistic nucleation model and incorporate it into a pore-scale reactive transport solver to simulate the mineral nucleation and growth in the porous media. Simulations are performed for different supersaturations, growth rates, and flow rates using a single-component mineral reaction. Simulations show that initial supersaturations strongly affect the pattern of secondary precipitate formation. Higher initial supersaturations lead to more uniformly dispersed nucleation on all the grains, while the lower initial supersaturations result in more isolated patterns. Decreasing the growth rate favors the formation of uniformly dispersed nuclei, whereas higher growth rates cause more isolated nucleation. Injection of fluid with a higher velocity gives rise to more precipitation. Moreover, comparison of probabilistic and deterministic nucleation showed that the isolated nucleation patterns cannot be modeled using the deterministic approach. The results showed that permeability for the porous media is influenced by the pattern of secondary precipitate growth and it is demonstrated that generally, the permeability has a direct relation with the initial supersaturation and an inverse relation with the growth rate and the flow rate. Finally, the model was applied for simulation of calcite nucleation and growth on quartz grains. The calcite nucleation and growth exhibit similar behavior to those observed for single-species simulations.

中文翻译:

多孔介质中成核和生长的孔尺度模型

在不同地质过程中流体与矿物之间的化学相互作用过程中,预测次生沉淀在多孔岩石中的何处形成非常重要,因为它有助于正确预测多孔介质的水动力特性。为此目的开发的反应性传输模型需要考虑成核过程,该成核过程本质上是概率性的。据我们所知,基于经典成核理论的成核的概率性质以前并未在反应性输运模型中得到解释。在这项研究中,我们开发了一种新的概率成核模型,并将其结合到孔隙尺度的反应输运求解器中,以模拟矿物成核和在多孔介质中的生长。针对不同的过饱和度,增长率,和流速采用单组分矿物反应。模拟表明,初始过饱和度强烈影响次级沉淀物形成的模式。较高的初始过饱和度会导致在所有晶粒上更均匀地分散形核,而较低的初始过饱和度会导致更孤立的图案。降低生长速率有利于形成均匀分散的核,而较高的生长速率则导致更多的孤立核。较高速度的流体注入会产生更多的沉淀。此外,概率成核与确定性成核的比较表明,无法使用确定性方法对孤立的成核模式进行建模。结果表明,多孔介质的渗透性受二次沉淀物生长方式的影响,并且表明,渗透性通常与初始过饱和度成正比,而与生长速率和流量成反比。最后,该模型被用于模拟方解石成核和生长在石英晶粒上。方解石的成核和生长表现出与单物种模拟观察到的相似的行为。
更新日期:2020-01-14
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