Pore-scale hydrodynamic evolution within carbonate rock&#8239;during&#8239;CO2 injection&#8239;and sequestration
Authors: Zhang Chi , Liu Siyan , Barati Reza 
Published: March 2021

&lt;p&gt;&lt;span&gt;The continuously rising threat of global warming caused&amp;#8239;by&amp;#8239;human activities related&amp;#8239;to&amp;#8239;CO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;2&lt;/sub&gt;&amp;#8239;emission is&amp;#8239;facilitating&amp;#8239;the development of&amp;#8239;greenhouse gas control technologies.&amp;#8239;Subsurface CO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;2&lt;/sub&gt;&amp;#8239;injection and&amp;#8239;sequestration&amp;#8239;is one of the promising techniques&amp;#8239;to store&amp;#8239;CO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;2&lt;/sub&gt;&amp;#8239;in&amp;#160;the subsurface.&amp;#8239;&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;However,&amp;#160;during CO&lt;sub&gt;2&lt;/sub&gt; injection,&amp;#160;the mechanisms of processes&amp;#160;like injectant immobilizations and trapping&amp;#160;and&amp;#160;pore-scale&amp;#8239;geochemical reactions such as mineral dissolution/precipitation&amp;#160;are not well understood.&amp;#160;Consequently,&amp;#160;the&amp;#160;multi-physics&amp;#160;modeling approach is essential&amp;#160;to&amp;#160;elucidate&amp;#160;the impact of&amp;#160;all potential factors&amp;#160;during CO&lt;sub&gt;2&lt;/sub&gt; injection,&amp;#160;thus&amp;#160;to facilitate the optimization of this engineered application.&lt;/span&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Here, we propose a coupled framework&amp;#8239;to fully&amp;#8239;utilize&amp;#8239;the capabilities of the geochemical reaction solver PHREEQC while preserving the&amp;#8239;Lattice-Boltzmann Method (LBM)&amp;#8239;high-resolution pore-scale fluid flow integrated with diffusion&amp;#8239;processes. The&amp;#8239;model&amp;#8239;can simulate&amp;#8239;the dynamic fluid-solid interactions with equilibrium, kinetics, and surface reactions under&amp;#8239;the&amp;#8239;reactive-transport scheme.&amp;#8239; In a simplified 2D spherical pack, we focused on examining&amp;#8239;the&amp;#8239;impact&amp;#8239;of&amp;#8239;pore sizes, grain size distributions, porosity, and permeability on the calcite dissolution/precipitation rate. Our simulation results show that the&amp;#8239;higher permeability,&amp;#8239;injection rate, and more&amp;#8239;local pore connectivity&amp;#8239;would significantly increase the reaction rate, then accelerate the&amp;#8239;pore-scale geometrical evolutions. Meanwhile, model accuracy is not sacrificed&amp;#8239;by reducing the number of reactants/species&amp;#8239;within the system.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Our modeling framework&amp;#8239;provides&amp;#8239;high-resolution details of the pore-scale fluid-solid interaction dynamics. To gain more insights into the mineral-fluid interfacial properties during&amp;#160;CO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;2&lt;/sub&gt;&amp;#8239;sequestration, our next step is to combine the electrodynamic&amp;#160;forces into the model.&amp;#160;Potentially, the proposed framework&amp;#160;can be used for model upscaling and adaptive subsurface management in the future.&amp;#8239;&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;