530. 韩国CCS过程中杂质与地球化学反应对含杂质CO₂封存效率协同影响的组分模拟研究

Compositional Simulation of the Synergistic Impact of Impurities and Geochemical Reactions on the Efficiency of Impure CO₂ Sequestration at a Korean CCS Site

碳捕集与封存（CCS）是实现碳中和的重要技术路径，但实际CO₂气流中常含有H₂S、CH₄等杂质，这些杂质会改变CO₂的物理性质并影响储层中的地球化学反应，进而影响封存效率。本研究以韩国东海气田Gorae-V构造为地质模型，利用CMG-GEM组分模拟器，系统评估不同浓度（3.5%、10%、20%）H₂S和CH₄杂质对CO₂封存效果的影响。本研究强调，在CCS项目设计和封存效率评估中必须考虑杂质类型与浓度对物理-化学过程的协同影响。

CMG软件应用情况

• 使用软件：CMG-GEM（Compositional Simulator）
• 模拟内容：
  • 多组分CO₂-H₂S-CH₄-盐水体系的流动与反应性传输；
  • 采用Peng-Robinson状态方程（PR-EOS）描述流体相态；
  • 应用过渡态理论（TST）模拟矿物溶解/沉淀反应；
  • 模拟时间：注入期10年 + 监测期100年；
  • 模拟区域：85×85×10网格，共72,250个网格块；
  • 模拟指标：CO₂封存效率、残余与溶解封存指数（RTI & STI）、孔隙体积变化、矿物反应速率等；
  • 使用WinProp进行PVT性质拟合，结合Fick定律模拟扩散过程。

主要结论

1. 杂质对CO₂物性影响显著：
   • CH₄降低密度（最多下降25.2%）和黏度，削弱残余封存；
   • H₂S提高密度和压缩性，延缓压力上升，有利于封存。
2. 地球化学反应受杂质调控：
   • CH₄增强硅酸盐矿物（如钠长石、钾长石）的溶解；
   • H₂S促进碳酸盐矿物（如方解石）的溶解；
   • 所有情景下孔隙体积变化小于1%，但矿物反应路径差异显著。
3. 封存效率变化明显：
   • 在20%杂质浓度下，CH₄使CO₂封存效率下降6.68%；
   • 相同浓度下，H₂S使封存效率提升1.44%；
   • 杂质类型和浓度显著影响RTI与STI，CH₄降低RTI约9%，H₂S略有提升。
4. 实际意义：
   • 含杂质CO₂注入对封存性能的影响主要由物理性质变化主导；
   • 建议在CCS项目前期评估中必须进行含杂质组分的模拟分析；
   • 后续研究需进一步考虑杂质对井筒腐蚀、盖层稳定性及次生矿物沉淀的影响。

作者单位

韩国江原大学氢能安全融合工程系

Abstract

Carbon capture and storage involves CO₂ injection into geological structures to mitigate industrial CO₂ emissions. CO₂ capture processing can lead to inclusion of impurities such as H₂S and CH₄, which alter the properties of CO₂, influencing geochemical reactions in reservoirs and CO₂ storage efficiency. In this study, the impact of impurities and geochemical reactions on CO₂ storage efficiency was analyzed using reservoir simulation. The impurities altered the properties of CO₂ depending on both their type and concentration. CO₂ mixture density decreased by up to 74.8% with 20% CH₄ impurity. Also, the concentrations of aqueous hydrogen ions and metal ions varied compared to those in pure CO₂ injection scenarios. As the results, geochemical reactions with CO₂ mixtures altered the pore volume by less than 1%. These findings indicate that impurities influence the gas storage capacity differently: H₂S impurities increase the storage capacity, while CH₄ impurities reduce it. The differences in CO₂ storage capacity become more pronounced as the impurity concentrations rise. Specifically, at 20% impurity, H₂S increased CO₂ storage capacity by 1.44%, CH₄ reduced it by 6.68%. Impurities modify CO₂ properties, and the resulting decrease in CO₂ density and volume percentage negatively affects the residual trapping efficiency, particularly when CH₄ is included. Overall, these findings demonstrate that impure CO₂ injection influences geochemical reactions and CO₂ properties, with combined effects on storage efficiency in saline aquifers.