Impacts of mineralogical compositions on different trapping mechanisms during long-term CO_{class="a-plus-plus">2} storage in deep saline aquifers

详细信息    查看全文

• 作者：Kairan Wang ; Tianfu Xu ; Hailong Tian ; Fugang Wang
• 关键词：CO2 storage ; Mineralogical compositions ; Numerical simulation ; Saline aquifers ; Trapping mechanisms
• 刊名：Acta Geotechnica
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：11
• 期：5
• 页码：1167-1188
• 全文大小：5,829 KB
• 刊物类别：Engineering
• 刊物主题：Continuum Mechanics and Mechanics of Materials
  Geotechnical Engineering
  Soil Science and Conservation
  Granular Media
  Structural Mechanics
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1861-1133
• 卷排序：11

文摘

Deep saline aquifers in sedimentary basins are considered to have the greatest potential for CO₂ geological storage in order to reduce carbon emissions. CO₂ injected into a saline sandstone aquifer tends to migrate upwards toward the caprock because the density of the supercritical CO₂ phase is lower than that of formation water. The accumulated CO₂ in the upper portions of the reservoir gradually dissolves into brine, lowers pH and changes the aqueous complexation, whereby induces mineral alteration. In turn, the mineralogical composition could impose significant effects on the evolution of solution, further on the mineralized CO₂. The high density of aqueous phase will then move downward due to gravity, give rise to “convective mixing,” which facilitate the transformation of CO₂ from the supercritical phase to the aqueous phase and then to the solid phase. In order to determine the impacts of mineralogical compositions on trapping amounts in different mechanisms for CO₂ geological storage, a 2D radial model was developed. The mineralogical composition for the base case was taken from a deep saline formation of the Ordos Basin, China. Three additional models with varying mineralogical compositions were carried out. Results indicate that the mineralogical composition had very obvious effects on different CO₂ trapping mechanisms. Specific to our cases, the dissolution of chlorite provided Mg2+ and Fe2+ for the formation of secondary carbonate minerals (ankerite, siderite and magnesite). When chlorite was absent in the saline aquifer, the dominant secondary carbon sequestration mineral was dawsonite, and the amount of CO₂ mineral trapping increased with an increase in the concentration of chlorite. After 3000 years, 69.08, 76.93, 83.52 and 87.24 % of the injected CO₂ can be trapped in the solid (mineral) phase, 16.05, 11.86, 8.82 and 6.99 % in the aqueous phase, and 14.87, 11.21, 7.66 and 5.77 % in the gas phase for Case 1 through 4, respectively.