基于室内注入试验的岩芯尺度玄武岩-CO2矿化封存固碳量优化计算方法研究OA

Basalt-CO2 mineral sequestration is an emerging CCUS(Carbon Capture,Utilization,and Storage)technology essential for achieving China's"dual carbon"strategy.Accurate evaluation of the sequestration potential of basalt formations is a key technical indicator for assessing the feasibility of mineral sequestration projects.Currently,various methods exist for calculating the mineral sequestration potential of basalt,such as the mineral replacement and unit mineralization methods;however,there is no industry consensus regarding the calculation principles,accuracy,and applicable conditionsof these approaches.Using an independently developed steady-state CO2 seepage test system,this study conducted laboratory injection-driven mineralization experiments to investigate the dynamic evolution of indicators such as solution ion concentration,permeability,and secondary mineral accumulationin basalt samples with varying pore and fracture characteristics from Wenchang,Hainan,during long-term mineral sequestration.By comparing the calculated values,the error ranges and underlying causes of various calculation methods were clarified.On this basis,an optimized calculation method for carbon sequestration capacity was proposed and applied to calculate the carbon sequestration capacity of basalt formations in Heishanling(HSL;Penglai Town,Wenchang City,Hainan)and the Bailonggang-Sanjia Port Area(SJG;Shanghai).The results show that:mineral dissolution dominates the early stages of the mineralization reaction,with Ca2+and Mg2+concentrations reaching supersaturation,followed by a slight permeability increase and a subsequent continuous decrease.The growth of secondary minerals shows obvious spatial patterns,with dissolution reactions dominating in the inlet section and precipitation dominating in the outlet section.Furthermore,pressure dissolution caused fracture apertures to decrease by 5.23%and 2.97%respectively.The 2.6%mass percentage of carbon on the surface of intact basalt,combined with fracture closure and pore"blockage,"accounts for the observed permeability reduction.The results indicate that basalt with larger pores and fractures exhibits a carbon sequestration potential 135.7%higher than that of intact basalt with small pores.Comparison between theoretical and experimental values shows that the mineral replacement method yields the lowest error(2.4%),while the unit mineralization and pore-filling methods significantly overestimate potential.The optimized calculation method improves calculation accuracy without the need for additional empirical parameters.Finally,the potential carbon sequestration capacities of the HSL and SJG sites were calculated to be 7.01×104 and 9.50×104 tons,respectively(for a 7500 m2 site area).These findings provide a scientific basis for the feasibility analysis of mineralization sequestration projects.