Numerical simulation of CO_2 mineral sequestration in basalt reservoir through an abandoned oil well: a case study in Xujiaweizi area, Northeast China

摘要

CO2-basalt-water interaction safely converts CO2 into carbonate minerals within a short period, which has been verified by the CarbFix project in Iceland. However, the neo-formed secondary silicates as well as carbonate readily fill the fluid paths in the basalt, preventing the CO2 from passing through the rocks, thereby greatly reducing the storage efficiency and increasing the storage costs. This is especially the case if the permeability of the original reservoir is low. To address this problem, we propose the use of hydraulic fracturing to enhance the permeability of the basalt reservoir, increase the sequestration space, and prolong the reservoir life. In this study, the basalt formation in the Xujiaweizi area in northeastern China was chosen as the research target due to its enormous CO2 sequestration potential (about 357 x 10(8) tons). First, the reservoir was investigated using actual geological, laboratory, and logging data. Second, reservoir stimulation was investigated using laboratory experiments and numerical simulations. Finally, a 10-year simulation of the CO2-basalt-water interaction was performed in the enhanced basalt reservoir to determine the difference in the physical and chemical behavior in the zones with different permeability. The results showed that the permeability of the fractured zone with good percolation conditions only decreased by 4.5% in 10 years, and CO2 sequestration capacity in this zone was as high as 1.19 kg/m(3).