Numerical simulation of CO2 leakage along faults from geologic carbon dioxide sequestration
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摘要: 安全性和封存效果是二氧化碳（CO2）地质封存（GCS）最受关注的问题，其中以断层/裂缝引起的场地不确定性因素较为复杂。利用储层多相流模拟软件TOUGH2/ECO2N，研究了不同情境下注入深部咸水层中的CO2沿断层发生泄漏的时间、速率、泄漏量等特征。通过15个场地尺度的模型结果分析表明，CO2注入方案、断层性质（发育位置、产状、几何形态、内部结构）、系统内岩层的组合形态对CO2泄漏均有影响。相同储存环境和断层发育条件下，CO2注入速率从1.59 kg/s增加至6.34 kg/s，CO2泄漏时间提前3 706 d，泄漏量在20 a后增加至注入总量的32.43%。断层发育位置对CO2封存影响极为显著，本次研究，距注入井100 m位置的断层可造成CO2的泄漏量在20 a后高达总注入量的63.39%。相同条件下，倾斜/窄小的断层比垂直/宽厚的断层对CO2及储层咸水的泄漏影响更小。断层渗透率增加一倍，可导致CO2泄漏量增加2.11%，泄漏速率约提高0.006~0.01 kg/s。
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关键词:
- CO2地质封存（GCS） /
- 咸水层 /
- CO2泄漏 /
- 断层 /
- TOUGH2
Abstract: Safety and storage performance are the most attracting issues for geological CO2 storage (GCS), in which the site uncertainties caused by faults/fractures are complex. Based on the reservoir multiphase flow simulator TOUGH2/ECO2N, the time, the CO2 leakage rate and the amount of leakage from the deep saline aquifer along the fault were studied under various conditions. The results of 15 site-scale models show that the CO2 injection scheme, fault properties (location, occurrence, geometry, and structure) and the combination of rock formations in the system have effects on CO2 leakage. Under the same reservoir environment and fault occurrence conditions, the CO2 injection rate increases from 1.59 kg/s to 6.34 kg/s, the CO2 leakage occurs 3 706 days earlier and the leakage amount increases by 32.43% in 20 years. The effect of fault location on CO2 storage is significant. In this study, a fault located at 100 m from the injection well will cause the CO2 leakage to be as high as 63.39% of the injection after 20 years. Under the same conditions, the inclination/narrow faults have less effect on the leakage of CO2 and brine than the vertical/ thick faults. An increase in the fault permeability by one time can lead to the leakage of CO2 to increase by 2.11% and the leakage rate to increase by 0.006~0.01 kg/s.-
Key words:
- geological CO2 storage (GCS) /
- saline aquifer /
- leakage /
- fault /
- TOUGH2
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