CCS工程中盖层渗透率对CO2逃逸的影响

THE EFFECT OF CAPROCK PERMEABILITY ON THE LEAKAGE OF CO_2 IN A CO_2 CAPTURE AND STORAGE PROJECT

针对CO2埋存后可能存在的逃逸问题进行了分析.在对ABAQUS商用软件进行二次开发的基础上,针对各个因素进行了计算;并对简单情况进行了理论推导,验证了数值模型的正确性.考虑到CO2逃逸过程中可能发生相态变化,数值模拟时分别采用理想气体状态方程和范德华方程以对结果进行比较.结果表明,在盖层均匀和通常的气藏条件下,CO2完全渗漏需要15×10^4年以上;盖层含井或有裂缝时会导致CO2快速逃逸,完全逃逸在1×10^4年左右,在选址时应该尽量避免.

The leakage after CO2 sequestration is critical in the evaluation of CO2 storage period and the stability of the cap-rock.In this paper,the commercial FEM software ABAQUS is used with a secondary development to analyze the key factors of CO2 seepage.Meanwhile the gas Vander-Walls equation is applied to the supercritical CO2 compared to the ideal gas equation.A simple theoretical result is obtained and verified in a good agreement with that of simulation.The results show that at least 150000 years are needed until CO2 escapes completely from a homogeneous cap-rock with a low permeability;the number storage duration is decreaseds to 10000 years when there is a high permeability leaky well or fractures,hence,fractures or leaky wells should be consolidated before sequestration or kept away from project areas.