关键词: CO₂封存, 泄漏, 数值模拟, 预测

Abstract: Evaluation method and risk control of CO₂ leakage are key issues for carbon capture and storage（CCS).In order to reveal affecting factors and features of CO₂ leakage during injection, a two-phase flow model was proposed to describe the leakage process, and numerical simulations were conducted using a commercial software COMSOL Multiphysics 3.5a.Based on comparison and extension of its solutions for a benchmark problem, the affecting factors, including distance between the injection well and leaky path, radius and permeability of leaky path, injection rate and injection depth, were investigated. The quantitative relationships between leakage rates and impact factors were obtained from simulations and data analysis.The results show that asymptotic leakage rates of CO₂ are linearly dependent on the reciprocal of distance between the injection well and leaky path, are quadratic with radius of leak path, and are linear with respect injection rates.The permeability of leaky path is the key factor controlling CO₂ leakage, whereas the increase of injection depth has little effect on decreasing CO₂ leakage rates.The proposed model and simulation results not only reveal the relationship between CO₂ leakage rates and impact factor quantitatively, but also provide analytical method and computational tools for site selection, evaluation of leakage and risk management of CO₂ injection into subsurface formations.

Key words: CO₂ storage, leakage, numerical simulation, prediction