A computational model for a multi-path leakage of geo-sequestered CO2

Abstract

A computational model for the combined CO2 leakage through abandoned wellbores and heterogeneous geological layers is introduced. The averaging theory is utilized to described the multiphase flow in the reservoir, and the drift flux model is utilized to describe the multiphase flow in the wellbore. The governing equations are solved numerically using a mixed-discretization finite element approach [1-3]. A stationary partition of unity is utilized to model the discontinuity in flow field between adjacent geological layers, and a moving partition of unity, together with the level set method, is utilized to model the movement of the fluid front in the wellbore. Due to the significant difference in the time scale between the flow in the wellbore and the reservoir, a multi-time-step scheme is introduced. The proposed computational model allows the use of structured, relatively coarse and geometry-independent finite element meshes.