• Methodological and Theory •

### Mathematical model and numerical analysis for leakage of fluid along geological fault during CO2 storage

ZHANG Lisong1(),JIANG Menggang1,LI Wenjie1,ZHANG Shiyan1,CHEN Shaoying1,WANG Wei1,SUN Zhixue2

1. 1. College of Pipeline and Civil Engineering, China University of Petroleum（East China）, Qingdao, Shandong 266580, China
2. School of Petroleum Engineering, China University of Petroleum（East China）, Qingdao, Shandong 266580, China
• Received:2021-12-16 Online:2022-10-26 Published:2022-09-27

Abstract:

The leakage of fluid （CO2, brine and freshwater） along fault is a crucial issue that cannot be ignored during CO2 geological storage. For this reason, the equations to describe the fluid leakage rate along faults in different stages are derived. Then, these equations are combined with mass and energy conservation equations to establish the fluid leakage model in CO2 storage processes by considering geologically activated faults. In such case, the crucial parameters （i.e., leakage time and leakage amount） for fluid leakage along a fault are obtained. The results of the effects of different parameters on leakage time and amount show the advanced initial time of CO2 leakage, the extended duration and the increased leakage amount of CO2, with CO2 injection rate and reservoir permeability increasing. Meanwhile, the initial time and duration of CO2 leakage are unchanged while the leakage amount of CO2 is increased, when increasing the fault permeability. In addition, the fault permeability has the greatest impact on the leakage amount of brine and freshwater, compared to CO2 injection rate and reservoir permeability. The numerical results show that brine starts to leak earliest, followed by CO2, freshwater. Meanwhile, the duration of CO2 leakage along a fault is the longest, while the duration of brine leakage is the shortest. Additionally, the leakage amount of CO2 is the largest, followed by brine leakage amount and the freshwater leakage amount.

CLC Number:

• TE09