Volume 57

A Novel Numerical Framework for Fracture Evolution Modeling in Coupled THMC Processes with Application to CO2 Geological Storage Qizhi Tan, Shuyang Liu, Baojiang Sun, Junrong Liu, Yanji, Wang

Abstract

CO2 geological sequestration has been widely adopted as a key strategy for mitigating greenhouse-gas emissions and addressing climate change. Previous simulation techniques typically coupled thermal, hydraulic, mechanical and chemical (THMC) processes, yet they often omit the fracture initiation and evolution mechanisms induced by high injection pressures and temperature gradients. In this study, a novel numerical framework is introduced to simulate fracture initiation and extension during CO2 storage. This method integrates the thermal, hydraulic, mechanical and chemical reaction (THMC) processes with dynamic fracture generation and propagation to enable accurate prediction of caprock integrity and long-term storage safety. The proposed numerical framework extended the Embedded Discrete Fracture Modeling (EDFM) to fracture initiation and extension based on tension and shear failure criteria, and dynamically updates the hydraulic properties of fractures throughout the simulation. Meanwhile, heat transfer between the injected CO2 and the reservoir, stress redistribution, and relevant geochemical reactions are fully coupled to assess the impacts of fracture evolution on multi-field dynamics. The proposed framework was demonstrated using a two-dimensional In Salah CO2 storage model. The results indicated that fractures first initiated around the CO2 injection well after approximately 5 years of injection, and then extended along the caprock-saline aquifer interface. In addition, it is observed that fracture evolution exerted a pronounced influence on surface deformation. The proposed framework provides a rigorous, quantitative tool for fracture evolution forecast and containment risk management in CO2 storage projects.

Keywords CO2 storage, fracture evolution, THMC coupling processes, EDFM