Chapter 16 - Hydrologic, Mechanical, Thermal, and Chemical Process Coupling Triggered by the Injection of CO2

Abstract

Geological carbon storage (GCS) is a promising technology to mitigate carbon dioxide (CO2) emission in the atmosphere. It involves complex thermal-hydrologic-mechanical-chemical (THMC) processes. The significance of THMC interactions is well recognized but not fully understood for the operation of GCS. Geomechanical and geochemical effects may significantly affect aqueous phase composition, porosity and permeability of the formation, which in turn influence flow and transport. All the associated physical and chemical mechanisms overall temporal and spatial scales need to be fully addressed by modeling of long-term GCS, which poses a significant challenge to theoretical modeling and numerical simulation. This chapter summarizes the current state-of-the-art research, which focuses on coupling of THMC processes as subsurface systems reequilibrate during and after the injection of CO2. The mechanisms of coupled THMC processes are described in detail in terms of spatial and temporal variability. The computational methods are categorized in terms of coupling logics. The key challenges and issues of THMC processes simulation are discussed in terms of experimental and numerical practices. This chapter provides a better understanding of dominant mechanisms related to fluid flow, geomechanics and geochemistry over time and spatial scales by means of variable physical and numerical simulation practices.