Modeling of Rock Structure Changes due to Stress Induced by CO 2 Sequestration

1. Modeling of Rock Structure Changes due to Stress Induced by CO2 Sequestration EGEE 520 – 2007 Denis Pone

2. Introduction • Geo-sequestration of CO2 is one of the most attractive option to reduce the increase emissions of greenhouse gases into the atmosphere. • CO2 injection into geological formations may give rise to a variety of unexpected chemical, and physical processes. • The permeability, the porosity and the storage capacity, which are reservoir key parameters, can then fluctuate due to CO2-rock interactions • Holloway, Energy Conversion and Management 1997, 38, (Supplement 1), S193-S198. • White, et al., Energy and Fuels 2005, 19, (3), 659-724.

3. Governing Equations • Stress-strain and Hydromechanics • Thermo-Mechanical Equation • Fluid Flow and Mechanical Strain Equation • Fluid Flow and Mechanical Strain Equation

4. Model Formulation • Chemical Engineering Module Momentum balance Darcy law • Multiphysics Module Heat transfer by conduction • Structural Mechanic Module Axial symmetry strain-stress CO2 Rock 3D to 2D

5. COMSOL Solution Effect of stresses on the rock structure Effect of temperature on the rock structure

6. COMSOL Solution Combined stress, thermal and flow effects on the rock structure

7. (a) (b) Model Validation (a) Distribution of normalized fracture width for combined thermo-elastic and poro-elastic effects at various times. (b) Total displacement along the structure model with COMSOL Ghassemi, Journal of Engineering Mechanics-Asce 2006, 132, (1), 26-33

8. Parametric Study

9. Conclusions • The model developed qualitatively described the behavior of the rock due to THM interactions as expected. • Most of the physical parameters used in this study, although realistic, were chosen arbitrary. • It is important to use specific rock parameter in order to access the stability of the model.