(760b) CO2 Leaks From Geological Storage: Geomechanics, Fluid Flow and Phase Transitions | AIChE

(760b) CO2 Leaks From Geological Storage: Geomechanics, Fluid Flow and Phase Transitions

Authors 

Gor, G. - Presenter, Rutgers, The State University of New Jersey
Prevost, J. H., Princeton University



Deep saline aquifers are considered as a promising option for long-term storage of carbon dioxide. However, risk of CO2 leakage from the aquifers through faults, natural or induced fractures or abandoned wells cannot be disregarded. Therefore, modeling of various leakage scenarios is crucial when selecting a site for CO2 sequestration and choosing proper operational conditions.

Carbon dioxide is injected into wells at supercritical conditions (t˚ > 31.04 ˚C, P > 73.82 bar), and these conditions are maintained in the deep aquifers (at 1-2 km depth) due to hydrostatic pressure and geothermal gradient. However, if CO2 and brine start to migrate from the aquifer upward, both pressure and temperature will decrease, and at the depth of 500-750 m, the conditions for CO2 will become subcritical. At subcritical conditions, CO2 starts boiling and the character of the flow changes dramatically due to appearance of the third (vapor) phase and latent heat effects.

When modeling CO2 leaks, one needs to couple the multiphase flow in porous media with geomechanics.  These capabilities are provided by Dynaflow, a finite element analysis program [1]; Dynaflow has already showed to be efficient for modeling caprock failure causing CO2 leaks [2, 3]. Currently we have extended the capabilities of Dynaflow with the phase transition module, based on two-phase and three-phase isenthalpic flash calculations [4]. We have also developed and implemented an efficient method for solving heat and mass transport with the phase transition using our flash module. Therefore, we have developed a robust tool for modeling CO2 leaks.

In the talk we will give a brief overview of our method and illustrate it with the results of simulations for characteristic test cases.

References:

[1] J.H. Prevost, DYNAFLOW: A Nonlinear Transient Finite Element Analysis Program. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ. http://www.princeton.edu/~dynaflow/ (last update 2012), 1981.
[2] M. Preisig, J.H. Prevost, Coupled multi-phase thermo-poromechanical effects. Case study: CO2 injection at In Salah, Algeria, International Journal of Greenhouse Gas Control, 5 (2011) 1055-1064.
[3] G.Y. Gor, T.R. Elliot, J.H. Prevost, Effects of thermal stresses on caprock integrity during CO2 storage, International Journal of Greenhouse Gas Control, 12 (2013) 300-309.
[4] M.L. Michelsen, J.M. Mollerup, Thermodynamic Models: Fundamentals and Computational Aspects. 2nd Edition, Tie-Line Publications, 2007.

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