Kevin G. Knauss1, James W. Johnson2, Carl I. Steefel2, John J. Nitao2
(1) Lawrence Livermore National Laboratory, Livermore, CA
(2) Lawrence Livermore National Laboratory
ABSTRACT: Evaluation Of The Impact Of CO2, Aqueous Fluid, And Reservoir Rock Interactions On The Geologic Sequestration Of CO2, With Special Emphasis On Economic Implications
The objective of this research is to evaluate the impacts of an impure CO2 waste stream on geologic sequestration using both reaction progress and reactive transport simulators. The simulators serve as numerical laboratories within which a series of experiments can be designed, carried out, and analyzed to quantify sensitivity of the overall injection/sequestration process to specific compositional, hydrologic, structural, thermodynamic, and kinetic parameters associated with the injection fluid and subsurface environment.
The simulations begin with simple batch-type reactions that simulate titration of an equilibrated reservoir rock/water system with a gas phase that starts off pure CO2 and has SO2 incrementally added to it. We then construct a series of simulations in which the batch-type reactions are perturbed by periodically flushing out the aqueous phase and permitting the evolved reservoir rock system to re-equilibrate with the "fresh" aqueous phase. This is a "rock-centered", pseudo-flow-through simulation. Both of these initial types of simulations are pure thermodynamic calculations: no reaction kinetics are invoked. We then construct a series of simulations that are equivalent to the first batch-type (closed system) reactions, but this time including dissolution kinetics for all of the mineral phases present in the reservoir rock and assuming a composition and modal abundance appropriate for a feldspathic sandstone containing clay and carbonate with and without an Fe-bearing phase. Several approaches to dealing with setting fO2 are investigated. In these simulations reaction progress is allowed to proceed for a time period of 30 years, appropriate for a real CO2 sequestration process.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado