DATE:

Friday, April 29, 2022

TIME:

3:30 PM

LOCATION:

GMCS 314

SPEAKER:

Dr. Christopher Paolini, Electrical and Computer Engineering, San Diego State University

ABSTRACT:

The numerical simulation of subsurface CO2 injection involves the solution of coupled systems that govern solute equilibrium, speciation, aqueous phase thermodynamic state, mineral dissolution and precipitation kinetics, and solute advective and diffusive transport through porous media. A short-term side-effect of subsurface CO2 injection in brine-bearing sandstones is a developing low-pH front that forms ahead of the bulk water injectant, due to differences in solute diffusivity. Rapid dissolution of CaCO3(s) and other carbonate minerals resulting from low-pH reservoir water can have significant environmental implications in geologic carbon sequestration. Dissolution of carbonate minerals can create unwanted pathways that will increase permeability and lead to a possible loss in CO2 containment. Additionally, the formation of H2CO3 can be vulnerable to wellbore integrity through corrosion of structures made from calcium-silica-hydrate compounds in Portland cements used to seal the annular volume between a casing and borehole wall. Temperature, pressure, and solute concentration measurements taken from an observation well during the Frio Pilot CO2 sequestration experiment showed a reduction in aqueous phase temperature with the arrival of the low-pH front, followed by a gradual rise in temperature upon arrival of a high concentration of bicarbonate ion. In this talk, we present a possible contributing factor to the variation in temperature between these two fronts by modeling aqueous-phase transient heat advection and diffusion, with the volumetric energy generation rate computed from solute-solvent interaction using the Helgeson-Kirkham-Flowers (HKF) model, which is based on the Born solvation model, for computing specific molar heat capacity and enthalpy of charged electrolytes. We show how a simulated injectant water temperature profile is shown to agree with sampled temperature time-series data acquired from bottom hole observation well sensors. Computation of aqueous phase temperature during subsurface injection simulation is important for the accurate modeling of mineral kinetic mechanisms, as forward dissolution rates are governed by an Arrhenius model.

HOST:

Matthew Weingarten

VIDEO: