GEOCHEMICAL MODELING OF LAMOTTE FORMATION FOR CARBON SEQUESTRATION IN MISSOURI

Various geochemical reactions that can occur upon CO₂ injection into sandstone formations in Missouri (MO) have been determined. The Geochemist's Workbench modeling program was used to simulate solubility trapping and mineral precipitation storage mechanisms during CO₂ geo-sequestration. Water quality and mineralogy of the LaMotte Sandstone in three regions (five counties) in Missouri were considered for modeling to determine the amount of CO₂ to be stored via solubility and carbonate (mineral) precipitation. Other parameters required for the model such as temperature, pressure and kinetics were obtained from literature. Green County (southwest MO), Atchison and Holts Counties (northwest MO), Ralls and Lincoln Counties (northeast MO) were considered to represent different groundwater provinces of Missouri. Modeling was completed for two periods; injection period (10 years) and post injection period (100 years). Carbon dioxide (CO₂) stored by solubility trapping during the injection period varied from one region to another depending on water chemistry and mineral phases in the formation. The amount stored via solubility trapping ranged from 57 g CO₂/kg of free formation water (northeast MO) for highly saline water to 88 g CO₂/kg of free formation water (southwest MO) for fresh water of Green County. Similarly, CO₂ stored via mineral trapping ranged from 2 g CO₂/kg of free formation water (northeast MO) to 12 g CO₂/kg of free formation water (southwest MO). The minerals that are expected to precipitate are alunite [KAl₃(SO₄)₂(OH)₆], nontronite-Mg [Mg_0.165Fe₂((Si,Al)₄O₁₀)(OH)₂.nH₂O], ), nontronite-K [K_0.3Fe₂((Si,Al)₄O₁₀)(OH)₂.nH₂O] and nontronite-Na [Na_0.3Fe₂((Si,Al)₄O₁₀)(OH)₂.nH₂O] gibbsite (Al(OH)₃), dolomite (CaMg(CO₃)₂), dawsonite [NaAlCO₃(OH)₂] and siderite [FeCO₃] with variations from one region to another. Major mineral contributions to CO₂ storage were due to siderite and dawsonite precipitation but the program predicts little mineral sequestration beyond injection period.

This material is based on work sponsored by the Department of Energy, National Energy Technology Laboratory under Award Number DEFG2610FE0001790 to Missouri State University.