On the potential for CO2mineral storage in continental flood basalts – PHREEQC batch- and 1D diffusion–reaction simulations

Abstract

Continental flood basalts (CFB) are considered as potential CO2 storage sites because of their high reactivity and abundant divalent metal ions that can potentially trap carbon for geological timescales. Moreover, laterally extensive CFB are found in many place in the world within reasonable distances from major CO2 point emission sources.Based on the mineral and glass composition of the Columbia River Basalt (CRB) we estimated the potential of CFB to store CO2 in secondary carbonates. We simulated the system using kinetic dependent dissolution of primary basalt-minerals (pyroxene, feldspar and glass) and the local equilibrium assumption for secondary phases (weathering products). The simulations were divided into closed-system batch simulations at a constant CO2 pressure of 100 bar with sensitivity studies of temperature and reactive surface area, an evaluation of the reactivity of H2O in scCO2, and finally 1D reactive diffusion simulations giving reactivity at CO2 pressures varying from 0 to 100 bar.Although the uncertainty in reactive surface area and corresponding reaction rates are large, we have estimated the potential for CO2 mineral storage and identified factors that control the maximum extent of carbonation. The simulations showed that formation of carbonates from basalt at 40 C may be limited to the formation of siderite and possibly FeMg carbonates. Calcium was largely consumed by zeolite and oxide instead of forming carbonates. At higher temperatures (60 – 100 C), magnesite is suggested to form together with siderite and ankerite. The maximum potential of CO2 stored as solid carbonates, if CO2 is supplied to the reactions unlimited, is shown to depend on the availability of pore space as the hydration and carbonation reactions increase the solid volume and clog the pore space. For systems such as in the scCO2 phase with limited amount of water, the total carbonation potential is limited by the amount of water present for hydration of basalt.

Turkish geothermal fields as natural analogues of CO 2 storage sites: Gas geochemistry and implications for CO 2 trapping mechanisms

“…The potential reservoirs for geologic storage of CO 2 include depleted (exploited) natural gas/oil fields Underschultz et al, 2011), saline aquifers (Soong et al, 2004;Schilling et al, 2009;Thomas et al, 2012), unmineable coal seams (Loizzoa et al, 2011), and basaltic rocks (Goldberg et al, 2008;Matter et al, 2009). The major trapping mechanisms responsible for storage of CO 2 in such reservoirs include structural trapping below the impermeable cap rock, residual trapping (residual immobilization of a few percent of injected CO 2 ), dissolution trapping (dissolution of CO 2 by the brine already present in the pore spaces of reservoir), and mineral trapping (trapping of CO 2 in mineral(s) precipitating as a result of fluidrock interaction) (Van Pham et al, 2012). Although the relative importance of these mechanisms is site specific, the latter suggestion (mineral trapping) is generally accepted as the safest for long-term storage (White et al, 2003).…”

Experimental study to better understand factors affecting the CO2 mineral trapping potential of basalt

“…9,[13][14][15][16][17][18][19] Basalt, on the other hand, is highly reactive in the presence of CO 2 and contains abundant divalent metal cations. 9,[20][21][22] Typically basalts (glassy and crystalline) contain about 7-10% Ca, 5-6% Mg, and 7-13% Fe by weight, and with natural fluxes of Ca and Mg from basaltic rocks being up to two orders of magnitude larger than those from other silicate-rich rocks. 9,23 Moreover, basalts are abundant worldwide, and the storage capacity has been suggested to be large, especially in continental flood basalts.…”

“…22,[35][36][37] Simulation results over a range of temperatures have predicted formation of siderite and Fe-Mg carbonates at 40°C, magnesite, siderite and ankerite at 60-100°C, and mixed Ca-Mg-Fe smectites and chlorite, calcite, amorphous silica and zeolites at T ࣙ150°C. 22,38 Additionally, Gysi and Stefánsson predicted that precipitation of SiO 2 and simple Al-Si minerals, Ca-Mg-Fe smectites and Ca-Mg-Fe carbonates predominated at pH < 6.5 whereas formation of Ca-Mg-Fe smectites, zeolites and calcite dominated at pH > 8. 37 The formation of secondary silicates containing divalent metal cations limits to some degree the potential of mineral carbonatization.…”

Carbonate formation on ophiolitic rocks at different pH, salinity and particle size conditions in CO2-sparged suspensions

“…Flow injection pilot tests and other feasibility studies have recognized the full potential of basaltic deposits for CO 2 storage [4, 5,22,33,36]. Other rock formations such as the Samail Ophiolite of the Sultanate of Oman have been considered in several studies for natural CO 2 sequestration sites [14,26].…”