A mesoscopic model of nucleation and Ostwald ripening/stepping: Application to the silica polymorph system

Özkan, Göksel; Ortoleva, P.

doi:10.1063/1.481685

Cited by 20 publications

(27 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Failure to account for such processes excludes from consideration the formation of metastable secondary phases in the system, and their eventual transformation into more stable phase assemblages as described by the Ostwald Rule of Stages (Ostwald, 1897). Earlier modeling of the Ostwald Rule is limited to those undertaken by Steefel and Van Cappellen (1990) and Ozkan and Ortoleva (2000). Substantial refinements would be needed to successfully model the systems under consideration in this paper.…”

Section: Model Limitationsmentioning

confidence: 99%

“…Other aspects relating to mineral transformation kinetics such as nucleation, the preferential formation and persistence of metastable phases (Steefel and van Capellen, 1990;Ozkan and Ortoleva, 2000) and Ostwald ripening are omitted from the current model. Discussion of their potential impact on the results of the simulations presented in this paper are deferred to Section 5.…”

Section: Geochemical Datamentioning

confidence: 99%

See 1 more Smart Citation

Numerical modeling of injection and mineral trapping of CO2 with H2S and SO2 in a sandstone formation

et al. 2007

View full text Add to dashboard Cite

Abstract. Carbon dioxide (CO 2 ) injection into deep geologic formations could decrease the atmospheric accumulation of this gas from anthropogenic sources. Furthermore, by co-injecting H 2 S or SO 2 , the products respectively of coal gasification or combustion, with captured CO 2 , problems associated with surface disposal would be mitigated. We developed models that simulate the co-injection of H 2 S or SO 2 with CO 2 into an arkose formation at a depth of about 2 km and 75°C. The hydrogeology and mineralogy of the injected formation are typical of those encountered in Gulf Coast aquifers of the United States. Six numerical simulations of a simplified 1-D radial region surrounding the injection well were performed. The injection of CO 2 alone or co-injection with SO 2 or H 2 S results in a concentrically zoned distribution of secondary minerals surrounding a leached and acidified region adjacent to the injection well. Co-injection of SO 2 with CO 2 results in a larger and more strongly acidified zone, and alteration differs substantially from that caused by the co-injection of H 2 S or injection of CO 2 alone. Precipitation of carbonates occurs within a higher pH (pH > 5) peripheral zone. Significant quantities of CO 2 are sequestered by ankerite, dawsonite, and lesser siderite. The CO 2 mineral-trapping capacity of the formation can attain 40-50 kg/m 3 medium for the selected arkose. In contrast, secondary sulfates precipitate at lower pH (pH < 5) within the acidified zone.Most of the injected SO 2 is transformed and immobilized through alunite precipitation with lesser amounts of anhydrite and minor quantities of pyrite. The dissolved CO 2 increases with time (enhanced solubility trapping). The mineral alteration induced by injection of CO 2 with either SO 2 or H 2 S leads to corresponding changes in porosity. 2Significant increases in porosity occur in the acidified zones where mineral dissolution dominates. With co-injection of SO 2 , the porosity increases from an initial 0.3 to 0.43 after 100 years. However, within the CO 2 mineral-trapping zone, the porosity decreases to about 0.28 for both cases, because of the addition of CO 2 mass as secondary carbonates to the rock matrix. Precipitation of sulfates at the acidification front causes porosity to decrease to 0.23. The limited information currently available on the mineralogy of naturally occurring high-pressure CO 2 reservoirs is generally consistent with our simulations.

show abstract

Section: Model Limitationsmentioning

confidence: 99%

Section: Geochemical Datamentioning

confidence: 99%

Numerical modeling of injection and mineral trapping of CO2 with H2S and SO2 in a sandstone formation

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The hybrid method similar to that described in [37] has been applied recently by Ozkan and Ortoleva [43] to model nucleation, Ostwald ripening and stepping in the silica polymorph system. In this method the cluster size domain is divided into two parts; for small clusters (n < N $ 100) discrete kinetic equations are applied, while for large clusters a continuous kinetic equation is written with respect to the ln(n) variable.…”

Section: Methodsmentioning

confidence: 98%

“…Similar to [37,43] we keep the original finite difference set of equations up to some number, N ) 1, of atoms in clusters. For larger sizes, the discrete Master equation is transformed, by the Taylor series expansion up to the second-order terms, into the continuous Fokker-Planck equation…”

Section: Methodsmentioning

confidence: 99%

“…In this method the cluster size domain is divided into two parts; for small clusters (n < N $ 100) discrete kinetic equations are applied, while for large clusters a continuous kinetic equation is written with respect to the ln(n) variable. In this approach the boundary condition between the discrete and continuous formulations are obtained from the continuity conditions [43].…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation