Analysis of Rates of Geochemical Reactions.- Transition State Theory and Molecular Orbital Calculations Applied to Rates and Reaction Mechanisms in Geochemical Kinetics.- The Mineral-Water Interface.- Kinetics of Sorption-Desorption.- Kinetics of Mineral Dissolution.- Data Fitting Techniques with Applications to Mineral Dissolution Kinetics.- Nucleation, Growth, and Aggregation of Mineral Phases: Mechanisms and Kinetic Controls.- Microbiological Controls on Geochemical Kinetics 1: Fundamentals and Case Study on Microbial Fe(III) Oxide Reduction.- Microbiological Controls on Geochemical Kinetics 2: Case Study on Microbial Oxidation of Metal Sulfide Minerals and Future Prospects.- Quantitative Approaches to Characterizing Natural Chemical Weathering Rates.- Geochemical Kinetics and Transport.- Isotope Geochemistry as a Tool for Deciphering Kinetics of Water-Rock Interaction.- Kinetics of Global Geochemical Cycles.

Kinetics of Water-Rock Interaction

New technologies, particularly those designed to address environmental concerns, have created a great demand for the rare earth elements (REE), and focused considerable attention on the processes by which they are concentrated to economically exploitable levels in the Earth’s crust. There is widespread agreement that hydrothermal fluids played an important role in the formation of the world’s largest economic REE deposit, i.e. Bayan Obo, China. Until recently, many researchers have assumed that hydrothermal transport of the REE in fluorine-bearing ore-forming systems occurs mainly due to the formation of REE-fluoride complexes. Consequently, hydrothermal models for REE concentration have commonly involved depositional mechanisms based on saturation of the fluid with REE minerals due to destabilization of REE-fluoride complexes. Here, we demonstrate that these complexes are insignificant in REE transport, and that the above models are therefore flawed. The strong association of H+ and F− as HF° and low solubility of REE-F solids greatly limit transport of the REE as fluoride complexes. However, this limitation does not apply to REE-chloride complexes. Because of this, the high concentration of Cl− in the ore fluids, and the relatively high stability of REE-chloride complexes, the latter can transport appreciable concentrations of REE at low pH. The limitation also does not apply to sulphate complexes and in some fluids, the concentration of sulphate may be sufficient to transport significant concentrations of REE as sulphate complexes, particularly at weakly acidic pH. This article proposes new models for hydrothermal REE deposition based on the transport of the REE as chloride and sulphate complexes.

Hydrothermal transport and deposition of the rare earth elements by fluorine-bearing aqueous liquids

[1] The dynamic behavior of magmatic hydrothermal systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The past 2 decades have seen steady growth of computational power and the development of numerical models that have eliminated or minimized the need for various simplifying assumptions. Considerable heuristic insight has been gained from process-oriented numerical modeling. Recent modeling efforts employing relatively complete EOS and accurate transport calculations have revealed dynamic behavior that was damped by linearized, less accurate models, including fluid property control of hydrothermal plume temperatures and three-dimensional geometries. Other recent modeling results have further elucidated the controlling role of permeability structure and revealed the potential for significant hydrothermally driven deformation. Key areas for future research include incorporation of accurate EOS for the complete H2O-NaCl-CO2 system, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2009RG000287

Numerical simulation of magmatic hydrothermal systems

https://link.springer.com/content/pdf/10.1007/s12182-019-0340-8.pdf

A review of CO 2 storage in geological formations emphasizing modeling, monitoring and capacity estimation approaches

Scale Prediction for Oil and Gas Production

Coupled phase and aqueous species equilibrium of the H2O–CO2–NaCl–CaCO3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite

The speciation equilibrium coupling with phase equilibrium in the H2O–CO2–NaCl system from 0 to 250 °C, from 0 to 1000 bar, and from 0 to 5 molality of NaCl

An equation of state is established for the gas phase of CO2–H2O in the range 0–28 MPa and 323–645 K. The equation for gaseous CO2–H2O mixtures can accurately reproduce the experimental volumes with an average deviation of 0.25% and a maximum deviation of 2.8%. An accurate model for the molar volumes and densities of liquid CO2–H2O and CO2–H2O–NaCl mixtures is developed. The most accurate experimental density data for the CO2–H2O system in the range 273–623 K and 0.7–35 MPa can be reproduced within ±0.05%, and the average deviation is 0.008%. The model for the liquid CO2–H2O–NaCl mixtures is developed on the basis of our CO2–H2O model and the H2O–NaCl model of Rogers and Pitzer (J. Phys. Chem. Ref. Data 1982, 11 ((1)) 15–81). No additional empirical parameter is introduced for the ternary. This model can predict the ternary density data within experimental errors and is expected to be valid up to 573 K. It is found that both the density model and the equation of state can be extrapolated up to 100 MPa or ...

Densities of the CO2-H2O and CO2-H2O-NaCl Systems Up to 647 K and 100 MPa

Injection of CO2 into gas reservoirs for CO2-enhanced gas recovery will initiate a series of geochemical reactions between pore fluids and solid phases. To simulate these conditions, the coupled multiphase flow and multicomponent reactive transport simulator OpenGeoSys-ChemApp was extended to take into account the kinetic nature of fluid/mineral reactions. The coupled simulator is verified successfully for the correctness and accuracy of the implemented kinetic reactions using benchmark simulations. Based on a representative geochemical model developed for the Altensalzwedel compartment of the Altmark gas field in northeastern Germany (De Lucia et al. this issue), the code is applied to study reactive transport following an injection of CO2, including dissolution and precipitation kinetics of mineral reactions and the resulting porosity changes. Results from batch simulations show that injection-induced kinetic reactions proceed for more than 10,000 years. Relevant reactions predicted by the model comprise the dissolution of illite, precipitation of secondary clays, kaolinite and montmorillonite, and the mineral trapping of CO2 as calcite, which starts precipitating in notable quantities after approximately 2,000 years. At earlier times, the model predicts only small changes in the mineral composition and aqueous component concentrations. Monitoring by brine sampling during the injection or early post-injection period therefore would probably not be indicative of the geochemical trapping mechanisms. One-dimensional simulations of CO2 diffusing into stagnant brine show only a small influence of the transport of dissolved components at early times. Therefore, in the long term, the system can be approximated reasonably well by kinetic batch modelling.

Modelling CO 2 -induced fluid–rock interactions in the Altensalzwedel gas reservoir. Part II: coupled reactive transport simulation

Sequestration of CO2 into a deep geological reservoir causes a complex interaction of different processes such as multiphase flow, phase transition, multicomponent transport, and geochemical reactions between dissolved CO2 and the mineral matrix of the porous medium. A prognosis of the reservoir behaviour and the feedback from large-scale geochemical alterations require efficient process-based numerical models. For this purpose, the multiphase flow and multicomponent transport code OpenGeoSys-Eclipse have been coupled to the geochemical model ChemApp. The newly developed coupled simulator was successfully verified for correctness and accuracy of the implemented reaction module by benchmarking tests. The code was then applied to assess the impact of geochemical reactions during CO2 sequestration at a hypothetical but typical Bunter sandstone formation in the Northern German Basin. Injection and spreading of 1.48 × 107 t of CO2 in an anticline structure of the reservoir were simulated over a period of 20 years of injection plus 80 years of post-injection time. Equilibrium geochemical calculations performed by ChemApp show only a low reactivity to the geochemical system. The increased acidity of the aqueous solution results in dissolution of small amounts of calcite, anhydrite, and quartz. Geochemical alterations of the mineral phase composition result in slight increases in porosity and permeability, which locally may reach up to +0.02 and 0.1 %, respectively.

Dedong Li

Papers

Coupled phase and aqueous species equilibrium of the H2O–CO2–NaCl–CaCO3 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to saturation of halite

The speciation equilibrium coupling with phase equilibrium in the H2O–CO2–NaCl system from 0 to 250 °C, from 0 to 1000 bar, and from 0 to 5 molality of NaCl

Densities of the CO2-H2O and CO2-H2O-NaCl Systems Up to 647 K and 100 MPa

Modelling CO 2 -induced fluid–rock interactions in the Altensalzwedel gas reservoir. Part II: coupled reactive transport simulation

OpenGeoSys-ChemApp: a coupled simulator for reactive transport in multiphase systems and application to CO2 storage formation in Northern Germany