An equation of state for the CH4-CO2-H2O system: I. Pure systems from 0 to 1000°C and 0 to 8000 bar

Duan, Zhenhao; Møller, Nancy; Weare, John H.

doi:10.1016/0016-7037(92)90347-l

Cited by 461 publications

(219 citation statements)

References 34 publications

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“…The basis of our fugacity model is the work of Spycher and Reed, 44 who proposed equations to predict all the second and third virial coefficients of the H 2 O-CO 2 system at temperatures up to 350 C. A more complicated system spanning a much wider range of conditions has been proposed by Duan et al, 45,46 but their level of detail is not required for the current application.…”

Section: Thermodynamic Datamentioning

confidence: 99%

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

Visscher

Vanderdeelen

Königsberger

et al. 2012

Journal of Physical and Chemical Reference Data

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The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO 3 ), nesquehonite (MgCO 3 Á3H 2 O), and lansfordite (MgCO 3 Á5H 2 O), a critical evaluation is presented based on curve fits to empirical and=or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO 2 with Sechenov parameters, and for various equilibria in the aqueous phase including the dissociation constants of CO 2 (aq) and the stability constant of the ion pair MCO 0 3 ðaqÞ (M ¼ alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consistent with two thermodynamic model variants are proposed. The model variant that describes the Mg 2þ ÀHCO À 3 ion interaction with Pitzer parameters was more consistent with the solubility data and with other thermodynamic data than the model variant that described the interaction with a stability constant.

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Section: Thermodynamic Datamentioning

confidence: 99%

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

Visscher

Vanderdeelen

Königsberger

et al. 2012

Journal of Physical and Chemical Reference Data

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“…In the absence of data on the solubility of H 2 O-NaCl vapour in CH 4 gas at high 729 temperature, we assumed that at 350 °C, the solubility of H 2 O in CH 4 gas is the same as that of 730 CH 4 in the corresponding brine (Duan et al, 1992a), and that the solvus of the system CH 4 -H 2 O-731 NaCl is roughly parallel to, but 100 o C higher, than that of the system CO 2 -H 2 O-NaCl for the 732 same salinity (Holloway, 1984). 733…”

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confidence: 99%

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

2016

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10Strange Lake is a mid-Proterozoic peralkaline granite pluton (Québec-Labrador, Canada) that 11 underwent extreme enrichment in high field strength elements (HFSE), including the rare earth 12 elements (REE). The HFSE mineralisation is confined to highly altered pegmatites and the most 13 altered parts of the granites, implying a genetic association between hydrothermal fluids and 14 HFSE enrichment. This study uses analyses of fluid inclusions to investigate the hydrothermal 15 evolution of the Strange Lake pluton and the role of hydrothermal processes in concentrating the 16 HFSE to potentially exploitable levels. 17Five groups of inclusions were distinguished. From earliest to latest, these groups are: primary 18 aqueous inclusions (~25 wt.% NaCl eq.) associated with melt inclusions (Group 1); primary 19 Fluid evolution commenced with the exsolution of a saline aqueous liquid (~25 wt.% NaCl eq.) 28 and an immiscible CH 4 +H 2 gas from the pegmatitic melt at temperatures of ~450-500 °C and a 29 pressure of ~1100 bars. During isobaric cooling, the gas component of the fluid was gradually 30 oxidised, evolving from being CH 4 -dominant to a CH 4 fluid with a significant proportion of 31 higher order hydrocarbons (due to oxidative coupling of methane induced by the consumption of 32 O 2 through the alteration of arfvedsonite to aegirine; ~325-360°C), and finally to a CO 2 -33 dominated fluid at ~300 o C. The apparent salinity of the aqueous fluid decreased from ~25 to 34 ~4.5 wt.% NaCl eq. due to fluid-rock interaction. The latter also caused precipitation of nahcolite 35 (as a result of the reaction of newly formed CO 2 with sodium from decomposing minerals), 36 formation of pseudomorphs after primary Na-zirconosilicates and Na-titanosilicates and 37 replacement of primary REE-silicates by bastnäsite-(Ce). Owing to this interaction, the carbonic 38 component of the fluid was consumed which, together with the consumption of H 2 O to form Al-, 39 K-and Fe-phyllosilicates, contributed to an increase in the fluid salinity (up to ~19 wt.% NaCl 40 eq.). 41 3 Light rare earth elements (LREE) were remobilised over 10s to 100s of metres by the high 42 temperature high salinity fluid (preserved as Group 1 and 2a inclusions), whereas heavy rare 43 earth elements (HREE) were remobilised on a much smaller scale by a late, low temperature 44 high salinity fluid (trapped as inclusion Group 5). Fluid preserved as inclusion Group 3 may have 45 been responsible for remobilisation of Zr and Ti. 46

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“…This model incorporates Pitzer specific interaction phenomenology, parameterized by solubility data, to describe the liquid phase. The vapor phase is described by our EOS developed earlier (Duan et al, 1992a) for the pure CH 4 , CO 2 and H 2 O species (Table 4) and by assuming ideal mixing of H 2 O and CH 4 . In this grant period, using a similar approach, we developed a model for the H 2 O-CO 2 -NaCl system that is applicable to temperatures from 50° to 300°C and for pressures from 0 to 1000 bar.…”

Section: Results/variances: Tequil Modelsmentioning

confidence: 99%

Models of Geothermal Brine Chemistry

Weare¹,

Weare²

2002

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PROJECT BACKGROUND: Many significant expenses encountered by the geothermal energy industry are related to chemical effects. When the composition, temperature or pressure of the fluids in the geological formation are changed, during reservoir evolution, well production, energy extraction or injection processes, the fluids that were originally at equilibrium with the formation minerals come to a new equilibrium composition, temperature and pressure. As a result, solid material can be precipitated, dissolved gases released and/or heat lost. Most geothermal energy operations experience these phenomena. For some resources, they create only minor problems. For others, they can have serious results, such as major scaling or corrosion of wells and plant equipment, reservoir permeability losses and toxic gas emission, that can significantly increase the costs of energy production and sometimes lead to site abandonment. In future operations that exploit deep heat sources and low permeability reservoirs, new chemical problems involving very high T, P rock/water interactions and unknown injection effects will arise.The ability to predict chemical behavior and heat content for wide ranges of composition, temperature and pressure would enable the design of optimal operating strategies to minimize or avoid these adverse chemical effects. Predicting reservoir and energy production chemistry will become even more important as deeper, higher temperature geothermal resources, with very high development costs, are utilized to meet future energy needs. Unfortunately, predicting the chemistry of geothermal systems is difficult because of the variability and complexity of the solidliquid-gas equilibria controlling chemical behavior. These equilibria are complicated functions of the system's composition, temperature and pressure (XTP). These variables are different for different resources and can vary over time and from well to well in a single resource. Marked changes in XTP variables also occur during energy extraction from a specific site. Reliance on experimental data for estimating behavior is generally inadequate because the data pertain to a given set of variables and are often for relatively low temperature (˜100°C) and pressure (≈1 bar). The chemical complexity of geothermal systems makes the extrapolation of data to different conditions problematic. New laboratory simulations are time-consuming and costly, particularly at high temperature and pressure. Moreover, the very high temperatures and pressures of deep crustal and magma resources, where the bulk of the earth's heat is stored, are difficult or impossible to duplicate by current experimental methods.Computer modeling technologies present the means to resolve these difficulties. Wellconstructed models, based on sound thermodynamic principles, can handle the complicated chemical reactions determining the behavior of geothermal energy production processes. They provide a means of succinctly summarizing large amounts of experimental data and of With support from the DOE Ge...

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An equation of state for the CH4-CO2-H2O system: I. Pure systems from 0 to 1000°C and 0 to 8000 bar

Cited by 461 publications

References 34 publications

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

Fluid evolution in the Strange Lake granitic pluton, Canada: Implications for HFSE mobilisation

Models of Geothermal Brine Chemistry

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