Modeling Geological Fluids to High Temperatures and Pressures
-
摘要: 几乎所有的地球化学过程都有地质流体参加, 定量地了解地质流体的物理化学性质是定量研究地球化学过程的基础.100多年以来, 广大化学和实验地球化学工作者做了大量的实验测定工作, 可是所有这些工作之和, 仅仅覆盖地球范围内一个不大的温压空间, 远远不能满足地球化学研究的需要.近年来, 我们试图通过分子水平上的研究, 结合热力学和统计力学方面的知识, 在重现前人实验结果的基础上, 研究实验工作者没有或不能研究的温压和成分空间, 得到了一系列能够精确预测地质流体在广阔的温压范围内的物理化学性质的状态方程.这些状态方程不仅能够重现实验数据, 而且具有良好的外延能力, 可以应用于地球化学领域诸多方面的研究.重点讨论了几个状态方程(包括纯流体状态方程含水溶液状态方程和含盐-水-气的状态方程) 在预测流体的溶解度、相平衡、化学位和PVT性质方面的应用.简要介绍了近年来笔者应用分子动力学和蒙特卡罗模拟在地质流体研究方面所取得的成果Abstract: Methodsfor predicting the thermodynamic properties of natural fluids over a large range of concentration, temperature and pressure are presented. With careful choice of phenomenology and parameterization, predictions can be made with accuracies similar to the experimental data.Resultspresented for the NaCl-CO2-CH4-H2O system suggest that these modeling methods can be used to extrapolate experimental measurements to high pressure and temperature regions difficult to access by experimental methods. For species such as CH4 and CO2, which are nonpolar and weakly interacting, a corresponding states representation yields results that are highly accurate and depend on only two temperature and pressure independent parameters. Predictions with such models of fluid/fluid coexistence at high temperature and pressures are within experimental accuracy. The role of molecular dynamics and Monte Carlo simulations in developing thermodynamic representations of natural system are discussed. For closed shell and nonpolar systems, simulation results agree very well with experimental data. Polar systems (H2O) at sufficiently high temperatures are also well described. On the other hand, the simulations for polar systems at low temperatures yield results only in qualitative agreement with data. Efforts to improve simulation methods for these systems are in progress.
-
图 1 地球内部的地质作用过程涵盖的温度-压力范围, 其中“Data”标志的区域表示已有的实验数据涵盖的温度-压力范围
Fig. 1. Temperature and pressure regimes corresponding to earth processes. The "Data" area indicates the region in which well characterized experimental data can be found
图 2 状态方程(Eq. (1)) 对纯CH4压缩因子的预测结果与实验数据的比较
图中Z=PV/RT, 实线和虚线表示状态方程的预测结果, 空心矩形、空心圆、实心圆、实心矩形代表的实验数据分别取自Deffet and Ficks (1965), Din (1961), Francesconi and Kristische (1978), Tsiklis and Linshits (1967)
Fig. 2. Comparison of the measured compressibility factor for CH4 with predictions of Eq. (1)
图 3 CO2-H2O体系的气-液相平衡
图中实线代表我们的状态方程的预测结果, 实心和空心的圆、矩形和三角形分别代表不同温度下的实验数据, 这些实验数据取自Todheide and Franck (1963)
Fig. 3. Phase coexistence for the system CO2-H2O. The solid line is the prediction of the EOS. Experimental data from Todheide and Franck (1963)
图 4 CH4-H2O体系的气-液相平衡
图中实线代表我们状态方程的预测结果, 实心圆代表的实验数据取自Welsch (1973), 实心三角代表的实验数据取自Sultanov and Skripka (1971)
Fig. 4. Phase coexistence for the system CH4-H2O. The solid line is the prediction of the EOS. Experimental data from Welsch (1973) (solid circles), Sultanov and Skripka (1971) (solid triangles)
图 5 CO2-H2O混合体系中CO2和H2O的逸度与相同温压条件下纯CO2和纯H2O逸度的比值随体系组成的变化关系
图中的曲线表示状态方程的预测结果, 在虚线部分对应的组成范围内体系处于两相区, 连接对角的两条直线代表理想混合状态对应的逸度的比值
Fig. 5. Ratio of mixture fugacities to end-member fugacities of CO2 and H2O in their mixtures at 300 ℃ and 700 ℃. The dashed lines show the two-phase region. The diagonal solid lines represent ideal mixing
图 6 H2O-N2体系在超临界区的相分离现象
对比态方程的预测结果与实验数据的比较, 实验数据取自VanHinsberg et al. (1993)、Costantino (1991)
Fig. 6. Supercritical fluid/fluid phase coexistence in the binary system H2O-N2
图 7 CO2-H2O体系的热焓
图中实线为对比态方程的预测结果, 矩形代表Dawe and Snowdon (1974)的实验数据
Fig. 7. Prediction of the Enthalpy model for the CO2-H2O system (solid lines). Data from Dawe and Snowdon (1974)
图 8 对比态方程预测的CO2-H2O体系的热焓-温度-密度相(依据此图可以获得地热井的喷出温度和气/液比)
Fig. 8. Enthalpy-temperature-density relationships for CO2-H2O mixtures. The steam ratio and wellhead temperature for a geothermal well can be obtained from this diagram
图 9 CO2-CH4体系的气液相平衡
图中实线代表蒙特卡罗吉布斯系综模拟方法的模拟结果, 圆和三角形代表Al-Sahhaf et al. (1983)的实验数据
Fig. 9. Phase equilibria for the binary CO2-CH4 system calculated by the MC Gibbs Ensemble simulation (solid lines). Experimental data from Al-Sahhaf et al. (1983).
图 10 CO2-CH4-N2三元系的气-液相平衡——蒙特卡罗吉布斯系综模拟结果与Al-Sahhaf (1990)的实验数据的比较
Fig. 10. Phase equilibria of the ternary system CO2-CH4-N2 calculated via a MC Gibbs Ensemble simulation vs. experimental data
图 11 文中第三部分介绍的状态方程预测的NaCl-H2O-CO2体系的PVTX性质与实验数据的比较
图中实线代表状态方程的预测结果, 实心圆代表Gehrig (1980)的实验数据, 虚线代表相边界, 虚线下方为两相不混溶区, 虚线上方为单相区
Fig. 11. Comparison of experimental PVTX properties in the ternary NaCl-H2O-CO2 with the prediction of the EOS of section 3. Data from Gehrig (1980). The dashed line is the phase boundary. The liquid and vapor two-phase field is below this boundary. The single fluid phase field is above this boundary
图 12 NaCl-H2O-CO2体系的气液相平衡(温度等于500 ℃, 压力为2 000×105 Pa)——状态方程的预测结果与Frantz et al. (1992)的合成流体包裹体实验数据的比较
Fig. 12. Calculated phase equilibria vs. data measured by the synthetic fluid inclusion method in the ternary NaCl-H2O-CO2 for T=500 ℃, P=2 000×105 Pa. Data from Frantz et al. (1992)
图 13 NaCl-H2O-CO2体系的气液相平衡(温度等于500 ℃, 压力为1 000×105 Pa)——状态方程的预测结果与Frantz et al. (1992)的合成流体包裹体实验数据的比较
Fig. 13. Calculated phase equilibria vs. data measured by the synthetic fluid inclusion method in the ternary NaCl-H2O-CO2 for T=500 ℃, P=1 000×105 Pa. Data from Frantz et al. (1992)
图 14 文中第三部分介绍的状态方程预测的NaCl-H2O-CH4体系的摩尔体积与实验数据的比较
图中实线代表状态方程的预测结果, 实心圆表示Krader and Frank (1987)测定的实验数据
Fig. 14. Comparison of the experimental volumes/mole in the ternary system NaCl-H2O-CH4 with the prediction of the EOS of section 3. Data from Krader and Frank (1987)
图 15 状态方程预测的NaCl-H2O-CH4体系的气-液不混溶相边界和共结线与Lamb et al. (1996)测定的合成流体包裹体实验数据的比较
Fig. 15. Comparison of experimental immiscibility boundary and tie-lines (synthetic fluid inclusion method) with the prediction of the EOS for the ternary NaCl-H2O-CH4 system at 500 ℃ and 1 000×105 Pa. Data from Lamb et al. (1996)
表 1 对比态方程对氮气和纯水体系PVT性质的预测结果
Table 1. Experimental PVT data vs. the corresponding state and other EOS
表 2 H2O-CO2体系的PVTX性质——对比态方程的预测结果与实验数据的比较
Table 2. Comparison of experimental PVTX data in the system H2O-CO2 with the corresponding state EOS
表 3 状态方程对高温高压条件下NaCl-CO2-H2O体系的密度的预测结果
Table 3. Prediction of density at high temperatures and pressures in the system NaCl-CO2-H2O
表 4 笔者建立的NaCl-H2O-CH4-CO2体系状态方程与实验数据以及Bowers-Helgeson方程(1983)的比较
Table 4. EOS of this study is compared with experimental data and with the EOS of Bowers-Helgeson (1983)
表 5 采用RWK2势能函数对水的PVT性质的模拟结果
Table 5. Simulated PVT properties for water using RWK2 model
表 6 盐-水体系的PVTX性质——模拟结果与实验数据的对比
Table 6. PVTX properties of salt-H2O system simulated results vs. experimental data
表 7 流体体系热力学性质的实验数据涵盖的温-压范围
Table 7. Thermodynamic measurements on fluid systems
-
Allen, M., Tildesley, D., 1987. Computer simulation of liquids. Oxford University Press. Al-Sahhaf, T., 1990. Vapor-liquid equilibria for the ternary system N2+CO2+CH4 at 230 and 250 K. Fluid Phase Equilibria, 55: 159-172. doi: 10.1016/0378-3812(90)85010-8 Al-Sahhaf, T., Kidnay, A., Sloan, E., 1983. Liquid+vapor equilibrium in the N2+CO2+CH4 system. Ind. Eng. Chem. Fundam. , 22: 372-380. doi: 10.1021/i100012a004 Anderko, A., Pitzer, K., 1993. Equation of state representation of phase equilibria and volumetric properties of the system NaCl-H2O above 573 K. Geochim. Cosmochim. Acta, 57: 1657-1680. doi: 10.1016/0016-7037(93)90105-6 Arshadi, M., Yamdagni, R., Kebarle, P., 1970. Hydration of halide negative ions in the gas phase. Ⅱ. Comparison of hydration energies for the alkali positive and halide negative ions. J. Phys. Chem. , 74: 1475-1482. doi: 10.1021/j100702a014 Belonoshko, A., Saxena, S., 1992. A unified equation of state for fluids of C-H-O-N-S-Ar composition and their mixtures up to very high temperatures and pressures. Geochim. Cosmochim. Acta, 56: 3611-3626. doi: 10.1016/0016-7037(92)90157-E Belonoshko, A., Shi, P.F., Saxena, S., 1992. Superfluid: A Fortran-77 Program for calculation of Gibbs free energy and volume of C-H-O-N-S-Ar mixtures. Compu. Geosci. , 18: 1267-1269. doi: 10.1016/0098-3004(92)90044-R Berendsen, H., Postma, J., Gunsteren, W.V., et al., 1981. Intermolecular forces. Reidel, Dordrecht, 331. Bowers, T.S., Helgeson, H.C., 1983. Calculation of the thermodynamic and geochemical consequences of nonideal mixing in the system H2O-CO2-NaCl on phase relations in geologic systems: Equation of state for H2O-CO2-NaCl fluids at high pressures and temperatures. Geochim. Cosmochim. Acta, 47: 1247-1275. doi: 10.1016/0016-7037(83)90066-2 Burnham, C., Holloway, J., Davis, N., 1969. The specific volume of water in the range 1 000 to 8 900 bars, 20 to 900 ℃. Amer. J. Sci. , 267-A: 70-95. Car, R., Parrinello, M., 1985. Unified approach for molecular dynamics and density-functional theory. Phys. Rev. Lett. , 55: 2471. doi: 10.1103/PhysRevLett.55.2471 Constantino, M., 1991. Supercritical phase separation in H2O-N2 mixtures. J. Phys. Chem. , 95: 9034-9036. doi: 10.1021/j100176a004 D'Ans, J., Bartels, J., Bruggencate, P., et al., 1967. Thermodynamiche eigenschaften von wasser and wasserdapf(International Skeleton Table). Landolt-Bornstein, 534-535. Dawe, R., Snowdon, P.N., 1974. Experimental high pressure enthalpies of N2(g)and CO2(g)in the range 273.15 to 373.15 K. J. Chem. Thermody. , 6: 293-301. doi: 10.1016/0021-9614(74)90183-9 Deffet, L., Ficks, F., 1965. Advanced thermodynamical properties. Technical Report 107, Symposium on Thermodynamical Properties. Purdue University, Lafayette, Indiana. Dimitrelis, D., Prausnitz, J., 1986. Comparison of two hardsphere reference systems for perturbation theories for mixtures. Fluid Phase Equilibria, 31: 1-21. doi: 10.1016/S0378-3812(86)87028-5 Din, F., 1961. Thermodynamic functions of gases. Butterworths, London. Duan, Z., Möller, N., Weare, J., 1992a. An equation of state for the CH4-CO2-H2O system: Ⅰ. Pure systems from 0 to 1 000℃ and from 0 to 8 000 bar. Geochim. Cosmochim. Acta, 56: 2605-2617. doi: 10.1016/0016-7037(92)90347-L Duan, Z., Möller, N., Weare, J., 1992b. An equation of state for the CH4-CO2-H2O system: Ⅱ. Mixtures from 50 to 1 000℃ and from 0 to 1 000 bar. Geochim. Cosmochim. Acta, 56: 2619-2631. doi: 10.1016/0016-7037(92)90348-M Duan, Z., Möller, N., Weare, J., 1992c. Molecular dynamics simulation of PVT properties of geological fluids and a general equation of state for nonpolar and weakly polar gases up to 2 000 K and 20 000 bar. Geochim. Cosmochim. Acta, 56: 3839-3845. doi: 10.1016/0016-7037(92)90175-I Duan, Z., Möller, N., Weare, J., 1995a. Equation of state for the NaCl-H2O-CO2 system: Prediction of phase equilibria and volumetric properties. Geochim. Cosmochim. Acta, 59: 2869-2882. doi: 10.1016/0016-7037(95)00182-4 Duan, Z., Möller, N., Weare, J., 1995b. Molecular dynamics simulation of water properties using RWK2 potential: From clusters to bulk water. Geochim. Cosmochi. Acta, 59: 3273-3283. doi: 10.1016/0016-7037(95)00216-M Duan, Z., Möller, N., Weare, J., 1996. A general equation of state for supercritical fluid mixtures and molecular dynamics simulation of mixture PVTX properties. Geochim. Cosmochim. Acta, 60(7): 1209-1216. doi: 10.1016/0016-7037(96)00004-X Duan, Z., Möller, N., Weare, J., 2000. Accurate prediction of thermodynamic properties of fluids in the system H2O-CO2-CH4-N2 up to 2 000 K and 100 kbar from a corresponding states/one fluid equation of state. Geochim. Cosmochim. Acta, 64: 1069-1075. doi: 10.1016/S0016-7037(99)00368-3 Dzidic, I., Kebarle, P., 1970. Hydration of the alkali ions in the gas phase, enthalpy and entropies of reactions m + (H2O)n-1+H2O= m+(H2O)n. J. Phys. Chem. , 74: 1466-1474. doi: 10.1021/j100702a013 Francesconi, A.Z., Kristische. K., 1978. Phasengleichgewiche and PVT-daten im system methanol-methan bis 3 kbar and 240℃ (Ph. D. ). Univ. Fridericiana Karlsruhe, Germany. Franck, E.U., Todheide, K., 1959. Thermische eigenschaften uberkristischer mischungen von kohlen-dioxyd and wasser bis zu 750 ℃ and 2 000 bar. Z. Phys. Chem. (Neue Folge), 22: 232-245. doi: 10.1524/zpch.1959.22.3_4.232 Frantz, J., Popp, R., Hoering, T., 1992. The compositional limits of fluid immiscibility in the system H2O-NaCl-CO2 as determined with the use of synthetic fluid inclusions in conjunction with mass spectrometry. Chem. Geol. , 98: 237-255. doi: 10.1016/0009-2541(92)90187-A Frost, D., Wood, B., 1997. Experimental measurements of the properties of H2O-CO2 mixtures at high pressures and temperatures. Geochim. Cosmochim. Acta, 61: 3301-3309. doi: 10.1016/S0016-7037(97)00168-3 Gehrig, M., 1980. Phasengleichgewichte and PVT-daten ternarer mischungen aus wasser, kohlen-dioxide and Natriumchlorid bis 3 kbar and 550℃. University of Karlsrube. Haar, L., Gallagher, J., Kell, G., 1984. NBS/NRC steam tables, thermodynamic and transport properties and computer programs for vapor and liquid states of water in SI units. Hemisphere Publishing Co., Washington D.C. . Harvie, C.E., Möller, N., Weare, J.H., 1984. The prediction of mineral solubilities in natural waters: The Na-K-Mg-Ca-H-Cl-SO4-OH-HCO3-CO3-CO2-H2O system to high ionic strengths at 25℃. Geochim. Cosmochim. Acta, 48: 723-751. doi: 10.1016/0016-7037(84)90098-X Johnson, E., 1992. An assessment of the accuracy of isochore location techniques for H2O-CO2-NaCl fluids at granulite facies pressure-temperature conditions. Geochim. Cosmochim. Acta, 56: 295-302. doi: 10.1016/0016-7037(92)90134-5 Krader, T., 1985. Phasengleichgewichte and kritische kurven des systems H2O-CH4-NaCl bis 250 MPa and 800 K. Institute for Physical Chemistry, Univ. Karlsrule. Krader, T., Frank, E., 1987. The ternary systems H2O-CH4-NaCl and H2O-CH4-CaCl2 to 800 K and 250 bar. Ber. Bunsenges. Phys. Chem. , 91: 627-634. doi: 10.1002/bbpc.19870910610 Lamb, W., Popp, R., Boockoff, L., 1996. The determination of phase relations in the CH4-H2O-NaCl system at 1 kbar, 400 to 600-degrees-cusing synthetic fluid inclusions. Geochim. Cosmochim. Acta, 60: 1885-1897. doi: 10.1016/0016-7037(96)00070-1 Marx, D., Sprik, M., Parrinello, M., 1997. Abinitio molecular dynamics of ion solvation: The case of Be2+ in water. Chemical Physical Letters, 273: 360-366. doi: 10.1016/S0009-2614(97)00618-0 McQuarrie, D.A., 1976. Statistical Mechanics. Harper & Row, New York. Millero, F., 1970. The apparent and partial volume of aqueous chloride solutions at various temperatures. J. Phys. Chem., 74: 356-362. doi: 10.1021/j100697a022 Mills, R., Liebenberg, D., Bronson, J., 1975. Sound velocity and the equation of state of N2 to 22 kbar. J. Chem. Phys. , 63: 1198-1204. doi: 10.1063/1.431457 Peng, D., Robinson, D., 1976. A new two constant equation of state. Ind. Chem. Eng. Data, 15: 59-64. Pettitt, B., Rossky, P., 1986. Alkali halides in water: Ion-solvent correlations and ion-ion potentials of mean force at infinite dilution. J. Chem. Phys. , 84: 5836-5839. doi: 10.1063/1.449894 Pitzer, K., 1987. Thermodynamic model for aqueous solutions of liquid-like density. In: Reviews in Minerology. Book Crafters, Inc., 97-142. Pitzer, K.S., Peiper, J.C., 1984. Thermodynamic properties of aqueous sodium chloride solutions. J. Phys. Chem. Ref. Data, 13: 1-105. doi: 10.1063/1.555709 Ree, F., 1986. Supercritical fluid phase separation: Implications for detonation properties of condensed explosives. J. Chem. Phys. , 84: 5845-5856. doi: 10.1063/1.449895 Reimers, J., Watts, R., Klein, M., 1982. Intermolecular potential functions and the properties of water. Chem. Phys. , 64: 95-114. doi: 10.1016/0301-0104(82)85006-4 Saul, A., Wagner, W., 1989. A fundamental equation for water covering the range from melting to 1 273 K at pressures up to 25 000 MPa. J. Phys. Chem. Data, 18: 1537-1563. doi: 10.1063/1.555836 Sterner, S., Bodnar, R., 1991. Synthetic fluid inclusions. X: Experimental determination of P-V-T-x properties in the CO2-H2O system to 6 kb and 700 ℃. Amer. J. Sci. , 291: 1-54. doi: 10.2475/ajs.291.1.1 Sultanov, R., Skripka, V., 1971. Moisture content of methane at high temperatures and pressures. Cazovaia Promyshlennost, 16: 54-57. Sun, R., Duan, Z., 2003. A new equation of state and Fortran 77 Program to calculate vapor-liquid phase equilibria of CH4-H2O system at low temperatures. Computers & Geosciences, 29: 1291-1299. Todheide, K., Franck, E., 1963. Das zweiphasengebiet and die kritische kurve in system kohlendioxide-wasser bis zu drucken von 3 500 bar. Z. Phys. Chem. (Neue Folge), 37: 387-401. doi: 10.1524/zpch.1963.37.5_6.387 Tsiklis, D., Linshits, L., 1967. Molar volumes and thermodynamic properties of methane at high pressures and temperatures. Dokl. Akad. Nauk SSSR, 176: 423-425. VanHinsberg, M., Verbrugge, R., Schouten, J., 1993. Hightemperature and high-pressure experiments on H2O-N2. Fluid Phase Equil. , 88: 115-121. doi: 10.1016/0378-3812(93)87105-A Walas, M., 1985. Phase equilibria in chemical engineering. Butterworths, London. Welsch, H., 1973. Die system xenon-wasser and methan-wasser bei holen drucken und temperaturen. Univ. Karlsruhe. Zhang, Y., Frantz, J., 1987. Determination of the homogenization temperatures and densities of super-critical fluids in the system NaCl-KCl-CaCl2-H2O using synthetic fluid inclusions. Chemical Geology, 64: 335-350. doi: 10.1016/0009-2541(87)90012-X -
下载:
点击查看大图
计量
- 文章访问数: 3763
- HTML全文浏览量: 462
- PDF下载量: 14
- 被引次数: 0
