Thermodynamic modeling of ternary CH4H2ONaCl fluid inclusions
Thermodynamic modeling of ternary CH4H2ONaCl fluid inclusions
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DOI：
10.1016/j.chemgeo.2012.11.003
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发表时间：
2013-01
期刊：
影响因子：
3.9
通讯作者：
Shide Mao;Jiawen Hu;Dehui Zhang;Yongquan Li
中科院分区：
文献类型：
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作者：
Shide Mao;Jiawen Hu;Dehui Zhang;Yongquan Li
本文报道了包括状态方程在内的热力学模型在三元CH4H2ONaCl流体包裹体中的应用。本文建立了一个描述CH4水合物-液-汽表面压力-温度-盐度关系的简单方程，用于计算包裹体的NaCl含量（盐度），其中在给定温度下，CH4水合物与汽-液共存的解离压力用纯CH4的压力方程计算。压力方程是温度和Ne灯校正的ch4拉曼峰位置位移的函数。根据这些关系，结合最新的ch4溶解度模型和PVTx模型，提出了一种新的迭代方法来计算CH4H2ONaCl包体的ch4含量，假设包体在ch4水合物熔化温度和气泡消失（均质）温度下的体积摩尔体积相同。该方法的一个突出优点是可以同时获得CH4H2ONaCl包体的组成、摩尔体积和均质压力，而不必使用基于光学观察或测量的ch4水合物解离温度下蒸汽气泡的体积分数。简要讨论了更新模型中CH4H2ONaCl流体包裹体的均质压力和等异点。基于显微测温和拉曼数据估计三元体系CH4H2ONaCl中包裹体PVTx性质的代码可从Chemical Geology或相应作者（maoshide@163.com）获得。
This paper reports the application of thermodynamic models, including equations of state, to ternary CH4H2ONaCl fluid inclusions. A simple equation describing pressure–temperature–salinity relations on the CH4hydrate-liquid-vapor surface has been developed to calculate the NaCl contents (salinities) of inclusions, where the dissociation pressure of CH4hydrate coexisting with vapor and liquid at a given temperature is calculated with a pressure equation of pure CH4. The pressure equation is a function of temperature and CH4Raman peak position shift corrected by Ne lamp. With these relations and the latest CH4solubility and PVTx models, a new iterative approach is presented to calculate the CH4contents of CH4H2ONaCl inclusions on the assumption that the bulk molar volume of an inclusion at the melting temperature of CH4hydrate and at the vapor bubble disappearance (homogenization) temperature are identical. A prominent merit of this method is that the compositions, molar volumes and homogenization pressures of CH4H2ONaCl inclusions can be simultaneously obtained without having to use volume fractions of vapor bubbles at the dissociation temperatures of CH4hydrates determined based on optical observations or measurements. The homogenization pressures and isochores of CH4H2ONaCl fluid inclusions from updated models are briefly discussed. The code to estimate PVTx properties of inclusions in the ternary system CH4H2ONaCl, based on microthermometric and Raman data, can be obtained from Chemical Geology or the corresponding author (maoshide@163.com).