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在实际案例分析中,采用传统地球化学温标计算的温度与实测温度往往有一定的差距,研究系统中矿物-流体的平衡状态、判断作为估算热交换温度的地热温标是否使用、选出最合适的计算结果非常重要.在讨论热水与矿物的平衡状态时,采用Na-K-Mg三角图解法和PHREEQCI程度模拟计算矿物饱和指数的方法进行研究,结果表明:(1)粤西沿海地热系统采集的23组水样的分析发现其热水水化学特征为热水呈中低温弱碱性、氟含量较高源于热水与花岗岩的水岩相互作用、由内陆至沿海地区水化学类型由HCO_3·Cl-Ca·Na型向Cl-Na型转化;(2)浅层水的混合使得硅温标的估算值低于实测温度;只有21号水样适合用阳离子温标,其热交换平衡温度为150~170℃;1号和19号样可用K-Mg温标计算其热交换温度下限值,分别为136.2和151.6℃,其余水样则适合用log(Q/K)-T平衡法估算,深部热水在经历深循环后上升至地表,在浅层受到冷水混合.
In actual case analysis, the temperature calculated by the traditional geochemical temperature scale usually has a certain gap with the measured temperature. The mineral-fluid equilibrium state in the system is studied to determine whether the geothermal temperature scale as the estimated heat exchange temperature is used, and the most suitable The results are very important.When discussing the equilibrium state of hot water and mineral, the method of using Na-K-Mg trigonometry and PHREEQCI to simulate and calculate mineral saturation index are studied. The results show that: (1) The coastal geothermal system in western Guangdong The analysis of the 23 groups of water samples found that the chemical characteristics of hot water are that the hot water is of low and medium temperature and weak alkaline, and the fluorine content is higher due to the interaction between water and rock of hot water and granite. From the inland to the coastal areas, HCO_3 · Cl-Ca · Na type to Cl-Na type; (2) The mixing of shallow water makes the estimated value of silicon temperature lower than the measured temperature; only 21 water samples suitable for cation temperature scale, the heat exchange equilibrium temperature 150 ~ 170 ℃. The lower limit of heat exchange temperature can be calculated by K-Mg temperature scale for No.1 and No.19 samples, respectively, which are 136.2 and 151.6 ℃ respectively. The remaining water samples are suitable to be estimated by log (Q / K) -T balance method, Deep hot water after going through the deep cycle Lifted to the surface, in the shallow cold water mixed.