Chemical and physical processes occurring in the Fushime geothermal system, Kyushu, Japan
Chemical and physical processes occurring in the Fushime geothermal system, Kyushu, Japan
复制标题
日本九州伏目地热系统中发生的化学和物理过程
DOI：
10.2343/geochemj.25.315
复制
发表时间：
1991
影响因子：
0.8
通讯作者：
Y. Yasuda
中科院分区：
文献类型：
--
作者：
K. Akaku;M. Reed;M. Yagi;K. Kai;Y. Yasuda
在勘探过程中，揭示了福山地热系统深层（深度约1000 ~ 2000 m）温度超过300℃的化学和物理特征。井排液含盐，储层水的最大Cl浓度与海水相似。水体中Mg、SO4含量较海水低，而K、Ca、Fe、Mn、Zn、Pb、SiO2等含量较海水高，表明地热流体来源于高温海岩相互作用。较长时间的排放试验表明，过量焓条件（即两相进料）普遍出现，高温储层中也发生了等温沸腾。从数据库中选择受测试引起的这些物理过程干扰最小的流体化学成分进行研究。它们表明，在未受扰动的储层中，沸腾和稀释占主导地位。水体中钾、钙浓度的变化表明储层中发生了含钾矿物的沉淀和含钙矿物的溶解。在计算Fushime水库水的流体-矿物平衡时，没有考虑溶解气体（CH4- co2、H2- h2o和N2-NH3）的氧化还原反应，因为考虑这些反应会导致分析的CH4、H2和SO4浓度与计算的浓度存在极大差异。计算表明，流体接近硬石膏饱和，与钠钾长石均接近平衡。然而，方解石的明显欠饱和表明。温度相对较低的井计算出较高的pH值（实测pH值也高于温度较高的井）。在储层条件下，它们与钾长石和钾云母大致处于平衡状态。相反，在温度较高的井中，较低pH值的水不与这对平衡。后者与这两种矿物作为蚀变产物共同存在的观察结果不一致。利用数值反滴定法对井底和地面设备中沉积的闪锌矿和方铅矿进行数值反滴定，导致高温油藏水体pH值升高。这调和了观察到的这些矿物的存在与高温井流体组成之间的分歧。因此，闪锌矿和方铅矿的沉淀最有可能是酸性的来源。
The chemical and physical features of the deeper part of the Fushime geothermal system (about 1000–2000 m depth), where temperatures exceed 300°C, have been revealed in the course of its exploration. The fluids discharged from wells are saline, and the maximum Cl concentrations of the reservoir waters are similar to that of seawater. The waters are depleted in Mg and SO4 but are enriched in K, Ca, Fe, Mn, Zn, Pb, SiO2, etc., over those of seawater, suggesting that the geothermal fluid originates from high temperature seawater-rock interaction. Relatively long term discharge testing shows that excess enthalpy conditions (i.e. two-phase feed) commonly develop, and that isothermal boiling has also occurred in the high temperature reservoir. The fluid chemical compositions that are the least disturbed by these physical processes caused by testing were selected from the data base for study. They indicate that boiling and dilution predominate in the undisturbed reservoir. Variations in the K and Ca concentrations of the waters suggest that the precipitation of K-bearing minerals and the dissolution of Ca-bearing minerals occur in the reservoir. Fluid-mineral equilibria for the Fushime reservoir waters were calculated without allowing for redox reactions for dissolved gases (CH4-CO2, H2-H2O and N2-NH3), because allowing for these reactions results in an extreme discrepancy between analytical CH4, H2 and SO4 concentrations and those calculated. Calculations show that the fluids are close to anhydrite saturation and are close to equilibrium with both Na/K-feldspars. However, apparent undersaturation with respect to calcite is indicated. Higher pH values are calculated for the reservoir waters in relatively lower temperature wells (the measured pH values are also higher than those of the higher temperature wells). They are approximately in equilibrium with K-feldspar and K-mica at reservoir conditions. In contrast, the lower pH waters in wells with higher temperature are not calculated to be in equilibrium with this pair. The latter is inconsistent with the observation that these two minerals are common as alteration products. The numerical back titration into the fluids of sphalerite and galena, which are observed in scale deposited in the wells and surface equipment, results in a pH increase in the high temperature reservoir water. This reconciles the disagreement between the observed presence of these minerals and fluid composition of high-temperature wells. Thus, the precipitation of sphalerite and galena is the most likely source of the acidity.
Sakai S 等人：“内源性内皮素 1 参与充血性心力衰竭大鼠心脏功能的维持；衰竭心脏中内皮素 1 的产生显着增加。”
DOI：
--
发表时间：
--
期刊：
影响因子：
--
作者：
通讯作者：
--