安宁地热田浅部热储水化学特征及补给通道位置

碳酸盐岩淡水热储层在我国西南地区广泛分布，安宁地热田毗邻昆明地热田西侧约40 km，是具有垂向双层热储结构的低温地热田.在深部地层缺乏钻探资料时，为了探究地热田成因，寻找深部热储向浅部热储的补给通道，使用了以下研究方法:（1）通过类比昆明地热田确定灯影组深部热储的水化学特征，（2）从水岩作用、水化学类型和主要离子相关性分析方面入手，阐述深部热储与浅部栖霞茅口组热储水化学特征的区别与联系，发现可用钠离子作为热水通道的指示因子，（3）以包括开采现状、实测温度和通道位置的数值反演模型验证通道的合理性.分析显示，浅部地热水为混合水，水化学类型（HCO₃-Ca·Mg型）明显受同层冷水控制，与深部地热水离子浓度差别大.浅部热储水各点的地热水化学特征差异小，仅钠离子浓度分布可与地热田温度分区和开发利用情况相呼应.对于补给通道的水化学数据分析结果和数值模拟结果嵌合较好，说明采用以钠离子分布为主的综合分析方法所推断的补给通道位置较为合理. 

Hydro-Geochemistry of Anning Geothermal Field and Flow Channels Inferring of Upper Geothermal Reservoir

Carbonatite geothermal reservoir with freshwater is widespread in Southwest China. Anning low temperature geothermal field, which has a dual vertical structure, is approximately 40 km adjacent to the west of Kunming geothermal field. For exploring formation of geothermal field and discovering flow channel through which deeper thermal water flows upwards to the upper reservoir under a poor-drilling data condition, three methods are employed in this paper. (1) Hydro-geochemical characteristics of the deeper reservoir (Dengying Formation) is determined with an analogy to the similar reservoir (also Dengying Formation) of Kunming geothermal field. (2) Sodium is recognized as a possible indicator of flow channel to the upper reservoir by elaborating the difference and connection between upper reservoir (Qixia-Maokou Formation) and deeper reservoir in consideration of water-rock interaction, hydrochemistry type and correlation of main ions. (3) An inverse numerical model, including exploitation quantity and measured thermal water temperature, is used to verify the rationality of channel location. Thermal water in upper reservoir is mixture, whose ion concentration is distinctive from the deeper thermal water, and its hydrochemistry type (HCO₃-Ca·Mg) is controlled by cold water around obviously. There are slight differences of hydrochemical characteristics among geothermal producing wells, except for sodium distribution, which is corresponding with the distribution of water temperature and exploitation status. The locations of flow channel obtained through hydrochemical data are well matched with numerical simulation results, which suggests that the inferring of flow channels through synthetical analyses mainly based upon the distribution of sodium may be feasible.