青海西宁城南新区杜家庄地热田地下水的地球化学特征

Geochemical Characteristics of Groundwater in the Dujiazhuang Geothermal Field in the South of Xining,Qinghai

依据青海省西宁市城南新区杜家庄地热田DR2005地热井地下热水的水化学资料,采用兰格利厄—路德维金图解法、同位素水文学方法、地球化学温标法等,对杜家庄地热田地下热水的补给机制、地下热水年龄、地热资源潜力等关键问题进行分析。分析结果表明杜家庄地热田地下热水源于大气降水入渗补给,但仍有现代冷水补给,地热田下部还存在着远高于DR2005地热井开采段温度的热储。依据研究区地热地质条件具可比性的地热生产井水化学动态观测资料推断,随着DR2005地热井开采时间的延续,地下热水水质将向淡化的方向发展。研究结果为杜家庄地热田的开发利用提供水文地球化学依据。

According to the chemical composition of thermal water from well DR2005 located at the Dujiazhuang geothermal field in the south of Xining, Qinghai, the groundwater recharge, age and geothermal resource potential of the thermal water are discussed by the use of Langelier-Ludwig diagram, isotopic hydrology and geother- mometer methods. These results show that geothermal water from Dujiazhuang geothermal field is meteoric origin, and has modern water recharge. Based on geothermometer, the temperature of Dujiazhuang geothermal field is far higher than that of well DR2005. Hydrochemical variation of the thermal water at the area with the same geological structure suggests that the water has a trend towards bicarbonate water. The above results provide the hydrogeochemical evidence for geothermal field exploitation of Dujiazhuang.