对流型地热区二氧化硅地热温标的应用研究

Application study on silica geothermal temperature scale in convective geothermal region

热储温度是评价地热资源不可或缺的参数,对于地热资源合理开发利用具有非常重要的意义。地热温标是确定深部热储温度的一种简单实用的方法。二氧化硅地热温标是应用最早也是最常用的地热温标,其应用的前提是地热流体在上行冷却过程中不发生混合(稀释)和沉淀,但对流型地热区深部高温地热流体在上涌过程中不同程度的与浅部冷水进行混合或稀释,所采水样是不同程度稀释的热冷混合水,采用二氧化硅地热温标公式计算出来的结果通常偏低,不能真正代表深部热储的温度,必须进行修正。常用的修正方法计算繁琐,可操作性和代表性差。根据五龙口地热区69组水样的SiO_(2)含量和水温的统计分析,修正计算得出较可靠且具有代表性的深部热储温度和SiO_(2)含量及热冷水混合比。该方法快捷实用,可供类似地热区热储温度预测时参考。

Thermal storage temperature is an indispensable parameter for evaluating geothermal resources,and it is of great significance for the rational development and utilization of geothermal resources.Geothermal temperature scale is a simple and practical method to determine the temperature of deep underground thermal storage.The silica geothermal temperature scale is the earliest and most commonly used geothermal temperature scale.The premise of its application is that the geothermal fluid does not mix(dilute)and precipitation during the upward cooling process,but the high-temperature geothermal fluid in the deep part of the convection-type geothermal area is in the upwelling process.Different degrees of mixing or dilution with shallow cold water,the water samples collected are hot and cold mixed water diluted to different degrees.The results calculated by the silica geothermal temperature scale formula are usually low and cannot truly represent the temperature of the deep thermal storage.Correction must be carried out,and the commonly used correction methods are cumbersome to calculate,and have poor operability and representation.According to the statistical analysis of SiO_(2) content and water temperature of 69 groups of water samples in Wulongkou geothermal area,a more reliable and representative deep thermal storage temperature,SiO_(2) content and mixing ratio of hot and cold water were obtained through correction and calculation.This method is fast and practical,and can be used as a reference for the temperature prediction of thermal storage in similar geothermal areas.