关中盆地西部眉县城区地热水赋存特征

Occurrence characteristics of geothermal water in Meixian of western Central Shaanxi Basin

地热资源的合理开发利用在推动能源结构转型、推进绿色清洁能源发展和实现新时代下“双碳”目标方面意义重大。眉县城区地下蕴藏着丰富的地热资源且开发潜力较大,但地热地质研究程度较低。从眉县城区地质构造、地层及热储层、地温场、水流场及水化学特征等方面综合分析,并总结了其地热水的赋存特征。结果表明,眉县城区热储层兼顾传导和对流的“二元聚热”特征,地热水属于中低温孔隙-裂隙复合地热系统,大地热流是地热水形成的“源”,区域深大断裂和次级断裂是地下热水补给和上涌的通道,同时接受地表水补给。热储层为蓝田-灞河组孔隙型砂岩热储和宽坪群裂隙型基岩热储及宽坪群基岩断裂带热储,热储层之间存在渗流和对流作用,具有一定的水力联系,区内较厚的第四系是良好的盖层。

The rational development and utilization of geothermal resources is of great significance in promoting the transformation of energy structure,advancing the development of green and clean energy and realizing the goal of“double carbon”in the new era.There are abundant geothermal resources in the underground of Meixian urban area with great exploitation potential,but the geothermal geological research degree is low.This paper analyzes and summarizes the occurrence characteristics of geothermal water in Meixian urban area from the characteristics of geological structure,strata and thermal reservoir,geothermal field,flow field and hydrochemistry.The results show that:The thermal reservoir in Meixian urban area is characterized by“dual heat accumulation”,which takes into account both conduction and convection.Geothermal water belongs to the composite geothermal system of medium and low temperature porosity and fracture.The ground heat flow is the“source”of geothermal water formation,and the regional deep and large faults and secondary faults are channels for underground hot water recharge and upwelling,while receiving surface water recharge.The thermal reservoir consists of porous sandstone thermal reservoir in Bahe Formation,and fractured bedrock thermal reservoir and bedrock fractured-zone thermal reservoir in Kuanping Group.There exists seepage and convection between the thermal reservoirs,and there is a certain hydraulic connection.The thicker Quaternary system in the area is a good cap layer.