Study On Shallow Geothermal Field And Hydrochemical Characteristics And The Influential Of Them In Yinchuan Plain

Geothermal energy is clean and renewable. In the case of increase ofenvironmental awareness of today people and lack of energy, government andrelevant department pay more attention to the study, prospecting and rationalexploitation of geothermal resource. Yinchuan plain is the most favorable prospectingarea of geothermal resource in Ningxia. In order to exploit and utilize the geothermalresource scientifically, rationally and effectively, the distribution characteristics andcontrolling factor of geothermal field and the transfer mode of geothermy from deeplayer to shallow layer or surface must be fully understand.This article bases on the research production of former. The data aboutgeothermy, water chemistry and isotope are collected to analyze the distributioncharacteristics of geothermal field and hydrochemical characteristics of shallowgroundwater. Then, analyze the influence factor of distribution of geothermal field,especially the the effect of fault structural; analyze the relationship between shallowhydrochemical characteristics and distribution of geothermal field; analyze therelationship between shallow hydrochemical characteristics and fault structural；andanalyze the relationship between shallow hydrochemical and isotopic characteristicsand geothermal water. Results of analysis are as follows:1. The value of temperature of constant temperature zone and geothermalgradient are bigger in the middle of Yinchuan plain than the value in the south andnorth part of the plain. And the areas near Luhuatai and Yinchuan fracture have thebig value of the middle of plain. The areas near Luhuatai fracture have the big valueof depth of constant temperature zone, however, the areas near Yinchuan fracture havethe small value.2. The influence factors of geothermal field include deep structures，active fault,lithologic conditions of strata and activities of groundwater.3. For unconfined water, the dominant hydrochemical facies are HCO3-Ca infront of Helan mountains and Qingtongxia gorge alluvial fan, HCO3-Mg in Yinchuanand the north of Jing Ziquan, SO4-Na in front of bedrock hill in southwest corner of the plain and the area between Lingwu and Taole, Cl-Na in Lingwu and Taole,SO4-Mg(Ca) in the north of Pingluo station, and the transitional form of the formmentioned above in the other areas of Yinchuan plain.4. The hydrochemical distribution characteristics in the geothermal anomalousarea of the middle of the plain show that the relativity between the hydrochemicaldistribution of the first and the second confined water and the fracture structure isobvious, but that the relativity between the hydrochemical distribution of unconfinedwater and the fracture structure is unobvious.5. The Piper graph shows that the evolution of shallow groundwater is affected bygeothermal water, and that the hydrochemical facies of shallow groundwater quicklytransform from HCO3-Na to Cl-Na.6. Isotopic study shows that shallow groundwater and deep thermal water havethe same source of supply and that D and18O in the deep thermal water have strongenrichment in the circulation process.