Research On The Arrangement Of Pumping And Recharging Wells Of Groundwater Heat Pump And The Effect Of Geothermal Resource Mining In Qihe

Geothermal energy is a new type of clean energy,with the development of groundwater heat pump and drilling technology,geothermal energy has been widely exploited.In the process of developing shallow geothermal energy,the quality of groundwater heat pump is closely related to the local hydrogeology and arrangement of well,at the same time,due to the complexity of stratum structure,there are many uncertainties in the exploitation of deep geothermal energy.In this paper,aiming at the development and utilization of shallow and deep geothermal resources in Qihe area,Shandong Province,by reading the data of project background and the academic papers,combining theoretical analysis,field test,geophysical exploration and numerical simulation,the research on the optimal arrangement of pumping and recharging wells of groundwater heat pump and the deep underground hot water mining effect in the study area are carried out,the main research contents are as follows:(1)The engineering background data and related theories were analyzed and summarized.After fully understanding the geological structure,hydrogeology and geothermal geological conditions in the study area,combined with the basic theories of groundwater seepage and heat transfer in the underground porous media,which laid the foundation for establishing the numerical analysis model of groundwater-heat transfer coupling.(2)Field tests were carried out to obtain hydrogeological parameters.In the study area,the hydrogeological exploration holes were constructed and the steady pumping experiment and recharging experiment were conducted.The permeability coefficient of the target aquifer,the curve equation of single well water flow,the amount of groundwater exploitable resource and the average recharge rate were obtained.Corrosion and scaling assessment of groundwater were carried out,the results show that groundwater in the area will not cause equipment corrosion and pipeline blockage.(3)The numerical simulation study on the optimal arrangement of pumping and recharging wells of groundwater heat pump was carried out.The numerical simulation was used to calculate the change of the geothermal field and the temperature of pumping wells of the single and group wells during the summer cooling season and winter heating season under the linear,L-shaped and semi-circular arrangement.The rational distance between pumping well and recharging well is determined to be 48m and the well group adopts the L-shaped arrangement due to the lowest temperature variation of pumping wells.Finally,reasonable suggestions are put forward for the operation and arrangement of groundwater heat pump.(4)The ground geophysical prospecting was carried out to understand the deep stratigraphic features of the study area.The geophysical prospecting was conducted by using controlled-source audio magnetotelluric method,magnetotelluric sounding method and resistivity sounding method to infer the position of broken rocks or karst development in Ordovician thermal reservoir.According to geophysical results,the location,depth and position of pimping water of geothermal wells were determined and water flow,temperature and quality were estimated.(5)The numerical simulation study of deep geothermal exploitation was carried out.The long-term mining pressure and water temperature of geothermal wells under different water discharge conditions were studied by constructing numerical model.The quantity of heat and available stored heat per unit area were calculated when geothermal wells are exploited for 30 years,and the protection range and rational distance of geothermal well were determined.The ground subsidence of normal exploitation and over exploitation of geothermal wells under different working conditions was simulated and forecast,and suggestions are put forward for the development and utilization of geothermal resources.