Development Research For Geothermal Energy In The Shallow-Thin Aquifer

In order to ensure the efficient and safe operation of the groundwater heat pumpsystem，it is usually used in the area where the water yield capacity of aquifer is high,thewater level and temperature is relatively stable. GWHP system is less application inshallow and thin aquifer areas, the corresponding research literature is also rare.It is often supposed to inject on mining layers to meet the water demand of GWHPsystem on the condition that shallow and thin aquifer is regarded as the target layer. In thislayer groundwater level and temperature have great dynamic variation, and groundwatertemperature, which is related to the water demand of heat pump system, is obviouslyaffected by recharging. Therefore, the reasonable arrangement of exploiting-rechargingprogramme is the basis of the effective and safe operation of heat pump system in certainregions.Jingxian in Anhui province is located on the mountain-pass of Qingyi river, whereloosening deposits on both sides are wide of0.5to3.0km and thick of15km. Looseningdeposits are typical dual structure. The upper part is the silty clay of3m thickness whilethe lower part is gravel layer, and the underlying bedrock is gompholite. In the aquifermainly composed of gravel a single well’s yield and recharge capacity can reach20to30m~3/h. A heat pump system whose water demand designed is230m~3/h occupies68,000m~2.A numerical simulation model with the combination of groundwater flow field andtemperature field based on the hydrogeological condition of the region where the instancelocated. The reasonable arrangement of exploiting-recharging programme is studied withthe construction demand of heat pump system. Tough2software is used to study thevariation rule of groundwater flow field and temperature field and estimate the applicationefficiency of water source heat pump system with different exploiting-recharging plans.The research shows:1. The aquifer in study area has High water-richness, water outflow from single well isstrong. but the total amount of the mining area can be limited. In order to meet the waterdemand of the heat pump system,it is necessary to implement injection. Pumping wellsgroup in the groundwater flow field downstream, Layout in the upstream is injection Wellsgroup. When the distance between the well groups is110m, pumping~injection scheme isthe most reasonable. But it is still difficult to make the efficient operation of heat pumpsystem. 2. There is Greater influence of working system for Groundwater temperature field inthe area of project, the heat breakthrough exist around the pumping wells at a certain extent.In consideration of the normal demand, assistant cold and heat producer is necessary.3. In the interim period, underground water flow field and temperature field canrapidly recover. The flow field generally recovered to natural state in30days; thetemperature field recovered relatively slow. In the best scheme, the temperature fieldbasicly recovered to natural state at the last minute.