Sustainable Development And Utilization Of Geothermal Resources In The Donglihu Hot Spring Resort Of Tianjin

The Donglihu Hot Spring Resort area is located in the junction of Dongli District andthe Binhai New Area of Tianjin, where is25km far from the downtown area ofTianjin. It is one of the eight scenic spots and seven nature reserves in Tianjin, and isalso the China’s first batch of "Chinese hot spring town”. It has been identified as theBinhai New Area tourist resort, which covers67.84square kilometers. It is thefamous hot spring resort and high-end service industry economic plate in Tianjin. Itplays an extremely important role in the development of the Binhai New Area.The resort area lies inside the Shanlingzi geothermal field. Geothermal resources inthis area are quite abundant. Porous type and bedrock fracture type of geothermalreservoirs occur in the area, including the Neogene Minghuazhen formation andGuantao formation, the Cambrian, the Ordovician, and the Jixian Wumishanformation geothermal reservoirs. The largest Cangdong fault which conducting waterand heat passes through the middle of the area. The wellhead outflow temperature isas high as102℃. The first geothermal well of the resort area was drilled in1986.There are22geothermal wells till now, and the annual production is212.6×104m3.With the increasing exploitation scale of geothermal resources, the pressure of thegeothermal reservoir decreases year by year. At the early stage of the productionperiod the hot water head of the Wumishan reservoir was up to40m above the groundsurface. However, in2013the water table of this layer is about117m below the landsurface. The water level has droped by157m in27years, with all annual decreasingrate of5.8m. With the economic development the demand of geothermal resources isincreasing, there are762×104m2construction area in the future, and the heat demandis about343MW. In order to achieve sustainable development, reasonable utilizationof the geothermal resources is an urgent research issue.This paper examines the structure characteristic, spatial distribution and formationmechanism of the geothermal reservoirs of the resort area of67.84km2.There are fivegeothermal reserivors in the resort area. The heat fluid of the different geothermalreserivors exist the thermal convection through the Cangdong fault. The averagegeothermal gradient reaches5.0℃/100m.The geothermal geologic model of the resortarea is built to evaluate the heat resources and the static reserves of the maingeothermal reservoir,and the total static reserves is105.83×108m3. The recoverable amount of the porous type reservoir and the bedrock fracture type are calculated byGMS and TOUGH2.0software platform.It is concluded that the geothermal resourcesexploitation amount of the entire resort area is883.77×104m3/a. A comprehensiveconsideration of the evaluation results, the status of development and utilization atpresent, energy demand and reasonable layout principle of geothermal wells, suggeststhat the resort area can add16geothermal production wells. The trend of the dynamicfield and temperature field is predicted, and they will not be changed clear. Themeasures of sustainable development utilization of geothermal energy are put forwardfrom aspects of the geothermal gradient utilization，increasing of the recharge and soon.