A Geothermal Sustainable Development Study Based On Assessment Of Mining Conditions And Reinjection Potential

Geothermal is a kind of clean and green energy. The Xiongxian geothermal field is rich with low-temperature geothermal resources stored in sedimentary sandstone and dolomite reservoirs. The exploited geothermal water is mainly used for space heating, greenhouse, spa and recreation. In recent years, the water level of the geothermal reservoir dropped rapidly due to economic development, technological improvements and increasing demand. In order to achieve sustainable development of geothermal energy, it is necessary to study the development and utilization state of geothermal exploitation, and assess the geothermal reinjection potential.The evaluation index system of geothermal mining condition involves various geothermal, geological, environmental, economic, technical and exploiting level factors of geothermal reservoir and its surrounding areas, which influence the efficiency of geothermal extraction directly or indirectly. In order to have a comprehensive assessment of geothermal exploitation and utilization status of Xiongxian County, an evaluation index system of geothermal exploitation and utilization conditions was built. And a series of parameters and available factors representing the geothermal reservoir feature were selected. An comprehensive evaluation zoning map was obtained based on expert scoring-making method, AHP process and GIS spatial analysis.Geothermal reservoir parameters are the foundation to understand reservoir performance. In the report, pumping tests of representative wells in areas with more production were analysed by using WellTester software to obtain permeability, hydraulic conductivity, effective reservoir thickness and other reservoir parameters.Geothermal reinjection potential assessment mainly involves the interpretation of reinjection experiment, tracer test and prediction of cooling effect of reservoir due to "cold water" reinjection. Reinjection experiment is used to study the effect of reservoir pressure and improvement of extraction conditions in geothermal field. Tracer tests are often carried out during reinjection testing, to study flow-paths and quantify fluid-flow between a reinjection well and one or more production wells, and to predict the possible cooling effect of reinjection. To predict the possible cooling of nearby production wells three simple models were used to simulate possible cold-front breakthrough in the Xiongxian geothermal field. This will provide basis and useful information for sustainable development of geothermal energy in Xiongxian County.