A laboratory experimental study of enhanced geothermal systems

With the growing interest in renewable energy resources, geothermal energy has become an important research topic. The research objective is to develop a more cost-effective laboratory-scale experimental setup than a full-scale field system to understand the effects of temperature alteration on 1) the thermal-hydro-mechanical interaction between a solid and fluid, and 2) the wellbore stability as a result of geothermal energy extraction. The proposed setup consisted of a steel pipe network, five concrete slabs to simulate a rock mass with two controlled horizontal discontinuities and two wellbores. Water was circulated using a water bath into the injection wellbore, through two continuities and out of the simulated reservoir from the extraction wellbore. The concrete slabs were heated and heavily instrumented with vibrating-wire sensors to measure the changes in strains, pore water pressures, and temperatures. Water circulated through the reservoir was measured for flow rate, pressure and temperature. Also, an overburden pressure was applied to the slabs to simulate actual overburden soil and rock. The workability of the laboratory-scale experimental setup for the geothermal energy investigation was confirmed.