Advances in New and Renewable Energy >
A Numerical Study to Heat Mining Process of Enhanced Geothermal Systems
Received date: 2013-05-20
Revised date: 2013-09-13
Online published: 2013-10-31
Enhanced geothermal system aiming to mine heat from hot dry rocks (HDR) locating within subsurface 3 ~ 10 km depths represents a promising renewable energy utilization technology. It normally needs to create an artificial heat reservoir in HDR by a certain rock-fracturing technology such as hydraulic stimulation and then to circulate heat transmission fluids through the heat reservoir to extract heat for earth-surface power-generation utilization. The flow and heat transport process in the subsurface reservoir has significant influence on the heat extraction performance of EGS. A detailed review on EGS numerical models is given first, and then a self-developed 3D transient model focusing on the subsurface thermo-fluidic process in EGS during heat extraction is briefly introduced. With this model, long-term operation processes of EGSs are simulated. Analyzing the simulation results reveals the formation mechanisms of “short circuit” flow in homogeneously fractured reservoir. We then perform a comparison study on the heat extraction performance of doublet and triplet EGSs. Comparing the seepage flow field and heat extraction ratio distribution for EGSs of different borehole layout, in combination of the state-of-the-art of borehole drilling and reservoir stimulation technologies, we further propose some possible strategies to restraining “short circuit” flow and improving the heat extraction performance of EGS.
Key words： EGS; HDR; geothermal energy; numerical model
CHEN Ji-liang , JIANG Fang-ming . A Numerical Study to Heat Mining Process of Enhanced Geothermal Systems[J]. Advances in New and Renewable Energy, 2013 , 1(2) : 187 -195 . DOI: 10.3969/j.issn.2095-560X.2013.02.011
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