Status and challenges of hot dry rock geothermal resource exploitation

Hot dry rock geothermal energy, as an unique renewable energy, is characterized with abundant reserves, wide distribution, carbon-free, stable and efficient supply. High-efficient development of hot dry rock geothermal energy is of great significance to promote the transformation of China’s energy structure and pursuit of low-carbon development. In this paper the distribution and petrogenesis of hot dry rock was presented, and the endowment and heat source mechanism of geothermal resources in China were introduced. Additionally, the main development methods of hot dry rock geothermal energy were elaborated including drilling and well completion, hydraulic fracturing, and heat extraction. Afterward, a future research outline was proposed aiming at fundamental scientific research. It was suggested that a combined theory of “rock mass characterization-drilling and completion-hydraulic fracturing-heat extraction-integrated regulation” would be worked as the main research route to investigate dynamic damage mechanisms and fracture network connection of hot dry rock, and the multiphase coupling mechanism of the thermal-hydraulic-mechanical-chemical effect in the heat extraction process would be elucidated. Finally, a new method of drilling, fracturing, heat extraction, and synthetical control theory of hot dry rock were formed, which was expected to provide a theoretical foundation for the efficient development of geothermal energy in hot dry rock.