Abstract
As a renewable energy source, geothermal energy is becoming more and more important in energy conservation, emission reduction and climate change. Medium- and low-temperature geothermal resources are widely distributed in the continental of China, and high-temperature geothermal resources also exist in southwest China. In recent years, the direct utilization of geothermal energy in heating and industry & agriculture has been developing rapidly. There is an urgent need to strengthen the study of geothermal basic theory to discover more efficient geothermal resources. At the same time, there is also an urgent need to develop geothermal utilization technologies to better and more efficiently utilize geothermal resources. This Special Collection includes 15 papers associated with four academic topics of basic geothermal fields, geothermal reservoir evaluation, hot dry rock or enhanced geothermal system (EGS) and geothermal utilization technology.
In this Special Collection, five papers focus on the basic geothermal fields in China. They mainly discuss deep geothermal processes, heat flow, thermal lithosphere and geothermal resource assessment. Zhang et al. and Tang et al. discuss the deep geothermal processes and thermal conductivity of the Sichuan Basin. Heat flow characteristics in Erlian Basin and South China Sea are discussed by Xu et al. and Dong et al., respectively. Wang Zhuting et al. discuss thermal regime of the lithosphere and geothermal potential in Xiong’an New Area, and Shi et al. assess the geothermal resource in the Harbin Area, Northeast China.
Geothermal reservoir evaluation is one of the most important topics in geothermal exploration and utilization. Sun et al. discuss the reservoir characteristics in the Cretaceous volcanic rocks of Songliao Basin, and Zhang et al. discuss the characteristics of geothermal reservoirs in the Wumishan Formation of the Middle-Upper Proterozoic in the Beijing-Tianjin-Hebei region.
The study of EGS or hot dry rock geothermal resource has now developed rapidly in China in recent years. Li et al. discuss hot dry rock geothermal resource potential in the Wudalianchi volcanic field, Northeast China. Liu Yanguang et al. study the working fluid of EGS in Zhacanggou geothermal field, Northeastern Tibet, China. Yan et al. discuss the injection rate of water in the Guide Basin hot dry rock.
Geothermal utilization technology includes many aspects. In this issue, water reinjection and heat pump system are introduced. Huo et al. simulate the reinjection temperature fields of deep geothermal wells by experiment; Liu Yan et al. propose a theoretical modeling framework of geothermal tail water reinjection to back-calculate the unknown parameters of geothermal reservoirs and predict the thermal breakthrough in the production well. In addition, Wang Wanli et al. study the sustainability of a ground source heat pump system, and Liu Xiantao et al. provide the concepts and characteristics of a U-shaped docking tube geothermal heating system.