Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.

The first power generation test of hot dry rock resources exploration and production demonstration project in the Gonghe Basin,Qinghai Province,China

Hot dry rock(HDR)is a kind of clean energy with significant potential.Since the 1970s,the United States,Japan,France,Australia,and other countries have attempted to conduct several HDR development research projects to extract thermal energy by breaking through key technologies.However,up to now,the development of HDR is still in the research,development,and demonstration stage.An HDR exploration borehole(with 236℃ at a depth of 3705 m)was drilled into Triassic granite in the Gonghe Basin in northwest China in 2017.Subsequently,China Geological Survey(CGS)launched the HDR resources exploration and production demonstration project in 2019.After three years of efforts,a sequence of significant technological breakthroughs have been made,including the genetic model of deep heat sources,directional drilling and well completion in high-temperature hard rock,large-scale reservoir stimulation,reservoir characterization,and productivity evaluation,reservoir connectivity and flow circulation,efficient thermoelectric conversion,monitoring,and geological risk assessment,etc.Then the whole-process technological system for HDR exploration and production has been preliminarily established accordingly.The first power generation test was completed in November 2021.The results of this project will provide scientific support for HDR development and utilization in the future.

The hydrochemical characteristics and its significance of geothermal water in both sides of large fault: Taking northern section of the Liaokao fault in north China as an example

Based on comparative analysis on hydrochemical characteristics of geothermal water in the north part of Liaokao fault,this research focuses on studying the indicative significance of hydrochemical characteristics for the formation of geothermal water.The result shows that:(1)There is no obvious hydraulic connection between the karst geothermal water(occurred in the east part of the Liaokao fault)and the sandstone geothermal water(occurred in the west part of Liaokao fault).(2)In a close hydrological environment,caused by tectonic activities,geothermal water remains longer time in reservoir,hence the water-rock interaction is more complete,with high degree of concentrations,whereas the renewable capacity of the water is weaker.(3)There is no high temperature mantle source fluid mixed in the geothermal water.Karst geothermal water occurred deep circulatory convection along Liaokao fault and its secondary fault,therefore there is deep crust source fluid added into the geothermal water,closer to the Liaokao fault,the greater affected by the deep crust fluid.However,sandstone geothermal water has weak deep circulatory convection.