Exploratory research into the enhanced geothermal system power generation project: The Qiabuqia geothermal field, Northwest China

Abstract Geothermal energy from hot dry rock is considered to be a source of clean renewable energy. This energy resource in the Gonghe basin of Northwest China is equivalent to 630.3 billion tons of standard coal and represents a massive potential source of geothermal energy. In particular, the Qiabuqia geothermal field located in the eastern part of the basin holds an average geothermal gradient in a granite stratum of 7.1 °C/100 m and reaches a temperature of 236 °C at 3705 m depth in its GR1 well. This major breakthrough in geothermal exploration technology is promising for accelerating the construction of the enhanced geothermal system demonstration power plant in China. Firstly, we initially used actual geological, field, and laboratory data pertaining to the Qiabuqia site to investigate the temperature, rock properties, and in situ stress state of the geothermal reservoir through laboratory analysis and numerical calculation methods. Secondly, a probable reservoir stimulation scheme for the GR1 well in Qiabuqia site on the basis of laboratory experiments and numerical simulation was explored. Finally, we designed a possible enhanced geothermal system and numerically investigated the effects of injection rate, well spacing, and injection temperature on the system performance, providing useful insight into hydraulic pressure, thermal production, and power generation processes for the Qiabuqia geothermal field. Results indicate that the Qiabuqia site is suitable for the development of a demonstration power plant with an installed capacity of 4.02–4.74 MW if a three-vertical-well system is used.