Study on Integrated simulations of heat recovery and power generation of high temperature geothermal systems

Abstract

The underground heat recovery and aboveground heat utilization in high temperature geothermal systems are studied separately in common research methods. To be clear, the utilization of aboveground heat is based on the fluid production temperature, and the influence of reinjection temperature and pressure on underground heat recovery are not considered. Underground heat recovery is based on close to ambient temperature and relatively random pressure, and less consideration is given to the optimal matching of exploitable heat of underground heat recovery and surface heat utilization system, such as pump power, flow, and pressure. However, geothermal development and utilization is an above ground and underground integrated system project. Therefore, the coupling method of reservoir-wellbore flow heat transfer and ground power generation system is proposed, which realizes the integrated optimization design of heat exchange in reservoir and ground heat transfer process. Based on the thermal-hydraulic-mechanical-chemical coupling mechanism and MPI parallel computing platform, this study developed a numerical simulation software of geothermal reservoir and wellbore. The simulation geothermal power system software is developed by encapsulating the core algorithm of medium and high temperature geothermal water power generation system based on organic Rankine cycle. Simulator for Multi-physics-coupling Geothermal system (SMG) is developed by the Exploration & Production Research Institute, Sinopec. SMG is a numerical simulation software integrating fluid flow and heat transfer process in injection well, reservoir, production well and ground power generation system. The integrated software can be used for the coupling analysis of heat exchange in reservoir and ground heat conversion in power generation cycle. This software has been used for power generation potential prediction of hot dry rock in Gonghe Basin, Qinghai Province, China. The prediction of water production temperature and system power generation under different circulating flow rates conditions are carried out. It realizes the prediction of operation characteristics of enhanced geothermal system and strongly support the optimization of development and utilization scheme.