Analysis on influencing factors of heat exchange efficiency of the medium-deep U-shaped geothermal wells in Xiong’an New Area, China

Abstract

As carbon dioxide emission becomes the key environmental problem concerned by all countries, the development of clean energy is getting extensive attention. As a kind of clean energy source, geothermal has been widely used in recent years. U-shaped geothermal well is a kind of well type suitable for middle and deep geothermal development, which has the advantages of high heat transfer efficiency and heat extraction without water extraction. This paper takes the geothermal in Xiong’an New Area as the research object, and uses the fluid dynamics software Fluent to conduct numerical simulation of geothermal development. In the model construction, gravity is ignored and the U-well model is simplified into a straight well model, which can accelerate the calculation speed. In order to verify the accuracy of the model, the simulation results were compared with the field test data. Several factors affecting heat transfer efficiency are systematically analyzed, including reservoir conditions such as formation temperature and thermal conductivity, well depth structures such as casing size and lateral length, and fluid parameters such as flow rate and inlet temperature. Simulation result shows that higher reservoir temperatures, longer lateral lengths, higher fluid flow rates, and lower inlet temperatures can significantly increase heat transfer efficiency.