Lv Jiaojiao¹, Sun Jia¹, Li Zhenguo¹, Guan Zhengrong², Zhang Ying¹

1.Power China Northwest Engineering Corporation Limited; 2. School of Mechanical Engineering, Xi'an Shiyou University

Abstract：

Medium-deep coaxial geothermal wells represent a transformative approach in the renewable energy sector, enabling efficient extraction of geothermal heat from depths exceeding 2000 meters without requiring natural aquifer systems. This comprehensive investigation examines the complex heat transfer mechanisms governing the performance of these innovative geothermal systems through an integrated methodology combining field experiments, numerical modeling, and laboratory analysis. The research systematically evaluates how critical operational parameters—including run-stop ratios, intermittent operation frequency, inlet temperature, and flow rate—impact system efficiency and thermal influence radius. Furthermore, it analyzes how formation properties such as thermal conductivity, specific heat capacity, density, and porosity affect heat extraction dynamics. Findings reveal that strategic intermittent operation can enhance average outlet temperature by up to 2.10% and extend thermal influence radius by 0.099 meters compared to continuous operation, while identifying optimal balance between operational intensity and geothermal reservoir recovery. The study also explores cutting-edge innovations in working fluids, drilling technologies, and system integration that significantly advance medium-deep coaxial geothermal well performance. This work provides both theoretical insights and practical guidance for optimizing coaxial geothermal systems, contributing to more efficient and sustainable geothermal energy utilization.

Key Words：

medium-deep coaxial geothermal well; Thermal-Fluid-Structure Interaction (TFSI); geothermal energy utilization; Ground Heat Exchanger(GHE)