The effect of composite cement-based materials on the heat loss of geothermal wellbores

Abstract

Geothermal energy, as a widely distributed, highly potential, stable, and reliable non-carbon-based clean renewable energy source, is crucial for energy transition and low-carbon development. Geothermal wells are the primary technical means for extracting geothermal energy. Geothermal wells, the core technology in geothermal energy development, consist of a multilayer composite system comprising casing, cement sheath, and formations, with a complex heat transfer process. This paper establishes a heat transfer model for the casing-cement-formation combination system and a thermal conductivity evaluation model for cementitious composites. Using numerical simulations, it analyzes the impact of sensitive factors, including fluid flow, thermal physical parameters of casing and cement sheath, and thermal properties of cement-based composites, on the heat extraction power of geothermal wells. The results indicate that the thermal conductivity of the cement sheath significantly influences the heat extraction power. Adding thermal insulation materials such as glass beads, slag microspheres, and aerogel particles to the cement sheath can effectively reduce its thermal conductivity, with aerogel particles being the most effective, reducing the thermal conductivity by approximately 30%. The models and findings in this study provide theoretical support and technical guidance for optimizing geothermal well design and improving geothermal energy development efficiency, contributing to the efficient utilization of geothermal energy.