Numerical Investigation on Thermal Performance in Low-enthalpy Geothermal System under the Impact of Anisotropic Reservoir Heterogeneity and Well Layout

Abstract

Abstract The utilization of low-enthalpy geothermal systems holds substantial potential for mitigating the greenhouse effect. However, the thermal efficiency of geothermal systems is significantly influenced by the spatial distribution of reservoir property, particularly permeability and porosity. In this work, we systematically investigate the impact of anisotropic heterogeneity in porosity and permeability on geothermal performance using numerical method. The thermal performance is evaluated based on parameters such as thermal production lifetime, thermal breakthrough time, and thermal production energy. Our findings indicate that with an increase in correlation length from 100 to 500m, highly heterogeneous reservoirs tend to regionalize pores, forming highly conductive fluid flow channels. This led to shorter thermal production lifetime and thermal breakthrough time. Moreover, the thermal performance varied significantly with different rotation angles in a double well layout, displaying a maximum difference of 41.17% compared to homogeneous reservoir. This difference decreased with the number of wells, reaching 32.82% and 16.66% in triple and quadruple well layouts, respectively. Consequently, the thermal performance was more stable under uncertain well positions in the quadruple well layout, but with reduced heat extraction efficiency. Our research results provide valuable insights into the impact of anisotropic heterogeneity on thermal performance in low-enthalpy geothermal systems.