Numerical simulation of flows in concentric and eccentric annulus – relevant to geothermal wells

Abstract

At the end of 20th century, the utilization of geothermal energy has increased by 150% forming a solid industry of relevant importance on global markets (Dickson & Fanelli, 2004). According to numerous analyses, this type of energy exploitation has a strong forecast of development in the future. High potential of progress is associated with complex studies to ensure the feasibility, safety and profitability of the investments. Numerical simulation of flows in geothermal exploitation is an essential tool to establish adequate results. The assessment of this process is a key factor for preparing schemes providing high overall efficiency (Vasini et al., 2017). Determining the most favorable parameters and approaches is the subject of plenty studies in the field of geothermal energy. This work analyzes the concept of geothermal energy and heat transfer in general, and in the wellbore. Furthermore, it investigates application of separate turbulence models on flow in concentric and eccentric annulus. Different assembly of pipes require adjusting diverse approaches to achieve finest results. When chosen models work for theoretical configurations, they do not automatically comply for the field cases. As for the eccentricity, the simulation shows valuable data of how the flow behaves in irregular, but very common position. Obtained results satisfy the benchmarks stated in the preceding researches. For instance, the thermal structures are more aroused near the outer wall of the assembly, than closer to the inner pipe. This outcome might be implemented in analyzing vortex generations in the annuli. Moreover, the study defines the dependence of heat transfer rate on the pipe materials. Conducted research might be used as an initial and easy to comprehend overview of the heat transfer phenomena in geothermal energy exploitation.