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Smart Wellbore Design for Scalable Closed-Loop Geothermal Energy
Elizabeth CAMBRE, Corey DUFRENE, Axel-Pierre BOIS
[Vallourec, USA]
Closed-loop geothermal systems are gaining momentum as a reliable and sustainable source of clean energy. A critical factor in optimizing their performance is the design of the wellbore, particularly the selection of casing and Vacuum Insulated Tubing (VIT) configurations. This study evaluates the thermal performance, friction pressure, and economic trade-offs associated with various casing and VIT size combinations. We focus on two casing sizes, 9 5/8" and 7", and three VIT configurations: 3.5" x 4.5", 4.5" x 5.5", and 5.5" x 7". These combinations are analyzed through thermal simulations and hydraulic modeling to assess heat retention, pressure drop, and overall system efficiency. A comprehensive cost-benefit analysis is performed across all casing sizes and VIT lengths, including full-length and strategically placed VIT sections in high-loss zones such as the upper wellbore. Preliminary findings indicate that a hybrid approach, using 7" casing with targeted deployment of mid-size VIT, can offer an optimal balance between thermal performance and cost. This paper provides actionable design guidelines and economic insights to support wellbore architecture decisions for enhanced closed-loop geothermal system efficiency.
Topic: Emerging Technology