Design and Optimization of Deep Coaxial Borehole Heat Exchangers for Cold Sedimentary Basins

Heating performance of various designs of coaxial deep borehole heat exchangers (DBHE) were numerically simulated in a cold sedimentary basin. Factors affecting performance, including: (1) depth, (2) repurposing an oil and gas (O&G) well or drilling a larger one, (3) repurposing options, (4) inner pipe material, made of either vacuum insulated tubing (VIT) or high-density polyethylene and (5) grout with different thermal conductivity were evaluated. Where an O&G well is available, the most cost-efficient option is repurposing, with the best performances obtained from the deepest and largest diameter wells. While VIT inner pipes performed better in some designs, their performances did not compensate for their cost