| Abstract |
Geothermal heat extraction from intermediate-depth systems (1–3 km) using closed-loop designs such as U-tube and double-pipe systems, offers a promising solution for heating community and agricultural facilities in colder regions, even where geothermal gradients are modest. In British Columbia (BC), the past two decades have seen the rapid development of horizontal unconventional gas wells, many of which now are suspended or near the end of their productive life due to their short operational spans. These inactive wells pose serious environmental and financial risks, as current abandonment methods (primarily cement-based sealing) are expensive, vulnerable to long-term failure, and effective for only 50–100 years. Repurposing these wells for geothermal energy presents dual benefit: it defers costly plug-and-abandonment liabilities while enabling renewable energy generation. Deep wells, particularly in the Montney region of northeast BC, exhibit favorable temperature gradients suitable for direct heating or electricity generation. Widespread use of pad drilling (5–30 wells from a single surface site) further enhances the economic viability of geothermal retrofits. This study assesses BC's geothermal potential by developing a geothermal suitability map and analyzing pad-drilled sites. We focus on the double-pipe closed-loop method, using the casing as the outer pipe and tubing as the inner conduit for a working fluid that extracts heat from surrounding rock. The study also examines intermittent extraction strategies to allow thermal recharge, improving long-term performance. By converting inactive gas wells into geothermal systems, this research advances sustainable energy development and demonstrates how BC can lead the clean energy transition through innovative geothermal solutions. |