Session: 11-10-01 Sustainability and Green Transition in Petroleum Industry

Submission Number: 156514

Assessing the Feasibility of Geothermal Energy Extraction From Depleted Oil and Gas Wells in British Columbia 

As global energy demand rises and countries commit to reducing fossil fuel consumption, new clean energy sources are essential. Geothermal heat from intermediate-depth systems (1–3 km) offers a promising option for heating community buildings and agricultural facilities, especially in colder countries, even where the geothermal gradient is low. There are several methods for extracting heat at these depths, such as U-tube and double-pipe systems, which are closed loop.

This study focuses on energy challenges in British Columbia (BC), where the past 2 decades have nearly exclusively developed horizontal unconventional gas wells. These wells have peak production over a relatively short span of years, followed by many years of low production and hence a relatively short life. Hence many of these wells are either suspended or nearing the end of their productive life. Current abandonment practices, rely on cement seals for well integrity, both inside and outside the casings. The thin annular cement is vulnerable to cracking that can allow corrosive brines to contact the steel casing. Wells showing leakage must be repaired before plugging and abandonment. These operations are costly, do not remove the long term liability for leakage and rely on the untested durability of the cement and its ability to seal. It may be that our current well abandonment practices are only effective for 50-100 years: this is simply unknown.

Deep wells often have a favorable temperature gradient relative to the surface, providing a heat source suitable for geothermal energy extraction. By converting suspended or inactive oil and gas wells into geothermal wells, it is possible not only to defer plug-and-abandonment costs and liability, but also to generate geothermal energy. Geothermal energy is a reliable, renewable, and abundant resource with minimal environmental impact. The energy extracted can be used for direct heating or electricity generation, presenting a viable alternative to partially replace fossil fuels. Most wells in Northeast BC are pad-drilled, with 5-30 wells drilled from the same surface location, which simplifies surface facility operations and makes geothermal extraction more profitable, even in cases of low geothermal gradient. This project examines potential wells in BC for geothermal exploitation and provides a geothermal map. A specific set of pad-drilled wells is then analyzed to estimate potential geothermal energy generation using mathematical modeling, with a focus on the double-pipe extraction method. In this approach, the well casing serves as the outer pipe, the tubing as the inner pipe, and a working fluid is injected down the annulus between them to extract heat from the formation. The study also considers intermittent extraction to allow formation temperature recovery, preserving the longevity of the underground heat sources. This research aims to support the practical application of geothermal energy and position the project as a leader in the sustainable energy transitions.

Presenting Author: Soheil Akbari University of British Columbia

Presenting Author Biography: Postdoctoral research and teaching flow