Assessment of geothermal energy potential from abandoned oil and gas wells in Alberta, Canada

Abstract

Repurposing abandoned oil and gas wells (AOGWs) into geothermal wells provides an effective solution for developing a sustainable energy resource and reducing the carbon footprint. It involves generating green electricity and heat, thereby transforming expensive, unused assets into profitable ones. This current research conducts a statistical assessment of the potential for geothermal energy extraction from AOGWs in Alberta, Canada. An efficient conjugate model of a geothermal system is developed for a double-pipe coaxial heat exchanger configuration that simulates transient heat extraction and is validated against a pilot test. Then, a Monte Carlo approach is employed to generate 10,000 samples representing abandoned wells in Alberta, which serve as inputs for simulating each well over two decades. The simulation results reveal that nearly 80% of the wells show positive potential for geothermal energy extraction. Nearly 0.5% of wells with an average outlet temperature of 109 °C qualify for electricity generation via the organic Rankine cycle. The majority are suitable for high to low-grade heating, with average outlet temperatures of 74 °C, 49 °C and 27 °C. A parametric study on inlet water temperature reveals that increasing the inlet temperature by steps of 5 degrees can reduce the produced energy from 20% to 60%. The results underscore the promising potential of repurposing AOGWs for geothermal energy.