In this study, reservoir simulations with economic analysis are performed to investigate the potential of utilizing oil and gas fields for geothermal development associated with enhanced hydrocarbon recovery and geological CO2 storage. Results show that the revenue from CO2 enhanced oil recovery, CO2 storage and geothermal development accounts for 54%, 40%, and 6% of the total revenue to repurpose oil fields, respectively. Meanwhile, the revenue from CO2 enhanced gas recovery, CO2 storage and geothermal development accounts for 12%, 82%, and 6% of the total revenue to repurpose gas fields, respectively. Additionally, the revenue is 18% higher from converting wells to enhanced hydrocarbon recovery, CO2 storage and geothermal development in the oil fields than those in the gas fields. We then conduct a first-of-its-kind evaluation of 16,990 oil fields and 71,907 gas fields in Canada for geothermal development with enhanced hydrocarbon recovery and geological CO2 storage. Results show that 213 oil fields and 2,639 gas fields with a reservoir temperature above 100 °C and buried depth of 800 m or deeper are suitable for the CO2 storage and heat mining projects. The 213 oil fields have CO2 enhanced oil recovery potential of 643 million barrels, geothermal resources of 4.5 billion GJ and CO2 storage capacity of 552 Mt. The 2,639 gas fields have CO2 enhanced gas recovery potential of 6.3 Tcf, geothermal resources of 16 billion GJ and CO2 storage capacity of 8 Gt.