Electricity generation from retrofitted abandoned oil and gas wells using a geothermal-driven organic rankine cycle

Repurposing abandoned oil and gas wells (AOGWs) as geothermal heat exchangers for electricity generation offers a promising pathway toward sustainable energy production. This study investigates key design parameters that influence geothermal-driven electricity generation from a retrofitted abandoned petroleum well located in the high-temperature formation of the Riau oilfield, Indonesia. A verified and validated conjugate transient ground-wellbore model is developed, coupled with a validated Organic Rankine Cycle (ORC) simulator, to evaluate the system’s performance over a 20-year period. The working fluids used in the wellbore and ORC are water and R245fa, respectively, and remain constant throughout the study. The design parameters subject to variation include ORC pump frequency, ORC expander rotational speed, geothermal wellbore mass flow rate, and casing insulation length. A base case analysis using typical operating conditions demonstrates that, for the limestone formation at a depth of 3 km with a geothermal gradient of 0.04 ∘ C/m, more than 72 kW of thermal energy can be delivered to the ORC by injecting water at 70 ∘ C and 1.5 kg/s. This thermal input is subsequently converted into 6.29 kW of electricity. Parametric studies show that, by optimizing ORC and wellbore operating conditions, daily electricity generation can increase from 151.2 kWh to approximately 250 kWh, which is sufficient to supply electricity to more than 20 households, or up to three times as many in rural settings. The study highlights the potential of retrofitting AOGWs for clean power generation, contributing to the decarbonization of the energy sector and providing economic benefits to society.