Numerical simulation of power production from abandoned oil wells in Ahwaz oil field in southern Iran

Abandoned oil and gas wells can be used as low temperature geothermal resources for heat extraction from geological formations. They can provide valuable potential sources of heat without the extra cost of deep drilling required in traditional geothermal projects. In this study, two oil wells (AZ and DQ) in southern Iran were numerically simulated using a 3D technique for heat extraction. The bottom-hole temperature of wells AZ and DQ were 138.7 °C and 159.8 °C, respectively. Heat transfer between the fluid injected into the well and the surrounding hot rock was simulated. Well casing geometry and an exact thermal gradient for two abandoned oil wells were considered. The simulation results were optimized for parameters such as input and output fluid flow rates and temperatures. The results revealed that, in addition to thermal gradient and input mass flow rate, well casing geometry and the size of injection and extraction pipes were essential to the output heat extraction rate. The small internal diameter of the wells and design of the injection and extraction pipes were limited, resulting in lower mass flow rate and higher power consumption by the injection pump. Total extractable rate of heat from wells AZ-II and DQ-II was 967 kW and 1842 kW, respectively, and net electricity generation using a geothermal binary cycle was 138 kW and 364 kW, respectively.