Simulation of Power Production from Dry Geothermal Well Using Down-hole Heat Exchanger in Sabalan Field, Northwest Iran

Abstract

In this research, a simulation was performed for evaluating power production from an abandoned geothermal well as an enhanced geothermal system by injecting a secondary fluid. Abandoned wells, due to lack of fluid or very low transmissivity, are regarded among the low-to moderate-temperature resources that have the potential for heat production without any cost for deep drilling. Accordingly, they are taken as suitable sources of energy. In the present paper, an abandoned geothermal well at Meshkinshahr geothermal field in Sabalan district, northwestern Iran, with 3176 m depth was simulated. The bottom-hole temperature of 148°C, as well as well casing size, and real thermal gradient for well were applied in the model. A 3D heat transfer simulation model was designed by considering a coaxial pipe as a down-hole heat exchanger between surrounding rocks of the well and injected fluid. Injected fluid to the well with specified pressure and temperature receives heat from rocks surrounding the well, until it reaches the bottom of the well and converts to vapor. The vapor returns to the surface from inner pipe with very low heat loss during its return. The inner pipe is isolated by a thin layer having a low heat conductivity to prevent heat loss from the returned fluid. It was observed that obtained heat in the well depends on temperature profile of the well, injection velocity, and fluid mass flow rate. The model results were optimized by selecting suitable parameters such as inlet injection speed and fluid flow rate to achieve the highest temperature of the fluid returned from the well. A binary power plant was also modeled to determine the extractable power using returned fluid as input using ammonia and isobutene, as working fluids in binary cycle. Finally, electric power of 270 kW was generated from well NWS3 using designed down-hole heat exchanger.

Geothermal energy extraction using abandoned oil and gas wells:Techno‐economicand policy review

“…Mehmood et al 26,64,65 conducted a series of studies to evaluate the potential of retrofitting abandoned oil well for geothermal energy extraction is Pakistan. Similar studies have been reported for abandoned oil wells in Iran, 66,67 Qatar, 19,68 India, 69 and Polland 70…”

Geothermal Power Production from Abandoned Oil Reservoirs Using In Situ Combustion Technology

“…They found that R123 has the most desirable characteristics in comparison with other working fluids. Noorollahi et al [15] further investigated two other types of working fluid (isobutene and ammonia) for power generation. A binary power cycle model was applied for power generation in their study to calculate the total electric power output.…”

Solar‐assisted geothermal power generation hybrid system from abandoned oil/gas wells

“…Geothermal energy is divided into three categories in terms of temperature and power source for generating electricity and heat that include high temperature sources, average temperature sources and low temperature sources which are in the range of temperatures above 200, 150–200 and 100–150°C, respectively. Low‐temperature geothermal sources are more common than the other two sources in the world, but its economic attractiveness is less due to lower power generation and lower heat [6, 7]. In this regard, a lot of studies have done to increase using of geothermal energy [8], optimisation of geothermal power cycle [9], blending and mixing of working fluids to increase efficiency [10] and finally increasing power generation and heat [11].…”