Performance evaluation of Kalina cycle subsystem on geothermal power generation in the oilfield

Geothermal energy resource of oilfield can be used to generate electricity in the high water-cut period. A cascade utilization system including Kalina cycle (KC) subsystem and oil production process subsystem is proposed. A model of the Kalina cycle subsystem is calculated numerically and validated. The KC subsystem is optimized by analyzing the thermal and exergetic efficiencies. The feasibility of removing the low-temperature (LT) recuperator and the turbine protection are then analyzed, respectively. Finally, the economic performance of the cascade utilization system is evaluated. Results show that the ammonia concentration and the inlet pressure of the turbine should be lower than that of the optimum points in order to ensure the system stability. The LT recuperator is not necessary for high condensation temperature. Lower ammonia concentration and higher pressure result in higher liquid amount at the turbine outlet. The economic benefits of the power plant in the oilfield are great and the total rewards of the crude oil and the power generation can reach 2 million dollars per year.