Techno-economic performance of multi-generation energy system driven by associated mixture of oil and geothermal water for oilfield in high water cut

Abstract

Geothermal energy is an important renewable energy. Oilfields in high water cut stage are also geothermal fields. We propose a geothermal cascade utilization system, including organic Rankine cycle (ORC) power generation, Li-Br absorption refrigeration, oil gathering and transportation heat tracing (OGTHT) and heat. Associated geothermal water from abandoned oil wells is used as a renewable heat source. The thermodynamic and economic analysis of the cascade utilization system is carried out by establishing a mathematical model. In ORC system, we use two-stage series evaporation to reduce irreversible losses. The results show that there is an optimum evaporation temperature to maximize the net output power, thermal efficiency and exergy efficiency. It is found that the mass flow of the working fluid has a great impact on the system performance. In economic analysis, we find that both cost and benefit increase with the increase of geothermal water temperature (Tgw in) and driving heat source temperature. We use the payback period (PBP) as a comprehensive evaluation index of economy. The results show that there is an optimal temperature combination to minimize PBP. The smallest payback period occurs at the Tgw in is 383 K and the driving heat source temperature is 363 K, which is 3.07 years.