Modeling and Mitigation of Wellbore Flashing During Initial Circulation After Prolonged Non-Circulation in Geothermal Systems

Abstract

Wellbore flashing—the rapid phase transition from liquid to vapor due to pressure and temperature variations—poses significant challenges in geothermal energy extraction, impacting both operational efficiency and equipment integrity. This study presents a comprehensive modeling approach to simulate phase change behaviors during wellbore flashing, particularly during the initial circulation after prolonged periods of non-circulation where elevated temperatures are present throughout the wellbore. Advanced numerical simulations are performed to analyze transient fluid flow and heat transfer during this initial circulation phase. The modeling framework developed in this study incorporates non-equilibrium phase change relaxation models to capture delayed phase transitions, providing a realistic representation of flashing phenomena. By integrating detailed thermal properties of geothermal fluids, wellbore materials, and surrounding formations, the simulations accurately predict the initiation and progression of flashing under various operational conditions. The results highlight the significant impact of initial circulation transients—during which elevated temperatures and low pressures are both present—on the initiation and development of wellbore flashing. Validation against publicly available data from the Utah FORGE dataset demonstrates the model's accuracy in matching observed temperature and pressure profiles under similar scenarios. Mitigation strategies, such as optimized circulation rates and pressure management techniques, are explored to reduce the risk of flashing and enhance wellbore stability. This research provides valuable insights into the mechanisms driving wellbore flashing during initial circulation after prolonged non-circulation. By emphasizing the importance of accurately modeling these transient conditions, the findings contribute to the development of effective strategies for improving the safety, reliability, and efficiency of geothermal operations, ultimately supporting the advancement of sustainable energy extraction technologies.