Analysis of heat recovery time predictions for multiple periods of temporary reinjection in geothermal well production at Lumut Balai field

Abstract

In Lumut Balai geothermal projects, where suitable reinjection wells are lacking, the temporary reinjection of hot fluid into high-temperature wells has become necessary, albeit risky. Initially designated as production wells, three wells have been temporarily repurposed as reinjection wells due to the urgent requirements for the commissioning of the Power Plant Operation. Over a period of approximately four years, a focus of concern has arisen, especially as the current project is in the process of developing Power Plant Unit 2, in which these three wells will revert to being production wells. A significant concern in this scenario is the duration required for the wells to return to their natural state. Our research approach encompasses several key steps: developing a twodimensional conceptual model of the geothermal reservoir, simulating the temperature distribution under natural operating conditions, assessing the effects of cold reinjection during three distinct periods (three months, six months, and one year), conducting a comprehensive evaluation of the results, with a specific focus on the evolution of the temperature profiles of the wells, the rate of thermal recovery, and associated risks. This research is aimed at deepening our understanding of the challenges posed by temporary hot reinjection in geothermal projects. Ultimately, it seeks to inform the development of best practices and effective reservoir and risk management strategies for addressing similar challenges in the future.