The effect of temperature on the sealability of bismuth–tin alloy plugs

Innovative solutions for plugging oil and gas wells are becoming increasingly important to ensure safe operations, save costs, and guarantee that the wells are sealed with a long-term perspective. Among these innovations, bismuth alloys have emerged as a potential sealing material, attracting attention for their distinctive properties. Despite the promising characteristics of bismuth alloys, comprehensive testing is required to fully understand their behavior and to validate their suitability as a sealing barrier. This study focuses on testing the sealability of eutectic bismuth-tin alloy plugs across a range of temperatures (23–120 °C). Examining this influence is crucial because bismuth alloys can be engineered to have specific melting points and characteristics, allowing them to respond effectively to the prevailing temperature conditions in the wellbore. To this end, the study employs an integrated approach, combining laboratory experiments and numerical simulations, to assess the performance of the plug under the influence of the variables pressure, temperature, and curing time through push-out tests. Preliminary results indicate that the sealing efficiency of the bismuth-tin alloy tends to increase over time at lower temperatures, whereas it decreases significantly as temperatures approach its melting point. Therefore, the eutectic bismuth-tin alloy can be employed safely as an environmental plug, but its applicability as a deep-set plug in high-temperature wells is questioned. In this case, selecting an alloy that has a higher melting point is recommended. This work not only underscores the necessity of understanding the thermodynamic influences on bismuth alloys but also sets the stage for future innovations in well sealing technologies, potentially establishing new industry standards.