Evaluating the Performance of a Cost-Effective Creep Testing Setup on Bismuth-Tin Alloy Specimens: Challenges and Future Directions

Abstract Well plugging and abandonment operations are critical in the oil and gas industry, especially when it comes to regulatory compliance and environmental safety. A key factor in this operation is the quality of the sealant used to close boreholes and prevent hydrocarbon migration. Bismuth alloys have emerged as a promising sealing material due to their distinctive properties. In the framework of P&A, investigating the creep behavior of the metal plug is essential to assess its sealing performance and long term integrity. Creep, by definition, is a time-dependent deformation occurring when metals are subjected to a constant load at high temperatures over an extended period. Typically, creep testing machines evaluate how a material performs under these conditions. However, due to the unavailability of such machines and the necessity to test the creep properties of a bismuth-tin metal alloy, a low-cost creep testing setup was developed. This paper aims to investigate the creep properties of the bismuth-tin metal alloy at various temperatures (40, 60, 90, and 120°C) using the setup developed. The setup includes a steel chamber heated by an oven exhaust and a loading device attached to a support structure linked to the chamber. Inside the chamber, a bismuth-tin specimen is installed, and weights are applied to induce the load. A thermometer and a length gauge monitor the temperature inside the chamber and record the change in length, respectively. The maximum load applied to the specimen can be 24 kg. Creep curves plotting strain versus time for the bismuth-tin alloy, under a constant load, were generated at different temperatures. Preliminary results indicate that creep effects become more pronounced at higher temperatures, where the cross-section of the tested specimen thins and ruptures more quickly. Although these results are not fully accurate, the study aims to evaluate the feasibility of this setup as a cost-effective alternative to expensive creep testing machines. This work is part of an extensive in-house research that contributes to the understanding of how this unique material behaves under downhole conditions, thus leading to better P&A practices in terms of enhanced safety and operational efficiency, reduced leakage risks, and minimized costs. The ultimate goal of this technology is to be qualified for widespread usage as a barrier element in P&A operations, meeting the requirements of the NORSOK D-010 standard.