LAUSR

Abstract Seal assembly is a critical component of wellhead for maintaining well integrity. Failure of seal assembly is often cited as a cause for well control incidents. Comprehensive review of existing literature and industry standards and guidelines indicate that limited information is available in public domain on functional aspects and fitness for service evaluation of elastomer hanger seal assembly. This work presents finite element modelling approach to evaluate performance and fitness-for-service of conventional elastomer hanger seal assembly. Three-dimensional computer models consisting of liner, casing, and seal assembly elements were used for this purpose. Sealability was assessed in terms of the contact stress generated at the seal-pipe interface. An analytical model was used to validate and confirm accuracy of FEA results. Parametric analyses were performed and operating curves were generated to understand the behavior of elastomer seal considering different design parameters, such as dimensions and material properties. Sensitivity analysis was performed to identify critical design parameters. Seal annular fit, amount of energization, elastic modulus, and Poisson's ratio were observed to be the most critical factors affecting sealability. All major predictors were incorporated into an empirical correlation that can be used to estimate contact pressure with ±2% error. Based on all the simulation results, recommendations are provided that will help industry/regulators alike in designing and assessing “fitness-for-service” of seal assemblies.