On the Sealability of Metal-to-Metal Seals with Application to Premium Casing Connections
- Dennis Ernens (Shell Global Solutions International BV, University of Twente) | Francesc Peréz-Ràfols (Luleå University of Technology) | Dennis Van Hoecke (OCAS NV) | Roel F. H. Roijmans (Shell Global Solutions International BV) | Egbert J. van Riet (Shell Global Solutions International BV) | John Vande Voorde (OCAS NV) | Andreas Almqvist (Luleå University of Technology) | Matthijn Bas de Rooij (University of Twente) | Serge Mathieu Roggeband (Shell Global Solutions International BV) | Willem Maarten Van Haaften (Shell Global Solutions International BV) | Marc Vanderschueren (OCAS NV) | Phillipe Thibaux (OCAS NV) | Henry Rihard Pasaribu (Shell Global Solutions International BV)
- Document ID
- Society of Petroleum Engineers
- SPE/IADC International Drilling Conference and Exhibition, 5-7 March, The Hague, The Netherlands
- Publication Date
- Document Type
- Conference Paper
- 2019. SPE/IADC Drilling Conference and Exhibition
- premium connections, sealability model, thread compounds, metal-to-metal sealing, phosphate conversion coatings
- 44 in the last 30 days
- 53 since 2007
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Metal-to-metal seals are used in connections of casing in oil and gas wells. This paper describes the mechanisms of sealing of metal-to-metal seals as investigated using an experimental set-up and a sealability model. Experiments were conducted for a variety of thread compounds and applied pin/box surface coatings. The results were used to validate a numerical model for sealability. The stochastic model couples a contact mechanics model with a flow model and takes the influence of all the surface topography features into account. Once validated, the model was used together with the experimental results to explain the sealing mechanisms of metal-to-metal seals.
The sealing configuration is a face seal with an R=80 mm round-off radius pressing against a flat. The face seal specimens were manufactured from P110 tubing. The used test set-up is designed for investigating only the metal-to-metal seal of the connection. The set-up can carry out rotary sliding under constant load to simulate surface evolution during make-up and subsequently perform a leakage test. The sealing limit is determined by applying 700 bar fluid pressure and then gradually reducing the normal force until leakage is observed. The data is subsequently used to validate a previously published model.
The results indicate a strong dependence of the type of thread compound used on the onset of leakage. The thread compound affects the amount of wear and thus changes the surface topography of the interacting surfaces. It is shown that the sealability model is capable to predict the onset of leakage within the experimental accuracy. The model shows further that certain surface topographical features improve the sealing performance. Namely, a turned against a flat surface topography leads to highly localized contact areas, which in turn yields the best sealing performance.
The combination of experimental data with the validated model leads to much deeper insights for the sealing mechanisms than what could be obtained using either on their own.
|File Size||1 MB||Number of Pages||21|
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