Investigation of Elastomer Seal Energization: Implications for Conventional and Expandable Hanger Assembly

Abstract

Elastomer seals are extensively used in various wellhead and casing/liner hanger equipment as barriers for isolating fluids. Seal assemblies have been identified as one of the major cause of well control incidents. Majority of hangers utilize conventional weight- or mechanical-set slip-and-seal assembly. The objective of this paper is to conduct a detailed investigation of seal energization in conventional and relatively newer expandable type hanger seal assembly. To achieve the objective, the finite element modeling approach was employed. Three dimensional computer models consisting of concentric casings and annular elastomer seal element were constructed. Seal energization process was modelled by manipulating boundary conditions. Conventional seal energization was mimicked by applying rigid support at the bottom of elastomer element and compressing it from the top. Expandable hanger type seal energization was modelled by radially displacing the inner pipe to compress annular seal element. Seal quality was evaluated in terms of contact stress values and profile along the seal-pipe interface. Different amounts of seal energization were simulated. Both types of seal energization processes yielded different contact stress profiles. For the same amount of seal volumetric compression, contact stress profiles were compared. In case of conventional seal energization, contact stress profile decreases from the compression side towards support side. The seal in expandable hanger generates contact stress profile that peaks at the center of contact interface and reduces towards the ends. Convectional seal assembly has more moving parts, making it more prone to failure or under-energization. Finite Element Models were validated using analytical equations, and a good match was obtained. The majority of research related to elastomer seal is focused on material properties evaluation. Limited information is available in public domain on functional design and assessment of seal assembly. This paper adds novel information by providing detailed assessment of advantages and limitations of two different seal energization process. This opens doors for further research in functional failure modes in seal assembly.

Investigation of Mechanical Numerical Simulation and Expansion Experiment of Expandable Liner Hanger in Oil and Gas Completion

“…e expansion rate of the hanger body, the expansion force pushing the expandable cone to move downward, and the hang force are main mechanical parameters in the study of the expandable liner hanger [38][39][40][41][42][43][44][45][46][47][48][49][50][51]. e visualization module in FE software is used to obtain parameters such as the contact stress between the rubber cylinder and the outer casing, the counter force of the expandable cone, and the radial expansion displacement of the expandable tube and indirectly calculate the minimum hydraulic thrust, the hang force, etc.…”

Service lifetime prediction of nitrile butadiene rubber gaskets used in plate heat exchangers

“…In general, they are elastomers, which present a suitable combination of viscoelastic properties and chemical resistance to severe environments. Among the current elastomeric materials, nitrile butadiene rubber (NBR) composes a group of common elastomer classes used in the oil and gas industries 1 …”

“…Many studies address the behavior of elastomer seals through commercial sheets, O‐rings or standard specimens. However, it is recommended for testing methodology the incorporation of field conditions to achieve reliable prediction of seal's performance 1,29 . In this context, Li et al 30 evaluated for EPDM joints used in tunnel segments, which were provided with the real geometry.…”

“…Among the current elastomeric materials, nitrile butadiene rubber (NBR) composes a group of common elastomer classes used in the oil and gas industries. 1 The elastomeric seal selection should consider performance factors to avoid its failure, which can be costly. 2 In this way, the aging of elastomers has been studied to determine their best use in each operational condition.…”

Evaluation on the Seal Performance of SMP-Based Packers in Oil Wells

“…For instance, a conventional rubber packer induces uniformly distributed contact stress at the interface. The contact stress reaches a peak at the center of the seal length for a swellable elastomer packer [ 33 ]. Theoretical studies have demonstrated that the seal thickness has little effect on the contact stress for longer packers [ 34 ].…”