Finite Element Analysis of Super Elastomer Mechanical Behavior and Failure for High Pressure Sealing Applications

Date

2023-05-11

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Abstract

Elastomer sealing performance is of critical importance for applications in oil/gas, chemical and aerospace industries where operation conditions are extremely harsh and safety consequences are significant. Such applications often push the material limits and challenge product designs. This study investigates the mechanical performances of rubber-based elastomer sealing packers used in hydraulic fracturing plugs. Packers are expected to sustain a 70MPa pressure difference, keep sealed at various downhole temperatures ( from 50oC-180 oC and above), and survive complicated chemical and flow conditions. Such applications not only challenge elastomer intrinsic physio-chemical property limits and the packer performances are also affected by the complex geometry/contacts, large sizes, and various static/dynamic loading conditions. Understanding the materials' behaviors and product performances of such sealing components are non-trivial and of critical application importance. In practice, the sealing performance of elastomer components is simply evaluated through pressure tests, and design modifications/optimizations are mostly conducted based on empirical analyses. Sealing performance criteria are not well established, and the dynamic seal setting process and consequent stress/strain evolution are not well understood. In this research, we developed integrated finite element simulation approaches to investigate the impacts of interfacial friction and packer geometry on elastomer stress/strain evolvement and deformation, and resulting effects on sealing performance. First, we found that the often-neglected friction forces between the packer and contact surfaces during setting can have a significant impact on maximum contact stress, average contact stress, as well as contact stress distribution, thus the packer sealing performances. A groove included in the packer also contributes to the initial deformation and subsequent stress/strain evolvement and performance. We then developed a support vector machine learning approach to predict the effects of input variables such as the setting force, packer length, and casing sizes on the final product sealing performances. Finally, we also developed a composite elastomer model to evaluate the additive silica particle effects on the material’s mechanical properties and then the sealing performances of packers. Our study effectively fills the knowledge gap between elastomer intrinsic mechanical properties and the performances of a product under actual working conditions so that critical parameters of seal design can be identified and optimized.

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Keywords

Elastomer seal, Contact stress, Sealing performance

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