JUSTIFICATION OF THE OPTIMAL ANAEROBIC SEALANT LAYER THICKNESS FOR THREADED CONNECTIONS OF CASING PIPES

Abstract

The influence of the thickness of an anaerobic sealant layer on the stress-strain state of threaded casing connections was investigated. This study is relevant because there is a need to improve the mechanical reliability of threaded connections that are subjected to significant axial loads and internal pressure during well operation. Particular attention was paid to how the geometric parameters of the sealing layer influence thread contact inter-action, equivalent stress distribution and contact pressure. The effect of variations in anaerobic sealant thickness on the mechanical behaviour of threaded casing connections was also considered. This study aimed to determine the influence of anaerobic sealant layer thickness on the stress-strain state of a threaded casing connection, and to identify a rational thickness based on numerical modelling. The investigation was performed using the finite
element method (FEM) in ANSYS Mechanical. A simplified three-dimensional model consisting of a casing pipe, a coupling and an anaerobic sealant layer was employed. Six configurations were analysed: a connection without sealant, and connections with sealant layer thicknesses of 0.02, 0.05, 0.10, 0.15 and 0.20 mm. A comparative
numerical analysis was performed to demonstrate the influence of the thickness of the anaerobic sealant layer on the distribution of equivalent stresses within the threaded contact region. The reference model without a sealant layer exhibited non-uniform stress distribution, with localised stress concentrations in specific areas of the thread profile. Models incorporating a sealing layer showed changes in the stress-strain state, which were associated with load redistribution between the contacting surfaces of the pipe and coupling. Comparing the calculated equivalent stress fields showed that the location and distribution of stress concentrations depend on the thickness of the
polymeric interlayer. Based on the comparative analysis presented, a sealant layer thickness of 0.10 mm was
identified as a rational value among the configurations investigated in terms of equivalent stress distribution. For this configuration, reduced localised stress concentrations and more favourable load transfer conditions between the engaged threads were observed. Increasing the sealant layer thickness further to 0.15–0.20 mm altered the contact interaction, highlighting the importance of considering polymer layer geometry when evaluating the
mechanical behaviour of threaded connections. The results obtained provide further insight into the relationship between anaerobic sealant layer thickness and the stress-strain state of threaded casing connections. The findings support the consideration of sealing layer geometry in the development of sealing solutions for casing connections. Further research should address the non-linear mechanical properties of the sealant, its non-uniform distribution after connection assembly, and the quantitative evaluation of sealing performance under formation fluid pressure.