Increasing the tightness of threaded connections of casing strings based on finite element modeling
DOI:
https://doi.org/10.31471/2304-7399-2026-22(83)-189-209Keywords:
casing, threaded connection, anaerobic sealant, horizontal well, finite element modelling, stress-strain stateAbstract
Analyzing the literature and professional publications, it was found that drilling horizontal wells allows to significantly increase the coverage of productive layers and increase the hydrocarbon recovery rate, but at the same time creates additional challenges for ensuring the stability of casing strings. The most vulnerable elements are threaded connections, which under the influence of combined loads (pressure, bending stresses, temperature gradients and vibrations) often lose their tightness, which leads to accidents during operation. The basic technological solutions to this problem are analyzed - the use of anaerobic sealants that can polymerize in an oxygen-free environment and ensure tight fit to metal surfaces even with micro-unevenness. They are characterized by high adhesion, resistance to aggressive fluids and temperatures up to 230 °C, and also retain their properties under the influence of vibrations and cyclic loads. Based on the conducted research, the results of numerical modelling of the stress-strain state of threaded connections of casing strings using the finite element method (FEM) are presented. It was established that the use of anaerobic sealants allows to reduce the stress concentration in the zone of the first turns of the thread, preserve the integrity of the seal and extend the service life of the casing string. The conducted comprehensive research and the obtained results indicate the feasibility of introducing anaerobic sealants into the practice of screwing casing pipes as an effective means of increasing the reliability and safety of casing strings in horizontal wells.
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