Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads

Abstract The design of drill pipe joint thread with unequal taper is proposed to investigate the fracture failure of the API NC38 used in the drill pipe joint of the SU36-8-4H2 well. The effect of changes in thread taper on the stress distribution and mechanical properties of drill pipe joints is an...

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Main Authors: Hangming Liu, Yongpeng Song, Shenghua Hu, Yuxian He, Jifang Wan, Xianzhong Yi, Song Hou
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-024-81691-6
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author Hangming Liu
Yongpeng Song
Shenghua Hu
Yuxian He
Jifang Wan
Xianzhong Yi
Song Hou
author_facet Hangming Liu
Yongpeng Song
Shenghua Hu
Yuxian He
Jifang Wan
Xianzhong Yi
Song Hou
author_sort Hangming Liu
collection DOAJ
description Abstract The design of drill pipe joint thread with unequal taper is proposed to investigate the fracture failure of the API NC38 used in the drill pipe joint of the SU36-8-4H2 well. The effect of changes in thread taper on the stress distribution and mechanical properties of drill pipe joints is analyzed and compared with the API standard thread to determine the optimal thread structure with unequal taper. The results reveal highly concentrated stress at the last engaged thread root of API NC38 single-shoulder thread (SUT) may cause early yield failure of the joint threads. Adjusting the unequal taper of the pin thread mitigates uneven stress distribution in NC38 single and double-shoulder threads and enhances connection strength, particularly for SUT-II and DUT-I. However, altering the box thread’s unequal taper modifies the stress concentration slightly in NC38 single and double-shoulder threads. This offers limited tensile and compressive strength improvement. The maximum Mises stress value of SUT-II is reduced by 56.69% compared to SUT. The maximum Mises stress value of DUT-I is reduced by 34.87% compared to NC38 double-shoulder joint thread (DUT). This design approach can guide the optimization of other API threads and enhance joint strength for non-API and specialized taper threads.
format Article
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institution Kabale University
issn 2045-2322
language English
publishDate 2024-12-01
publisher Nature Portfolio
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series Scientific Reports
spelling doaj-art-a876238835e04c24bebc63ea4615ced02024-12-29T12:19:36ZengNature PortfolioScientific Reports2045-23222024-12-0114111810.1038/s41598-024-81691-6Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loadsHangming Liu0Yongpeng Song1Shenghua Hu2Yuxian He3Jifang Wan4Xianzhong Yi5Song Hou6The Seventh Geological Brigade of Hubei Geological BureauThe Seventh Geological Brigade of Hubei Geological BureauThe Seventh Geological Brigade of Hubei Geological BureauSchool of Mechanical Engineering, Yangtze UniversityChina Energy Digital Technology Group Co., Ltd.School of Mechanical Engineering, Yangtze UniversitySchool of Mechanical Engineering, Yangtze UniversityAbstract The design of drill pipe joint thread with unequal taper is proposed to investigate the fracture failure of the API NC38 used in the drill pipe joint of the SU36-8-4H2 well. The effect of changes in thread taper on the stress distribution and mechanical properties of drill pipe joints is analyzed and compared with the API standard thread to determine the optimal thread structure with unequal taper. The results reveal highly concentrated stress at the last engaged thread root of API NC38 single-shoulder thread (SUT) may cause early yield failure of the joint threads. Adjusting the unequal taper of the pin thread mitigates uneven stress distribution in NC38 single and double-shoulder threads and enhances connection strength, particularly for SUT-II and DUT-I. However, altering the box thread’s unequal taper modifies the stress concentration slightly in NC38 single and double-shoulder threads. This offers limited tensile and compressive strength improvement. The maximum Mises stress value of SUT-II is reduced by 56.69% compared to SUT. The maximum Mises stress value of DUT-I is reduced by 34.87% compared to NC38 double-shoulder joint thread (DUT). This design approach can guide the optimization of other API threads and enhance joint strength for non-API and specialized taper threads.https://doi.org/10.1038/s41598-024-81691-6Drill pipe joint threadUnequal taperComplex loadMechanical behavior
spellingShingle Hangming Liu
Yongpeng Song
Shenghua Hu
Yuxian He
Jifang Wan
Xianzhong Yi
Song Hou
Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
Scientific Reports
Drill pipe joint thread
Unequal taper
Complex load
Mechanical behavior
title Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
title_full Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
title_fullStr Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
title_full_unstemmed Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
title_short Design and mechanical properties analysis of drill pipe’s joint thread with unequal taper under complex loads
title_sort design and mechanical properties analysis of drill pipe s joint thread with unequal taper under complex loads
topic Drill pipe joint thread
Unequal taper
Complex load
Mechanical behavior
url https://doi.org/10.1038/s41598-024-81691-6
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AT shenghuahu designandmechanicalpropertiesanalysisofdrillpipesjointthreadwithunequaltaperundercomplexloads
AT yuxianhe designandmechanicalpropertiesanalysisofdrillpipesjointthreadwithunequaltaperundercomplexloads
AT jifangwan designandmechanicalpropertiesanalysisofdrillpipesjointthreadwithunequaltaperundercomplexloads
AT xianzhongyi designandmechanicalpropertiesanalysisofdrillpipesjointthreadwithunequaltaperundercomplexloads
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