西南石油大学学报(自然科学版) ›› 2016, Vol. 38 ›› Issue (5): 179-184.DOI: 10.11885/j.issn.16745086.2014.07.28.01

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Theoretical Analysis of Sphere to Cone Sealing Performance for Tubing and Casing Premium Connection

XU Honglin1, LI Tianlei3,4, YANG Bin1, SHI Taihe2, ZHANG Zhi2   

  1. 1. School of Petroleum and Natural Gas Engineering, Chongqing University of Science & Technology, Shapingba, Chongqing 401331, China;
    2. State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    3. China Petroleum Engineering Co. Ltd., Southwest Company, Chengdu, Sichuan 610041, China;
    4. Sichuan Research Division of the CNPC Key Laboratory for Mechanical and Environmental Behavior of Tubular Goods, Chengdu, Sichuan 610017, China
  • Received:2014-07-28 Online:2016-10-01 Published:2016-10-01

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Abstract: To study the sphere to cone surfaces sealing structure in tubing and casing premium connection,on the basis of Hertz contact mechanics and considering the sealing surface makeup torque, the sealing contact stress model has been established in this paper. The effects of the spherical radius, elastic modulus of sphere and the sealing surface makeup torque on the sealing width and stress were analyzed. And the measures for improving the sealing performance of spherical sealing were proposed. The results show that the contact width increases parabolically,contact stress decreases exponentially and the contact stress tends to be distributed evenly with the increase of spherical radius,the contact width increases and the contact stress decreases with the decrease of the elastic modulus of sphere,both of the contact width and stress increase parabolically with the increase of sealing surface makeup torque. To enhance the sealing performance of spherical sealing structure,we suggest the following measures: a proper larger spherical radius, a lower elastic modulus of cladding alloy sphere and a properly controlled sealing surface makeup torque for sealing width increase and a proper lower sealing contact stress. The obtained results can be of theoretical significance for sealing parameters optimization, makeup torque control and connection sealing integrity improvement.

Key words: tubing and casing, premium connection, sphere sealing, contact width, contact stress, theoretical analysis

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