P110T Casing Material’s Relation of Creep and Relaxation for the Sealing Surface of Premium Connection in High Temperature Gas Well
Creep or stress relaxation is considered as a mainly factor of reducing the contact pressure on the sealing surface of premium connection, causing the gas leakage in the high temperature gas well. In this paper, the creep tests of P110T casing material were conducted under different temperatures (120, 200, 300 °C). According to the experimental data, the fitting mathematical model of P110T casing material’s steady creep strain rate was obtained under the different temperature and loading by the Least Square method. Then, the relation of creep and relaxation was presented, and an innovation stress relaxation model was put forward from the creep strain rate. Finally, applying with the stress relaxation model, P110T casing material’s stress relaxation varying with time was obtained. The results show that, the stress relaxation was obvious in the initial phase and it decreased with time increasing. The stress decreased significantly and tended to a stable value. And the environmental temperature and initial stress had a significant influence on the stress relaxation. This study can be used for the designing of the premium connection’s structure, or prediction their service life in the high temperature gas well.
KeywordsPremium connection Contact pressure Sealing mechanism Creep Stress relaxation
The authors are grateful to the support from the National Natural Science Foundation of China (No. 51574198) and Research Fund for the Doctoral Program of Higher Education of China (No. 20135121110005).
- 2.J. Takano, M. Yamaguchi, H. Kunishige, Development of premium connection “KSBEAR” for withstanding high compression, high external pressure, and sever bending. Kawasaki Steel Tech. Rep. 47, 14–22 (2001)Google Scholar
- 4.J. Wang, Y. Feng, K. Lin et al., Comparison analysis of premium connection’s seal structure. J. China Univ. Petrol. 34(5), 125–129 (2010)Google Scholar
- 5.E.P. Cernocky, G.A. Valigura, F.C. Scholibo et al., A standardized approach to finite element analysis of casing-tubing connections to establish relative sealing performance as a function of design geometry, machining tolerances, and applied loads (Computational mechanics, CIMNE, Barcelona, Spain, 1998), pp. 1–19Google Scholar
- 6.M. Sugino, K. Nakamura, S. Yamaguchi et al., Development of an innovative high-performance premium threaded connection for OCTG, in Offshore Technology Conference (Houston, Texas, USA, May 2010)Google Scholar
- 7.G. Carcagno, The design of tubing and casing premium connections for HTHP wells, in SPE High Pressure/High Temperature Sour Well Design Applied Technology Workshop Conference (The Woodlands, Texas, 2005, SPE-97584-MS)Google Scholar
- 8.G. Ong, S. Yamaguchi, R. Imai, Successful casing drilling experience with premium connection for production casing application on a subsea well, in Proceeding of the SPE Asia Pacific Oil & Gas Conference and Exhibition (2013)Google Scholar
- 9.N. Matsuki, Y. Morita, H. Kawashima, Evaluation of premium connection design conditions, in ASME ETCE Drilling and Production Symposium (Feb 1985), pp. 73–85Google Scholar
- 14.D. Zhang, F. Wei, Exposition and argumentation on constrained least square method. Journal of computational mechanics. 11, 398–403 (2000)Google Scholar