Performance of Tubular Connections Under the Loading Conditions of Horizontal Wells
- Eiji Tsuru (Ueno, Masakatsu) | Masakatsu Ueno (Nippon Steel Corp.) | Masao Ogasawara (Nippon Steel Corp.) | Tetsuo Yonezawa (Japan National Oil Corp.)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- December 1996
- Document Type
- Journal Paper
- 242 - 248
- 1996. Society of Petroleum Engineers
- 1.6 Drilling Operations, 3 Production and Well Operations, 5.4.6 Thermal Methods, 1.14.1 Casing Design
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This study deals with the negative effects of bending stress and casing wear on tubular connections. The joint strength of three connection types. API long round thread (LTC). API buttress thread (BTC) and typical premium (PJ) was measured using a full-size combined loading tester. Measurements were also made for the connections simulating wear induced by drilling operations. The sealing ability of the connections was evaluated under bending and wearing conditions. Numerical simulations were undertaken to investigate the failure mechanism of the connections.
The results indicate that LTC joint strength is lowered by bending. though that of BTC and PJ is not degraded. Joint strength is reduced in direct proportion to the wear area ratio of the pipe body. In sealing ability. only the premium connection maintained leak resistance under combined loading with bending. Axial loading is more detrimental to sealing integrity than the bending moment. In conclusion. the connection performance data can be useful in designing safer horizontal well casings.
Horizontal wells have become popular owing to their oil efficiency. In horizontal wells. casing strings including connections are subjected to bending in addition to axial load and pressure. Furthermore. the inner surface of the casing is worn by drilling operations. The performance evaluation of connections using tests that simulate actual well operating conditions can be useful in casing design for horizontal wells. Recent studies have been conducted on pipe body performance to determine collapse and burst resistance to bending and wear. However. few studies have been undertaken to investigate connection performance under bending and wearing conditions. The objective of this study is to estimate the negative influence of bending and wear on joint strength. and to investigate the effects of bending and wear on the sealing ability of the connections.
The strength and sealing ability of the connections were evaluated under constant bending angle using the combined loading tester. Strain measurements were performed to determine the failure mechanism under bending. Finite element analysis (FEA) was used to investigate the effect of bending on connection performance. This paper presents the results of our study. which show that the joint strength of the buttress-type thread connection is not lowered by the application of bending. while is that of the round-type thread connection is degraded. Furthermore. joint strength decreases in proportion to the pipe area owing to casing wear. In sealing ability. only the premium connection maintained gas tightness under combined loading with bending. However. water leakage occurred in all API connections except tubing. The sealing deterioration produced by bending is less than that by axial loading.
|File Size||312 KB||Number of Pages||7|