The influence of manufacturing technology and imperfections on casing collapse strength is not considered in API bulletin 5C3. In the meantime, the current casing true collapse strength cannot be predicted accurately by API bulletin 5C3. For these cases, the joint API/ISO work group ISOTC67 SC5 WG2b has proposed the current API bulletin 5C3 and presented a new collapse strength model with manufacturing imperfections, such as ovality, eccentricity, residual stress, etc., which improves the casing strength calculation accuracy and benefits much more for casing strength design rather than just using API bulletin 5C3. The study on the new ISO collapse model has found that it cannot be used to predict the collapse strength of all pipe sizes, and the current study results are greatly different from actual conditions, which is not the last goal to propose API bulletin 5C3 for the joint API/ISO work group ISOTC67 SC5 WG2b. So, based on the new ISO collapse model, a new oil country tubular goods (OCGT) strength equation, “new equation” for predicting all OCTG sizes collapse strength under external load only has been presented in this paper. Numerical and experimental comparisons show that there is a safety margin appropriate to the desired target reliability level between the predictive values calculated by the new equation and test collapse data, and the new equation calculation accuracy is higher than that of API and ISO, which will make great improvements in the casing design of deep and superdeep wells on the basis of guaranteeing casing material safety.
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February 2011
Research Papers
A New OCTG Strength Equation for Collapse Under External Load Only
Yong-Xing Sun,
e-mail: yohancesun@yahoo.com.cn
Yong-Xing Sun
Drilling and Production Technology Research Institute
, Guanghan 618300, China; State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University
, Chengdu 610500, China
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Yuan-Hua Lin,
Yuan-Hua Lin
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,
Southwest Petroleum University
, Chengdu 610500, China
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Zhong-Sheng Wang,
Zhong-Sheng Wang
Drilling and Production Technology Research Institute
, Guanghan 618300, China
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Tai-He Shi,
Tai-He Shi
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,
Southwest Petroleum University
, Chengdu 610500, China
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Hong-Bin Liu,
Hong-Bin Liu
Drilling and Production Technology Research Institute
, Guanghan 618300, China
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Ping Liao,
Ping Liao
Northeast Sichuan Gas Field,
Southwest Oil and Gas Co.
, Daxian 635000, China
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Xiang-Dong Shen
Xiang-Dong Shen
Northeast Sichuan Gas Field,
Southwest Oil and Gas Co.
, Daxian 635000, China
Search for other works by this author on:
Yong-Xing Sun
Drilling and Production Technology Research Institute
, Guanghan 618300, China; State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University
, Chengdu 610500, Chinae-mail: yohancesun@yahoo.com.cn
Yuan-Hua Lin
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,
Southwest Petroleum University
, Chengdu 610500, China
Zhong-Sheng Wang
Drilling and Production Technology Research Institute
, Guanghan 618300, China
Tai-He Shi
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,
Southwest Petroleum University
, Chengdu 610500, China
Hong-Bin Liu
Drilling and Production Technology Research Institute
, Guanghan 618300, China
Ping Liao
Northeast Sichuan Gas Field,
Southwest Oil and Gas Co.
, Daxian 635000, China
Xiang-Dong Shen
Northeast Sichuan Gas Field,
Southwest Oil and Gas Co.
, Daxian 635000, ChinaJ. Pressure Vessel Technol. Feb 2011, 133(1): 011702 (5 pages)
Published Online: January 20, 2011
Article history
Received:
June 18, 2009
Revised:
May 23, 2010
Online:
January 20, 2011
Published:
January 20, 2011
Citation
Sun, Y., Lin, Y., Wang, Z., Shi, T., Liu, H., Liao, P., and Shen, X. (January 20, 2011). "A New OCTG Strength Equation for Collapse Under External Load Only." ASME. J. Pressure Vessel Technol. February 2011; 133(1): 011702. https://doi.org/10.1115/1.4001947
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