Mechanical Stability Analysis of Subsea Wellhead for Deepwater Production to Earthquake Load

Abstract:

Subsea wellhead for deepwater production subjects to axial force, lateral force and bending moment under the seismic loading, the effect of subsea christmas tree and casing string’s gravity. Joint action of these forces makes it is possible that horizontal displacement exceeds the limitation and thus loses the stability. A mechanical analytical model of subsea wellhead for deepwater production is established on the basis of the pile foundation theories and material mechanics, the seismic load and behavior between casing string and formation are considered. The analyses on lateral displacement, angular distortion, bending moment and shear force show that the affection of lateral load is focus on the upper section of casing string, and the lateral displacement of subsea wellhead for deepwater production increases along with earthquake load and thus decreases stability. The stability improves notably with the increase of coefficient of soil reaction. Therefore it is necessary to obtain the on-the-spot geological data in shallow formation. The wellhead stability may be improved to different degrees by taking measures such as minimizing axial load, enhancing the conductor bending strenth, increasing the depth of the casing string in soil, reducing the outcropping length of the casing string.

• Periodical: Applied Mechanics and Materials (Volumes 44-47)
• Pages: 1061-1065
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.44-47.1061
• Online since: December 2010
• Authors: Wen Sheng Xiao, Xiu Juan Lin, Hong Yan Wang
• Keywords: Deepwater Production, Earthquake Load, Mechanical Analysis, Subsea Wellhead

References

[1] Fang Huacan: Offshore Drilling and Production Equipments and Structures (Petroleum Industry Press, Beijing 1990), in Chinese.

[2] Xie Bin, Zhang Aixia and Duan Menglan: Acta Petrolei Sinica Vol. 28(2007), P. 115~118, in Chinese.

[3] Sterling Lewis and Jay Suter: the 2008 IADC/SPE Drilling Conference(Orlando, Florida, U.S.A., 4–6 March 2008). Paper No. IADC/SPE 112723.

[4] Robert Voss and Tony Moore: the 2003 Offshore Technology Conference(Houston, Texas, U.S.A., 5–8 May 2003).

[5] M. daCosta and H. J. Hartley: the 1988 Offshore Technology Conference (Houston, Texas, 4-7 May 1988) . Paper No. OTC 8579.

[6] Hu Sen and Tian Guozhi. Soil Mechanics and Foundation Engineering(The Yellow River Conservancy Press, Henan 2008), in Chinese.

[7] Zhao Minghua, Zou Xinjun, Luo Songnan, et al : Chinese Journal of Geotechnical Engineering Vol. 26(2004),P. 767~77, in Chinese.

[8] Guan Zhichuan, Su Kanhua and Su Yinao: Acta Petrolei Sinica Vol. 30(2009),P. 285~29. in Chinese.

[9] M.M. Jordan, K. Sjuraether, I.R. Collins, N. D. Feasey and D. Emmons: the 2001 SPE Annual Technical Conference and Exhibition(New Orleans, Louisiana, 30 September–3 October 2001) . Paper No. SPE 71557.

[10] Don Aldridge, Baker Oil Tools, and Paul Dodd: the 1996 SPE Asia Pacific Oil and Gas Conference(Adelaide Australia, October 28~31, 1996) . Paper No. SPE 36991.