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Original scientific paper

https://doi.org/10.21278/brod73301

NUMERICAL INVESTIGATIONS ON THE EFFECTS OF SEABED SHALLOW SOILS ON A TYPICAL DEEPWATER SUBSEA WELLHEAD SYSTEM

Xingkun Zhou orcid id orcid.org/0000-0002-7911-3686 ; Department of Marine Engineering, Dalian Maritime University, Dalian; National Center for International Research of Subsea Engineering Technology and Equipment, Dalian Maritime University, Dalian
Jinghao Chen ; Beijing Key Laboratory of Pipeline Critical Technology and Equipment for Deepwater Oil & Gas Development, Beijing Institute of Petrochemical Technology, Beijing
Zhengguang Ge ; National Center for International Research of Subsea Engineering Technology and Equipment, Dalian Maritime University, Dalian
Tong Zhao ; Beijing Key Laboratory of Pipeline Critical Technology and Equipment for Deepwater Oil & Gas Development, Beijing Institute of Petrochemical Technology, Beijing
Wenhua Li ; Department of Marine Engineering, Dalian Maritime University, Dalian; National Center for International Research of Subsea Engineering Technology and Equipment, Dalian Maritime University, Dalian


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Abstract

Deepwater subsea wellheads may be significantly threatened under extreme sea conditions and operations, especially when the seabed is composed of very soft clay properties. A numerical model of a deepwater wellhead system is established using the classic ocean pipe element and nonlinear spring element of ANSYS to examine the behaviors of subsea wellheads in diverse seabed soil. Nonlinear spring elements coded in the APDL language are used to model three types of seabed soils: very soft soil, soft soil, and firm soil. The dynamic and quasi-static behaviors of the wellhead system in the typical coupled and decoupled models of the drilling riser system are particularly investigated in depth. The effects of the nonlinear seabed soil properties on the detailed wellhead are realistically simulated using time domain and extremum analysis. The results show that the softer the seabed soil, the greater the displacement, rotation angle, curvature, and bending moment of deepwater subsea wellheads. When the seabed soil reaches a particular depth, the mechanical characteristics of the wellheads under the three types of seabed soil conditions are almost simultaneously close to zero. Overall, several conclusions reached in this study may provide some useful references for design and stability analysis.

Keywords

Subsea wellhead; Seabed soil; Mechanical behaviour; Nonlinear spring

Hrčak ID:

280326

URI

https://hrcak.srce.hr/280326

Publication date:

1.7.2022.

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