### Abstract

With the increase in demand and supply gap in the oil and gas industry, new developments of oil and gasinfrastructure are moving into deeper water. This requires design and construction of long high temperature and high pressure pipelines from deep sea to shore. These pipelines are subjected to cyclic expansion during operating cycles. Accumulated axial movement due to repeated thermal cycles may lead to global displacement referred to as ‘walking’. Walking rates depend on the restraint associated with seabed friction. In conventional analyses, seabed friction is independent of the rate of thermal loading and expansion but it has been recognised that the sliding resistance between a pipe and the seabed varies with velocity, partly due to drainage effects. In this paper a numerical model is used to explore the effect of velocity-dependent seabed friction. A velocity-dependent friction model is implemented in commercial software ABAQUS and validated via single element and simple (flat seabed) pipeline cases. This model features upper and lower friction limits, with a transition that occurs as an exponential function of velocity. A parametric study is performed using differing rates of heating and cool-down in walking situations driven by seabed slope, SCR end tension and the difference between heat up and cool down rates. The walking behaviour is compared to cases with constant friction and solutions are proposed to express the velocity-dependent response in terms of an equivalent constant friction. These equivalent friction values can then be applied in existing simple solutions or more complex numerical analyses, as a short cut method to account for velocity-dependent friction.

Original language | English |
---|---|

Pages (from-to) | 296-308 |

Number of pages | 13 |

Journal | Applied Ocean Research |

Volume | 82 |

DOIs | |

Publication status | Published - 1 Jan 2019 |

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*Applied Ocean Research*, vol. 82, pp. 296-308. https://doi.org/10.1016/j.apor.2018.10.028

**Subsea pipeline walking with velocity dependent seabed friction.** / Guha, Indranil; White, David J.; Randolph, Mark F.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Subsea pipeline walking with velocity dependent seabed friction

AU - Guha, Indranil

AU - White, David J.

AU - Randolph, Mark F.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - With the increase in demand and supply gap in the oil and gas industry, new developments of oil and gasinfrastructure are moving into deeper water. This requires design and construction of long high temperature and high pressure pipelines from deep sea to shore. These pipelines are subjected to cyclic expansion during operating cycles. Accumulated axial movement due to repeated thermal cycles may lead to global displacement referred to as ‘walking’. Walking rates depend on the restraint associated with seabed friction. In conventional analyses, seabed friction is independent of the rate of thermal loading and expansion but it has been recognised that the sliding resistance between a pipe and the seabed varies with velocity, partly due to drainage effects. In this paper a numerical model is used to explore the effect of velocity-dependent seabed friction. A velocity-dependent friction model is implemented in commercial software ABAQUS and validated via single element and simple (flat seabed) pipeline cases. This model features upper and lower friction limits, with a transition that occurs as an exponential function of velocity. A parametric study is performed using differing rates of heating and cool-down in walking situations driven by seabed slope, SCR end tension and the difference between heat up and cool down rates. The walking behaviour is compared to cases with constant friction and solutions are proposed to express the velocity-dependent response in terms of an equivalent constant friction. These equivalent friction values can then be applied in existing simple solutions or more complex numerical analyses, as a short cut method to account for velocity-dependent friction.

AB - With the increase in demand and supply gap in the oil and gas industry, new developments of oil and gasinfrastructure are moving into deeper water. This requires design and construction of long high temperature and high pressure pipelines from deep sea to shore. These pipelines are subjected to cyclic expansion during operating cycles. Accumulated axial movement due to repeated thermal cycles may lead to global displacement referred to as ‘walking’. Walking rates depend on the restraint associated with seabed friction. In conventional analyses, seabed friction is independent of the rate of thermal loading and expansion but it has been recognised that the sliding resistance between a pipe and the seabed varies with velocity, partly due to drainage effects. In this paper a numerical model is used to explore the effect of velocity-dependent seabed friction. A velocity-dependent friction model is implemented in commercial software ABAQUS and validated via single element and simple (flat seabed) pipeline cases. This model features upper and lower friction limits, with a transition that occurs as an exponential function of velocity. A parametric study is performed using differing rates of heating and cool-down in walking situations driven by seabed slope, SCR end tension and the difference between heat up and cool down rates. The walking behaviour is compared to cases with constant friction and solutions are proposed to express the velocity-dependent response in terms of an equivalent constant friction. These equivalent friction values can then be applied in existing simple solutions or more complex numerical analyses, as a short cut method to account for velocity-dependent friction.

KW - Subsea pipelines

KW - Velocity dependent seabed friction

KW - Walking

UR - http://www.scopus.com/inward/record.url?scp=85056869518&partnerID=8YFLogxK

U2 - 10.1016/j.apor.2018.10.028

DO - 10.1016/j.apor.2018.10.028

M3 - Article

VL - 82

SP - 296

EP - 308

JO - Applied Ocean Research

JF - Applied Ocean Research

SN - 0141-1187

ER -