Riser Concepts for High Motion Vessels in Ultradeep Water

Head, W.J.; Power, Thomas L.; Royer, Brian

doi:10.4043/24229-ms

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…Sexton and Agbezuge(1976) researched the influence of both random waves and vessel motion on connected drilling risers. Head et al(2013) and Royer et al(2014) evaluated various potential concepts of a steel catenary riser for high-motion vessels operating in ultra-deepwater. analysed the out-of-plane vortex-induced vibration of a steel catenary riser caused by vessel motions and evaluated its fatigue damage.…”

Section: Introductionmentioning

confidence: 99%

Dynamic analysis of a hang-off drilling riser considering internal solitary wave and vessel motion

Fan

Wang

et al. 2017

Journal of Natural Gas Science and Engineering

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Hang-off mode of a drilling riser is occasionally needed during subsea installation/platform relocation operations or evacuation after an emergency disconnection. A suspending riser without any restriction at its bottom is more flexible and more dangerous in complex sea states than a connected riser with excess axial tension. Internal solitary waves (ISWs) can particularly exert a sudden impact and shearing force on risers, and vessel motion can expand horizontal dynamic responses of the risers. In this paper, considering vessel motion and the combined excitation of ocean currents, surface waves and ISWs, a dynamic model is constructed based on the Euler-Bernoulli theory, in which ISW is simulated by the Korteweg-de Vries (KdV) equation with a two-layer seawater model. Then, the structural governing equation is numerically solved by the Wilson- method and preconditioned generalized minimal residual method (GMRES) with a self-developed MATLAB program. Case calculation shows that ISW can largely increase the envelopes of riser properties in the upper seawater layer and dramatically expand the horizontal deviation of the bottom of a hang-off riser during ISW spreading. Particularly, the dynamic responses of a riser will be larger with ISW amplitude augmentation, and larger with an increase in the density difference between the two seawater layers. In addition, vessel motion can increase the horizontal deviation along the entire length of a riser with a range that is nearly the same as that of the vessel motion amplitude, and increase the envelopes of bending moment and shearing force at the lower section of the riser near the riser bottom. Therefore, limiting the vessel motion amplitude, optimizing the vessel towing speed, maintaining a lower marine riser package (LMRP) at the riser bottom to strengthen axial tension, and using slick joints with larger wall thicknesses in the upper depth may be effective engineering considerations. More importantly, much attention should be paid to avoid the riser bottom/LMRP striking other subsea equipment in oceans in which ISWs occur frequently.

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Section: Introductionmentioning

confidence: 99%

Dynamic analysis of a hang-off drilling riser considering internal solitary wave and vessel motion

Fan

Wang

et al. 2017

Journal of Natural Gas Science and Engineering

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Parametric analysis on the global design of flexible riser under different environmental conditions using OrcaFlex

Amaechi,

Butler,

Beddu

et al. 2024

PLoS ONE

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The application of flexible risers has led to increased production of fluid contents in the marine industry. This paper presents the design challenges of a flexible riser subjected to internal pressure under deep-water conditions, at a water depth of 2000 m. Parametric variations with extensive dynamic analysis were carried out. The study highlights include the global analysis of lazy-wave configuration for the design of flexible risers, to understand the failure of flexible risers and application of hybrid configurations on flexible pipes. For the global analysis, the design of the riser was modelled in OrcaFlex by considering different sections and then analysed for the influence of effective tension, bending moment and environmental conditions. This riser model is multi-layered and was mainly subjected to the fluid pressure load and the environmental load. Model validations were performed with existing lazy-wave models. In the global design, the riser was assessed when connected to the vessel, but vessel motion was not included, additionally, three different environmental conditions were applied on the model. Also, the suitability of the adopted configuration for the proposed flexible riser was adopted considering it as a sustainable marine structure. Stress profile, tension profile and bending moment for the risers were presented and conclusions were made on the study. Some fatigue study is recommended in future study to be undertaken on the riser.

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Assessment of Ultra Deepwater Riser Concepts for High-Motion Vessels

Royer

Power

Ayewah

et al. 2014

Day 2 Tue, May 06, 2014

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The paper presents the results of the second half of a study funded by Research Partnership to Secure Energy for America (RPSEA) under project 10121-4401-02 Ultra-Deepwater Riser Concepts for High Motion Vessels. In the first half of the study, candidate riser systems consisting of alternatives to the steel catenary riser in both geometry – for the purpose of isolating the fatigue-critical riser touchdown zone from the motions of the vessel – and material were identified then down-selected to meet the constraints of high motion vessels like the conventional semi-submersible or a ship-shape floating, production, storage, and offloading vessel (FPSO). In addition to water depths approaching 10,000 feet, the present-day challenges of high pressure, high temperature, and sour well product are incorporated into the problem being framed. Results from dynamic analyses of riser concepts passing through the down-selection process are used to assess both utilization of strength capacity and fatigue performance. Comparisons of dynamic responses highlight the differences of each riser concept's behavior and provide understanding of the limitations of riser concepts. Assessments to other criteria such as cost, failure modes, and installation considerations are also used to ascertain safe riser systems that meet the performance demand of high-motion vessels.

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Riser Concepts for High Motion Vessels in Ultradeep Water

Cited by 3 publications

References 4 publications

Dynamic analysis of a hang-off drilling riser considering internal solitary wave and vessel motion

Dynamic analysis of a hang-off drilling riser considering internal solitary wave and vessel motion

Parametric analysis on the global design of flexible riser under different environmental conditions using OrcaFlex

Assessment of Ultra Deepwater Riser Concepts for High-Motion Vessels

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