Steel Steep Wave Riser as an Alternative Configuration for FPSO’s Compliant Risers

Volume 5B: Pipeline and Riser Technology ◽

10.1115/omae2015-41098 ◽

2015 ◽

Author(s):

Paulo S. D. Pereira ◽

Marcio M. Mourelle ◽

Ludimar L. de Aguiar

Keyword(s):

Fixed Point ◽

Extreme Events ◽

Final Choice ◽

Vortex Induced Vibration ◽

Sea Bottom ◽

Alternative Configuration ◽

Steep Wave

The work was focused in the chase for alternative configurations that could resist to the high FPSO motions in the Brasil’s Pre-Salt harsh wave environment, and that could also be less compliant laterally when compared to the SLWR solution. A case study was taken where an infield 8 inch SLWR configuration has been taken for comparisons. After adjusting the SSWR (Steel Steep Wave Riser) main characteristics such as top angle, buoyant section length, buoyancy modules geometry and spacing, feasible configurations have been obtained. For a configuration to be considered as feasible, a set of verifications have been carried out including extreme events, wave fatigue, vortex induced vibration and installation. The verification was performed considering several riser top connection positions and azimuths along the FPSO riser support balcony. The interference with neighboring risers has been also taken as an important issue, but was taken solely for comparison with the SLWR configurations. The installation phase has been focused including the stages of bottom connection, normal pipe lay and the connection at the FPSO. The main problems associated to the installation phase of the steep wave configuration were identified and addressed in the discussion presented. As the SSWR configuration has a fixed point at the sea bottom, two different solutions for this connection have been studied, and the final choice is described. The main differences between SSWRs and SLWRs, and the possible advantages of the SSWR configuration are discussed and a direct comparison is presented.

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Analysis of Dangerous Sea States in the Northwestern Mediterranean Area

Journal of Marine Science and Engineering ◽

10.3390/jmse9040422 ◽

2021 ◽

Vol 9 (4) ◽

pp. 422

Author(s):

Alessio Innocenti ◽

Miguel Onorato ◽

Carlo Brandini

Keyword(s):

Extreme Events ◽

Mediterranean Area ◽

Rayleigh Distribution ◽

Surface Elevation ◽

Wave Steepness ◽

Sea Waves ◽

Operational Forecasts ◽

Long Time ◽

Simulated Field

Extreme sea waves, although rare, can be notably dangerous when associated with energetic sea states and can generate risks for the navigation. In the last few years, they have been the object of extensive research from the scientific community that helped with understanding the main physical aspects; however, the estimate of extreme waves probability in operational forecasts is still debated. In this study, we analyzed a number of sea-states that occurred in a precise area of the Mediterranean sea, near the location of a reported accident, with the objective of relating the probability of extreme events with different sea state conditions. For this purpose, we performed phase-resolving simulations of wave spectra obtained from a WaveWatch III hindcast, using a Higher Order Spectral Method. We produced statistics of the sea-surface elevation field, calculating crest distributions and the probability of extreme events from the analysis of a long time-series of the surface elevation. We found a good matching between the distributions of the numerically simulated field and theory, namely Tayfun second- and third- order ones, in contrast with a significant underestimate given by the Rayleigh distribution. We then related spectral quantities like angular spreading and wave steepness to the probability of occurrence of extreme events finding an enhanced probability for high mean steepness seas and narrow spectra, in accordance with literature results, finding also that the case study of the reported accident was not amongst the most dangerous. Finally, we related the skewness and kurtosis of the surface elevation to the wave steepness to explain the discrepancy between theoretical and numerical distributions.

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A new approach to detect extreme events: a case study using remotely-sensed precipitation time-series data

Remote Sensing Applications Society and Environment ◽

10.1016/j.rsase.2021.100618 ◽

2021 ◽

Vol 24 ◽

pp. 100618

Author(s):

Philipe Riskalla Leal ◽

Ricardo José de Paula Souza e Guimarães ◽

Fábio Dall Cortivo ◽

Rayana Santos Araújo Palharini ◽

Milton Kampel

Keyword(s):

Time Series ◽

Extreme Events ◽

Time Series Data ◽

Remotely Sensed ◽

Series Data ◽

Precipitation Time Series ◽

New Approach

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Wave-Induced Sediment Motion Beyond the Surf Zone: Case Study of Lubiatowo (Poland)

Archives of Hydro-Engineering and Environmental Mechanics ◽

10.1515/heem-2015-0017 ◽

2015 ◽

Vol 62 (1-2) ◽

pp. 27-39 ◽

Cited By ~ 5

Author(s):

Grzegorz R. Cerkowniak ◽

Rafał Ostrowski ◽

Magdalena Stella

Keyword(s):

Surf Zone ◽

Shear Stresses ◽

Research Station ◽

Wave Parameters ◽

Sea Bottom ◽

Theoretical Investigations ◽

Deep Water Wave ◽

Offshore Wave ◽

Wave Induced

AbstractThe paper presents results of field and theoretical investigations of a natural sandy shore located near the IBW PAN Coastal Research Station in Lubiatowo (Poland, the south Baltic Sea). The study site displays multi-bar cross-shore profiles that intensively dissipate wave energy, mostly by breaking. The main field data comprise offshore wave parameters and three cross-shore bathymetric profiles. Waveinduced nearbed velocities and bed shear stresses are theoretically modelled for weak, moderate, strong and extreme storm conditions to determine sediment motion regimes at various locations on the seaward boundary of the surf zone. The paper contains a discussion on the depth of closure concept, according to which the offshore range of sea bottom changes can be determined by the extreme seasonal deep-water wave parameters.

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Monitoring of an Uncontrolled Gas Flow by Sea Bottom Seismic Instruments – A North Sea Case Study

First EAGE Passive Seismic Workshop - Exploration and Monitoring Applications ◽

10.3997/2214-4609.201402570 ◽

2006 ◽

Author(s):

K. A. Berteussen ◽

K. Kolbjørnsen ◽

D. O. Larsen ◽

P. Kristiansen

Keyword(s):

North Sea ◽

Gas Flow ◽

Sea Bottom

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The impact of climatic extreme events on the feasibility of fully renewable power systems: A case study for Sweden

Energy ◽

10.1016/j.energy.2019.04.128 ◽

2019 ◽

Vol 178 ◽

pp. 695-713 ◽

Cited By ~ 6

Author(s):

Stefan Höltinger ◽

Christian Mikovits ◽

Johannes Schmidt ◽

Johann Baumgartner ◽

Berit Arheimer ◽

...

Keyword(s):

Power Systems ◽

Extreme Events ◽

Renewable Power ◽

The Impact

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The use of restraints in Rietveld refinement of molecular compounds; a case study using the crystal structure determination of tryptamine free base

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768102011370 ◽

2002 ◽

Vol 58 (5) ◽

pp. 835-840 ◽

Cited By ~ 12

Author(s):

Harriott Nowell ◽

J. Paul Attfield ◽

Jason C. Cole

Keyword(s):

Crystal Structure ◽

Rietveld Refinement ◽

Free Base ◽

Final Choice ◽

X Ray ◽

Global Weight ◽

Efficient Packing ◽

Molecular Compounds

The previously unknown crystal structure of the biogenic compound tryptamine, in the form of a free base (C10H12N2), has been solved from X-ray powder diffraction data using simulated annealing followed by restrained Rietveld refinement [space group P212121, a = 12.28593 (6), b = 8.53351 (4), c = 8.49385 (4) Å, Z = 4, final reduced-χ2 = 5.255]. A restrained Rietveld refinement was carried out in which the global weight factor, f, of the stereochemical restraints was gradually lowered. The effect of the relaxation of restraints on the crystal structure and on χ2 was studied and a criterion for the final choice of f is reported. The crystal structure reported here shows efficient packing involving weak intermolecular hydrogen bonding and a herringbone-type packing pattern.

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Estimate of Storm Induced Beach Erosion Through the ETS Approach

Volume 2: Structures, Safety and Reliability ◽

10.1115/omae2008-57749 ◽

2008 ◽

Author(s):

Rosaria E. Musumeci ◽

Carla Faraci ◽

Felice Arena ◽

Enrico Foti

Keyword(s):

Return Period ◽

Extreme Events ◽

Coastal Erosion ◽

Beach Erosion ◽

Coastal Protection ◽

Shoreline Retreat ◽

Submerged Breakwater ◽

The One

In the present paper the risk of beach erosion is evaluated by applying the Equivalent Triangular Storm (ETS). The selected case study is ‘La Plaja’ beach located in the South of Catania, Sicily. The proposed approach has shown that when the ETS model is applied, a shoreline retreat has been found which on average overestimates the one obtained by means of actual storm data of about 35%. The model has been applied for the determination of the return period of shoreline recession due to beach erosion during extreme events in order to recover risk maps, which can provide useful information in the planning of coastal interventions. Finally the model has been applied to predict the shoreline retreat in the presence of a submerged breakwater, confirming that the introduction of such coastal protection work strongly limits the risk of coastal erosion.

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Flexible Spools Solution for Hybrid Risers Base for Green Fields Developments

Volume 5A: Pipeline and Riser Technology ◽

10.1115/omae2015-41271 ◽

2015 ◽

Author(s):

S. Tarbadar ◽

S. Legeay ◽

M. Bonnissel ◽

O. Nossa ◽

A. Karnikian

Keyword(s):

Soil Properties ◽

Deep Water ◽

Oil Fields ◽

Direct Connection ◽

Flexible Pipe ◽

Vortex Induced Vibration ◽

Single Top ◽

Dynamic Loadings ◽

Operating Constraints ◽

Steep Wave

Rigid spools are commonly used at the riser base of hybrid riser systems such as STTRs (Single Top Tensioned Risers) or BHORs (Bundle Hybrid Offset Risers) for the deep water oil fields. Rigid spools design is critical and governed by numerous operating constraints such as dynamic loadings (due to motion of the vertical riser, Vortex Induced Vibration, slugging, etc.), soil properties and soil/spools/structures interaction. Recent surveys on existing brown fields have highlighted unexpected issues on existing rigid spools. To solve these issues, an innovative flexible spool solution has been developed, combining unbonded flexible pipe structures in a “steep wave” configuration to accommodate the riser motions and FLET (Flowline End Termination) excursions avoiding soil deterioration and preventing unexpected spool behavior which could ultimately jeopardize its integrity. A steep wave configuration solution can be introduced with distributed buoyancy over the flexible spools length. This design allows a direct connection between the riser base assembly and the flowline termination, solving the embedment issue and easing accommodation of the hybrid riser motions. This paper describes the recent issues with rigid spools design and describes the solutions developed with flexible spool configurations to provide a more reliable riser base spools system for green fields.

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