NDP – Riser & Mooring Project - EPIM · PDF filewere used. Catenary Offset Buoyant Riser Arrangement This work describes the development of a new flexible (compliant) Steel Riser

NDP – Riser & Mooring Project Reports archived in License2Share (L2S)

21/04/2016

TITLE DESCRIPTION INSTITUTION AUTHOR DATE

2D model testing of risers

The model test is set up to study the structural interaction of long vertical risers exposed to steady currents. The methodology applied is model tests in reduced scale, using idealized representation of prototype riser systems. The vertical risers are modelled by rigid pipe segments elastically suspended and exposed to steady currents. Furthermore, these tests give information on structural interaction, in particular information on the frequency of impact and the relative velocity at which impact occurs. (Appendices A – G are reported separately).

Danish Hydraulic Institute, Hørsholm, DK

Bryndum, M. B. and H. Andersen

1999-12-21

3D NDP Model Testing Risers. Riser Collision Impulse and Energy

In 1999 MARINTEK has conducted a new test program for NDP, aiming at more extensive investigations of the force impulse and energy involved in riser collisions. Contrary to the tests in 1998 the new test program has concentrated on test conditions well above the current defining on-set of collisions. Furthermore, the force impulse transducer has been changed, and the riser spacing has been reduced. The present report describes

the results of the new test series.

MARINTEK - Norwegian Marine Technology Research Institute, Trondheim

Huse, E. 1999-10-14

Additional analysis of data from VIV measurements Part 1. Selecting experimental data.

The objective of this project is to extract as much information as possible from existing measurements of VIV on risers. The main issue will be to describe the character of the response under various conditions, and identify parameters that control this character. The report discusses which VIV analyses that may be done. A review of related VIV experiments carried out at MARINTEK is also given.


Lie, H. 2002-11-04

Additional analysis of The objective of this project is to extract as much MARINTEK - Norwegian Lie, H. and K. E. 2004-01-23

data from VIV measurements Part 2. Analysis of experimental data.

information as possible from existing measurements of VIV on risers. The main issue will be to describe the character of the response under various conditions, and identify parameters that control this character. The present part of the work addresses two different VIV experimental sets of data; the first data set is from a large-scale testing program undertaken at Hanøytangen near Bergen in 1997, and the other is from a model test conducted at MARINTEK where a rotating rig has been used to set up different current profiles, e.g. uniform, linear sheared profile and also 3D skewed profiles.

Marine Technology Research Institute, Trondheim

Kaasen

Additional VIV Analysis. Analysis of skew current rotating rig data.

Model test data from a rotating rig test in the model tank are analysed. Due to the geometry of the rig, a non-uniform current was achieved. This report describes the different geometries in detail, and gives an overview of relevant parameters describing the skew current. A skew coordinate system (mostly referred to as local) is presented and used to analyse VIV-response on the riser.


Kristiansen, T. 2005-01-25

Additional VIV Analysis. Attenuation study.

MARINTEK has on several occasions analysed data from VIV experiments in full scale and model scale. The present project estimates coherence and correlation functions for cross-flow for four selected test cases from the Hanøytangen experiments, test cases 31, 39, 51 and 66. These correspond to towing velocities of 0.36, 0.64, 1.14 and 1.96 m/s, respectively. The data investigated are the directly measured bending moments.


Kristiansen, T. 2004-02-02

Additional VIV analysis. Fatigue analysis of

The objective has been to perform VIV analysis using test data from Hanøytangen. The test data consists of measured bending moments, current data and riser data.

MARINTEK - Norwegian Marine Technology Research Institute,

Baarholm, G. S. 2003-06-06

Hanøytangen data. Fatigue damage is calculated based on measured data and the results is compared to fatigue found by using VIVANA and SHEAR7. Peak probability distribution is computed for a number of time series. Chaos theory is briefly considered.

Trondheim

Analysis of dual riser clashing tests

NDP carried out model tests of dual riser clashing in Towing Tank III at MARINTEK in the fall of 2003. The objective of the present work has been to perform analyses on the model test data acquired during those tests. The emphasis of the work was to describe the distribution of hits between the two risers, to compute relative riser velocities at clashing, to compute the wake induced oscillations (WIO) of the downstream riser, and to compute vortex-induced vibrations (VIV).


Baarholm, R. and T. Kristiansen

2004-06-29

Background information for the design guideline for Riser Fatigue

The main objective of the study was to recommend fatigue analysis procedure and design criteria for deep water risers. A key issue was to obtain an acceptable failure probability for FLS either by use of rational fatigue safety factors or by direct application of a reliability based approach. In the Design Guideline (the upcoming Recommended Practice RP-F204) an approach with increasingly advanced methods of evaluation is recommended.

Det Norske Veritas; Oslo Chezhian, M. et. al.

2004-05-05

Benchmark study of riser VIV. Response Data. Nykhøgda

The report collects VIV response data from full-scale measurements during the exploration drilling operation at Nykhøgda. The full-scale riser measurements on the drilling rig are performed by Robit a.s. on commission for BP. Some analyses have been done by Robit and Seaflex.


Lie, H. and K. E. Kaasen

1998-08-13

Benchmark study for riser interference

Because of the existence of high currents in the Norwegian deepwater area it is expected that the spacing

Shell International Deepwater Services, The Hague, NL

Efthymiou, M. 1998-07-01

design tools between marine risers attached to a floating platform will need to be rather large to avoid collision and this may have a significant impact on the size and cost of a production platform in this area. An additional problem is that the methods used for determining the riser spacing and the results obtained vary widely from one consultant to another. To address these problems a benchmark study was initiated into the capabilities of Riser Interference design tools. This report brings together and discusses the results of this benchmark study and highlights the similarities and differences in the methods used and results obtained. It also draws some conclusions regarding the riser spacing requirements for a Tension Leg Platform (TLP) under conditions representative of those at the Vøring Plateau.

Calibration of SHEAR7 using full-scale riser data from Nyk High drilling riser

The VIV (vortex-induced vibration) prediction program SHEAR7 has been used to find the VIV response for 43 current cases for a drilling riser at Nyk High. The true response was known in advance, and for each case the input parameters to SHEAR7 were varied in order to get the best possible fit to the full-scale results. The set of parameters giving least sum-squared difference between the full-scale and calculated displacement along the riser was appointed the best fit for the given case


Vikestad, K. 1999-08-03

Calibration of SHEAR7 using full-scale riser data from the Helland Hansen drilling riser

The VIV (vortex-induced vibration) prediction program SHEAR7 has been calibrated against measured full-scale results from the HeIland Hansen drilling riser (L=688 m, D=1.13 and 0.5 m, tension dominated first natural frequency approximately 0.025 Hz). Typical current velocities varied from 0.1 to 0.4 m/s, 57 different cases


Vikestad, K. and F. Solaas

1999-12-15

were used.

Catenary Offset Buoyant Riser Arrangement

This work describes the development of a new flexible (compliant) Steel Riser concept for harsh environment in deep water. The key drivers are to enable steel risers on marginal field developments and increase flexibility of floater concepts. Catenary Offset Buoyant Riser Arrangement (COBRA) consists of a catenary riser section with a long, slender buoyancy module on top which is tethered down to sea bed.

Subsea 7, Stavanger NN (HAA) 2011-03-31

Catenary Offset Buoyant Riser Arrangement

This document summarises the results of installation analysis performed for the COBRA Steel Catenary Riser (SCR) from the Subsea 7 installation vessel ‘Seven Seas’. The SCR is installed by the J-lay method through a central moonpool on the vessel. The critical stage of the installation operation is when the integrated buoyancy can is deployed through the splash zone on the J-lay system.

Subsea 7, Stavanger NN (HB/JT) 2011-03-31

CFD calculation of two circular cylinders

The report presents simulation results of the hydrodynamic response of two cylinders in ambient uniform flow using the CFD program NAVSIM. The two cylinders have different diameters; the largest being twice the smallest. The cylinders are placed at different relative positions and are kept fixed during each simulation case.

Hydro Oil & Energy, Research Centre, Bergen (now Statoil)

Meisingset, H. C. and K. Herfjord

2002-01-09

Consolidated Pipe-Soil Interaction Model (2)

As part of the NDP Riser & Mooring project which objective is the identification of cost effective riser and mooring solutions for Deepwater Norway, DNV has consolidated research and development on riser-soil interaction and established a computation model for riser-soil interaction for application in global dynamic response analysis.

Det Norske Veritas, Oslo Voie, P. E. et. al. 2013-12-19

Consolidated pipe-soil interaction model (1)

Summary of literature study on pipe-soil interaction and a outlining of the consolidated pipe-soil interaction model.

Det Norske Veritas, Oslo Voie, P. E. 2012-05-18

Deep Water Model Test Methods. Design of mooring systems for hybrid testing of semisubmersible at 1100 m and 3000 m water depth

The purpose of the present study is to design anchor line systems for mooring of a semi-submersible floating production unit (FPU) in North Sea conditions at 1100m and 3000m water depth. The computer optimization program MOOROPT is used together with the computer program MIMOSA.


Reinholdtsen, S. 1998-08-14

Deep Water Model Test Methods. Hybrid simulation with FPSO in 3000m water depth.

The study concerns hybrid simulation of a FPSO moored in 3000 m water depth. The purpose of the study is to design a steel rope catenary mooring system for the FPSO and to do numerical case studies of the system by application of coupled analysis procedure utilizing the computer program system RIFLEX-C. (One data report is reported separately).


Ormberg, H. 1999-02-07

Deep Water Model Test Methods. Hybrid testing 1:150 scale model tests. Main Report

As part of the development work to establish a design verification method for deep water mooring systems, model tests with a catenary moored semisubmersible platform in the scale of 1:150 have been carried out the Ocean Basin laboratory. (One data report is reported separately).


Moe, V. and O. Øritsland

1999-04-08

Deep Water Model Test Methods. Model test with a semisubmersible in multidirectional waves. Main Report.

Model tests in scale 1:55 with a floating semisubmersible in multidirectional random waves are reported. (One data report is reported separately).


Stansberg, C. T. 1999-05-26

Deep Water Model Test Methods. Numerical simulation using 1;55 simplified model test input data. Main Report.

The report comprises a case study where MARINTEK's in-house coupled analysis software RIFLEX-C has been applied on a 3000m semi-submersible system. (Data reports are reported separately in Vol. 1-4).


Lian, W. 1999-03-15

Deep Water Model Test Methods. Recommendations and guidelines on hybrid testing with experience from case studies

The report discusses methods for replacing full-depth model tests of floating offshore systems in deep water with truncated test set-ups combined with computer simulations (hybrid testing). Complete mooring tests are recommended if possible and criteria for when and how to run hybrid testing are proposed. Methods for running truncated model tests are described, where details of mooring lines and risers, and vessel motions, are sought to be kept as similar as possible to the full-depth case.


Stansberg, C. T. et. al.

1999-04-08

Deep Water Station Keeping Reliability Study. Phase 1 Summary Report

The key objective of the work was to develop reliability based techniques for the consistent assessment of deep water station keeping systems (including; conventional mooring, pure DP and hybrid systems). The Phase 1 study has made a firm foundation for further work in Phase 2. In particular assessment techniques have been proposed in which structural reliability and Monte Carlo simulation methods are integrated to give annual excursion exceedance probabilities.

Noble Denton Europe Ltd. (merger with Germanischer Lloyd in 2009, now DNV GL, Oslo)

NN (RBB) 1999-06-22

Deep Water Station Keeping Reliability Study. Phase 2

The reliability assessment methods developed in an initial (Phase 1) study were applied to the Ocean Alliance operating all year on Nyk High in a 1400m water depth. Results were calculated for three typical cases, i.e. conventionally moored, thruster assisted moorings (TAM) and pure DP.

Noble Denton Europe Ltd. (merger with Germanischer Lloyd in 2009, now DNV GL, Oslo)

NN (RBB) 1999-06-22

Deep-water riser fatigue: Parametric studies, reliability modelling and analysis

In the present report, safety factors relevant for fatigue damage due to waves and Vortex-Induced-Vibration for deepwater metallic risers are considered. This topic is addressed in relation to four different riser configurations (Case studies): · Case I and II: Vertical tensioned 12” risers suspended from a Spar buoy at water depths of 500m and 1000m, respectively · Case III and IV: Steel catenary risers suspended from a Spar buoy, both at 1000m. For Case III, the riser diameter is 12”, while for Case IV it is 30”.


Stokka, T. et. al. 2003-09-05

Deepwater drilling riser subjected to Vortex Induced Vibration. Time domain code verification.

A numerical model to predict Vortex Induced Vibrations on vertical risers have been developed and implemented in a specific software by ENI/Agip and Politecnico di Milano. Such model is based on the use of the Finite element method and on the computation of time varying hydrodynamic forces by means of an “equivalent oscillator. The present report documents the executed analyses and presents a comparison with the experimental data from the Helland Hansen drilling riser monitoring program. A series of comments is then presented on the obtained results and on the possible approach to improve the numerical/experimental matching

Eni SpA & Politecnico di Milano, Milan, Italy

Fossati, F. et. al. 1999-12-02

Deepwater Riser Systems. Riser local impact. Determination of damage

The objectives of this study are to: • Define what is meant by ‘damage’ and the identify the relevant dynamic parameters determining damage during an impact event, • Define the form of design curves to relate damage to the dynamic parameters,

Mott MacDonald - Advanced Mechanics and Engineering, Croyden, UK

Wilmshurst, S. R.

1999-08-01

• Provide analytical approaches that can be used to determine the ‘damage’ sustained by the riser during an impact event.

Deepwater Riser Systems. Riser local impact. Investigation of oblique impacts and riser impact program development

The aim of this part of the study is to investigate the effects on the risers of the more realistic case of an oblique impact event. The results obtained from this study are compared with the results from other studies in order to assess the severity of damage due to localisation of the impact.


Chan, H. 1999-03-01

Deepwater Riser Systems. Riser lcal impact. Simulation of Marintek tow tank riser collision test

The primary objective of the work reported here is to determine the participating mass in riser impacts using ABAQUS F.E. analyses, which have already been validated using tests carried out at Liverpool University, U.K.. The results with the values derived using scale tests. The scale tests reported in a further document written by Marintek.


Wilmshurst, S. R.

1999-03-01

Design Basis Riser analysis is required as a part of the design and the purpose of this document is to summarise the data that will be used in the analysis and also to provide the design basis for the overall system.

Brown & Root Energy Services, UK (now KBR, formerly Kellogg Brown & Root, and subsidiary of Halliburton)

BRB / BH 1998-03-23

DHI 2D Riser Model Test Data Revisited

The University of Glasgow has analysed the work carried out by Danish Hydraulic Institute (DHI) on 2D riser model testing with the scope to (1) analyse the DHI test data, with the emphasis on the combined effects of VIVs and the low-frequency large-amplitude motions, to propose and verify simplified force models for estimating fluid loading on the two cylinders, (2) to verify and improve our work on the low-frequency large-amplitude motions, in particular, and (3) to propose design criteria for estimating

Universities of Glasgow, Department of Naval Architecture and Marine Engineering, Glasgow, UK

Huang S. and M. Wu

2002-10-01

the critical current speed.

Drag Amplification of a Long Flexible Pipe Due To VIV

In 2003 a series of model tests were performed in a towing tank at MARINTEK on two vertically top tensioned risers in order to investigate wake-induced riser clashing. Out of a total of 148 runs for the smooth riser, clashing did not occur in 61 cases. In these 61 cases, the hydrodynamic loading on the upstream riser is considered to be unaffected by the downstream riser, and the test data can be used to analyse the drag amplification due to cross-flow VIV response. This work is carried out by the University of Glasgow.

Universities of Glasgow, Department of Naval Architecture and Marine Engineering, Glasgow, UK

Huang S. and M. Khoransanchi

2005-08-01

Dual Riser Clashing Model Tests. Main Report

This report presents the work and results related to the dual riser clashing tests with two high length-to-diameter ratio (L/D) risers. Two instrumented riser models were tested vertically, both with and without suppression devices and bumper elements. To simulate ocean current the riser models were towed at different velocities using a towing carriage. The riser spacing, the inflow angle and the riser top tensioned were varied systematically during the test program.


Baarholm, R. 2004-02-17

Dynamic Responses of Deepwater Risers With Slug Flow

The report quantifies the effects of slug flow in selected riser configurations. Tension- and curvature changes due to the slug passage are estimated by means of time-domain simulation with RIFLEX.


Fylling, I. J. 1999-03-23

Effect of damping on VIV response in flexibles

The first phase of the work contained: (1) Investigation of damping behaviour for two different umbilicals and two different flexible risers using numerical tools as Helica, Riflex and Shear7 – that is finding the hysteresis damping for the different riser structures with different internal contact forces (by varying effective tension and internal

Det Norske Veritas, Oslo Henøen, V. C. 2014-02-28

pressure), (2) Studying the sensitivity on VIV response to damping level – what is the effect on VIV fatigue life with respect to the damping applied?, (3) The analyses above were performed on a free hanging configuration at 1500m water depth – defined as base case. Based on the results from these analyses it was decided to perform similar analyses on different configuration types, and (4) Recommendation of further activities in order to improve and validate the models for predicting structural damping and dynamic analysis of flexibles.

Effect of waves and floater motions on current induced VIV response

The purpose of the present report is to summarise available knowledge on the effect of waves and floater motions upon the current-induced VIV response of deep sea risers. The summary is based mainly on ”Mo, K., Vortex Induced Vibrations of a Riser with Forced Motions, Model Tests in Current and Waves” and “ Vikestad, K., Vortex induced vibrations (VIV) of an elastically mounted circular cylinder in current and variable flow”, both reports from MARINTEK.


Huse, E. 1999-11-19

Effectiveness of fairings. Main Report

The present work studies the effectiveness of fairings on deepwater risers compared to bare riser configurations. The focus has been on (1) the possibility of instability (fluttering) for two different fairing profiles (chord-to-thickness ratios (c/t) of 2.00 and 2.33) and (2) given unstable profile, can instability occur for higher modes than the 1st mode?


Braaten, H. and H. Lie

2005-06-10

Enhanced Risk Based Fatigue Criterion

Publication based on work provided for NDP. Paper presented at the 14th International Deep Offshore Technology Conference held in New Orleans, Louisiana, 13-15 November 2002

DOT 2002, New Orleans, Louisiana, US

Mørk, K. et. al. 2002-11-13

Experimental Estimation of Hydrodynamic Loading on SCC Fairings

Novel experiments to determine the mechanical loads that fairing may experience while in the wave zone or due to current drag

Oceanic Consulting Corporation, St. John’s, NL Canada

Islam, M. S. et. al.

2013-01-25

Experimental Investigation of Dual Riser Interaction

Publication based on work provided for NDP. Proceedings of OMAE2005: 24th International Conference on Offshore Mechanics and Arctic Engineering 12-16 June 2005, Halkidiki, Greece

OMAE 2005 Baarholm, R. et. al.

2005-06-12

Experimental Investigation of Vortex-Induced Vibration of Long Marine Risers

Publication based on work provided for NDP. Flow Induced Vibration, de Langre & Axisa ed. Ecole Polytechnique, Paris, 6-9th July 2004.

Ecole Polytechnique, Paris

Trim, A. D. et. al. 2004-07-06

Experimental Investigation of Vortex-Induced Vibration of Long Marine Risers

Publication based on work provided for NDP. (Received 6 October 2004; accepted 4 March 2005).

Elsevier Ltd., Oxford, UK Trim, A. D. et. al. 2005-03-04

Experimental Study on VIV Suppression Devices

This report describes the experimental program undertaken by Oceanic Consulting Corporation (OCC) to evaluate vortex induce vibration suppression devices through the use of various fairing configurations for Statoil ASA.



2013-01-31

Fabrication and installation study of dual hybrid riser

The objective of this study has been to survey for potential manufacturing sites, develop fabrication procedures and cost estimates for the dual hybrid riser described in Appendix C. Outline procedures for towing and installation of the riser system have also been described and critical steps identified and analysed. Areas for further work are also suggested.

Kværner Oil & Gas, Oslo NN (TK) 1998-08-07

Feasibility study on monitoring of behaviour of riser arrays

This study is focused on the behaviour and interaction in an array of rigid risers.

CorrOcean - Robit Technology AS (now Emerson Process Management/Roxar, Porsgrunn)

Pettersen, B. T. I. Bern

1998-12-03

Flow around fixed cylinder. Measurements with PIV. Computations with CFD.

This report is a summary of work done on flow around a fixed circular cylinder. The basis are two reports, one from experimental work and measurements with PIV and one is from computations with CFD program. The objective has been to learn about phenomena important for VIV on risers, and extract information to use in prediction programs. The validation and possible improvements of CFD programs is also a result of the tests.

Hydro Oil & Energy, Bergen (now Statoil) and University of Oslo

Herfjord K. and J. Grue, J.

2004-05-06

Forcing mechanisms for VIV. An investigation using PIV and force measurements

Reporting experiments carried out in a tank 25 m long, 0.5 m wide, filled with water at depth 0.82 m.

University of Oslo, Oslo Grue, J. 2004-03-22

Functional specification for 4” NB rigid riser and connectors

This specification defines the minimum functional requirements to be met by the 4”NB rigid riser components and their assembly system.


NN (BRB/BH) 1998-04-06

Functional specification for a titanium stress joint

This specification defines the minimum functional requirements to be met by the stress joint.


NN (BRB/BH) 1998-04-08

Functional specification for

This specification defines the minimum functional requirements to be met by the mid-water and surface

Brown & Root Energy Services, UK (now KBR,

NN (BRB/BH) 1998-04-09

buoyancy units buoys formerly Kellogg Brown & Root, and subsidiary of Halliburton)

Functional Specification for Riser Straps, Spacer Blocks and Hang-Off Brackets

This specification defines the minimum functional requirements to be met by the riser straps, spacer blocks and hang-off brackets.


NN (BRB/BH) 1998-04-08

Further Foinaven Dynamic Umbilical Analysis

High quality data are being recorded by the Foinaven Umbilical Monitoring System (FUMS) installed on the Foinaven Petrojarl by BPP Technical Services for the life of the installation. Full data records are available from March 1997 to November 1998. The system provides information on the relative effects of vessel motion, and current (including VIV) on the stresses in the DC2 dynamic umbilical. The stresses are derived using a specially designed curvature sensor which acts at the entry of the umbilical into the underside of the turret, and measurement of top tension. Additional sensors monitor turret heave, pitch and roll (aligned with the umbilical), turret surge, sway and heading, and significant wave height.

BPP Technical Services Ltd., London, UK

Lyons, G. 1999-11-30

Global analysis procedure for riser interaction

The study aims for consensus on hydrodynamic interaction model for riser collision assessments in pure current conditions. The scope of work has primarily been to consider a load formulation for Wake Induced Oscillations (WIO) accounting for possible Vortex Induced Vibrations (VIV). Based on the observations from this study including review of NDP work, a load formulation to be applied for riser collision assessments including the

Det Norske Veritas, Oslo Kalleklev, A. J. et. al.

2003-03-13

calculation procedure is outlined as input to a Design Guideline

HYBER User Manual Version 2.1

This document is the user manual for HYBER. Thus the document specifies the graphical user interface and the functionality of HYBER.

Norsk Hydro, Sintef & Ceetron

Herfjord, K. et. al.

2004-12-01

Hyber database for smooth cylinders with equal diameters based on CFD

This report gives the database for HYBER as computed by the CFD program NAVSIM. The database contains data for a large number of distinct relative positions between the two cylinders.

Hydro Oil & Energy, Bergen (now Statoil)

Herfjord, K. 2002-01-01

Hyber databases from measurements

This report is an assembly of reports made for documenting the results from model tests at DHI. The DHI tests were done to produce databases for the program HYBER for assessing riser interaction and clashing. HYBER was extracted from tests with fixed cylinders.


Herfjord, K. and H. C. Meisingset

2005-08-05

Hydrodynamic characteristics of riser fairings. Comparison of full scale and model scale test results

Fairings are used to prevent or attenuate vortex induced vibrations (VIV) of marine risers and pipes and to reduce drag forces. Model tests of different types of fairing have been carried out by Marintek and Oceanic. Marintek has tested fairings fitted on a pipe of diameter 80 mm, while the Oceanic tested a larger pipe (0.325 m diameter) and corresponding fairings. A main purpose of the tests at Oceanic was to test at realistic full scale Reynolds numbers.

MARINTEK - Norwegian Marine Technology Research Institute; Trondheim

Kaasen, K. E. 2013-12-19

Hydrodynamic damping of non-VIV oscillations of a circular cyllinder section subjected to constant current.

This work is mainly based on the results from three doctoral theses. The first one is Gopalkrishnan‘s (1993) experimental data with a cylinder driven normal to the incident flow. Second is Venugopal’s (1996) where a damping model for VIV (vortex-induced vibrations) is

MARINTEK - Norwegian Marine Technology Research Institute

Vikestad, K. 1999-11-17

proposed, partly based on the work done by Gopalkrishnan, and the third is Vikestad’s (1998) where damping data are given for an external response for a cylinder freely oscillating due to vortex shedding. The damping results and models are compared in order to improve the understanding of the damping of VIV and, if needed, come up with a new model for better describing the damping.

Impact of Slugging on Riser Behaviour. Summary Report

This study examines the dynamic impact of slugs on the risers and the need or not for inclusion of such forces in deep water riser analysis. The slug impact is assessed by conducting multiphase flow calculations with the OLGA transient multiphase code to predict the slug lengths, velocities, density variation and hold up at various locations in the riser, and taking the predicted slug data and predict the riser behaviour using both RIFLEX and FLEXCOM and excluding any other loading like currents and vessel motions.

BP Amoco Exploration Upstream Technology Group, Sunbury, UK

Moros, A. and P. Fairhurst

1999-02-01

Improved VIV Predictions. Riser VIV Data Analysis. Helland-Hansen

The aim of the work is to analyse the full-scale measurements of accelerations and rotations of the drilling riser on Nykhøgda, Vemadomen and Helland Hansen to quantify VIV in terms of excited frequencies, eigenmodes and amplitudes for use in calibration of the SHEAR7 program. This report contains the analysis of the Helland Hansen data.


Solaas, F. and K. E. Kaasen

1999-08-20

Improved VIV Predictions. Riser VIV Data

The aim of the work is to analyse the full-scale measurements of accelerations and rotations of the drilling riser on Nykhøgda, Vemadomen and Helland

MARINTEK - Norwegian Marine Technology Research Institute,

Lie, H. et. al. 1999-12-11

Analysis. Nykhøgda

Hansen to quantify VIV in terms of excited frequencies, eigenmodes and amplitudes for use in calibration of the SHEAR7 program. This report contains the analysis of the Nykhøgda data.

Trondheim

Improved VIV Predictions. Riser VIV Data Analysis. Vema

The aim of the work is to analyse the full-scale measurements of accelerations and rotations of the drilling riser on Nykhøgda, Vemadomen and Helland Hansen to quantify VIV in terms of excited frequencies, eigenmodes and amplitudes for use in calibration of the SHEAR7 program. This report contains the analysis of the Vemadomen data.


Solaas, F. and K. E. Kaasen

1999-07-07

Knowlegde gained from test campaigns

The overall objective of the present report is to summarise NDP testing campaigns related to riser VIV and interference in order to establish a recommended design/analysis practice for deep water risers.

Det Norske Veritas, Oslo Kalleklev, A. J. et. al.

2006-05-19

L-RISER JIP PHASE 2 28” ID GAS EXPORT RISER DESIGN REPORT

This report includes the results of a 28” ID export riser configured for both 850m and 1750m water depth, connected to a semi submersibles production unit in the North Norway area.

Inocean (Marine Operations & Naval Design), Oslo

TJL 2003-11-26

Marine Growth Removal Study

This study evaluates marine growth removal techniques and recommends frequencies for its removal and inspections. Further it discusses Remotely Operated Vehicles (ROV) and their cost, and provide concepts for marine growth removal tooling.

Oceaneering International Inc., Houston, TX, USA

NN (CLL) 2013-11-11

Marine Growth Removal Study Findings

The study covered: (1) ROV classes that could be used for inspection and removal and recommended minimal class that could meet all the requirements, (2) compared the various standards with respect to inspection frequency criteria, and (3) the most common methods to remove growth, pros & cons of each method, and requirements to

Oceaneering International Inc., Houston, TX, USA

Leman Jr, C. 2013-12-17

use them.

Model Tests of Dual Risers

The report presents the results of a number of model tests performed as part of the second phase of NDP. The tests comprise fixed pipe tests, VIV tests and tests in which the pipes were allowed to move with two distinctly different periods simultaneously. More than 400 tests were performed. Results are used to validate numerical models for full-scale riser response prediction. Appendices A – E are reported separately.

DHI - Water & Environment, Hørsholm, DK

Bryndum, M. B. et. al.

2002-11-19

Modelling riser deflections with application to the Helland Hansen drilling riser

This report describers a mathematical modelling technique for computing displacements, including vortex induced vibrations, of cylindrical risers subjected to ocean currents.


Furnes, G. 1999-12-20

Monitoring of VIV on drilling riser on Helland-Hansen

The response monitoring equipment was installed on the drilling riser on the rig "Ocean Alliance" during drilling on Helland-Hansen from April 17 to July 2, 1998. The report presents reference information for the collected data, giving positions and orientation of the sensors, as a basis for further analysis of the data. The results from the processing of acceleration, rotation rate, ADP current velocity and ADP temperature data give indications of the quality of the collected time series and helps identifying the most interesting parts of the data material. Appendices A – D are reported separately.


Pettersen, B. et. al.

1999-10-22

Monitoring of VIV on drilling riser on Vema

This report presents reference information for the collected data, giving positions and orientation of the sensors, as a basis for further analysis of the data. No corrections of raw data have been made, but clock and sensor offsets and


NN 1998-08-17

other reference information for the further use of data is given. Appendices A – C covering analysis and results are reported separately.

Multivariate Signal Analysis – Empirical modelling of drilling riser (Feasibility Study)

M.Sc. thesis which comprises techniques to handle large amounts of data. These methods are applied on vibration measurements collected from an instrumented riser at Nyk High in 1300 m water depth. In all are 1111 time series with 4096 samples from 14 sensors analysed. The thesis is carried out at Telemark Institute of Technology, Dep. Of Process Automation.


Gundersen, V. 1998-05-26

NDP - Deep Water Model Test Methods. Numerical Extrapolation of Model Tests with Truncated Mooring.

A floater with mooring lines was tested at the ultra small scale 1:150 in the Ocean Basin at MARINTEK. Tests for two different water depths (550 and 1100 m), using three different mooring systems were carried out (1100 m truncated and 1100 m complete system, and 3000 m truncated mooring system).


Yttervik, R. et. al.

1999-04-08

NDP Riser Array Interference. Framework and Design Methodology (Revision 02)

The study outlines a methodology for engineering analysis and design of riser interference/collision based on experience and information gained through NDP Riser Array Interference. The present report constitutes a first step towards a Recommended Practice document and includes a state-of-the-art introduction to the main building stones for riser collision assessment (hydrodynamic interaction model, global analyses model, collision load effect model and acceptance criteria).

Det Norske Veritas, Oslo Sødahl, N. and K. Mørk.

2001-04-27

NDP Riser High Mode VIV Tests – Main Report

High mode VIV-tests were performed in MARINTEK’s Offshore Basin on a 38m long riser. The riser was towed at different speeds, simulating uniform and triangular shear current, and measurements were made In-line and cross-


Braaten, H. and H. Lie

2005-04-13

flow of micro bending strain and accelerations along the riser.

NDP Riser High Mode VIV Tests – Modal Analysis

The work extracts information on the VIV behaviour from measured data in order to describe the character of the response under various conditions (with special attention to the behaviour of a partly straked riser). This is done by means of modal analysis.


Kristiansen, T. and H. Lie

2005-01-31

NDP Riser High Mode VIV Tests – Response Analysis

In this report, some results from the high mode VIV-tests performed in the MARINTEK Offshore Basin December 2003 are presented. A 38m long riser was towed at different speeds, simulating uniform and triangular shear current. Measurements were made In-Line (IL) and Cross-Flow (CF) of micro bending strain and accelerations along the riser.


Kristiansen, T. and H. Lie

2005-04-13

NDP Riser High Mode VIV Tests – Fatigue Analysis

The aim of the project is to study cross-flow (CF) and in-line (IL) fatigue damage for a naked riser and riser with VIV suppression devices.


Baarholm, G. S. 2005-01-24

NDP Riser Slugging Analysis (Final report)

The report describes analysis to investigate the dynamic effects of slugs on hybrid riser configurations operating in a 1200m water depth. This is to determine the requirement for the inclusion of slugging effects in deep water riser analysis.

2H - Offshore Engineering Ltd, Woking, Surrey, UK

NN (DT) 1999-03-12

NDP survey of methods and tools for riser VIV and interaction

NDP R&M has conducted a considerable amount of work related to VIV and interaction of risers. The work has consisted of model tests, benchmark computations versus field measurements, development of recommended practices on riser fatigue due to VIV and on riser interaction, as well as development of a program for

Hydro Oil & Energy, Research Centre, Bergen

Herfjord, K. 2005-10-14

assessing riser interaction. In the present report, methodologies for computations and actual program systems are listed and discussed.

New steel riser solutions for deep water and harsh environment (2)

The study covers development and assessment of new flexible steel riser solutions for harsh environment and deep water. The drivers are to enable steel risers on marginal field developments and increase flexibility of floater concepts. The main conclusion is that robust compliant all-steel riser solutions can be developed for the high motion platforms, water depths and weather conditions under consideration, and installed.

Det Norske Veritas, Oslo Voie, P. E. et. al. 2013-12-19

New steel riser solutions for deep water and harsh environment (1)

The study covers development and assessment of new flexible steel riser solutions for harsh environment and deep water. The drivers have been to enable steel risers on marginal field developments and increase flexibility of floater concepts. The main conclusion is that robust compliant all-steel riser solutions can be developed for the high motion platforms, water depths and weather conditions under consideration, and installed.

Det Norske Veritas, Oslo Hansen-Zahl, K. et. al.

2012-12-07

NPD Code validation Subproject: “VIV prediction method using damped modes” Final report - Draft version

This is one of the 4 activities under the NPD Code validation project in which 10 specified load cases associated with the Helland Hansen (HH) riser were to be analysed and compared to the results from field measurements. The 10 load cases represent the current profiles during 10 time periods for which the measurements indicated that significant VIV motions took place. In the activity reported on herein a newly developed MATLAB program, VICoMo, (see later) was used.

NTNU (SINTEF), Trondheim

Moe, G. 1999-12-17

Overview of VIV- The purpose of this report is to present an overview of the MARINTEK - Norwegian Kristiansen, T. 2005-04-13

related work done at MARINTEK 2002 - 2005

VIV-related activities performed at MARINTEK in the period 2002 – 2005 and to give readers a guide to where information from the activities can be found.

Marine Technology Research Institute, Trondheim

et. al.

Outline installation procedure for a deep water test riser

This document defines the outline procedure for installation, temporary release and recovery of the test riser from a semi-submersible drilling rig Saipem Scarabeo 5.


NN (BRB/BH) 1998-04-06

Parametric 2D tests of straked risers

Model tests of two-dimensional sections of 19 different riser pipes (1 bare and 18 straked risers) have been conducted in Towing tank III at MARINTEK. The primary objective of the tests was to study the efficiency of different strake configurations of suppression VIV motion. A detailed documentation of the riser models, instrumentation, test arrangement, test program, data analysis and discussion of results are given.


Baarholm, R. 2005-05-20

PIV and VIV. Report to Norsk Hydro.

This document aims at presenting the updated technical features of the PIV system used in the Hydrodynamic Laboratory at the Mechanics Division, Department of Mathematics, University of Oslo.

University of Oslo, Department of Mathematics

Sanchis, A. et. al.

2005-09-21

PIV investigation of vortex-induced vibrations on a spring-mounted cylinder and the effect of strakes.

The present work reports on experiments with Particle Image Velocimetry (PIV), focusing on the vortex-induced vibration problem in two degrees of freedom. The peak amplitude obtained exceeds by far the expected value for the current parameters and the results departs notably from other studies. PIV brings additional elements to conclude that the system response cannot be predicted by the traditional set of parameters used.

University of Oslo, Department of Mathematics

Sanchis, A. et. al.

2005-05-27

Preliminary Hazard This document is the record of the Preliminary Hazard Brown & Root Energy NN (JEB/DC) 1998-04-09

Analysis Report Analysis (PHA) performed in respect of the above scope of work on 18.11.97 at Brown & Root’s offices in Stavanger.

Services, UK (now KBR, formerly Kellogg Brown & Root, and subsidiary of Halliburton)

Qualification of the Short Crab Claw (SCC) and the Aims Dual-fin Splitter (ADFS) Fairings: High Reynolds Number VIV Experiments of Tandem and Offset Pipes

This report presents the results from tests conducted at the 200-meter Towing Tank at the Ocean, Coastal, and River Engineering in St. John’s, NL Canada.



2013-01-30

Recommended Practice DNV-RP-F203

The overall objective of this document is to recommend a methodology for engineering analysis, and to provide rational design criteria and guidance for assessment of riser interference.

Det Norske Veritas, Oslo Kalleklev, A. J. 2005-02-01

Recommended Practice DNV-RP-F204

The objective of this document is to outline the methodology for performing fatigue assessment of metallic risers subjected to repeated load fluctuations and supplement the details on fatigue analysis methods recommended in DNV-OS-F201. See also DNV-RP-F203.

Det Norske Veritas, Oslo 2005-07-01

Review of Guidelines for Fatigue Design

A number of documents relevant for design of risers with respect to accumulated fatigue damage have been reviewed: API RP 2RD, DNV Dynamic Risers (2001), DNV Freespan Guidelines (Draft 2001), ABS Pipelines and Risers (2001), Fatigue Safety Factors for Deepwater Risers (Report by Bernie Stahl, prepared for BP), and OMAE-2001


Leira, B. J. 2003-05-09

paper by Mørk,K, Sødahl,N and Souza,L.

Riser Collision Analysis of Vøring SPAR

Estimating conditions causing impacts, the collision frequency and the “magnitude” of the impacts by different global Riser Collision Analysis of Vøring SPAR

MARINTEK - Norwegian Marine Technology Research Institute

Holmås, T. and B. Leira

2000-05-19

Riser Collision Tests: Local Riser Collision Tests

This report documents findings in a test series on connectors impacting bare riser pipe, with a “concentrated edge” or “indentor” on the hammer pipe making the contact. Appendix A reported separately.

Shell E&P Technology Company, Houston, Texas

Morrison, D. et. al.

1999-04-27

Riser Collision Tests: VIV (Vortex-Induced Vibration) collision tests

The main objectives of the tests were to determine the magnitude of clashing in VIV-induced vibrations, by conducting and analyzing three-dimensional model tests on bare pipes and on pipes fitted with riser hardware such as strakes and connectors.


Morrison, D. et. al.

1999-11-01

Riser Current Interference Study (Shell) Final Report

The objective of this study was to estimate the minimum riser spacing requirement for several riser pairs, installed on a TLP under the environmental conditions of the Vøring Plateau in the Norwegian Sea. Shell’s in-house software suit TIARA was used for the purpose.


Xing Yu 1998-02-01

Riser Design Report The purpose of this report is to present the analytical work that has been performed initially to develop, and then to define the design.

Brown & Root Energy Services

BRB / SJM 1998-07-23

Riser Interference Study (MARINTEK)

The study covers numerical analysis to determine the necessary spacing between risers to prevent them from clashing into each other in current.


Huse, E. 1999-12-15

Riser Interference and Contact. Methodology for Prediction

The force model (HYBER) has been implemented in an existing, general 3D mechanical response tool, (finite element approach) to simulate riser interference and contact. The response tool is able to give estimates on local damage on the risers. The simulation tool covers a


Holmås, T. et. al. 2002-12-31

number of actual environmental conditions, such as uniform current, shear current, depth varying current direction, floater motion and more. Smooth risers as well as risers with strakes for any configuration are handled.

Riser Interference Study

The report presents clearance results and riser spacing requirements for two adjacent, nominally identical production risers attached to a TLP in static conditions representative of the Vøring Plateau, riser interference analysis using FLEXCOM-3D and validation using RIFLEX.

2H - Offshore Engineering Ltd, Woking, Surrey, UK

NN 1998-01-13

Riser Interference Study (SPARS)

The task of this report is to determine the minimum spacing required between two adjacent risers to avoid contact between the two risers, given the riser properties, including mud weights and tension factors. Two riser configurations are studied, a single casing production riser and a larger diameter single casing drilling riser, both fitted with suppression devices to reduce vortex induced vibrations. The water depth is 1000 meters (3280 ft), and the current profile is similar to currents at the Helland-Hansen Block (PL210). Helland-Hansen current is considered strong compared to other deepwater sites included in the 15th Licensing Round.

Spars International Inc., Houston, Texas, USA

NN (THF) 1999-06-22

Riser Interference Study (MCS). Executive summary

This study examines the interference characteristics of two adjacent rigid risers under the influence of in-line current loading. In particular, wake effects behind the upstream riser are modelled using a customised version of the Flexcom-3D software. The study has been performed as part of a benchmark study for the Norwegian Deepwater Programme (NDP) to compare riser interference analysis software tools.

MCS International, Barendrecht, NL

NN ?

Riser Wake Interaction. Collisions in Riser Arrays of Different Configurations

The main objective of the project described in the present report was to provide systematic experimental data for verification of numerical methods for predicting criteria for on-set of collisions, including not only tandem configuration, but also staggered and crossed configurations. A further objective was to illustrate the possibility of avoiding riser collisions by controlling the tensioners to provide equal payout instead of constant tension for the different risers in the array. (There are 34 separate reports accompanying the study)


Huse, E. 1998-12-08

Riser Wake Interaction. Effect of Strakes on Riser Interaction

The main objective of the investigation described in the present report was to provide systematic experimental data for the effect of strakes on the collision criteria. A further objective was to measure the force impulse involved in the collisions, and try to obtain information and physical understanding of the statistics of the collision process. (There are 34 separate reports accompanying the study)


Huse, E. 1998-12-11

Riser Wake Interaction. Summary Report from Tests in 1998

MARINTEK has performed two extensive series of model tests, aiming at determining criteria for on-set of collisions in deep sea riser arrays, and also trying to measure the impulse and energy involved in the collisions. The tests have been quite successful in meeting these objectives. The detailed results are described in two project reports, Refs.1 and 2. The present note summarises the most important aspects of the test results. (There are 34 separate reports accompanying the study)


Huse, E. 1998-12-16

Risk based fatigue safety factors for deepwater risers

Publication based on work provided for NDP. This paper was prepared for presentation at the 15th International Deep Offshore Technology Conference held in Marseille,

DOT 2003, Marseille, France

Chezhian, M. et. al.

2003-11-19

France, 19-21 November 2003

Simplified assessment of VIV fatigue damage DRAFT

The complexity of VIV mechanisms and difficulties in finding accurate VIV predictions demonstrate the need for simplified and transparent methods for screening purposes. A simplified method for estimation of fatigue damage due to VIV of risers is implemented in MATLAB code (SIMVIV) by MARINTEK. This note summarizes the method and gives some comments to the choice of input parameters. Finally, a case study on the Schiehallion riser is presented.

Det Norske Veritas, Oslo KJM/MRON 2004-03-11

Simplified VIV (SIMVIV)

This report presents a novel approach for approximate calculation of the fatigue damage from vortex induced vibrations (VIV) of marine risers. The method is based on experience from a large number of laboratory tests with models of full length risers and also full scale measurements.


Baarholm, G. S. 2003-11-13

Specification for a Riser Gooseneck Assembly

This Specification defines the minimum functional requirements to be met by the gooseneck assembly.


NN (BRB/BH) 1998-04-08

Specification for Coiled Tubing for Rigid Annulus Line

This Specification defines the minimum requirements to be met by the coiled tubing for the annulus line which attaches to the rigid riser.


NN (BRB/AW) 1998-03-04

Tangential drag effects on straked risers

The work comprises the following: • Sum up industry practice, experiences and guidelines for estimation of hydrodynamic force coefficients (Cd, Ca) • Describe theory, assumptions and limitations of current

Det Norske Veritas, Oslo Nestegård, A. et. al.

2013-08-05

practice • Provide guidance/estimates for hydrodynamic force coefficients (based on 2D empirical data accounting for strake pitch and height) to be used in the generalized Morison’s equation of industry standard riser analysis tool • Outline measures to obtain improved (more accurate) estimates.

Tanker export system - Design Basis

The study considers offshore loading in deep waters off Northern Norway (Vøring Basin). APL’s relevant products are studied and their suitability for such operation assessed. The design basis for selecting loading systems for deep waters (1500 m) outside Northern Norway is given. The Field is produced with a TLP and several offloading alternatives are screened. Both Direct Shuttle Loading with no or limited field storage as well as FSO alternatives are described.

Advanced Production and Loading AS (now BW Offshore, Oslo)

NN (AB) 1999-03-30

Tanker export system - Study Report, NDP Tanker Export System

The study presents tanker export systems for deepwater applications, based on APL’s offshore loading technology and the design basis (APL doc.no. 980376SP). The Vøring Plateau location is chosen for this study, with a water depth of 1500 m. The field is sought developed with a TLP without storage capacity, and a tanker export system.

Advanced Production and Loading AS (now BW Offshore, Oslo)

NN (HHj) 1999-05-25

TANKER EXPORT SYSTEM STUDY. FINAL REPORT

The report discusses a development for an improved Export Tanker System to export the oil produced from an hypothetical field located in the Vøring Plateau, in 1300 to 1500 m water depth. By Export Tanker System is meant the whole system from the production platform to the reception terminal; ‘improved’ means better than ‘conventional’ systems in terms of cost and availability. For the purpose of the study, the production platform is

Kværner Oil & Gas, Lysaker and & Single Buoy Moorings (SBM), The Netherlands

Isnard, J. L. 1998-09-01

assumed to be a tension leg platform (TLP), having the following features: direct offloading from the platform is not permissible and no oil storage capacity available onboard.

Tension Leg Riser Concept. Fabrication & Intallation Study

This report presents the findings of a study performed under the Norwegian Deepwater Programme (NDP) to investigate fabrication and installation feasibility of a hybrid riser system, referred to as a Tension Leg Riser system, for use with an FPSO in the Voring Plateau at a water depth of 1200m. (Project is reported in 7 separate reports)


Dogruyol, T. 1998-12-11

Theoretical model for response frequency identification

The purpose of this report is to describe in detail the theory applied for identification of possible response frequencies and associated excitation zones valid for a non-uniform riser in sheared current.


Larsen, C. M. 2000-04-07

Un-coupled SCR’s supported to Sub-surface Buoy

This work describes the development of a new flexible (compliant) Steel Riser concept for harsh environment in deep water. The key drivers are to enable Steel Catenary Rrisers (SCR) on marginal field developments and increase flexibility of floater concepts. In the “Un-coupled SCR’s supported to Sub-surface Buoy” concept four SCRs are supported to a sub-surface buoy which is tethered down to sea bed.

Subsea 7, Stavanger NN (MCE) 2011-03-31

Verification manual for HYBER. State of the art technology for riser interference assessment

Verification manual of HYBER. The technology is based on strip theory and pre-established interaction coefficients from lab tests and CFD computations. Databases for both smooth risers and risers with strakes are available. The load model combined with general 3D nonlinear dynamic finite element technology makes it possible to solve arbitrarily configured risers and umbilical exposed to

USFOS - Reality Engineering, Bergen

NN 2005-02-20

complex environmental data.

Verification of HYBER, smooth pipes

Verification of the computer code HYBER. Analysis of Smooth pipes.


Herfjord, K. 2005-02-12

Verification of the computer code HYBER, risers with strakes

This Appendix gives the results from the simulations of the cases with strakes, and without bumpers.


Herfjord, K. 2004-08-27

VIV Predictions. Comparison of VIVANA with full-scale riser data from Helland Hansen drilling riser

This report is a part of the Code validation project in DEEPER. The purpose of this activity is to assess the ability of alternative available VIV analysis codes to predict riser VIV response, and to increase the confidence in these alternative VIV prediction programs.


Passano, E. et. al.

2000-04-07

VIV Data acquisition - Nyk High

This report presents reference information for the collected data, giving positions and orientation of the sensors, as a basis for further analysis of the data. No corrections of raw data have been made, but clock and sensor offsets and other reference information for the further use of data is given.


Pettersen, B. 1997-11-18

VIV response character and dominating frequency

This report presents a theoretical and experimental investigation on the character of the VIV response of a riser/cable. Important parameters like Strouhal number, velocity profile, and diameter distribution is discussed.


Vikestad, K. 2000-04-07

VIV of drilling risers, NDP blind test of CFD based programs

BP has conducted prototype measurements of drilling riser response in current at Schiehallion and Svinoy areas at the British islands. The depths were 360 m and 1070 m, respectively. The measurements were done with packages of accelerometers placed at positions along the risers. At Schiehallion, 5 loggers were used and at Svinoy, 9 loggers were used. Norsk Hydro has done computations with the


Herfjord, K. and H. Meisingset

2003-11-26

program system Navsim-Usfos Coupler, based on separate programs for fluid load and structural response, and a third program for organizing the communication between them.

VIVA program results and Helland Hansen data. Final Report including re-analysis comparison

Comparisons between VIVA predictions and full scale experimental data for the Helland Hansen deepwater riser in 700 m water depth are presented.

Massachusetts Institute of Technology, Cambridge, US

Triantafyllou, M. S.

Undated

Vortex Induced Vibrations of a riser with forced motions. Model tests in current and in waves. Main Report

The purpose of this report is to present the results of an experimental investigation of the effect of waves and floater motions upon the current-induced VIV response of marine risers. The investigation was done in the form of model tests in a 10 m deep towing tank where the upper end of the riser model could be subjected to forced motions and waves at the same time. Current was modelled by towing the test set-up along the tank.


Mo, K. 1999-12-10

Vortex Induced Vibrations of a riser with forced motions. Model tests in current and in waves. Data Report

The data report contains plots of acceleration and position time series of all tests. Tranverse motions measured by accelerometer 9 are selected. Spectra of all accelerations and positions are presented.


Mo, K. 1999-03-24

Vortex-induced vibration (VIV) on an elastically mounted circular cylinder in constant and variable flow.

The report presents the results from experimental work on vortex-induced vibrations on a flexibly mounted circular cylinder section. The main objective of the experiments was to investigate the response of an elastically mounted (only in cross-flow direction) circular cylinder when subjected to a variable current consisting of both a constant and a


Vikestad, K. 1999-05-04

harmonic part. The rigid cylinder section was 2 meters long and 75 mm wide and mounted horizontally in a towing tank (25 m long, 2.5 m wide and 1.2 m deep).

Documents

NDP – Riser & Mooring Project - EPIM · PDF filewere used. Catenary Offset Buoyant Riser Arrangement This work describes the development of a new flexible (compliant) Steel Riser