Model Testing of Ultra-Deepwater Floater Systems: Truncation and Software Verification Methodology

2006 ◽  
Author(s):  
Rolf Baarholm ◽  
Ivar Fylling ◽  
Carl Trygve Stansberg ◽  
Ola Oritsland
Keyword(s):  
Time Domain ◽  
Software Verification ◽  
Production Systems ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Test Results ◽  
Set Up ◽  
Verification Methodology ◽  
Good Agreement

Model tests for global design verification of floating production systems in depths beyond 1000m–1500m cannot be made directly at reasonable scales. Truncation of mooring line and riser models, software calibration, as well as extrapolation and transformation to full depth and full scale, are required. Here, the first two of the above three items are addressed. The paper emphasizes the important matters to be taken into account. The choice of proper procedures for the set-up and the interpretation, and consistent and well documented methods, are essential. A case study with a deep-water semisubmersible is presented. In general, good agreement between model test results and analytical results from time-domain coupled analysis of the floater system responses is found.

Research on the Static and Dynamics Characteristics of Soft Yoke Mooring System Based on Multi-Rigid Body Interaction

2020 ◽  
Author(s):  
Hongwei Wang ◽  
Zizhao Zhang ◽  
Gang Ma ◽  
Rongtai Ma ◽  
Jie Yang
Keyword(s):  
Time Domain ◽  
Rigid Bodies ◽  
Coupled Analysis ◽  
Mooring System ◽  
Accurate Analysis ◽  
Restoring Force ◽  
Stiffness Characteristics ◽  
The Time Domain ◽  
Multi Body ◽  
Good Agreement

Abstract Select the common mooring system-soft yoke mooring system as the research object. The soft yoke mooring system is regarded as a structure composed of multiple rigid bodies, and the theoretical analysis of multi-body dynamics is used to discuss the interaction of multi-rigid bodies. The classical HYSY113 FPSO is selected as an example, for the soft yoke mooring system, the stiffness characteristics and static restoring force curved compared with those of software OrcaFlex, and they are in good agreement, which verify the reliability of the formula derived, and it is a prerequisite for the accurate simulations in further steps. Coupled analysis to the whole system in time domain is also carried out both in OrcaFlex and AQWA, and the representative response of the FPSO under different environmental conditions is compared, the results are consistent well with each other. It is a good reference for the future study in this field. Good static characteristics are a prerequisite for accurate analysis of time-domain motion. By comparing the results in the time domain, it is found that under the same working conditions, the analysis results calculated by different commercial software (AQWA and OrcaFlex) may be different. We need to perform design analysis based on the characteristics of the software.

Towards the Integration of Analysis and Design of Mooring Systems and Risers: Part I — Studies on a Semisubmersible Platform

2002 ◽  
Author(s):  
Stael Ferreira Senra ◽  
Fabricio Nogueira Correa ◽  
Breno Pinheiro Jacob ◽  
Ma´rcio Martins Mourelle ◽  
Isai´as Quaresma Masetti
Keyword(s):  
Motion Analysis ◽  
Production Systems ◽  
Companion Paper ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Mooring System ◽  
Analysis And Design ◽  
Design Methodologies ◽  
Campos Basin ◽  
Fully Coupled

The objective of this paper is to study different analysis methodologies for the design of floating production systems. The main issues are the use of uncoupled and coupled analysis methods, and the integration in the analysis and design of the mooring system and the risers. This paper is a companion to another paper also presented in the OMAE2002 Conference [1] The present paper begins describing a “basic” classic, uncoupled methodology, and proceeds with comments on some refinements in the representation of the behavior of the lines in the motion analysis of the vessel. Comments regarding the introduction of some level of integration between mooring line and riser behavior are also presented. These issues are illustrated with studies applying some of the considered design methodologies to the P-18 semi-submersible platform in Campos basin. The companion paper [1] proceeds describing a fully coupled methodology, and some hybrid methodologies that combine coupled and uncoupled analysis tools, and illustrates their application to a DICAS system for deepwater applications in Campos basin.

An Integrated Methodology for the Design of Mooring Systems and Risers of Floating Production Platforms

2012 ◽  
Author(s):  
Aldo Roberto Cruces Girón ◽  
Fabricio Nogueira Corrêa ◽  
Breno Pinheiro Jacob ◽  
Stael Ferreira Senra
Keyword(s):  
Production Systems ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Design Practice ◽  
Structural Behaviour ◽  
Coupled Models ◽  
Mooring Lines ◽  
Hydrodynamic Behaviour ◽  
Integrated Methodology ◽  
Analysis Tools

Nowadays, coupled analysis tools that allow the simultaneous modelling of the hydrodynamic behaviour of the hull and the structural behaviour of the lines of floating production platforms have been increasingly used. The use of such tools is gradually allowing the introduction of some feedback between the design of risers and mooring systems. In the current practice, that comprises the so-called “hybrid” methodologies, mooring designers have been using these tools to consider the influence of the risers on the platform motions. On the other hand, riser designers can use motions that result from coupled simulations for the analysis of each riser. Such integration is already being implemented in the design practice of Petrobras; however, elsewhere the design of risers and mooring systems may still be performed separately, by different teams, therefore not fully exploiting the benefits that the coupled analysis tools can provide. In this context, this work describes an innovative, fully integrated methodology for the design of mooring systems and risers of floating production systems (FPS). This methodology considers different design stages (from preliminary to advanced), integrating the design activities of mooring lines and risers in a single spiral, allowing gains in efficiency and cost reduction. The initial design stages already include a feedback between riser and mooring analyses. The integrity of the risers can be considered in the mooring design by determining their safe operational zones, and therefore, mooring line pretensions can be modified to improve its structural performance. Then, in advanced stages critical design cases for both mooring and risers systems can be identified and rigorously verified by using fully coupled models. The application of the proposed methodology is illustrated with a case study of a typical FPS, representative of the platforms that have been recently considered for deepwater applications. It should be stressed that the methodology described here does not reflect the current design practice of Petrobras. Presently it is merely a proposal that is being studied and assessed; this work comprises the first draft of the methodology, which will be enhanced and consolidated as the result of current and future studies.

Towards the Integration of Analysis and Design of Mooring Systems and Risers: Part II — Studies on a DICAS System

2002 ◽  
Author(s):  
Fabri´cio Nogueira Correa ◽  
Stael Ferreira Senra ◽  
Breno Pinheiro Jacob ◽  
Isai´as Quaresma Masetti ◽  
Ma´rcio Martins Mourelle
Keyword(s):  
Motion Analysis ◽  
Production Systems ◽  
Companion Paper ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Mooring System ◽  
Analysis And Design ◽  
Design Methodologies ◽  
Analysis Methods ◽  
Campos Basin

The objective of this paper is to study different analysis methodologies for the design of floating production systems. The main issues are the use of uncoupled and coupled analysis methods, and the integration in the analysis and design of the mooring system and the risers. This paper is a companion to another paper also presented in the OMAE2002 Conference [1]. That paper describes a “basic” classic, uncoupled methodology, and comments on some refinements in the representation of the behavior of the lines in the motion analysis of the vessel. Comments regarding the introduction of some level of integration between mooring line and riser behavior are also presented in the companion paper [1], and these issues are illustrated with studies applying some of the considered design methodologies to the P-18 semi-submersible platform in Campos basin. The present paper proceeds describing some hybrid methodologies that combine coupled and uncoupled analysis tools, and illustrates their application to a DICAS system for deepwater applications in Campos basin.

Application of Vibration Analysis in Ball Bearing Fault Detection

2005 ◽  
Author(s):  
F. Bakhtiary-Nejad ◽  
A. H. Nayeb ◽  
S. E. Yeganeh
Keyword(s):  
Fault Detection ◽  
Computer Program ◽  
Time Domain ◽  
Vibration Analysis ◽  
Ball Bearing ◽  
Detection Method ◽  
Ball Bearings ◽  
Test Results ◽  
Localized Defects ◽  
Set Up

In this paper, existence of localized defects in a ball bearing has been diagnosed using vibration analysis. First, different kinds of faults which occur in ball bearings have been investigated. Then an analytical model has been proposed for determining the damaged ball bearing vibrations due to a localized defect. Also various methods of fault detection have been evaluated. Next, in order to examine the ball bearings, a testing set-up has been designed and constructed. Then by preparing a computer program, which calculates defect frequencies, some ball bearings have been tested. The test results were originally derived in time-domain. Then by using vibration analysis of healthy and damaged ball bearings in frequency-domain, a fault detection method for ball bearings has been proposed.

A Comparison of Coupled and Uncoupled Dynamic Analysis for the Flexible Riser in Shallow Water

2013 ◽  
Author(s):  
Chul-hee Jo ◽  
Do-youb Kim ◽  
Yu-ho Rho
Keyword(s):  
Shallow Water ◽  
Time Domain ◽  
Production Systems ◽  
Single Point ◽  
Gas Permeation ◽  
Dynamic Responses ◽  
Coupled Analysis ◽  
Flexible Riser ◽  
Extensive Experience ◽  
Flexible Risers

Flexible risers have been used extensively in recent years for floating and early production systems. Such risers offer the advantage of having inherent heave compliance in their catenary thereby greatly reducing the complexity of the riser-to-rig and riser-to subsea interfaces. Another advantage with flexible risers is their greater reliability. Concerns about fatigue life, gas permeation and pigging of lines have been overcome by extensive experience with these risers in production applications. In this paper, flexible riser analysis results were compared through coupled and uncoupled dynamic analyses methods. A time domain coupled analysis capability has been developed to model the dynamic responses of an integrated floating system incorporating the interactions between vessel, moorings and risers in a marine environment. For this study, SPM (Single Point Mooring) system for an FSU in shallow water was considered. This optimization model was integrated with a time-domain global motion analysis to assess both stability and design constraints of the flexible riser system.

Hybrid Verification of a Deepwater FPSO Using Truncated Model Tests and Numerical Simulations

2021 ◽  
Author(s):  
Xiangbo Liu ◽  
Ching Theng Liong ◽  
Nitesh Kumar ◽  
Kie Hian Chua ◽  
Allan Ross Magee ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Water Depth ◽  
Return Period ◽  
Line Length ◽  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Test Results ◽  
Set Up

Abstract This paper presents verification of a deep water FPSO with a semi-taut mooring system using model tests and numerical modelling commonly referred to as the hybrid method. The vessel under investigation is a FPSO of 310m in length and 47m in beam with an internal turret mooring system of 12 lines in 2000m water depth. Two configurations of the mooring systems i.e. inline and bisecting are investigated for sea-states up to 1000yr return period. A full depth mooring system has been developed for the FPSO and model tests will be carried out to verify the model. Due to limitations to the size of the model basins, the model tests will be carried out for a truncated mooring setup. Non-linear horizontal stiffness of a single mooring line and the complete mooring system with truncation is compared to that of the existing full depth mooring system. Discrepancies in the vertical forces due to truncation of line length will be discussed in the paper. A numerical model of the truncated set-up will be calibrated using model test results.

Ultra-Deepwater Model Testing of a Semisubmersible and Hybrid Verification

2008 ◽  
Author(s):  
Timothy E. Kendon ◽  
Ola Oritsland ◽  
Rolf J. Baarholm ◽  
Svein I. Karlsen ◽  
Carl-Trygve Stansberg ◽  
...  
Keyword(s):  
Model Test ◽  
Water Depth ◽  
Deep Water ◽  
Low Frequency ◽  
Line Tension ◽  
Model Tests ◽  
Test Results ◽  
Test Verification ◽  
Good Agreement

Model test verification of floater systems in ultra-deep water meets limitations when it comes to available laboratory sizes. Systems in depths beyond 1000–1500 m cannot be tested at reasonable scales without the truncation of the mooring and riser system. The development of methods and procedures to overcome this problem has been addressed through extensive research programs at MARINTEK (VERIDEEP, VERIDEEP Extension, NDP, DEMO2000). This led to a hybrid verification procedure which combines reasonable truncation principles, model tests of the truncated system, and numerical simulations, to estimate the system’s response at full depth. There is, however, still a need to address the actual influence from the truncation procedure, and from the integration with simulations, on the final extrapolated full depth results. This paper presents a case study for the validation of the procedure, that compares full depth model test results of a semisubmersible in water depth 1250m against the extrapolated full depth results obtained from a truncated system of 500m. Results are presented for line tension and vessel responses in 3 seastates. In general the extrapolated full depth results were found to be in good agreement with the full depth model tests. However, the results confirmed expectation that the low frequency response has the greater uncertainties and presents the greatest challenge for the procedure.

Ultradeepwater Monobuoys

2003 ◽  
Author(s):  
Mauro C. Oliveira
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Calibration Procedure ◽  
Coupled Analysis ◽  
Global Behavior ◽  
Test Results ◽  
Mooring Lines ◽  
Analysis And Design ◽  
Deep Waters ◽  
Hull Forms

This work deals with the analysis and design of monobuoys for deep waters. The monobuoy performance evaluation is carried out using a time domain computer program due to the non linearities present in this problem. This program is used to simulate the behavior of the monobuoy under the action of waves, wind and current. A coupled analysis between the floater and the mooring lines, considering its inertia, is also employed. Initially a validation study is conducted comparing the numerical simulations with model test results for a 400 meters water depth CALM buoy. The test comprises an operational condition with a tanker connected to the buoy under the action of wave, current and wind loads. From these results a calibration procedure of the numerical simulation is proposed and different hull forms are assessed in order to verify its global behavior. The main objective is to check if there are improvements in comparison with more conventional shapes relatively to the riser forces in the connection point.

The development and maintenance of animal recording systems in Greece: a case study

1998 ◽  
Vol 23 ◽  
pp. 27-39
Author(s):  
A. Georgoudis ◽  
A. Baltas
Keyword(s):  
Animal Species ◽  
Production Systems ◽  
Herd Size ◽  
Flock Size ◽  
Dairy Sheep ◽  
Future Planning ◽  
Sheep Population ◽  
Improvement Programme ◽  
Set Up

SummaryAnimal performance recording and breeding in Greece aim at improving milk production of pure-bred cattle under intensive systems and of sheep and goats under semi-intensive or extensive production systems. Although milk recording was established in Greece by the Ministry of Agriculture in 1952, it is only since 1978 that it has been carried out more systematically on larger populations and in the frame of a more specific genetic improvement programme for each animal species and breed. For the application of this programme, close co-operation has been set up among the competent services of the Ministry of Agriculture, the Agricultural Universities of the country and the relevant farmers' organisations which are in the process of being established. Milk is recorded on 61 867 dairy cows (29% of the total dairy population) in 1 425 herds (average herd size 43 cows), 31 611 dairy sheep (0.36% of the total sheep population) in 429 flocks (average flock size 72 ewes) and 3 296 goats (0.06% of the total goats population) in 36 flocks (average flock size 92). The procedures of performance recording and the future planning, aiming at increasing the number of animals and the recorded traits as well as the supporting of the farmers in managing their herds/flocks, are presented.

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