On the Calibration of Coefficients of Friction for Pipeline-Seabed Interaction

2010 ◽  
Author(s):  
Deepak V. Datye
Keyword(s):  
Contact Interaction ◽  
Variable Coefficients ◽  
Rational Representation ◽  
Interaction Behavior ◽  
Seabed Interaction ◽  
Subsea Pipelines ◽  
Pipeline Design ◽  
Resistance Data ◽  
Underlying Soil ◽  
3D Problem

Subsea pipelines placed on the seabed can buckle due to thermal and mechanical loads. This buckling, and the associated pipe walking phenomena, can lead to large stresses in the pipe sections and at the pipe end attachments. These high stresses need to be accounted for in pipeline design. An accurate simulation of pipeline buckling for design purposes requires a rational representation of the nonlinear large deformations of the underlying soil, which entails a large 3D problem to be solved with repeated remeshing in the Lagrangian setting. However, it is possible to reduce this effort and forgo the direct modeling of the underlying soil by modeling the pipe as a beam, the seabed as a surface, and the resistance offered by the soil to the pipe through an appropriate contact interaction behavior between the pipe and the seabed. This contact interaction behavior can be expressed through variable coefficients of friction between the pipeline and the seabed. In this paper the Coupled Eulerian-Lagrangian technique is used to evaluate the resistance offered by the plastic soil to the pipeline; the resistance data are then used to calibrate these coefficients of friction, which are in turn used in an implicit dynamic analysis for simulating the buckling deformations of a representative pipeline, modeled as a beam, in contact with the seabed, which is modeled as a surface.

Modelling spatial variability in as-laid embedment for high pressure and high temperature (HPHT) pipeline design

2016 ◽  
Vol 53 (11) ◽  
pp. 1853-1865 ◽  
Author(s):  
Z.J. Westgate ◽  
W. Haneberg ◽  
D.J. White
Keyword(s):  
Spatial Variability ◽  
Mitigation Measures ◽  
Physical Mechanisms ◽  
Lateral Resistance ◽  
Project Costs ◽  
Seabed Interaction ◽  
Subsea Pipelines ◽  
Design Analyses ◽  
Pipeline Design ◽  
The Impact

Subsea pipelines are being designed to accommodate higher temperatures and pressures. Current modelling approaches that adopt constant lateral seabed resistance along the pipeline do not capture the high spatial variability in as-laid pipeline embedment from field observations, which strongly affects the lateral resistance. Ignoring spatial variability when designing pipelines with engineered buckles leads to higher predictions of axial force along the pipeline, with reduced likelihood of buckle formation. This can result in excessive mitigation measures being adopted, such as sleepers or counteract structures, which significantly increase project costs. Spatial variability of pipeline embedment is not currently handled rationally in design because an understanding of the physical mechanisms that cause as-laid embedment and methods for accurately predicting it have only recently emerged. This paper illustrates how the influence of these physical mechanisms that drive embedment can be extracted from field survey data and then modelled synthetically in design analyses. The impact of embedment variability and the resulting variation in lateral seabed resistance on the lateral buckling response is illustrated. The framework represents an improvement in the way geotechnical uncertainty and variability is handled in pipeline–seabed interaction analyses for use in pipeline design, and has already begun to be implemented in practice.

Case Studies Highlighting Rapid Repair Methods of Pressurised Pipelines Damaged by Anchors

2018 ◽  
Author(s):  
Dale Millward
Keyword(s):  
Case Studies ◽  
Health And Safety ◽  
Cost Effective ◽  
Pipeline System ◽  
Subsea Pipeline ◽  
Damage Scenarios ◽  
Fail Safe ◽  
Subsea Pipelines ◽  
Marine Vessels ◽  
Pipeline Design

Effective pipeline design and regular maintenance can assist in prolonging the lifespan of subsea pipelines, however the presence of marine vessels can significantly increase the risk of pipeline damage from anchor hazards. As noted in the Health and Safety Executive – Guideline for Pipeline Operators on Pipeline Anchor Hazards 2009. “Anchor hazards can pose a significant threat to pipeline integrity. The consequences of damage to a pipeline could include loss of life, injury, fire, explosion, loss of buoyancy around a vessel and major pollution”. This paper will describe state of the art pipeline isolation tooling that enables safe modification of pressurised subsea pipelines. Double Block and Bleed (DBB) isolation tools have been utilised to greatly reduce downtime, increase safety and maximise unplanned maintenance, providing cost-effective solutions to the end user. High integrity isolation methods, in compliance with international subsea system intervention and isolation guidelines (IMCA D 044 / IMCA D 006), that enable piggable and unpiggable pipeline systems to be isolated before any breaking of containment, will also be explained. This paper will discuss subsea pipeline damage scenarios and repair options available to ensure a safe isolation of the pipeline and contents in the event of an incident DNV GL type approved isolation technology enables the installation of a fail-safe, DBB isolation in the event of a midline defect. The paper will conclude with case studies highlighting challenging subsea pipeline repair scenarios successfully executed, without depressurising the entire pipeline system, and in some cases without shutting down or interrupting production.

scholarly journals Effect of Gain in Soil Friction on the Walking Rate of Subsea Pipelines

2019 ◽  
Vol 7 (11) ◽  
pp. 401 ◽  
Author(s):  
Zhaohui Hong ◽  
Dengfeng Fu ◽  
Wenbin Liu ◽  
Zefeng Zhou ◽  
Yue Yan ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Pipeline System ◽  
Gas Industry ◽  
Steel Catenary Riser ◽  
Wide Range ◽  
Offshore Oil And Gas ◽  
Subsea Pipelines ◽  
Offshore Oil ◽  
Pipeline Design

Subsea pipelines are commonly employed in the offshore oil and gas industry to transport high-pressure and high-temperature (HPHT) hydrocarbons. The phenomenon of pipeline walking is a topic that has drawn a great deal of attention, and is related to the on-bottom stability of the pipeline, such as directional accumulation with respect to axial movement, which can threaten the security of the entire pipeline system. An accurate assessment of pipeline walking is therefore necessary for offshore pipeline design. This paper reports a comprehensive suite of numerical analyses investigating the performance of pipeline walking, with a focus on the effect of increasing axial soil resistance on walking rates. Three walking-driven modes (steel catenary riser (SCR) tension, downslope, and thermal transient) are considered, covering a wide range of influential parameters. The variation in walking rate with respect to the effect of increased soil friction is well reflected in the development of the effective axial force (EAF) profile. A method based on the previous analytical solution is proposed for predicting the accumulated walking rates throughout the entire service life, where the concept of equivalent soil friction is adopted.

Heat-Transfer Characteristics of Subsea Pipelines Embedded in Multilayered Soils

SPE Journal ◽  
2020 ◽  
Vol 25 (03) ◽  
pp. 1128-1139
Author(s):  
Dong-Su Park ◽  
Mun-Beom Shin ◽  
Young-Kyo Seo
Keyword(s):  
Heat Transfer ◽  
Analytical Formula ◽  
Soil Conditions ◽  
Burial Depth ◽  
Overall Heat Transfer Coefficient ◽  
Scale Experiment ◽  
Subsea Pipelines ◽  
Multilayered Soils ◽  
Pipeline Design ◽  
Good Agreement

Summary A good pipeline design must ensure that the heat loss is small enough for flow assurance despite unfavorable hydrate and wax depositions. The objective of this study is to experimentally verify a formula for the modified overall-heat-transfer coefficient (OHTC) that considers multilayered soil conditions for steady-state subsea pipelines. A laboratory-scale experiment is conducted to simulate the flows of cold seawater and hot crude oil inside the pipes immersed in multilayered soils at nine burial-depth rates. The obtained results are in good agreement with the data obtained by a previously derived OHTC analytical formula.

Machine Learning for Subsea Pipeline Reeling Mechanics

2020 ◽  
Author(s):  
Eric Giry ◽  
Vincent Cocault-Duverger ◽  
Martin Pauthenet ◽  
Laurent Chec
Keyword(s):  
Design Of Experiments ◽  
Wall Thickness ◽  
Large Diameter ◽  
Local Buckling ◽  
Statistical Regression ◽  
Element Analysis ◽  
Excessive Strain ◽  
Weld Area ◽  
Subsea Pipelines ◽  
Pipeline Design

Abstract Installation of subsea pipelines using reeling process is an attractive method. The pipeline is welded in long segments, typically several kilometers in length, and reeled onto a large diameter drum. The pipeline is then transported onto such reel to the offshore site where it is unreeled and lowered on the seabed. The deformation imposed on the pipeline while spooled onto the drum needs to be controlled so that local buckling is avoided. Mitigation of such failure is generally provided by proper pipeline design & reeling operation parameters. Buckling stems from excessive strain concentration near the circumferential weld area resulting from strength discontinuity at pipeline joints, mainly depending on steel wall thickness and yield strength. This requires the characterization of critical mismatches obtained by trial and error. Such method is a long process since each “trial” requires a complete Finite Element Analysis run. Such simulations are complex and lengthy. Occasionally, this can drive the selection of the pipeline minimum wall thickness, which is a key parameter for progressing the project. The timeframe of such method is therefore not compatible with such a key decision. The paper discusses the use of approximation models to capitalize on the data and alleviate the design cost. To do so, design of experiments and automation of the computational tool chain are implemented. It is demonstrated that initial complex chain of FEA computational process can be replaced using design space description and exploration techniques such as design of experiments combined with advanced statistical regression techniques in order to provide an approximation model. This paper presents the implementation of such methodology and the results are discussed.

Simple Numerical Models for Pipeline Walking Accounting for Mitigation and Complex Soil Response

2011 ◽  
Author(s):  
Daniel Carneiro ◽  
David Murphy
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Interaction Model ◽  
Soil Response ◽  
Dimensional Finite Element ◽  
Loading And Unloading ◽  
Three Dimensional Finite Element ◽  
Internal Pressures ◽  
Subsea Pipelines ◽  
Pipeline Design

Non-buried subsea pipelines subjected to high internal pressures and high operational temperatures (HP/HT) may experience significant axial expansion. Asymmetries in the loading and unloading in startups and shutdowns (e.g. due to seabed slope, temperature transients or riser tension) may cause the axial displacements to accumulate over operational cycles, in a ratcheting process often called “pipeline walking”. Despite the complexity of the pipe-soil interaction governing this behavior, several analytical and simple numerical models have been used for estimating the total accumulated pipeline axial displacement. These simple models are powerful tools in preliminary phases of a pipeline design, although their use is limited due to the simplifications. This paper presents results of a simple numerical model able to account for additional features in the preliminary walking assessment, such as loads on mitigation systems. The models were originally prepared to assess walking mitigation for some rigid flowlines in a recently installed subsea system, and remarkable agreement with complex three-dimensional finite element models was observed. The effect of different types of mitigation systems on the global behavior of the pipelines is presented and discussed. The influence of the pipe-soil interaction model employed is also investigated.

Dimensionless Groups of Parameters Governing the Ice-Seabed Interaction Process

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Hamed Azimi ◽  
Hodjat Shiri
Keyword(s):  
Deep Understanding ◽  
Efficiency Coefficient ◽  
Element Analysis ◽  
Design Factor ◽  
Dimensionless Groups ◽  
Group A ◽  
Seabed Interaction ◽  
Subsea Pipelines ◽  
Expensive Model ◽  
High Range

Abstract Prediction of subgouge soil deformation during an ice gouging event is a challenging design factor in Arctic subsea pipelines. An accurate assessment of ice keel–seabed interaction requires expensive model testing and large deformation finite element analysis. Proposing reliable analytical/empirical solutions needs a deep understanding of the key parameters governing the problem. In this study, dimensional analysis of subgouge soil deformations was conducted and eight dimensionless groups of parameters were identified to facilitate proposing potential new solutions. A comprehensive dataset was established for horizontal and vertical subgouge deformations in both sand and clay seabed. Using the identified dimensionless groups, linear regression (LR) models were developed to estimate the horizontal and vertical deformation. Moreover, a sensitivity analysis (SA), as well as an uncertainty analysis (UA), was carried out to identify the superior LR models and the most influential parameter group. A high range of correlation coefficient (R), Nash-Sutcliffe efficiency coefficient (NSC), and variance accounted for (VAF) along with a low range of errors was achieved for the best LR model. The results of the superior LR models were also compared with the existing empirical equations. The study showed that the shear strength parameters of the seabed soil and the ratio of gouge depth to gouge width are the governing dimensionless parameters to model the horizontal and vertical subgouge soil deformations.

A Numerical Simulation Procedure for Vortex-Induced Vibration of Pipelines With Free Span

2013 ◽  
Author(s):  
Raphael I. Tsukada ◽  
Celso K. Morooka
Keyword(s):  
Numerical Simulation ◽  
Great Influence ◽  
Estimation Procedure ◽  
Vortex Induced Vibration ◽  
Simulation Procedure ◽  
Sea Bottom ◽  
Lift And Drag ◽  
Subsea Pipelines ◽  
Semi Empirical ◽  
Pipeline Design

Long subsea pipelines are generally used to connect an offshore petroleum production facility and a petroleum terminal at the coast, to export produced oil or gas. In the pipeline way though the sea bottom, free pipeline spans happen due to the uneven and irregularities of ocean ground. In this portion of the pipeline length, the sea current can cause forces in the pipe, as the drag and vortex-induced vibration forces, respectively. These forces can have great influence in the structural stress and fatigue damage. Therefore, they must be carefully analyzed and considered in the pipeline design. The present work aims to introduce a numerical simulation procedure based on a semi-empirical VIV model to predict dynamic response of a pipeline with free span. Computations were carried out in time domain using finite element method. Beam elements considering large displacements and rotation were used to represent the pipe behavior. The VIV forces are calculated based on hydrodynamic coefficients, like added mass, lift and drag coefficients. In order to verify the accuracy of the VIV estimation procedure, comparisons with experimental results are presented.

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