Overview of the Lateral Buckling and Walking Designs of Deepwater Pipelines in Offshore Brazil

2019 ◽  
Author(s):  
Rafael F. Solano ◽  
Carlos O. Cardoso ◽  
Bruno R. Antunes
Keyword(s):  
Oil And Gas ◽  
Design Guidelines ◽  
Mitigation Measures ◽  
Design Parameters ◽  
Clayey Soils ◽  
Lateral Buckling ◽  
Buckling Behavior ◽  
The World ◽  
Global Buckling ◽  
Subsea Pipelines

Abstract Last two decades have been marked by a significant evolution on the design of HP/HT subsea pipelines around the world. The HotPipe and SAFEBUCK JIPs can be seen as the first deepened developments in order to obtain safe design guidelines for subsea pipelines systems subjected to global buckling and walking behaviors. The adopted design approach have been to allow exposed pipeline buckles globally on seabed in a safe and controlled manner. Otherwise, the walking phenomenon has been in general mitigated constraining axial displacements by means of anchoring systems. After several design and installation challenges concerning lateral buckling and pipeline walking behaviors, nowadays there is a significant amount of deepwater pipelines operating with buckle initiators (triggers) as well as walking mitigation devices in offshore Brazil. Oil and gas pipelines, short gathering lines and long export lines, installed by reeling and J-lay methods, in other words different kinds of subsea pipelines have operated on very soft clayey soils and have formed planned lateral buckles as well as rogue buckles. This paper presents the main characteristics and design challenges of the deepwater pipelines subjected to the lateral buckling behavior, also highlighting mitigation measures to constrain the walking phenomenon of some pipelines. The relevant design results are highlighted as type and number of buckle triggers, buckle spacing, type and locations of walking mitigations. Envelopment of the main design parameters are mapped in order to identify some trends. Finally, survey images of operating pipelines are presented confirming behaviors predicted in the design phase.

Expansion Design Philosophy to Prevent Buckle Walking at Very Uneven Seabed

2009 ◽  
Author(s):  
Ragnar T. Igland ◽  
Marit Irene Kvittem ◽  
Dmitry Vysochinskiy
Keyword(s):  
Oil And Gas ◽  
Local Buckling ◽  
Design Parameters ◽  
Operational Conditions ◽  
Design Philosophy ◽  
Buckling Behavior ◽  
Start Up ◽  
Continuous Survey ◽  
Standard Design ◽  
Global Buckling

Subsea flowline development for a field on the Norwegian Continental Shelf comprises design of HP/HT flowlines for oil and gas transport from subsea manifolds. Flowline engineering faces several challenges related to flowlines crossing very uneven seabed. Among them is choosing an expansion design philosophy that minimizes the need for continuous survey and intervention work updates. Control of buckling behavior is ensured by use of rock berms. The standard design of the rock dumps according to [1] is based on buckle sharing criterion for axial friction capacity, which aims to control initiation of buckles. However, fulfilling the buckle sharing criterion alone does not provide sufficient control of pipeline behavior through the different operational conditions. In addition to buckle sharing criterion fulfillment [1], anchoring rock berms shall also ensure that the point of zero axial displacement is inside the berm for all operational conditions. This will give control over feed-in lengths and counter pipeline walking between sections. Criteria for ARBs are established, covering post buckle and shutdown conditions in addition to buckle sharing. Unstable buckle configuration during shutdown/start-up cycles is defined as buckle walking. Redistribution of feed-in between buckles is frequently observed as the cause of buckle walking. Use of uplift cover is avoided or minimized in order to eliminate extra axial friction and the uncertainty around such friction, and thus to guarantee that the sectioning by anchoring rock berms (ARBs) is working. Within each section between ARBs the axial force in the system is held at a minimum level by controlled buckling. The combination of isolated pipeline sections with minimum axial restraint within the section provides control over unstable buckling behavior. Thus the risk of unexpected buckles is minimized. This is particularly important for uneven seabed. 3D global buckling analyses are performed by ANSYS with upper bound, best estimate and lower bound design parameters for friction in accordance with [1] and capacity control for local buckling of pipeline in accordance with [2].

Application of Deterministic and Probabilistic Methods in Pipeline Lateral Buckling Design

2012 ◽  
Author(s):  
Hammam Zeitoun ◽  
Maša Branković ◽  
Edwin Shim ◽  
EuJeen Chin ◽  
Benjamin Anderson
Keyword(s):  
Structural Reliability ◽  
Design Guidelines ◽  
Probabilistic Methods ◽  
Design Solution ◽  
Design Parameters ◽  
Pipeline System ◽  
Limit States ◽  
Lateral Buckling ◽  
Current Design ◽  
Subsea Pipelines

Subsea pipelines lateral buckling design has significantly evolved over the last years as more pipeline projects have moved into more challenging environments and into high temperature / high pressure (HT/HP) design application. Knowledge and understanding of pipeline lateral buckling has improved with design application resulting in refined and enhanced design approaches. Using current design approaches, it is now quite acceptable to control lateral buckle formation along the pipeline by using buckle triggers or to allow uncontrolled lateral buckles, provided that the various design limit states are satisfied. A number of design methodologies can be used to check the acceptability of uncontrolled buckling or to design for controlled buckling including deterministic, probabilistic buckle formation and full Structural Reliability Assessment (SRA) methods. Using SRA or probabilistic methods is usually an attractive design option as lateral buckling design involves dealing with a large number of uncertainties and variation in design parameters. These methods help to ensure the reliability of the proposed buckle initiation scheme. However, the use of these methods is also associated with a number of challenges such as the need to identify key parameters influencing the design and quantifying their uncertainties. Deterministic design approaches on the other hand are simpler to apply. However, they do not provide means to quantify the reliability of the proposed buckling scheme or the design risks. The choice of input parameters in a deterministic design is also relatively subjective which can possibly result in an overly conservative or unconservative design solution depending on the adopted design approach, selected design parameters and pipeline system being considered. Design guidelines and recommended practices such as SAFEBUCK (20) offer comprehensive guidelines to design for lateral buckling. However when faced with a range of complex variables, the designer needs to be aware of the effect of these parameters on the overall design. This paper describes the application of Deterministic and Probabilistic design approaches in lateral buckling design. The paper starts by describing these approaches, their advantages and limitations. The paper then explores a number of key uncertainties and variation in design parameters that the designer is faced with and its effect on the pipeline response.

Interaction between Upheaval/Lateral and Propagation Buckling in Subsea Pipelines

2014 ◽  
Vol 553 ◽  
pp. 434-438
Author(s):  
Hassan Karampour ◽  
Faris Albermani
Keyword(s):  
Horizontal Plane ◽  
Oil And Gas ◽  
Vertical Plane ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Upheaval Buckling ◽  
Oil And Gas Pipelines ◽  
Global Buckling ◽  
Internal Pressures ◽  
Subsea Pipelines

Due to high service temperatures and internal pressures in oil and gas pipelines, axial compression forces are induced in the pipe due to seabed friction. Slender trenched pipelines can experience global buckling in the vertical plane (upheaval buckling) while untrenched pipelines buckle in the horizontal plane (lateral buckling). Furthermore, deep subsea pipelines subjected to high external hydrostatics pressures can undergo catastrophic propagation buckling. In this study, the possible interaction between upheaval/lateral buckling and propagation buckling is numerically investigated using finite element analysis. A new concept is proposed for subsea pipelines design that gives higher capacity than conventional pipelines.

Evaluation of Design Premises and Uncertainties on the Thermo-Mechanical Behavior of a Subsea Pipeline

2014 ◽  
Author(s):  
Bruno Reis Antunes ◽  
Rafael Familiar Solano ◽  
Alexandre Hansen
Keyword(s):  
Formation Process ◽  
Mechanical Design ◽  
Design Stage ◽  
Stress And Strain ◽  
Lateral Buckling ◽  
Friction Factors ◽  
Global Buckling ◽  
Pipeline Route ◽  
Seabed Bathymetry ◽  
Subsea Pipelines

Buckle formation process is a key subject for the design of subsea pipelines laid on the seabed and operating under high pressure and high temperature (HP/HT) conditions. When the controlled lateral buckling methodology is adopted triggers are placed along pipeline route in order to increase the buckle formation probability in specific locations, sharing pipeline expansion between these sites and reducing the level of stress and strain in each buckle. Despite of its importance, buckle formation process is influenced by several parameters such as the seabed bathymetry, engineered triggers, lateral out-of-straightness (OOS) and pipe-soil interaction. While the first two items above can be defined with reasonable accuracy at previous stages of design, lateral OOS will only be known with tolerable confidence after pipeline installation. The level of uncertainty related to pipe-soil interaction is also considerable since pipeline embedment and friction factors are estimated using equations that include empirical correlations and field collected data. In addition these parameters are influenced by the installation process. Due to these uncertainties, conservative premises are usually assumed in order to obtain a robust pipeline thermo-mechanical design. After pipeline installation and/or start of operation an investigation can be performed in order to confirm the assumptions considered in the design. This paper presents a comparison of premises adopted during design stage of a pipeline based on the controlled lateral buckling methodology and the feedback obtained with the post-lay survey performed. After a brief introduction, pipeline embedment, global buckling at crossings, lateral OOS and sleepers’ height are some of the subjects addressed. Finally, conclusions and recommendations are presented in order to support future similar projects.

Assessment of Parameters Influencing Lateral Buckling of Deep Subsea Pipe-in-Pipe Pipeline System Using Finite Element Modeling

2014 ◽  
Author(s):  
M. Masood Haq ◽  
S. Kenny
Keyword(s):  
Boundary Conditions ◽  
Load Capacity ◽  
External Pressure ◽  
Design Parameters ◽  
Parameter Study ◽  
Pipeline System ◽  
Limit States ◽  
Lateral Buckling ◽  
Global Buckling ◽  
External Forces

The operational requirements for subsea pipeline systems have progressed towards higher design temperatures and pressures (HTHP). To address flow assurance requirements, pipe-in-pipe systems have been developed. For pipelines laid on the seabed, or with partial embedment, the potential for lateral buckling; in response to operational loads, external forces and boundary conditions, has become a major factor in engineering design. The effective axial force is a key factor governing the global lateral buckling response that is influenced by parameters such as internal and external pressure, and operating and ambient temperature. Other design parameters that influence lateral buckling include global imperfections or out-of-straightness, pipe/soil interaction characteristics and installation conditions. Global buckling reduces the axial load capacity of the pipeline that may impair operations and exceed serviceability limit states. Results from a numerical parameter study on lateral buckling response of a subsea pipe-in-pipe (PIP) pipeline are presented. The parameters examined include pipe embedment, pipe out-of-straightness (OOS), soil shear strength, soil peak and residual forces and displacements, variation in soil properties distributed along the pipeline route, and external pressure associated with the installation depth. The observed pipe response was a complex relationship with these parameters and kinematic boundary conditions.

Global Buckling Characteristics of Offshore Bundled Pipeline System

2021 ◽  
Author(s):  
Danar Tri Yurindatama ◽  
Nawin Singh ◽  
Vinod Pillai
Keyword(s):  
Actual Condition ◽  
Design Parameters ◽  
Pipeline System ◽  
Process Data ◽  
Standard Requirement ◽  
Buckling Behavior ◽  
Offshore Pipeline ◽  
Global Buckling ◽  
The Impact ◽  
Analytical Approaches

Abstract In recent years, the global buckling assessment of offshore pipelines in High Pressure-High Temperature (HPHT) condition become increasingly challenging since more complex pipeline system arrangement e.g. pipe(s) or cable(s) is strapped onto a larger pipeline, are rapidly utilized in many areas. Yet, the detailed guideline to assess the buckle of bundles remains unclear, therefore this study will focus to investigate on a methodical and reproducible approach to analyze in-service buckling behavior of bundled offshore pipeline system. The global buckling behavior of bundled offshore pipeline system in this study is investigated using commercial Finite Element (FE) software. Two carbon steel pipelines with different diameter are bundled and the buckling behavior is studied under the influence of buckle triggers. In the actual condition, the rogue buckle trigger is generated from OOS (out of straightness) or imperfection e.g. due to laying tolerance. Varying dimension parameter such as diameter ratio between the main pipeline and strapped pipeline are considered to understand the impact of this parameter on the buckle behavior. The study begins with a comparison of the results using numerical and analytical approaches on a straight pipeline in an unbuckled condition for validation purposes. The design parameters including wall thickness, process data, and pipe-soil interaction data, are varied since it influences the buckle behavior. In addition, some design parameter such as material properties and pipeline length will be adopted from a typical offshore pipeline project and the values are fixed so the exercise can focus on the most governing parameters. Following this, two numerical modelling methods, the equivalent properties method and the connector method, are presented in this study to simulate bundled systems. With a good agreement between the analytical and numerical approach, some buckle trigger is introduced on the numerical model of the bundled pipeline so the system is able to buckle and the behavior can be evaluated further. The strain level, lateral displacement, axial feed-in and pipe integrity shall be reported in the post-buckle conditions for both main pipe and strapped pipe as per current code and standard requirement. With more reliable results of buckling assessment for bundled pipeline system, it gives technical confidence and a major saving in both Capital Expenditure (CAPEX) and Operational Expenditure (OPEX). Industry has put serious effort through various Joint Industry Projects (JIP) to develop the global buckling assessment guideline in order to ensure long term integrity operation. Although the JIP guideline is predominantly for single pipeline system, similar assessment is demanded also for bundled pipeline system which described in this study. Key findings of the assessment are presented along with an overview of the design process and the typical mitigation techniques to be considered for similar subsea pipeline projects.

Lateral Buckling Response of Subsea HTHP Pipelines Using Finite Element Methods

2013 ◽  
Author(s):  
M. Masood Haq ◽  
S. Kenny
Keyword(s):  
Internal Pressure ◽  
Operating Temperature ◽  
Complex Function ◽  
External Pressure ◽  
Parameter Study ◽  
Embedment Depth ◽  
Lateral Buckling ◽  
Structural Support ◽  
Global Buckling ◽  
Subsea Pipelines

Subsea pipelines are subject to load effects from external hydrostatic pressure, internal pressure, operating temperature, ambient temperature and external reactions (e.g. seabed, structural support). These parameters influence the effective axial force that governs the pipeline global buckling response. Other factors, including installation stress, seabed slope, soil type, and embedment depth, can influence the pipe effective force. Pipelines laid on the seabed surface or with limited embedment may experience lateral buckling. The resultant mode response is a complex function related to the spatial variation in these parameters and kinematic boundary conditions. In this paper, results from a parameter study, using calibrated numerical modelling procedures, on lateral buckling of subsea pipelines are presented. The parameters included pipe diameter to wall thickness (D/t) ratio, pipe out of straightness (OOS), operating temperature and internal pressure, external pressure associated with the installation depth, and seabed lateral and axial friction properties.

scholarly journals Statistical Analysis of Parameters of Selected Worldwide Yacht Ports and Marinas in Terms of Design Guidelines

2018 ◽  
Vol 25 (1) ◽  
pp. 205-217 ◽  
Author(s):  
Lucjan Gucma ◽  
Kinga Drwięga ◽  
Radosław Butrymowicz
Keyword(s):  
Statistical Analysis ◽  
North America ◽  
South Asia ◽  
Design Guidelines ◽  
Google Earth ◽  
Design Parameters ◽  
Current Development ◽  
The World ◽  
Design Analyses

AbstractIn relation to the current development of the sailing, modernization and development of yacht ports and marinas are necessary. The preparations process, stages of the design, analyses and finally construction of yacht ports is time-consuming and laborious. In the article a statistical analysis of selected design parameters was described. In order to carry out the analysis a database was created based on 210 ports from different regions of the world such as: Europe, North America, Australia and South Asia. Google Earth was used to obtain the actual values of the analyzed parameters. Most of achieved results was described in the form of tables or graphs.

scholarly journals Lateral Buckling Theory and Experimental Study on Pipe-in-Pipe Structure

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 185 ◽  
Author(s):  
Zechao Zhang ◽  
Hongbo Liu ◽  
Zhihua Chen
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Thermal Loading ◽  
Oil And Gas ◽  
Critical Force ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Theoretical Derivation ◽  
Initial Imperfections ◽  
Global Buckling

With the increasing depth of marine oil and gas exploitation, more requirements have been proposed on the structure of deep-sea oil pipelines. The influencing factors of lateral buckling of a pipe-in-pipe (PIP) structure containing initial imperfections and its critical force were investigated in this study by conducting an experiment, a finite element analysis, and a theoretical derivation. The change laws on the influence of initial imperfections of the PIP structure during thermal loading were revealed through an experimental study by using imperfection amplitude and wavelength as parameters. Appropriate finite element models were established, and the influences of initial imperfections, pipe-soil interaction, and the height and the number of centralizers on the global buckling critical force of the PIP structure were analyzed. The formulas of global buckling critical force of inner and outer pipes and that under pipe-soil interaction was obtained by using a theoretical derivation method. A comparative verification with experimental and finite element (FE) models result was conducted, which provided a corresponding basis for steel pipeline design.

Validation of Residual Curvature Installation for Lateral Buckling Management Using Structural Reliability Analysis (SRA)

2017 ◽  
Author(s):  
Martin Teigen ◽  
Malik M. Ibrahim
Keyword(s):  
Finite Element ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Control Method ◽  
Multivariate Interpolation ◽  
Design Parameters ◽  
Bending Moments ◽  
Lateral Buckling ◽  
Residual Curvature ◽  
Subsea Pipelines

The method of using residual curvature during pipeline installation, primarily for the purpose of lateral buckling control, has caught an increasing amount of attention over the past few years [1], [9]. The use of residual curvature sparked a particular interest after positive experiences from a 26 km long pipeline on Statoil’s Skuld project (2012) in the Norwegian Sea [7]. As such, a range of technical papers elaborating on the topic have recently been published [6], [7], [9]. Some of this work has identified some particularly novel applications for the residual curvature method including freespan mitigation to reduce the requirement for seabed intervention, allowing for direct pipeline tie-ins, use with s-lay installation and even for steel catenary risers [10], [11]. However, these applications are currently only identified and not yet proven successful in any published work. This technical paper focusses on validating the use of residual curvature for the purpose of lateral buckling control in subsea pipelines installed by reel-lay. The residual curvature method demonstrates high buckling reliability without the use of subsea structures or additional installation equipment, with a controlled buckle response and favourable operational bending moments [1]. The residual curvature method has been shown less sensitive to some design parameters than other lateral buckling control methods [6]. However, published work also show that high strains will develop for short residual curvature lengths, high pipe-seabed frictions and for certain levels of residual strains [6]. Previous research has predicted the behaviour of residual curvature as a means of controlling lateral buckling in a deterministic approach [6], [7], [9]. However, performing a lateral buckling design with a probabilistic approach can offer a more realistic design and demonstrate higher reliability. There is a range of research on probabilistic approaches for lateral buckling design of subsea pipelines, but there is little published work on the same approach for residual curvature in particular. For this reason, this paper suggests a method for determining the likelihood of buckling and the associated bending moments via structural reliability analysis (SRA). A numerical model combining Finite Element (FE) Analysis and a Monte Carlo simulation is applied. A similar approach has already been presented by others for a different lateral buckling control method, and involves forming a database of finite element solutions followed by multivariate interpolation for the stochastic variables [16]. The multivariate interpolation necessitates a permutation of the cases in an FE result database. In order to keep the simulation efficient, only a limited number of variables are treated as stochastic. The variables that are considered as stochastic are those that have been determined that the lateral buckling response due to residual curvature is sensitive to. The variations of the remaining parameters are also accounted for but in a simpler way. The suggested SRA is used to assess the reliability of a pipeline that resembles the Skuld pipeline. The proposed SRA validates that residual curvature is a reliable lateral buckling control method irrespective of great variations in the design parameters that cannot be quantified easily, such as target residual strain. The proposed SRA also serves as a cost attractive solution in the qualification testing, by potentially relieving the installation contractor from the expensive exercise of performing an additional straightening trial.

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