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.

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.

Modeling the Dynamic Lateral Buckling Response of Subsea Pipelines Using Rate-Dependent Seabed Friction

2014 ◽  
Author(s):  
Zack Westgate ◽  
Kin Yin Chee ◽  
Alastair Walker
Keyword(s):  
Slow Rate ◽  
Low Friction ◽  
Lateral Buckling ◽  
Dynamic Finite Element ◽  
Rate Dependent ◽  
Friction Factors ◽  
Wide Range ◽  
Element Approach ◽  
Subsea Pipelines ◽  
Key Parameter

As subsea pipeline installation methods become increasingly sophisticated through use of increased vessel power and advanced stability and positioning controls, pipelines are likely to exhibit lower levels of horizontal out-of-straightness on the seabed than currently considered to occur during the lay process. This has resulted in an increased tendency for the problematic phenomenon of snap-buckling to occur as part of the controlled lateral buckling design. A key parameter affecting the pipeline response during lateral buckling is the friction between the pipeline and the seabed, which is strongly influenced by the rate of pipe displacement. Under stable buckle formation, the relatively slow rate of pipe displacement is more predictable and leads to acceptable strains in the pipeline. During the formation of less stable snap-through buckles, the rate of pipe displacement can mobilize a wide range in friction factors that can cause high strains in the pipeline. Quasi-static methods cannot model the dynamic transition between a high friction (drained) response and a low friction (undrained) response. To circumvent this problem in design, a fully dynamic finite element approach is required which captures the rate-dependent frictional response. This paper presents the results of a series of FE analyses that illustrate how the changing seabed friction affects the lateral buckling response of typical subsea pipelines. A contractile seabed is modeled, chosen to capture the general case where high values of slow drained friction are followed by low values of fast undrained friction, leading to changes in the buckle shapes compared to those obtained from static buckle modeling. The results are used to examine the conditions under which dynamic buckle analysis should be used and the effects of dynamic pipeline response on the levels of strain and deformation induced in buckles.

Offshore Pipelines Thermo-Mechanical Performance

2010 ◽  
Author(s):  
Luca Suschitz ◽  
Shaju Nair
Keyword(s):  
Mechanical Performance ◽  
Three Dimensional ◽  
Fluid Temperature ◽  
Offshore Pipelines ◽  
Macro Scale ◽  
Global Buckling ◽  
Pipeline Route ◽  
Design Solutions ◽  
Seabed Bathymetry ◽  
Acceptability Criteria

Higher production fluid temperature and pressure requires increased offshore hydrocarbons pipeline performance. Thermal-mechanical loading induces considerable compression in pipelines resulting in potential elastic instability. One family of design solutions restrains the pipeline, impeding its displacement and maintaining the axial compression. A second family of design solutions aims to relieve this compression in a controlled manner thereby allowing the pipeline to either displace sideways or axially. For both options, the global buckling design needs a peculiar set of input parameters, methods of assessment and an acceptability criteria. This paper presents an original development in the methodology to determine the sections of the pipeline route that are susceptible to global buckling. The process has found remarkable benchmark in field applications. Specific attention is given to a macro scale of the entire pipeline routing while addressing anisotropies such as out-of-straightness, crossings, sideways-installation adjustments, sequence of loading and three-dimensional seabed bathymetry.

Initial Approach to Assess Lateral Buckling Behavior: Comparison Between Design and Operational Condition of Offshore Pipeline

2010 ◽  
Author(s):  
Rafael Familiar Solano ◽  
Bruno Reis Antunes ◽  
Alexandre Santos Hansen
Keyword(s):  
Mechanical Design ◽  
Design Strategy ◽  
Operating Conditions ◽  
Lateral Buckling ◽  
Campos Basin ◽  
Buckling Behavior ◽  
Offshore Pipeline ◽  
Route Length ◽  
Oil Export ◽  
Pipeline Route

Recently Petrobras has been developing a production module of Roncador field through the P-52 platform in the Campos Basin, offshore Brazil. This platform is a floating production facility located in deep water and was tied back to the PRA-1 platform in shallow water by an 18-inch pipeline in order to export the oil production. This pipeline operates under high pressure and high temperature (HP/HT) conditions and was laid on the seabed. As a result of the extreme operating conditions, this pipeline is highly susceptible to lateral buckling and a buckle initiation strategy based on triggers to control the buckling behavior was designed. Thus sleepers and distributed buoyancies were designed and installed along the pipeline route. In addition to the buckles at the triggers, some additional, on-bottom, buckles were assessed in order not to compromise the design strategy. In recent geophysical data surveys carried out along the route length with the pipeline in operation, both engineered and on-bottom buckles were identified. This paper aims to present the thermo-mechanical design of the P-52 oil export pipeline, performing a comparison between some results obtained in design and observed during operation. Thus this paper intends to evaluate the pipeline as-built plus the operational pipeline configurations, and to assess the robustness of the design strategy applied regarding lateral buckling behavior.

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.

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.

Lateral Buckling and Walking Design of a Pipeline Subjected to a High Number of Operational Cycles on Very Uneven Seabed

2014 ◽  
Author(s):  
Rafael F. Solano ◽  
Bruno R. Antunes ◽  
Alexandre S. Hansen ◽  
T. Sriskandarajah ◽  
Carlos R. Charnaux ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Structural Integrity ◽  
Mechanical Design ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Control Approach ◽  
Temperature Conditions ◽  
Oil Export ◽  
Global Buckling

Global buckling is a behavior observed on subsea pipelines operating under high pressure and high temperature conditions which can jeopardize its structural integrity if not properly controlled. The thermo-mechanical design of such pipelines shall be robust in order to manage some uncertainties, such as: out-of-straightness and pipe-soil interaction. Pipeline walking is another phenomenon observed in those pipelines which can lead to accumulated displacement and overstress on jumpers and spools. In addition, global buckling and pipeline walking can have strong interaction along the route of a pipeline on uneven and sloped seabed, increasing the challenges of thermo-mechanical design. The P-55 oil export pipeline has approximately 42km length and was designed to work under severe high pressure and high temperature conditions, on a very uneven seabed, including different soil types and wall thicknesses along the length and a significant number of crossings. Additionally, the pipeline is expected to have a high amount of partial and full shutdowns during operation, resulting in an increase in design complexity. During design, many challenges arose in order to “control” the lateral buckling behavior and excessive walking displacements, and finite element analysis was used to understand and assess the pipeline behavior in detail. This paper aims to provide an overview of the lateral buckling and walking design of the P-55 oil export pipeline and to present the solutions related to technical challenges faced during design due to high number of operational cycles. Long pipelines are usually characterized as having a low tendency to walking; however in this case, due to the seabed slope and the buckle sites interaction, a strong walking tendency has been identified. Thus, the main items of the design are discussed in this paper, as follows: lateral buckling triggering and “control” approach, walking in long pipelines and mitigate anchoring system, span correction and its impact on thermo-mechanical behavior.

scholarly journals Buckle Interaction in Deep Subsea Pipelines

2013 ◽  
Author(s):  
Hassan Karampour ◽  
Faris Albermani
Keyword(s):  
Deep Water ◽  
Numerical Study ◽  
Local Mode ◽  
Imperfection Sensitivity ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Design Capacity ◽  
Global Buckling ◽  
Subsea Pipelines

The paper investigates the interaction between propagation buckling and lateral buckling in deep subsea pipelines. Lateral buckling is a possible global buckling mode in long pipelines while the propagation buckling is a local mode that can quickly propagate and damage a long segment of a pipeline in deep water. A numerical study is conducted to simulate buckle interaction in deep subsea pipelines. The interaction produces a significant reduction in the buckle design capacity of the pipeline. This is further exasperated due to the inherent imperfection sensitivity of the problem.

Reliability of Lateral Buckling Formation From Planned and Unplanned Buckle Sites

2008 ◽  
Author(s):  
Andrew Rathbone ◽  
Mahmoud Abdel-Hakim ◽  
Gary Cumming ◽  
Knut To̸rnes
Keyword(s):  
Risk Assessment ◽  
High Pressure ◽  
Quantitative Risk Assessment ◽  
Design Solution ◽  
Lateral Buckling ◽  
Detailed Design ◽  
High Pressure High Temperature ◽  
Global Buckling ◽  
Subsea Pipelines ◽  
Design Stress

Global buckling for exposed HPHT (High Pressure / High Temperature) subsea pipelines is an important feature that needs to be assessed during detailed design. By safely triggering controlled buckles at predetermined locations and considering the potential for rogue buckles to be triggered by seabed or pipelay out-of-straightness features, a robust design solution can be obtained. This paper presents a methodology whereby quantitative risk assessment may be carried out on the reliability of lateral buckling initiation systems, considering the pipeline in its entirety, rather than considering each intended buckle individually. This method accounts for buckle interaction when calculating the post-buckle loads, and allows simple incorporation of potential rogue sites through vertical and/or horizontal out-of-straightness. The results of the risk assessment can be defined in terms of buckle formation reliability, and design stress/strain criteria.

Lateral buckling of subsea pipelines triggered by dual sleepers

2021 ◽  
Vol 116 ◽  
pp. 102863
Author(s):  
Zhenkui Wang ◽  
Yougang Tang ◽  
Nuo Duan
Keyword(s):  
Lateral Buckling ◽  
Subsea Pipelines
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