Upheaval Buckling Analysis of Partially Buried Pipeline Subjected to High Pressure and High Temperature

2011 ◽  
Author(s):  
Jason Sun ◽  
Han Shi ◽  
Paul Jukes
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Soil Cover ◽  
Resistance Force ◽  
Soil Resistance ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Lateral Buckling ◽  
Upheaval Buckling ◽  
Global Buckling

Offshore industry is now pushing into the deepwater and starting to face the much higher energy reservoir with high pressure and high temperature. Besides the significant impacts on the material, strength, and reliability of the wellhead, tree, and manifold valve; high Pressure (HP) also leads to thicker pipe wall that increases manufacturing and installation cost. High Temperature (HT) can have much wider impact on operation since the whole subsea system has to be operated over a greater temperature range between the non-producing situations such as installation, and long term shut down, and the maximum production flow. It is more concerned for fact that thicker wall pipe results in much greater thermal load so to make the pipeline strength and tie-in designs more challenging. Burying sections of a HPHT pipeline can provide the advantages of thermal insulation by using the soil cover to retain the cool-down time. Burial can also help to achieve high confidence anchoring and additional resistance to the pipeline axial expansion and walking. Upheaval buckling is a major concern for the buried pipelines because it can generate a high level of strain when happens. Excessive yielding can cause the pipeline to fail prematurely. Partial burial can have less concern although it may complicate the pipeline global buckling behavior and impose challenges on the design and analysis. This paper presents the studies on the upheaval buckling of partially buried pipelines, typical example of an annulus flooded pipe-in-pipe (PIP) configuration. The full-scale FE models were created to simulate the pipeline thermal expansion / upheaval / lateral buckling responses. The pipe-soil interaction (PSI) elements were utilized to model the relationship between the soil resistance (force) and the pipe displacement for the buried sections. The effects of soil cover height, vertical prop size, and soil resistance on the upheaval and lateral buckling response of a partially buried pipeline were investigated. This paper presents the latest techniques, allows an understanding in the global buckling, upheaval or lateral, of partially buried pipeline under the HPHT, and assists the industry to pursue safer but cost effective design.

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.

Global Buckling Mitigation of Buried Pipelines: Lateral Resistance Assessment

2015 ◽  
Author(s):  
Martin Gallegillo ◽  
Guillaume Hardouin
Keyword(s):  
Design Guidelines ◽  
Buried Pipelines ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Upheaval Buckling ◽  
Lateral Resistance ◽  
Rock Cover ◽  
Global Buckling ◽  
Cover Design ◽  
Analytical Tools

This paper presents an approach to rock cover design for un-trenched pipelines installed on the seabed and rock-dumped for protection against dropped objects, anchor chain impact and fishing/trawling activities. This is found in some North Sea locations which present challenging conditions for trenching while protection is necessary due to intensive fishing activities. Under these circumstances the pipeline must remain within the rock berm and, hence, it must be designed against global buckling. Whereas there are clear design guidelines addressing upheaval buckling behaviour, the resistance to lateral buckling to maintain a pipeline within the rock berm has received less attention in the literature. The aim of this paper is to present a method to design a rock berm to mitigate against lateral buckling of rock-dumped pipelines based on the horizontal out-of-straightness survey data provided to the designer. The main challenges associated with this activity at different design phases are also introduced, including the use of analytical tools as well as detailed finite element analysis.

From Installation to Operation: A Full-Scale Finite Element Modeling of Deep-Water Pipe-in-Pipe System

2009 ◽  
Author(s):  
Jason Sun ◽  
Paul Jukes
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
High Temperature ◽  
Deep Water ◽  
Compressive Load ◽  
Analysis Tool ◽  
Realistic Interaction ◽  
Global Buckling ◽  
Advanced Analysis ◽  
Lock In

Developments of deep water oil reservoirs are presently being considered in the Gulf of Mexico (GoM). Pipe-in-Pipe (PIP) systems are widely used and planned as the tie-back flowline for high pressure and high temperature production (HPHT) due to their exceptional thermal insulation capabilities. The installation of PIP flowline in deep water, disregarding the laying method, can present real challenges because of the PIP string weight. The effect of the lowering displacement as well as the lock-in compressive load acting on the inner pipe for the commonly used un-bonded PIP is also a major concern. Such effects will enhance the total flowline compression when the high temperature and high pressure are applied after start-up; they greatly increase the severity of the global buckling and result in local plastic collapse at a larger bending curvature section or strain localization area. An even greater concern is that industry fails to realize the seriousness of such failure potential, and the PIP is generally treated as a composite single pipe which does not evaluate the PIP load response correctly, especially the inner pipe lock-in compression omitted. It could result in an unsafe design for HPHT production. This paper endeavors to provide a trustworthy solution for the HPHT PIP systems from installation to operation by using the advanced analysis tool — “Simulator”, an ABAQUS based in-house Finite Element Analysis (FEA) engine. “Simulator” allows the PIP pipes being modeled individually with realistic interaction between the pipes. A systematic process was introduced by using a generic deep-water PIP flowline as a working example of J-Lay installation and HPHT production. The load and stress responses of the PIP at all installation stages were calculated with a high level of accuracy, they were then included in the global buckling analysis for the HPHT operation. The study demonstrated the effectiveness of Loadshare, an industry-leading solution; which reduces or eliminates the inner pipe lock-in compression and improves the PIP compressive load capacity for the high temperature operation.

Global Buckling of a Pre-Pressurized Flexible Flowline

2013 ◽  
Author(s):  
Zhengmao Yang ◽  
Daniel Karunakaran
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Tensile Force ◽  
Flexible Pipe ◽  
Upheaval Buckling ◽  
Axial Tension ◽  
Lateral Resistance ◽  
Rock Cover ◽  
Global Buckling

For the protection from object drop/fishing trawl impact, flexible flowline is normally trenched or rock-dumped. And hence, upheaval buckling is promoted by the elevated temperatures and high pressures. In order to reduce the rock cover requirement for mitigation of upheaval buckling, rock-dumping or trenching while the flexible pipe are pressurized has been performed successfully in several north sea projects. The temperature and pressure induced elongation of flexible pipe are design dependent. For high pressure flexible flowline, the pressure expansion is significantly higher than conventional rigid pipelines. Due to the low bending stiffness and high pressure expansion, a flexible flowline will buckle laterally when it is pre-pressurized in hydro-test before trenching or rock-dumping. As a consequence, lateral imperfections are induced and will be kept after trenching or rock-dumping due to lateral resistance and bending stress relaxation of the flowline. In these locations, the flowline tends to deform laterally in operating. On the other hand, when the flowline is de-pressurized after trenching or rock-dumping the contraction of the flowline is restrained by the surrounding soils or rocks, and hence axial tension force can be obtained. When the flowline starts to operate, this tensile force will neutralize part of the compressive axial force, and therefore the required upheaval resistance is reduced. In this paper, global buckling of a pre-pressurized flexible flowline has been studied, and the influence on the requirement of rock covers is presented.

scholarly journals Poro-Elastoplastic Modelling of Uplift Resistance of Shallowly-Buried Pipelines

2017 ◽  
Author(s):  
Wen-gang Qi ◽  
Yu-min Shi ◽  
Fu-ping Gao
Keyword(s):  
Pore Pressure ◽  
Compressive Force ◽  
Friction Angle ◽  
Soil Resistance ◽  
Buried Pipeline ◽  
Axial Compressive Force ◽  
Uplift Force ◽  
Upheaval Buckling ◽  
Heating And Cooling ◽  
Wave Induced

During operational cycles of heating and cooling of submarine pipelines, variations of temperature and internal pressure may induce excessive axial compressive force along the pipeline and lead to global buckling of the pipeline. Reliable design against upheaval buckling of a buried pipeline requires the uplift response to be reasonably predicted. Under wave loading, the effective stress of soil could be reduced significantly in the seabed under wave troughs. To investigate the effects of wave-induced pore-pressure on the soil resistance to an uplifted buried pipeline, a poro-elastoplastic model is proposed, which is capable of simulating the wave-induced pore-pressure response in a porous seabed and the development of plastic zones while uplifting a shallowly-buried pipeline. The uplift force on the buried pipeline under wave troughs can be generated by the pore-pressure nonuniformly distributed along the pipe periphery. Numerical results show that the value of uplift force generally increases linearly with the wave-induced mudline pressure under troughs. Parametric study indicates that the peak soil resistance (under wave troughs) decreases with increasing wave height and wave period, respectively. The ratio of peak soil resistance under wave action to that without waves is mainly dependent on the normalized wave-induced mudline pressure, but influenced slightly by the internal friction angle of soil.

scholarly journals Lateral Buckling Induced by Trawl Gears Pull-Over Loads on High Temperature/High Pressure Subsea Pipeline

2012 ◽  
Author(s):  
Iswan Herlianto ◽  
Qiang Chen ◽  
Daniel Karunakaran
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Fe Analysis ◽  
Commercial Fishing ◽  
Lateral Buckling ◽  
External Interference ◽  
Global Response ◽  
Subsea Pipeline ◽  
Non Linear ◽  
Temperature And Pressure

Lateral buckling has become a challenge to deep water and high pressure/high temperature (HP/HT) flowlines. In areas that support major commercial fishing industries (e.g. the North Sea in Norway and Atlantic Margin in UK), there is high possibility of interaction between flowlines and fishing trawl gears. This interaction can expose the flowlines to substantial loads and induce lateral buckling. This paper presents global response of subsea pipeline as a result of trawl gear pull-over loads. The external interference from trawl gear pull-over loads can create substantial imperfection or out-of-straightness on the pipeline and may also generate global lateral buckling. The pull-over loads can also induce excessive bending moments and strains in the buckle region. To be able to understand the global response of the pipeline under pull-over loading conditions, a Finite Element (FE) analysis is carried out based on DNV OS F101 [1], DNV RP F110 [2] and DNV RP F111 [3] using general FE analysis software ANSYS v13. Non-linear transient analysis is used to incorporate the non-linear effects, such as the pipeline material nonlinearity, and the response of a structure under the action of pull-over time-dependent loads [8]. The FE analysis covers two periods of duration, i.e. during pull-over duration and post pull-over duration. The analysis during pull-over duration deals with the pipeline global response as a result of trawl gear pull-over loads. The pipeline is subjected to substantial horizontal and vertical pull-over forces from the trawl gear. For post pull-over duration, the FE analysis was carried out for an additional five seconds. In this period, the pull-over loads are no longer applied. However, the pipeline may expand further due to temperature and pressure loads on pipeline. The FE analysis result shows that the pull-over loads induce out-of-straightness on the pipeline and may cause lateral buckling. The pipeline deforms laterally at the pull-over location. The DNV displacement condition code check is used to check the integrity of the pipeline. The pipeline may in the risk under the trawl gears pull-over loads. This paper also shows the development of lateral buckling on the pipeline under different magnitudes of trawl gear pullover loads and lateral soil frictions. Further work should also take into account different dimension of pipeline, as the variation of operating temperature and pressure and variation of lateral and axial soil friction combinations to obtain better conclusions.

The Interaction of Free Span and Lateral Buckling Problems

2004 ◽  
Author(s):  
Nelson Szilard Galgoul ◽  
Julia Carla Paulino de Barros ◽  
Rony Peterson Ferreira
Keyword(s):  
Vortex Shedding ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Upheaval Buckling ◽  
Axial Forces ◽  
Traditional Design ◽  
Engineering Problems ◽  
Global Buckling ◽  
Present Design ◽  
Pipeline Vibration

The traditional design approach for most engineering problems, of which pipelines are no exception, is to segment the project and to present design solutions for each of these design items. When setting up a pipeline schedule, therefore, one will find an item called free span analyses and another called global buckling, which covers both lateral and upheaval buckling problems. This has been justifiable so far, because freespan vibrations have traditionally been treated totally dissociated from the axial force on the pipe, while lateral buckling is a problem to which, only recently, the industry has turned its attention. DNV has a tradition of being the regulatory agency, which has a lead on vortex shedding problems. This tradition has recently been confirmed, when they issued a new freespan vibration guideline [1], in which they are now considering the interaction of axial forces in the calculation of the pipeline vibration frequency. Shortly after this code was issued, the authors undertook three large pipeline projects, in which the use of the aforementioned code was a contractual requirement. If on one hand, however, the owner insisted upon the use of the new DNV code, on the other he was not willing to accept the very short free span limits, which were resulting from the calculations. Because of this, the authors were forced to look at the problem in further depth, thus resulting interesting conclusions, which will be presented in this paper. These point out some conservative aspects of the code, and make suggestions as to how this conservatism can be overcome, in order to use the DNV safety approach and still produce larger spans, by properly focusing on the freespan buckling problem. In addition to this, the authors have concluded that the freespan buckling problem cannot be dissociated from global buckling, because, in general, it was found that the pipe not seldom moves from a local span buckling mode to a global lateral buckling mode, thus giving the free span problem a completely different emphasis. The experience gained during these projects will be shared in this paper.

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