Feasibility Study of Residual Curvature Method for Deep Water Pipelines

Abstract In recent years the residual curvature (RC) method has been used to provide buckle initiators to control and mitigate the lateral buckling of pipelines for some shallow water projects. With the appropriate planning of the controlled buckles using RC sections, an acceptable design of the pipeline in-place behavior is achieved. However, the RC method has not yet been applied to deep-water pipelines. The twist of RC sections in the sagbend during installation has been observed, and the orientation of as-laid RC section on the seabed is difficult to control in deep-water pipelines. The effects of as-laid RC-section orientation on in-place lateral buckling in deep water are unknown. The FRIC user subroutine in the Abaqus finite-element software suite has been developed for modelling pipe-soil interactions based on uncoupled axial and lateral soil resistances that are assumed to be independent of vertical pipe penetration after initial embedment into the soil surface. However, the penetration of a twisted RC section can vary dramatically from a normal pipeline on the seabed. The UINTER user subroutine in Abaqus was selected for presenting 3D pipe-soil interactions that incorporate the variations of independent axial and lateral soil resistances as a function of pipe penetration more accurately. UINTER is used in the present study to account for the effects of soil penetration on the lateral buckling performance of a pipeline with RC sections in soft clay. The analysis results show that the RC section twists in the sagbend area during installation, and the twist angle reaches its maximum value just prior to the RC section touching the seabed. The in-place lateral buckling analysis is carried out after the installation analysis is finished. The analysis results demonstrate the feasibility of applying the RC method as the primary buckle triggering mechanism for deep water pipelines, and it shows how the RC orientation affects the pipeline in-place performance in terms of strength and fatigue damage (only the stress ranges for use in fatigue calculations are shown in the paper).

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Benefits and Deep Water Install Ability Challenges of Residual Curvature Method for Lateral Buckling Mitigation

Volume 5B: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2017-61387 ◽

2017 ◽

Author(s):

Erwan Karjadi ◽

Phil Cooper ◽

Henk Smienk ◽

Ferry Kortekaas

Keyword(s):

High Pressure ◽

Deep Water ◽

Local Buckling ◽

Bending Moment ◽

Lateral Buckling ◽

Curved Pipe ◽

Fea Model ◽

Water Pipelines ◽

Residual Curvature ◽

Curved Section

One way to control lateral buckling in the operation phase for High Pressure High Temperature (HPHT) pipelines is by deliberately introducing residual curvature sections at intervals along the pipeline by adjusting the straightener settings of the pipelay tower, as described in a patent held by Statoil [1]. This method has been applied with reel-lay installation for a number of shallow water pipelines in Europe (Statoil’s Skuld project and Total’s Edradour project). The paper presents the benefits as well as the feasibility of the use of Residual Curvature Method (RCM) to control lateral buckling for deep water applications which involves high top tension in the overbend and high pressure and twist of the RC section in the sagbend. The study cases consider the application of the method for pipelines in 1850m water depth which are pushing the pipe top tension close to the limit of the capacity of the tensioners of Heerema Marine Contractor’s (HMC) Reel-lay vessel the Aegir. There are some challenges of the application of the residual curve method for deep water pipelines. Due to high top tension, some potential issues are investigated during lowering of the curved section from the straightener, passing the tensioners and through the J-lay tower into the water to the seabed. Detailed analyses have been performed to check the interaction of the residual curved pipe section against the tensioners (the effect of the squeeze load on the RC section) and to assess the maximum bending moment generated when the residual curved section is under high top tension below the tensioners against the Load Controlled Condition (LCC) for local buckling bending moment limit. Another consideration is the increase of hydrostatic pressure in deep water which could limit the allowable bending moment in the sagbend when lowering the curved sections to the seabed. Discussions are presented to the feasibility of the concept including the proposed ways of mitigation for the aforementioned potential issues. The paper will also show an improved prediction of pipe twist/roll by comparing a published analytical 2D plane solution against the 3D FEA model prediction. The improved prediction, which considers the out of plane bending component of the pipe catenary, results in an increase of pipe twist in the sagbend section. This reduces the bending moment in the residual curved section when entering the sagbend and increases the probability to roll the curved section over to the horizontal plane on the seabed.

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Numerical study on the lateral breakout behaviour of deep-water pipelines in clays with surficial crust

Ocean Engineering ◽

10.1016/j.oceaneng.2020.108239 ◽

2020 ◽

Vol 218 ◽

pp. 108239

Author(s):

Abhishek Ghosh Dastider ◽

Neelanjan Sarkar ◽

Santiram Chatterjee

Keyword(s):

Deep Water ◽

Numerical Study ◽

Water Pipelines

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Lateral Buckling Mitigation in Deep Waters - A Total Installed Costs Comparison

10.4043/30969-ms ◽

2021 ◽

Author(s):

Hemant Priyadarshi ◽

Matthew Fudge ◽

Mark Brunner ◽

Seban Jose ◽

Charlie Weakly

Keyword(s):

Shallow Water ◽

Deep Water ◽

Cost Effective ◽

Cost Comparison ◽

Lateral Buckling ◽

Track Record ◽

Deep Waters ◽

Residual Curvature ◽

Mitigation Techniques ◽

Mitigation Methods

Abstract The paper introduces lateral buckling mitigation techniques (sleepers, distributed buoyancy sections, and residual curvature method or RCM) used in deep water fields and provides a total installed cost comparison of these solutions in relative terms. A hypothetical deep-water scenario is used to compare all techniques within the same site environment. Historic benchmarks have been used to make a relative comparison of these buckle mitigation methods on the engineering, procurement, fabrication, and installation fronts. In addition, risks associated with engineering, procurement/fab and installation have been listed to illustrate the risks versus rewards tradeoff. While sleepers and distributed buoyancy have been previously used in deep water, RCM doesn't have a significant track record yet. RCM is a proven and cost-effective buckle mitigation solution in shallow water. This paper compares its application in deep water to the prevailing buckle mitigation methods and confirms if it creates value (savings and reduces risks) for an offshore installation project. It is assumed that each mitigation method is appropriate for the hypothetical deep-water scenario.

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Deepwater Pipeline Challenges

ASME 2015 India International Oil and Gas Pipeline Conference ◽

10.1115/iogpc2015-7932 ◽

2015 ◽

Author(s):

Nitesh Sinha ◽

Raj Kishore

Keyword(s):

Deep Water ◽

Oil And Gas ◽

Deep Waters ◽

Additional Manufacturing ◽

Water Pipelines ◽

Exploration And Production ◽

Maximum Water ◽

Mitigation Design ◽

The Government ◽

Increasing Demand

With the ever-increasing demand of energy in the country, the Indian exploration and production is now compelled to move into deepwater frontiers. The country’s energy reserve is getting exhausted with drying shallow water assets and the mainland is already overwhelmed with the pressure of sustaining the world’s second largest population. Therefore, “the upstream oil and gas fraternity of the country” has to now enter “less explored” Indian deepwater block which has already started with the launch of the NELP block by the government. Although, the world has moved into deepwater long back, the Indian industry is still developing the ways and means to tackle the challenges involved in deep water. This paper presents the insights into design and installation of deepwater pipelines along with case study of Middle East to India Deepwater Pipeline (MEIDP) of M/s SAGE, which shall be laid at a maximum water depth of 3450 m. This paper broadly elucidates the challenges in designing the deepwater pipelines such as requirement of thick-walled line pipes to sustain collapse due to external over-pressure and tensile stresses generated due to installation forces, pipeline route selection and optimization, geo-hazard assessment & mitigation, design against fault line crossings/ seismic design, free span, repair systems, seabed intervention etc. It also covers the additional manufacturing & testing requirements including tighter tolerances for line pipes suitable for deepwater installations. It also highlights the deepwater installation capabilities of Pipe lay Barges for the laying of pipeline in the deepwater to ultra-deep waters along with new evolving testing and commissioning philosophies. This paper intends to bring awareness among the “oil and gas fraternity” regarding challenges involved in deep water pipelines with respect to design, installation etc.

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Soil Characterisation for Installing and Operating Deep-Water Pipelines

Volume 5: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2016-54838 ◽

2016 ◽

Author(s):

Antonio Borges Rodriguez ◽

Vishal Dantal ◽

Victor Bjorn Smith ◽

Roselyn Carroll

Keyword(s):

Deep Water ◽

Site Investigation ◽

Pipeline System ◽

Accurate Assessment ◽

Operational Conditions ◽

Axial Forces ◽

Seabed Topography ◽

Water Pipelines ◽

Efficient Planning ◽

Touchdown Point

Deep-water developments rely on pipeline and riser systems to transfer hydrocarbon products to floating facilities or potentially longer tie-back pipelines to shallow water platforms/onshore facilities. Depending on the nature of the product and operational conditions, the pipeline and riser system design may need to consider a range of dynamic processes during operation such as (i) controlled lateral buckling of the pipeline in order to relieve excessive constrained axial forces induced by temperature and pressure changes in the system; (ii) the accumulation of pipeline axial displacement or ‘walking’; and (iii) evolution of the pipe-soil interaction at the riser seabed touchdown point due to the dynamic behaviour of the riser. Under these conditions, the reliable structural assessment of the pipeline system relies upon accurate assessment of the pipeline-soil interaction (PSI), from the initial lay embedment of the pipeline to the evolution of the lateral and axial response over the lifetime of the facilities. Accurate assessment of these PSI parameters requires adequate characterisation of the seabed topography, seabed processes (e.g. geohazards) and the soil properties. This paper proposes ways for efficient planning of the geophysical and geotechnical site investigation activities and subsequent soil element and physical model testing for the assessment of relevant PSI parameters in deep-water.

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