Flexible and Rigid Pipe Solutions in the Development of Ultra-Deepwater Fields

2003 ◽  
Author(s):  
Adriano Novitsky ◽  
Fin Gray
Keyword(s):  
Oil Industry ◽  
Technical Cooperation ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Collapse Resistance ◽  
Flexible Pipes ◽  
Campos Basin ◽  
Flexible Risers ◽  
Girth Welds ◽  
Full Scale Tests

The development of the offshore segment during the last three years was remarkably important for the oil industry due to some major achievements observed in the technical area, more specifically on the development of pipe solutions for ultra deepwater (UDW) applications. Brazil and Gulf of Mexico (GoM) have lately been the two main regions for application of proven pipe solutions in UDW. In Brazil, flexible pipes have been widely used in the development of UDW fields by Petrobras, while in the GoM, rigid pipelines and SCRs have been used for the majority of deepwater field developments. The main advances in flexible pipe technology are linked to the development of two major Petrobras fields located in the Campos Basin named Roncador and Marlim South. Technip-Coflexip has, through Technical Cooperation Agreements with Petrobras, designed, tested and installed flexible pipes, proving the fitness of this kind of product to UDW applications. The qualification of flexible risers for 1500m WD and flexible flowlines for 2000m WD are highlighted as being the main achievements. Extensive testing programs including, collapse, fatigue and offshore full scale tests have been put in place in order to simulate the design conditions to be seen by the pipes during installation and operation phases. The main design aspects in UDW like collapse, radial and lateral buckling of tensile armours, fatigue and thermal insulation will be covered in this paper and the current available technologies to tackle these issues will be presented. Similar design and qualification issues exist for rigid pipelines and risers (SCRs). The following three areas are specifically covered in this paper: collapse resistance of steel pipe; fatigue strength of plastically strained girth welds: and qualification of pipe-in-pipe thermal performance. These are some of the key areas of reeled pipe in deepwater applications that require successful project qualification. Technip-Coflexip has performed internal R&D programs on these areas as well as project specific qualifications. Both will be addressed by the paper.

Cathodic Protection Design Consideration for an Offshore Flexible Riser Connected to an Impressed Current System

2021 ◽  
Author(s):  
Thierry Dequin ◽  
Clark Weldon ◽  
Matthew Hense
Keyword(s):  
Cathodic Protection ◽  
Sacrificial Anode ◽  
Flexible Riser ◽  
Flexible Pipe ◽  
Linear Resistance ◽  
Flexible Pipes ◽  
Flexible Risers ◽  
Impressed Current ◽  
Host Structure ◽  
Impressed Current Cathodic Protection

Abstract Flexible risers are regularly used to produce oil and gas in subsea production systems and by nature interconnect the subsea production system to the floating or fixed host facilities. Unbonded flexible pipes are made of a combination of metallic and non-metallic layers, each layer being individually terminated at each extremity by complex end fittings. Mostly submerged in seawater, the metallic parts require careful material selection and cathodic protection (CP) to survive the expected service life. Design engineers must determine whether the flexible pipe risers should be electrically connected to the host in order to receive cathodic protection current or be electrically isolated. If the host structure is equipped with a sacrificial anode system, then electrical continuity between the riser and the host structure is generally preferred. The exception is often when the riser and host structure are operated by separate organizations, in which case electrical isolation may be preferred simply to provide delineation of ownership between the two CP systems. The paper discusses these interface issues between hull and subsea where the hull is equipped with an impressed current cathodic protection (ICCP) system, and provides guidance for addressing them during flexible pipe CP design, operation, and monitoring. Specifically, CP design philosophies for flexible risers will be addressed with respect to manufacturing, installation and interface with the host structure’s Impressed Current Cathodic Protection (ICCP) system. The discussion will emphasize the importance of early coordination between the host structure ICCP system designers and the subsea SACP system designers, and will include recommendations for CP system computer modeling, CP system design operation and CP system monitoring. One of the challenges is to understand what to consider for the exposed surfaces in the flexible pipes and its multiple layers, and also the evaluation of the linear resistance of each riser segment. The linear resistance of the riser is a major determinant with respect to potential attenuation, which in turn largely determines the extent of current drain between the subsea sacrificial anode system and the hull ICCP system. To model the flexible riser CP system behavior for self-protection, linear resistance may be maximized, however the use of a realistic linear resistance is recommended for evaluation of the interaction between the host structure and subsea system. Realistic flexible linear resistance would also reduce conservatism in the CP design, potentially save time during the offshore campaign by reducing anode quantities, and also providing correct evaluation of drain current and stray currents.

Prediction and Qualification of Radial Birdcage and Lateral Buckling of Flexible Pipes in Deepwater Applications

2015 ◽  
Author(s):  
Linfa Zhu ◽  
Zhimin Tan ◽  
Victor Pinheiro Pupo Nogueira ◽  
Jian Liu ◽  
Judimar Clevelario
Keyword(s):  
Failure Modes ◽  
Local Buckling ◽  
External Pressure ◽  
Design Guidelines ◽  
Prediction Theory ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Operation Conditions ◽  
Flexible Pipes ◽  
Compressive Loads

Increasing oil exploitation in deepwater regions is driving the R&D of flexible pipes which are subjected to high external pressure loads from the hydrostatic head during their installation and operation. One of the challenges of flexible pipe design for such applications is to overcome the local buckling failure modes of tensile armor layers due to the combination of high external pressure, compressive loads and pipe curvature. This paper presents the latest progress in local buckling behavior prediction theory and the qualification process of flexible pipes. First, the mechanisms of two types of buckling behaviors, radial birdcage buckling and lateral buckling, are described. For each failure mode, the analytical buckling prediction theory is presented and the driving parameters are discussed. As part of the qualification process, the ability to resist radial birdcage and lateral buckling must be demonstrated. Suitable test protocols are required to represent the installation and operation conditions for the intended applications by deep immersion performance (DIP) tests. Several flexible pipes were designed based on radial birdcage and lateral buckling prediction theory, and pipe samples were manufactured using industrial production facilities for DIP tests. The results clearly show that flexible pipes following current design guidelines are suitable for deepwater applications. An alternative in-air rig was developed to simulate the DIP tests in a controlled laboratory environment to further validate the model prediction as a continuous development.

Annulus Testing for Condition Assessment and Monitoring of Flexible Pipes

2004 ◽  
Author(s):  
Jon Olav Bondevik ◽  
Sigmund Lunde ◽  
Rune Haakonsen
Keyword(s):  
Barrier Layer ◽  
Nitrogen Pressure ◽  
Condition Assessment ◽  
Reliable Operation ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Assessment And Monitoring ◽  
Flexible Risers ◽  
Paper Address ◽  
Vacuum Testing

The Norwegian operator Norsk Hydro has more than 80 flexible dynamic risers and service lines in operation at different platforms. Riser integrity monitoring programs have been established for the flexible risers in order to ensure safe and reliable operation. SeaFlex has performed annulus testing on a large number of these risers as a part of the programs. The free annulus volume of a flexible pipe is defined as the volume between the extruded internal pressure barrier layer and the extruded external sheath subtracted the volume occupied by pressure- and tension armor, tape and eventual other layers. Two methods are presently used by the industry for annulus free volume testing of flexible pipes, namely nitrogen pressure testing and vacuum testing. Both methods identify trends of volume reduction with time and to detect annulus flooding. Annulus testing has proven to be an efficient and reliable tool for detecting annulus flooding, blocked vent ports and outer sheet damages. This paper address the challenges related to annulus testing of flexible pipes, advantages, experiences and how such tests and the results are used for condition assessment and monitoring of the risers.

Tie-in of a Rigid Pipeline to a Flexible Rise: Design and Installation — Challenges and Lessons Learnt

2019 ◽  
Author(s):  
Gianbattista Curti ◽  
Francois Lirola ◽  
Gianluigi Pirinu ◽  
Diego Pavone ◽  
Frederic Perrin
Keyword(s):  
West Africa ◽  
Bearing Capacity ◽  
Water Depth ◽  
Lessons Learned ◽  
Analysis Approach ◽  
Capacity Analysis ◽  
Flexible Pipe ◽  
Horizontal Connection ◽  
Flexible Pipes ◽  
Flexible Risers

Abstract This paper presents the experience made with the engineering and execution of the tie-in of flexible risers to rigid pipelines on a project recently completed in West Africa. Five production and injection pipelines (10” and 6”) were tied back to the host platform with flexible risers, in Lazy wave configurations, in ∼600m water depth. The risers are directly connected to the terminations structures (PLETs) of the rigid pipelines, through horizontal connection systems. The structures forming the tie-in (risers, PLETs and pipelines) have been designed to accommodate axial displacements of the pipelines in the range 0.3m to 1.0m, as positive displacements (expansions) and −0.1m to −0.7m as negative displacements (contractions) of the pipelines, respectively towards and away from the risers, due to pipelines thermal expansions and pipe walking. Note that along some of the lines anchoring structures have been installed to control pipe walking. The tie-in interface loads were to be limited, in order not to threaten the flexible pipe, the PLETs and the connectors, and, despite the small pipeline end displacements, keeping the interface loads within allowable values, was a challenge. The positive displacements were causing interface loads as high as 80% of the allowable values, while the negative displacements were causing up to 90% utilization of the capacity of the connectors and 95% of the allowable loading of the foundations of the PLETs. The main drivers of such high loadings are the stiffness of the flexible pipe, combined with the layout of the tie-in. Extensive in place analyses were done to simulate the effects of progressive displacements of the pipelines, the pipe-soil interactions and the specifics of the behaviour of the flexible pipes (hysteretic stiffness). Full 3D FE analyses of the foundations (mud mats) of the PLETs were done, to circumvent the limitations of a classical bearing capacity analysis approach. As built information were also used, to remove some conservatisms in the assumptions initially taken in the design. A special installation procedure was implemented, to achieve a layout of the riser at the approach of the pipeline capable to better relieve the displacements of the pipelines and reduce interface loads. Feedbacks from the installation are given in the paper. The lessons learned are also presented: a “flexible” pipe is a “stiff” structure and a direct tie-in to the pipeline may become an issue, if not addressed early enough during the execution of the project, when it can be too late to add mitigation structures, like intermediate tie-in spools, or to change significantly the routing of the risers and pipelines.

Lateral Buckling of Armor Wires in Flexible Pipes: Reaching 3000m Water Depth

2011 ◽  
Author(s):  
Philippe Secher ◽  
Fabrice Bectarte ◽  
Antoine Felix-Henry
Keyword(s):  
Deep Water ◽  
Failure Modes ◽  
External Pressure ◽  
Internal Diameter ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Flexible Pipes ◽  
Valid Solution ◽  
Sour Service ◽  
Water Depths

This paper presents the latest progress on the armor wires lateral buckling phenomena with the qualification of flexible pipes for water depths up to 3,000m. The design challenges specific to ultra deep water are governed by the effect of the external pressure: Armor wires lateral buckling is one of the failure modes that needs to be addressed when the flexible pipe is empty and subject to dynamic curvature cycling. As a first step, the lateral buckling mechanism is described and driving parameters are discussed. Then, the program objective is presented together with flexible pipe designs: - Subsea dynamic Jumpers applications; - Sweet and Sour Service; - Internal diameters up to 11″. Dedicated flexible pipe components were selected to address the severe loading conditions encountered in water depths up to 3,000m. Hydrostatic collapse resistance was addressed by a thick inner carcass layer and a PSI pressure vault. Armor wires lateral buckling was addressed by the design and industrialization of new tensile armor wires. The pipe samples were manufactured using industrial production process in the factories in France and Brazil. The available testing protocols are then presented discussing their advantages and drawbacks. For this campaign, a combination of Deep Immersion Performances (DIP) tests and tests in hyperbaric chambers was selected. The DIP test campaign was performed End 2009 beginning 2010 in the Gulf of Mexico using one of Technip Installation Vessel. These tests replicated the actual design conditions to which a flexible pipe would be subjected during installation and operation. The results clearly demonstrated the suitability of flexible pipes as a valid solution for ultra deep water applications. In addition, the DIP tests results were compared to the tests in hyperbaric chambers giving consistent results. This campaign provided design limitations of the new designs for both 9″ and 11″ internal diameter flexible pipes, in sweet and sour service in water depths up to 3,000m.

Stresses in Tensile Armour Layers of Unbounded Flexible Risers Loaded With External Pressure: Application to Lateral Buckling Mode

2017 ◽  
Author(s):  
Fabien Caleyron ◽  
Jean-Marc Leroy ◽  
Martin Guiton ◽  
Pascal Duchêne ◽  
Pascal Estrier ◽  
...  
Keyword(s):  
Failure Modes ◽  
External Pressure ◽  
Engineering Model ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Periodic Model ◽  
Scale Test ◽  
Flexible Risers ◽  
Offshore Field

Life6 software, developed by IFP Energies nouvelles, is the local model used by Technip to determine stresses in tensile armour layers of unbounded flexible risers. These stresses and their variations are then used to predict fatigue limits of the dynamically loaded risers. Life6 is based on periodic conditions to reduce the model length, with the assumption that all the tensile armour wires of a same layer share the same kinematics. This paper firstly presents recent improvements to obtain a better modeling of tensile armour wires kinematics, when the flexible riser loading includes external pressure. New models of the external sheath and the anti-buckling tapes have been developed and implemented in Life6. The results are successfully compared to a Finite Element periodic model. Applications to lateral buckling prediction of tensile armour layers are secondly presented in the paper. Indeed, in the design of flexible pipelines for offshore field developments, lateral buckling is one of the critical failure modes for the tensile armour wires, being associated with external pressure and flexible pipe cyclic bending. The latest developments made on the modeling of the external kernel of the flexible pipe allow to use Life6 as the basis of the enhancement of the lateral buckling engineering model used by Technip. It has been calibrated and validated against an extensive full scale test data base resulting in a physical, reliable and fast engineering model to predict lateral buckling mode. In accordance with standards, Technip methodology for flexible pipe lateral buckling determination ensures a robust and competitive design.

Effect of Installation on Collapse Performance of Flexible Pipes

2017 ◽  
Author(s):  
Fabien Caleyron ◽  
Vincent Le Corre ◽  
Laurent Paumier
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
External Pressure ◽  
Residual Effects ◽  
Cyclic Plasticity ◽  
Flexible Pipe ◽  
Collapse Resistance ◽  
Flexible Pipes ◽  
Offshore Field ◽  
Finite Elements Model

This paper investigates the effect of installation on collapse performance of flexible pipes. In the design of flexible pipelines for offshore field developments, one of the critical failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, Technip methodology for flexible pipe collapse resistance determination ensures a robust and competitive design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations. As the industry is moving to deeper and deeper water, there is a greater need to understand all factors which could affect collapse. This includes residual effects due to the high installation loads from the laying system. As a consequence, Technip has performed several collapse tests on samples previously submitted to a loading representative of installation conditions (tension and crushing). Moreover, Technip and IFP Energies Nouvelles have developed and improved over the past few years a Finite Elements model dedicated to collapse prediction. The model accounts for the detailed geometry of the wires (carcass, pressure vault, spiral), ovalization, cyclic plasticity, contacts and residual stresses due to manufacturing. It allows to evaluate the effect of installation on the ovalization and plasticity of each layer and the collapse performance of the flexible pipe. The purpose of this paper is to present the collapse tests results and the corresponding calculations performed with the Finite Elements Model on several cases representative of Technip flexible pipes portfolio.

Flexible Pipe Sensitivity to Birdcaging and Armor Wire Lateral Buckling

2004 ◽  
Author(s):  
Mauro Pastor Braga ◽  
Peter Kaleff
Keyword(s):  
Failure Modes ◽  
Failure Process ◽  
Performance Criteria ◽  
Pipe Failure ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Cyclic Bending ◽  
Testing Procedures ◽  
Flexible Pipes ◽  
Dip Test

Petrobras has been successfully dealing with deep water floating production systems using flexible pipes since 1977. During the completion of Marlim South 3 well in 1977, Petrobras was surprised by the occurrence of two birdcage type failures. At that time, Marlim South 3, in a water depth of 1709 m was the deepest offshore production well in operation. Since then, Petrobras has been testing flexible pipes using a field test known as DIP test. In a DIP test, an empty end capped sample of a flexible pipe, about 150m long, is partially supported by the sea bottom and connected to a lay vessel by a pipe follower or a wire rope. The flexible pipe has to withstand a 4 hour period of cyclic bending due to the motions of the lay vessel. The DIP test has provided Petrobras with information on a new failure mode: lateral buckling in the armor wire. Although a birdcage failure is equally undesirable, lateral buckling of the armor wires implies more danger because it can go unnoticed. In 2001, a research project was set up by the Research and Development Center of Petrobras that was aimed at reproducing the flexible pipe failure modes under laboratory conditions. The purpose was to obtain a better understanding of the failure process, as well as to develop testing alternatives to avoid the significant costs related to DIP tests. In order to assess the effect of cyclic bending as a major factor in degrading the longitudinal compressive strength of flexible pipes 15 destructive tests were performed on 4 inch diameter flexible pipe samples. Two test rigs that accommodated three types of test and a number of test procedures were developed in the project. The number of bending cycles to failure for each sample was determined when subjected to compressive action corresponding to its operational depth. Tests to evaluate the effect of pre-existing damage were also conducted. Special attention was devoted to the effect of layer arrangement on compressive failure. The test results clearly identified the basic failure modes under investigation (i. e. birdcaging and lateral buckling of the armor wires). Suggestions regarding simplified testing procedures and corresponding performance criteria are also presented.

Safety Factors for Fatigue Analysis of Flexible Pipes Based on Structural Reliability

2012 ◽  
Author(s):  
Fernando dos Santos Loureiro Filho ◽  
Edison Castro Prates de Lima ◽  
Luís Volnei Sudati Sagrilo ◽  
Fernando Jorge Mendes de Sousa ◽  
Carlos Alberto Duarte de Lemos
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Fatigue Analysis ◽  
Design Criterion ◽  
Flexible Riser ◽  
Safety Factors ◽  
Common Procedure ◽  
Flexible Pipes ◽  
Campos Basin ◽  
Flexible Risers

Structural reliability–based methodology [1,2] has been proposed for fatigue analysis of flexible pipes tension armours. In this methodology a design criterion is verified using a standard reliability analysis approach and checking if the fatigue failure probability is equal to or less than a target value. The use of reliability analysis in the every day design practice is not yet a common procedure. Hence, in this paper we present the calibration of safety factors for Brazilian environmental conditions to be used in the standard fatigue analysis of flexible riser tension armours. The calibration is performed in order to guarantee the same target probability of failure. The safety factors are calibrated considering four flexible risers, two connected to FPSOs and the other two to semi-submersibles located in different water depths in Campos Basin offshore Brazil.

scholarly journals Burst pressure prediction of fiber-reinforced flexible pipes with arbitrary generatrix

2021 ◽  
Vol 16 ◽  
pp. 155892502199081
Author(s):  
Guo-min Xu ◽  
Chang-geng Shuai
Keyword(s):  
Transfer Matrix ◽  
Linear Equations ◽  
Burst Pressure ◽  
Fiber Reinforced ◽  
Flexible Pipe ◽  
Theoretical Derivation ◽  
Design And Optimization ◽  
Flexible Pipes ◽  
Novel Method ◽  
Winding Angle

Fiber-reinforced flexible pipes are widely used to transport the fluid at locations requiring flexible connection in pipeline systems. It is important to predict the burst pressure to guarantee the reliability of the flexible pipes. Based on the composite shell theory and the transfer-matrix method, the burst pressure of flexible pipes with arbitrary generatrix under internal pressure is investigated. Firstly, a novel method is proposed to simplify the theoretical derivation of the transfer matrix by solving symbolic linear equations. The method is accurate and much faster than the manual derivation of the transfer matrix. The anisotropy dependency on the circumferential radius of the pipe is considered in the theoretical approach, along with the nonlinear stretch of the unidirectional fabric in the reinforced layer. Secondly, the burst pressure is predicted with the Tsai-Hill failure criterion and verified by burst tests of six different prototypes of the flexible pipe. It is found that the burst pressure is increased significantly with an optimal winding angle of the unidirectional fabric. The optimal result is determined by the geometric parameters of the pipe. The investigation method and results presented in this paper will guide the design and optimization of novel fiber-reinforced flexible pipes.

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