IPC2008-64251

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1 Copyright © 2008 by ASME

Proceedings of IPC20087th International Pipeline Conference

September 29-October 3, 2008, Calgary, Alberta, Canada

IPC2008-64251

SUBSEA PIPELAYING SIMULATION BY THE “SITUA-PETROPIPE”

SOFTWARE - A USER FRIENDLY ALTERNATIVE

Danilo Machado Lawinscky da Silva Carl Horst Albrecht Breno Pinheiro Jacob

LAMCSO – Laboratory of Computer Methods and Offshore Systems – PEC/COPPE/UFRJRio de Janeiro, RJ, Brazil

Isaias Quaresma Masetti Claudio Roberto Mansur Barros Arthur Curty Saad

PETROBRAS – Petróleo Brasileiro S.A.

ABSTRACT

Currently, Petrobras (the Brazilian state oil company)

performs numerical simulations of pipelaying operations

employing commercial software, such as OffPipe [1]. However,

such tools presents restrictions/limitations related to the user

interface, model generation and analysis formulations. These

limitations hinder its efficient use for analyses of installation

procedures for the scenarios considered by Petrobras, using the

BGL-1 barge (owned by Petrobras) or other vessels,

considering for instance particular types of stingers depending

on depth and pipeline, with different lengths and geometries

adapted to certain laying conditions in S-Lay procedures.Therefore, the objective of this work is to present the

development and application of a tailored, in-house non-

commercial computational tool in which the modules follow

Petrobras users’ specifications, in order to overcome the

limitations for specific needs and particular scenarios in the

simulation of several types of pipeline procedures. Such tool,

called SITUA-PetroPipe, presents a friendly interface with the

user, for instance allowing the complete customization of the

configuration of laybarge and stinger rollers. It also includes

novel analysis methods and formulations, including the ability

of coupling the structural behavior of the pipe with the

hydrodynamic behavior of the vessel motions under

environmental conditions.

INTRODUCTION

Installation of pipelines and flowlines constitute some of the

most challenging offshore operations. The technical challenges

have spawned significant research and development efforts in a

broad range of areas, not only in studies regarding different

installation methods, but also in the formulation and

implementation of new computational tools required to the

numerical simulation. This work addresses this latter issue.

The most common installation methods are the S-Lay, J-

Lay, and Reel-Lay methods, schematically shown in Figure 1,

and Towing methods, schematically shown in Figure 2 [2,3,4].

Figure 1 – S-Lay, J-Lay and Reel-Lay Methods.

In the S-Lay method, as the laying barge moves forward,

the pipe is eased off the stern, curving downward through the

water until it reaches the touchdown point. After touchdown, as

more pipe is played out, it assumes the “S” shaped curve. To

reduce bending stress in the pipe, a stinger is used to support

the pipe as it leaves the barge. To avoid buckling of the pipe, a

tensioner must be used to provide appropriate tensile load to the

pipeline [5]. This method is used for pipeline installations in arange of water depths from shallow to deep.

In the J-lay method, the pipe is dropped down almost

vertically until it reaches touchdown; after that it assumes the

“J” shaped curve. J-Lay barges have a tall tower on the stern to

weld and slip pre-welded pipe sections. With the simpler

pipeline shape, the J-Lay method avoids some of the difficulties

of S-Laying such as tensile load forward thrust, and can be used

in deeper waters.

In the Reel-Lay method, the pipeline is installed from a

huge reel mounted on an offshore vessel. Pipelines are

assembled at an onshore spool-base facility and spooled onto a

reel which is mounted on the deck of a pipelay barge.

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mandatory for the accurate numerical simulation, analysis and

design [9,10,11,12]. Coupled analysis formulations consider the

non-linear interaction of the hydrodynamic behavior of the FPS

hull with the structural/hydrodynamic behavior of the mooringlines and risers, represented by Finite Element models. In the

implementation of such analysis tools, the 6-DOF equations of

motion of the platform hull are coupled with the equations of

motion of the FEM model of the lines.

It can intuitively be seen that the use of coupled

formulations is important not only for the design of production

platforms, but also for the simulation of offshore installation

operations. In the case of pipelines in S-Lay operations, even in

shallow waters the motions of the laybarge can be significantly

affected by the structural behavior of the pipeline.

Also regarding pipelines in S-Lay installation operations, it

should be considered that the contact mechanism between the

pipeline and the launching structure is complex, specified onlyin some points of the ramp and stinger.

Traditionally, Petrobras has been performing numerical

simulations of pipelaying operations employing commercial

software, such as OffPipe [1]. However, such tools present

limitations related not only to the user interface, but also to the

model generation and analysis formulations. These limitations

hinder its efficient use for analyses of installation procedures

for the scenarios considered by Petrobras, using the BGL-1

barge or other vessels, considering for instance particular types

of stingers depending on depth and pipeline, with different

lengths and geometries adapted to certain laying conditions in

S-Lay procedures.

Therefore, the objective of this work is to present thedevelopment of a in-house computational tool, referred as

SITUA-PetroPipe, that overcomes the limitations for specific

needs and particular scenarios in the simulation of several types

of pipeline procedures, and addresses the requirements

regarding the analysis formulations mentioned above.

As will be described in the remainder of this work, such tool

presents an extremely friendly interface with the user, allowing

for instance the complete customization of the configuration of

laybarge and stinger rollers.

SITUA–PROSIM

The SITUA-PetroPipe tool may be seen as specialized

modules of the SITUA-Prosim system [13], which has beendeveloped since 1997, in cooperation by Petrobras and

LAMCSO (Laboratory of Computer Methods and Offshore

Systems, at the Civil Engineering Department of

COPPE/UFRJ, Federal University of Rio de Janeiro)1. This

system constitutes a computational tool that performs coupled

static and dynamic nonlinear analyses of a wide range of

offshore operations.

The PetroPipe modules described here are based in the

SITUA graphical interface, and in the Prosim numerical solver

1 It should be pointed out that the SITUA-Prosim and the PetroPipe

modules are not commercial programs; all rights are reserved to Petrobras.

[14]. This numerical solver comprises a time-domain nonlinear

dynamic analysis program, which has been employed by

Petrobras since 1998 in several design activities related to

floating production systems.The coupled formulation of the Prosim program

incorporates, in the same computational code and data

structure, a hydrodynamic model to represent the hull and a

finite element model to represent the structural hydrodynamic

behavior of the mooring lines, risers and pipelines. This

coupled formulation allows the simultaneous determination of

the motions of the hull, and the structural response of the lines.

Moreover, the results will be more accurate since all dynamic

and nonlinear interaction effects between the hull and the lines

are implicitly and automatically considered. Details of such

coupled model are presented elsewhere [9,14], and will not be

reproduced here

The original Prosim code was oriented towards the analysisand design of FPS, considering their installed and operational

situations. Later, the SITUA-Prosim system was developed by

incorporating a graphical interface and adapting / specializing

the code for the analysis of installation and damage situations

(hence its name, from the Portuguese SITUações de instalação

e Avaria).

The SITUA interface is designed to work as a pre-processor

and model generator for the Prosim finite-element based

numerical analysis modules, and to provide facilities for

statistical and graphical post-processing and visualization of

results. The model generation procedures of the interface

incorporate an analytical catenary solver, able to represent

complex configurations such as lines with multiple segmentsand different materials, connected to other lines or to platforms,

and with flotation elements such as buoys or segments with

distributed floaters.

The interface allows a very simple and intuitive definition

of the model of a line. The user needs only to specify the

number, length and type of segments that comprise the line. A

database with several material types is incorporated in the

system. Another enhanced facility for the definition of lines for

actual operations of the BGL barge consists in the definition of

two of the parameters that define a catenary (including anchor

position, horizontal force, total top axial tension), in a

“variable-length” procedure. The system then automatically

adjusts the laid length of the top segment of the mooring line tocomply with the given parameters.

A series of adaptations and enhancements had already been

incorporated in the SITUA-Prosim system, intended to

specialize its use for simulation of the BGL-1 mooring

procedures. Some highlights of these tools are described in the

text that follows; more details can be found in [15].

Interaction with Seabed

The computational tool is able to incorporate the correct

definition of the seabed from bathymetric curves. It can also

automatically consider the position of the subsea obstacles, and

determine possible interferences between the mooring lines or

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the pipeline with obstacles. This is performed through a

specialized interface with the SGO (Obstacles Management

System) database system. This system, developed by Petrobras,

contains frequently updated information about the bathymetryand position of subsea obstacles, gathered by a special vessel

equipped with a ROV (Remote Operated Vehicle) [16].

The seabed is modeled by a surface mesh in which the z-

coordinate represents the depth. Soil-pipe interaction effects are

modeled through nonlinear scalar elements associated to each

node that comprises the spatial discretization of the pipeline.

Such scalars act on the seabed, representing the friction

between pipe and soil, and also as contact springs on the

vertical direction [17,18].

Friction effects on the seabed are represented by an

elastoplastic formulation that allows the consideration of

anisotropic friction, through the definition of distinct soil-

resistance coefficients for the axial and lateral directions of thepipeline [19].

Barge Motion and Interference Management Modules

As mentioned before, during pipelaying the barge is moved

periodically one pipe length ahead, along a predefined route.

The planning of such procedure consists in the definition and

charting of a series of points on this route, specifying the

positioning of the anchors, the lines, the buoys and the hull of

the barge.

In order to help the BGL-1 barge crew to develop safe

mooring procedures and to define the sequence of mooring

operations that leads to the barge motion, the system is able to

calculate the motions of the barge due to the operationsperformed with its mooring lines, leading to changes in their

catenary configuration (including placement of buoys, variation

of the onboard/released cable lengths, and relocating anchors).

During the simulation of such mooring operations by the

SITUA interface, a specialized interference management

module can be employed to characterize interference situations.

Such situations are detected when an obstacle falls into an

“exclusion volume” defined around segments of a line laying

on the seabed, and a vertical distance below suspended

segments, with risks of collision and damage to the line and/or

the obstacle (a manifold, another pipeline, etc.).

Figure 5 presents a 3D view where the exclusion region

around one line is graphically displayed, showing a possibleinterference situation with a previously installed pipeline. A

more detailed visualization, including the definition of the types

of obstacles and distances from the line, can be observed in 2D

views such as the depicted in Figure 6. In these views the

interferences are indicated by red arrows, with the

corresponding distances, and a tag defining the obstacle.

Once the possible interferences are identified, the BGL-1

operator can take measures to avoid them, including the

placement of buoys in given positions along the line. Figure 7

shows a configuration of a mooring line with two buoys, to

keep the line suspended well over subsea obstacles.

Figure 5 – 3D View of Exclusion Region with Interference.

Figure 6 – 2D View Detailing Interference.

Figure 7 – 3D View of Mooring Lines with Buoys.

SITUA–PETROPIPEAs mentioned before, the PetroPipe modules include new

tools developed following the Petrobras users’ specifications.

These tools are intended to automate the generation of

numerical models for the simulation of pipeline installation

procedures (for instance, allowing the complete customization

of the configuration of the laybarge and stinger rollers).

Moreover, the PetroPipe modules address the requirements

regarding the analysis formulations mentioned in a precedingsection, including the coupling of the structural behavior of the

pipe with the hydrodynamic behavior of the vessel motions.

Also, the contact of lines (mooring lines, risers, pipelines) with

the platform can be rigorously modeled during a nonlinear

dynamic analysis, as well as the contact involving different

lines or even the contact of one line with itself.

Modeling of Contact

Traditional contact models consider for instance a

generalized scalar element, consisting of two nodes linked by a

non-linear gap spring [20]. Here, the contact model consists of

a generalized elastic surface contact algorithm. The contact is

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modeled by augmentation of the global stiffness matrix, based

on the orientation and contact stiffness of the contact surfaces.

Details of this algorithm are presented in [19,21].

The algorithm has been shown to be able of capturing thedetailed characteristics of the interaction between mooring

lines, risers, pipelines, hulls, in a sophisticated model such as

the illustrated in Figure 8, depicting the contact between the

pipeline and the rollers of the laybarge stinger. A more detailed

example will be presented in the application presented later.

Figure 8 – Contact Model.

Tensioner Model

As mentioned before, the tensioner (Figure 4) is intended to

control the tension level in the pipeline during the pipelaying

operation, by keeping it within a feasible operational range.

In the PetroPipe modules, the tensioner is represented by a

specialized generalized scalar element, automatically added to

the pipeline top end, which consists of two nodes linked by a

nonlinear gap spring. Force-displacement or stiffness-

displacement functions associated to each local direction are

defined, and the local coordinates systems can also be updated

at each simulation step.

To simulate the tensioner behavior in keeping the tension

level at the defined range, the axial stiffness of this element

continually varies, leading to changes in the element length as

the pipeline end moves back and forth. It should be recalled

that the pipeline end motions are induced by the tensioner

behavior and by the barge motions applied at the tensioner. The

tensioner model is schematically shown in Figure 9.

All main characteristics of the tensioner machine are

incorporated in this model, including:

• Operational Range – defines the range of desired tension

values; the tensioner is not activated whenever the pipelineend tension is within this range.

• Response Delay – Whenever the pipe tension leaves the

operational range, the tensioner is activated but only after a

given time delay, when it effectively starts working.

• Response Velocity – After the tensioner effectively starts

working, it does not restore the tension level immediately,

but after a certain period defined by its design response

velocity.

• Displacement Limit – This defines the limit in which the

tensioner can move the pipeline back and forth in order to

compensate its tension level.

Figure 9 – Tensioner Model.

MODELING OF PIPELINE INSTALLATIONPROCEDURES

In the following sections, the facilities incorporated in the

PetroPipe modules are illustrated by their application to real-

case pipeline installation scenarios.

Lateral Deflection Procedure

The Lateral Deflection procedure, associated to towing

methods, may be used to move the pipeline into the sea. In this

context, it consists basically on deflecting the pipeline to the

sea (after assembled at the coastline) using a cable connected to

a tug boat. The characterization of the deflection procedure

involves the determination of the better velocity and direction

of the tug boat when the pipeline is leaving the shore in order to

minimize its efforts (especially due to the curvatures).

Figure 10: Lateral Deflection Procedure

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The PetroPipe modules have been employed to model such

a procedure for an actual scenario, as presented in [6]. Some

steps of the results of numerical simulations for this procedure

are illustrated in Figure 10: the pipeline is on shore (1), at thecoastline, before starting towing (2), the pipeline leaves shore

(3,4) and is towed to the installation site.

Towing

As mentioned before, tow-in operations are performed in

many situations to transport pipelines of several lengths.

Usually, Petrobras performs these operations following a lateral

deflection procedure such as the previously described. In the

typical configuration for surface tow, the pipe is towed using a

front and a back tugboat aligned at the transportation route, as

shown in Figure 11.

Figure 11: Towing – Typical Configuration.

Numerical simulations of actual operations were performed

using the SITUA-PetroPipe system, in order to assess the

pipeline behavior under environmental loadings. The studies

presented in [7] include an alternative configuration, shown in

Figure 12, where the tugboats are not aligned. Smaller values of

cable tension were obtained when the pipeline is nearly alignedwith the direction of the resultant of the environmental

loadings.

Figure 12: Tow-in – Alternative Configuration.

A contingency procedure was also analyzed in [7], for asituation in which the back tugboat is disconnected and only the

front tugboat is pulling the pipeline. This configuration

simulates a situation in which one of the tugboats loses control

and its cable is disconnected. The results of the analyses

indicated that the smaller values of cable tensions were found

in configurations where the back tugboat is disconnected,

indicating that the best situation occurs when it does not tension

the pipe, or simply when it is not connected to the pipe.

Therefore, from the results of the numerical simulations, the

actual pipeline transportation was performed by Petrobras using

only one tugboat, employing a smaller boat only to accompany

the transport operation for safety reasons, and to perform the

maneuvers needed for the subsequent pipeline launching

process. During the operation, all numerical predictions related

to the pipeline behavior were confirmed.

Shore Pull

The shore pull operation illustrated here consists in pulling

the pipe from the BGL-1 barge onto the shore by a winch. The

winch needs to keep adequate pulling force to ensure that the

pipe is maintained under controlled tension within the allowed

stress/strain limits. The forces applied must be controlled such

that no damage to the pipeline anodes or coating occurs.

Buoyancy aids can be used if required to keep pulling tension

within acceptable limits.

During the numerical simulation by the SITUA-PetroPipe

system, forces in the pipeline and cable are analyzed including

any overloading, friction and dynamic effects that may occur.

Figure 13 shows snapshots from the animation of the numerical

results, as the pipeline is pulled from the barge and arrives on

the shore.

Figure 13 – Shore Pull Operation.

GENERATION OF A S-LAY MODEL

The complete generation of an S-Lay model using the

specialized interface of the SITUA-PetroPipe is described inthe following sections.

Laybarge Characteristics

Figure 14 and Table 1 illustrate the main geometric

characteristics of the BGL-1 barge. Detailed actual data, in

terms of the geometrical and hydrodynamic characteristics of

the BGL-1 hull, were provided by Petrobras and employed to

generate the model of the barge hull, represented in Figure 15.

The geometric data are used in the definition of the contact

surface of the barge hull.

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Figure 14 – BGL-1 Geometry

Table 1 – Main geometric characteristics of BGL-1

Propriety Values (real scale)Drought 5.182 m

Height 9 m

Beam 30 m

Length 120 m

Figure 15 – SITUA-PetroPipe BGL-1 Model

Ramp and Stinger Data

Figure 16 illustrates the configuration of the ramp and

stinger considered for the application described here. The local

ramp-stinger coordinate system has its origin on the stern shoe,

X-axis positive direction from bow to stern and Z-axis vertical

with positive direction upwards, as indicated in Figure 17. The

geometric data of ramp and stinger are summarized in Tables 2

and 3, respectively.

The geometric data of the stinger structure are also used in

the definition of its contact surface. During the finite element

analysis the stinger is considered a rigid body connected to the

barge hull and all contact forces acting on it are transferred to

the barge. The hydrodynamic characteristics of the stinger are

incorporated at the barge hull model by its hydrodynamic

coefficients.

Figure 18 shows typical configurations for roller boxes on

the laybarge stinger and ramp, respectively.

Figure 16 – BGL-1, Ramp and Stinger Geometry

Figure 17 – Ramp/Stinger, Local Coordinate System.

Table 2 – Ramp – radius 150 mElement X (m) Z (m) Length (m)

Tensioner -56.335 1.550 -

Roller Box 1 -38.905 1.094 2.75 Roller Box 2 -26.574 0.768 2.75

Roller Box 3 -18.078 0.034 2.75 Roller Box 4 -9.292 -1.241 2.75

Roller Box 5 -0.432 -3.157 3.00

Table 3 – Stinger – radius 150 mElement X (m) Z (m) Offset (m) Length (m)

Roller Box 1 5.277 -4.632 0.687 4.00

Roller Box 2 9.094 -5.825 0.687 4.00 Roller Box 3 12.856 -7.156 0.694 4.00 Roller Box 4 16.586 -8.555 0.714 4.00 Roller Box 5 20.275 -10.099 0.748 4.00

Roller Box 6 23.882 -11.770 0.793 4.00 Roller Box 7 27.443 -13.581 0.850 4.00

Roller Box 8a 29.361 -15.198 0.919 -- Roller Box 8 30.883 -15.835 0.950 --

Figure 18 –Configuration of Rollers (Stinger and Ramp)

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As mentioned before, this configuration of the laybarge

ramp and stinger roller boxes can be easily and completely

customized by the new modules of the graphical interface of

the SITUA-PetroPipe system, as illustrated in Figures 19, 20and 21. A general view of the generated model for the BGL-1 is

shown in Figure 21.

Figure 19 – Ramp Configuration.

Figure 20 – Stinger Configuration.

Mooring Lines

The BGL-1 has eleven fairleads, but in usual operations

only nine or ten mooring lines are connected. All mooring lines

are composed by two segments, with characteristics presented

in Table 4. The length value for segment 2 corresponds to the

total length available on the winch drum; the released length

varies during the mooring operations, as presented in [15].

The catenary solver provides the results defining the

equilibrium configuration of the mooring system, and the

interference management module allows the identification of

several possible interferences with obstacles. All interferences

are successfully avoided by placing two buoys on most of the

lines. Detailed tables indicating position in the line measured

from the anchor, and the length of the pendant for each buoy,

can be found in [15].

Figure 21 – General View of the Generated Model

Table 4 – Characteristics of Mooring Line Segments

Segment Length (m) Material1 (anchor) 150 R3S Stub Chain 3”

2 1780 (max) EEIPS Steel Wirerope 2.5”

Pipeline All pipeline characteristics can be defined by the user. A

database with common material properties and usual pipeline

characteristics, such as wall thickness and coating, is

incorporated in the system. The model generated here considers

a typical 16-in pipeline, with physical and geometric properties

presented in Table 5.

Table 5 – 16-in Pipeline data

Parameter Value Unit

Outside Diameter 0.40640 mWall Thickness 0.011125 mYield Stress 414000 kN/m2

Modulus of Elasticity of steel 207000 MPa

Axial Stiffness (EA) 2859694.14 kNFlexional Stiffness (EI) 55894.90 kN*m2

Poisson Coefficient 0.3 -

Density of steel 77 kN/m3

Corrosion Coating Thickness 0.0032 mCorr. Coating Weight Density 9.32 kN/m3 Concrete Coating Thickness 0.0381 m

Concrete Coating Weight Density 21.974 kN/m3 Hydrodynamic Diameter 0.489 mTube Length 12 mField Joint Length 0.6 m

Joint Fill Weight Density 10.065 kN/m3 Weight in Air 2.255935 kN/mWeight Submerged 0.368493 kN/m

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Visualization of the Complete Model

The initial equilibrium configuration of the pipeline is

generated using dynamic relaxation techniques as proposed in

[22]. The top tension in the pipeline is the parameter thatdefines the “S” shape. The generated S-Lay configuration is

shown in the figures that follow.

The actual bathymetric data and soil properties are

considered for the pipeline behavior on seabed. Information

about free-spans is then available during analysis.

Figure 22 –S-Lay Model, Views of Initial Configuration

Typical Results

Figure 23 – Von Mises Stress (static).

Figure 24 – Von Mises Stress (dynamic).

Besides typical results in terms of tension and Von Mises

stresses along the pipe length, as shown in Figures 23 and 24,

information about distances between the pipeline and its

supports as well as the reaction at each roller box are generatedduring static and dynamic analyses.

Specific reports are automatic generated for relevant

information such as distance from the laybarge stern and the

pipeline touchdown point. Reports for all relevant information

about the mooring lines are also automatic generated.

FINAL REMARKS

The in-house computational system described in this work

has already been employed by the BGL-1 crew in the

simulation and planning of actual mooring procedures for

pipeline laying operations in Campos Basin. The system has

been shown to be able to calculate the motions of the barge due

to the operations performed with its mooring lines (including

placement of buoys, and variation of the onboard/released cable

lengths), taking into account general seabed data and

interferences with subsea obstacles.

Regarding the simulation of the actual pipeline launching

process, the Prosim finite-element numerical solver already

included a 3D frame element that can account for all material

and geometrically nonlinear effects that arise in the pipeline

behavior during the laying operation. It was also able to couple

the structural behavior of the pipe with the hydrodynamic

behavior of the vessel motions under environmental conditions,

considering all mooring lines also modeled by Finite Elements,

which in itself is a step further over traditional methods for the

numerical simulation of pipelaying operations.

In order to comprise an accurate and user-friendly

alternative for the analysis of pipeline installation procedures,

some adaptations in the SITUA interface and in the Prosim

numerical solver were needed.

Therefore, this work described some of the recent

implementations that comprise the SITUA-PetroPipe modules,

including: a) Generation of initial finite-element meshes for the

S-laying configuration of the pipeline by a dynamic relaxation

procedure; b) Inclusion of generalized scalar elements to

represent the tensioner; c) Implementation of automatic

customization facilities for the definition of the ramp and

stinger rollers; d) Development of a rigorous contact algorithm

to represent the variable contact between the pipeline and therollers; e) Generation of finite-element models for other types

of laying operations that may eventually be considered for the

BGL-1 or other laybarges, including J-lay and reeling methods.

Due to limitations in space, these latter facilities (regarding J-

Lay and Reeling procedures) could not be presented here, and

will be demonstrated in future works.

As the result of the recent implementations described in this

work, the SITUA-PetroPipe system now comprises a

computational tool intended to improve the applicability and

accuracy of analysis of pipeline installation operations, making

the simulations more realistic.

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Several parametric studies are currently being performed

considering the described modeling facilities, for different

scenarios including shallow to deep waters, and different

pipeline sizes. The results of these studies will also allow theprecise assessment of the influence of the application of the

coupled model (barge + mooring lines + pipeline) on the

dynamic pipeline-laybarge behavior in such different scenarios,

indicating where a coupled pipelay analysis, rather than a

traditional uncoupled analysis, is required.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the members of the

BGL-1 crew that actively contributed with the development of

the SITUA-PetroPipe software, with valuable comments and

suggestions.

REFERENCES

[1] Malahy Jr, R.C., "OffPipe User's Guide - Version 2.05",1996.

[2] Guo, B., Song, S., Chacko, J., Ghalambor, A., Offshore

Pipelines, United States, Elsevier, 2005.

[3] Kyriakides, S., Corona, E., Mechanics of Offshore

Pipelines, Volume 1: Buckling and Collapse, Slovenia,

Elsevier, 2007.

[4] Bai, Y., Bai Q., Subsea Pipelines and Risers, Great

Britain, Elsevier Science, 2d Ed edition, 2005.

[5] Clauss, G.F., Saroukh, A., Weede, H., “Prediction of

Limiting Sea States for Pipelaying Operations”. Procs of

the 17 th Int. Conf. on Offshore Mechanics and Arctic

Engineering, Lisbon, Portugal, 1998.

[6] Silva, D.M.L., Bahiense, R.A., Jacob, B.P., Torres,F.G.S., Medeiros, A.R., Costa, M.N.V., “Numerical

Simulation of Offshore Pipeline Installation by Lateral

Deflection Procedure”. Procs of the 26 st Int. Conf. on

Offshore Mechanics and Arctic Engineering, San Diego,

USA, 2007.

[7] Silva, D.M.L., Bahiense, R.A., Jacob, B.P., Torres, F.G.S,

Medeiros, A.R., “Analysis of an Alternative Pipeline

Installation Procedure that Combines Onshore Deflection

and Offshore Transportation”. Procs of the Marine

Operations Specialty Symposium, Singapore, 2008.

[8] Torselletti, E., Vitali, L., Bruschi, R., Levold, E.,

Collberg, L., “Submarine Pipeline Installation Joint

Industry Project: Global Response Analysis of PipelineDuring S-Laying”. Procs of the 25th Int. Conf. on Offshore

Mechanics and Arctic Engineering, Hamburg, Germany,

2006.

[9] Senra, S.F., Corrêa, F.N., Jacob, B.P., Mourelle, M.M.,

Masetti, I.Q., “Towards the Integration of Analysis and

Design of Mooring Systems and Risers: Part I — Studies

on a Semisubmersible Platform”. Procs of the 21st Int.

Conf. on Offshore Mechanics and Arctic Engineering,

Oslo, Norway, 2002.

[10] Ormberg, H., Fylling I. J., Larsen K., Sodahl N., “Coupled

Analysis of Vessel Motions and Mooring and Riser

System Dynamics”. Procs of the 16 th Int. Conf. on

Offshore Mechanics and Arctic Engineering, Yokohama,

Japan, 1997.

[11] Wichers, J.E.W., Devlin, P.V. “Effect of Coupling of

Mooring Lines and Risers on the Design Values for aTurret Moored FPSO in Deep Water of the Gulf of

Mexico”. Procs. of the 11th Intl. Offshore and Polar

Engineering Conference, Stavanger, Norway, 2001.

[12] Heurtier, J.M., Buhan, P.Le, Fontaine, E., Cunff, C.L.,

Biolley, F., Berhault, C., “Coupled Dynamic Response of

Moored FPSO with Risers”. Procs. of the 11th Intl

Offshore and Polar Engineering Conference, Stavanger,

Norway, 2001.

[13] Jacob, B.P., Masetti, I.Q., “Prosim: Coupled Numerical

Simulation of the Behavior of Moored Units” (in

Portuguese), COPPETEC-Petrobras Internal Report, Rio

de Janeiro, 1997.

[14] Jacob, B.P., “Prosim Program: Coupled Numerical

Simulation of the Behavior of Moored Floating Units –

Theoretical Manual, ver. 3.0” (in Portuguese),

LAMCSO/PEC/COPPE, Rio de Janeiro, 2005.

[15] Masetti, I.Q., Barros, C.R.M., Jacob, B.P., Albrecht, C.H.,

Lima, B.S.L.P., Sparano, J.V., “Numerical Simulation of

the Mooring Procedures of the BGL-1 Pipeline Launching

Barge”. Procs of the 23st

Int. Conf. on Offshore Mechanics

and Arctic Engineering, Vancouver, Canada, 2004.

[16] SGO User Manual (in Portuguese) – Petrobras, Rio de

Janeiro, 2002.

[17] Saevik, S., Giertsen, E., Bernten, V., “Advances in Design

and Installation Analysis of Pipelines in Congested Areas

with Rough Seabed Topography”. Procs of the 23rd Int.

Conf. on Offshore Mechanics and Arctic Engineering,Vancouver, Canada, 2004.

[18] Michalopoulos, C.D. “Nonlinear Random Response of

Marine Pipelines in Contact with the Seabed”.

Proceedings of the 5th

Int. Conf. on Offshore Mechanics

and Arctic Engineering, Tokyo, Japan, 1986.

[19] Silva, D.M.L., Corrêa, F.N., Jacob, B.P., “A Generalized

Contact Model for Nonlinear Dynamic Analysis of

Floating Offshore Systems”, Procs of the 25st

Int. Conf. on

Offshore Mechanics and Arctic Engineering, Hamburg,

Germany, 2006.

[20] Grealish, F., Lang, D., Connolly, A., Lane, M., “Advances

in Contact Modelling for Simulation of Deepwater

pipeline Installation”, Rio Pipeline Conference &Exposition, Rio de Janeiro, Brazil, 2005.

[21] Silva, D.M.L., Pereira, A.C.P., Jacob, B.P., “A Contact

Model for the Simulation of Line Collision in Offshore

Oil Exploitation”, Procs of the XXVIII Latin American

Congress on Computational Methods in Engineering,

Port, Portugal, 2007.

[22] Silva, D.M.L., Jacob, B.P., Rodrigues, M.V., “Implicit

and Explicit Implemetation of the Dynamic Relaxation

Method for the Definition of Initial Equilibrium

Configurations of Flexible Lines”. Procs of the 25st Int.

Conf. on Offshore Mechanics and Arctic Engineering,

Hamburg, Germany, 2006.

Documents

IPC2008-64251