Post on 18-Feb-2022
Offshore Platforms Sizing Offshore Platforms Sizing Optimization through Genetic Optimization through Genetic
Algorithms Algorithms
Mauro Costa de OliveiraMauro Costa de OliveiraPetrobrasPetrobras
DeepDeep WaterWater FloatingFloating ProductionProductionSystemSystem
HowHow to to selectselect thethe bestbestdimensionsdimensions//shapeshape for for thethe floaterfloater??
BestBest PlatformPlatform ShapeShape andandDimensionsDimensions
BestBest PlatformPlatform ShapeShape andandDimensionsDimensions
BestBest PlatformPlatform ShapeShape andandDimensionsDimensions
DeepDeep WaterWater FloatingFloating ProductionProductionSystemSystem PlatformPlatform Design Design BasisBasis
DeepDeep WaterWater FieldField ScenarioScenario–– OilOil CharacteristicsCharacteristics–– EnvironmentEnvironment, , SoilSoil–– InfrastructureInfrastructure
ProcessProcess PlantPlant CharacteristicsCharacteristicsSubseaSubsea SystemSystem InterfaceInterfaceBuilding RequirementsBuilding RequirementsRules and RegulationsRules and Regulations
Design Design ProcessProcess
Selection of the main dimensions of a deep water Selection of the main dimensions of a deep water floating production system can be an exhaustive floating production system can be an exhaustive trial and error exercise;trial and error exercise;
A rational approach to guide the designer in this A rational approach to guide the designer in this search can be very usefulsearch can be very useful
Develop an organized searching processDevelop an organized searching process
MainMain Design Design ParametersParameters
ProcessProcess plantplant weightweight andand areaarea;;SubseaSubsea SystemSystem Interface;Interface;StabilityStability;;MotionsMotions (SCR);(SCR);BuildingBuilding//InstallationInstallation ConstraintsConstraints;;Internal Compartments Volume and Internal Compartments Volume and Distribution;Distribution;
ProcessProcess PlantPlant AreaArea andandArrangementArrangement
WeightWeight
BuildingBuilding ConstraintsConstraintsQuayQuay ConditionsConditions
BuildingBuilding ConstraintsConstraintsDeckDeck MatingMating
Transit ConditionTransit Condition
SubseaSubsea SystemSystem InterfaceInterface
SubseaSubsea Interface Interface SteelSteel CatenaryCatenary RiserRiser
Sea BedSea Bed
PLEMPLEMFlowlineFlowlineSCRSCR
Flex JointFlex Joint
Wat
er D
epth
Wat
er D
epth
StabilityStability
InitialInitial StabilityStability –– MetacentricMetacentricHeightHeight (GM)(GM)IMO CriteriaIMO Criteria
MotionsMotions in in WavesWaves
Fatigue Fatigue SeaSea States States SteelSteel CatenaryCatenary RisersRisers
point wave direction case
(from where it comes)Hs(m) Tp(s) alfa gama of vertical motion(m)P1 south 2.75 11.71 0.0019 1.16 02s05aP2 south 2.75 11.71 0.0019 1.16 02s05aP3 south 2.75 11.71 0.0019 1.16 02s05aP4 south 2.75 11.71 0.0019 1.16 02s05aP5 south 2.75 11.71 0.0019 1.16 02s05aP6 south 2.75 11.71 0.0019 1.16 02s05aP7 south 2.75 11.71 0.0019 1.16 02s05aP8 south 2.75 11.71 0.0019 1.16 02s05a
0.20560.17680.180.18
seastate category #1 - fatigue medium swellwave data (Jonswap spectrum) max. standard deviation
0.20560.20560.17680.1768
P1 P5
P6 P3
P7
P3
P2
P2
P1
P8
P4P4
NORTH
P1 P5
P6 P3
P7
P3
P2
P2
P1
P8
P4P4
NORTH
InternalInternal CompartmentsCompartments
BallastBallast AmountAmountEquilibriumEquilibrium in in ParallelParallel DraftDraft
Some Some AlternativesAlternatives to to SelectSelect thetheBestBest DesignDesign
““Manual” Evaluation of Some DesignsManual” Evaluation of Some Designs
AutomaticAutomatic GenerationGeneration ofof SeveralSeveral DesignsDesigns–– DrawDraw backback: : UnfeasibleUnfeasible designsdesigns–– AnalysisAnalysis andand selectionselection ofof thethe datadata
OptimizationOptimization–– GeneticGenetic AlgorithmsAlgorithms
Performance Performance TestsTests
SCR Fatigue Motions < Fixed
LimitsHydrodynamic
GM > 0.0 mGM > 0.3 mGM > 2.0 mInitial Stability
Parallel Draft
Equilibrium
Parallel Draft
Equilibrium
Parallel Draft Equilibrium /
Volume of Ballast > 15% of the Displacement
Loading Cond. / Ballast
Quay Condition
Transit Condition
Operation Condition
OptimizationOptimization ProcedureProcedure
Tool used to carry out the optimization process Tool used to carry out the optimization process was the program was the program ModeFrontierModeFrontier from ESTECOfrom ESTECO;;Genetic Algorithm Genetic Algorithm NSGANSGA--II scheduler;II scheduler;Develop a prescribed number of generations Develop a prescribed number of generations with a fixed number of memberswith a fixed number of members;;CoupleCouple thethe geneticgenetic algorithmalgorithm withwith thethe analysisanalysisprogramsprograms;;
OptimizationOptimization ProcedureProcedure
INPUT DATA
STABILITY ANALYSIS
OUTPUT DATA
MOTION ANALYSIS
OptimizationOptimization ProcedureProcedureInput Input VariablesVariables
OptimizationOptimization ProcedureProcedureInput Input VariablesVariables
2.517400Platform Heading related to NorthHEADING (degrees)
0.2764025DraftDRAFT (m)
2.497252.8Length of Transv and
Longit Pontoons between columns
LONG_PONTOON_LENGTH
(m)
0.626216Pontoon HeightPONTOON_DEPTH(m)
0.630279.6Longit Pontoon and Column Breadth
LONGIT_BREADTH(m)
StepBaseUpperBound
LowerBoundDescriptionName
ConstraintsConstraints
Dimensions / Volume / Quayside Draft
52.7GreaterMinimum Pontoon Length95LesserMaximum Total Length70GreaterMinimum Total Length
84500LesserMaximum Displacement0.32LesserMaximum Amount of Ballast0.18GreaterMinimum Amount of Ballast
0.5GreaterMinimum Freeboard in Quay Condition
11LesserMaximum Quay Draft
ConstraintsConstraints
Minimum GMt / GMl
0.3GreaterTransit Condition1GreaterQuay Condition
1.9GreaterOperating Condition
ConstraintsConstraints
Maximum Vertical Motion at SCR Connection Points
0.321LesserP1B Sea 3.75 m 12.08 s
0.23LesserP2A Sea 2.75 m 11.71 s0.23LesserP2B Sea 2.75 m 11.71 s
0.321LesserP1A Sea 3.75 m 12.08 s
0.321LesserP2A Sea 4.25 m 11.70 s
0.23LesserP1B Sea 2.75 m 11.71 s
0.23LesserP1A Sea 2.75 m 11.71 s
ObjectivesObjectives
The minimization of the vertical motion RMS The minimization of the vertical motion RMS in points P1A and P3 with the south and in points P1A and P3 with the south and southwest sea statessouthwest sea states
P1 P5
P6 P3
P7
P3
P2
P2
P1
P8
P4P4
NORTH
P1 P5
P6 P3
P7
P3
P2
P2
P1
P8
P4P4
NORTH
SummarySummary
1.1. Define 5 input variablesDefine 5 input variables2.2. Generate the hull, internal compartments, lightweight Generate the hull, internal compartments, lightweight
and variables loadsand variables loads3.3. Evaluate Quay Condition Equilibrium and Initial StabilityEvaluate Quay Condition Equilibrium and Initial Stability4.4. Evaluate Transit Condition Equilibrium and Initial Evaluate Transit Condition Equilibrium and Initial
StabilityStability5.5. Evaluate Operating Condition Equilibrium and Initial Evaluate Operating Condition Equilibrium and Initial
StabilityStability6.6. Evaluate Extreme Motions and Fatigue MotionsEvaluate Extreme Motions and Fatigue Motions7.7. Extract Output DataExtract Output Data8.8. Return to the BeginningReturn to the Beginning
ResultsResults5046 designs generated;5046 designs generated;672 different ones;672 different ones;35 feasible;35 feasible;563 unfeasible;563 unfeasible;74 failed in the equilibrium;74 failed in the equilibrium;
ResultsResults
ResultsResults
ResultsResults
ResultsResults
0HEADING (degrees)
36.4DRAFT (m)
52.8LONG_PONTOON_LENGTH (m)
9.6PONTOON_DEPTH (m)
18LONGIT_BREADTH (m)
ValueInput Variables
ResultsResults
ResultsResults
24698.81Steel Structure WeightSTEEL WEIGHT (t)12.08Buoyancy HeightKB (m)28.48Height of CoGKG (m)
84458.77DisplacementDISPLACEMENT (t)0.226Ballast AmountBALLAST (%)88.8Total LengthTOTAL_LENGTH (m)2.52Oper GM LongitGM_LONG (m)
0Oper HeelHEEL (degree)0Oper TrimTRIM (degree)
2.52Oper GM TransvGM_TRANS (m)
ValueDescriptionOutput Variables
ConclusionConclusion
Optimization Procedure is Feasible to Use in the Optimization Procedure is Feasible to Use in the Selection of Main Dimensions of a Deep Water Selection of Main Dimensions of a Deep Water FloaterFloaterFurther questions:Further questions:
Mauro Costa de OliveiraMauro Costa de Oliveira((mauro@petrobras.com.brmauro@petrobras.com.br))
Thank youThank you