441
1 INTRODUCTION
During last years the demand for natural resources
rapidly increased. In addition to landbased sources
the submarine deposits are exploited intensively. In
parallelwiththeextractionofseabasinsresourcesthe
renewableenergysourcesarebuiltandexploitedon
the sea. These facts necessitate the transfer of
hydrocarbons and energy ashore. Under the bottom
ofthesea,numerousnetworksofpipelinesandcables
have been laid. Technological development allows
layingpipelinesandcablesontheevergreaterdepths
and the int
ensification of exploration and extraction
materialsfromunderbottomdepositsresultedina
significant increase in the amount of undersea
i
nfrastructure. China, for example, have a 3000 km
undersea pipelines and in the next decade are
planning to triple the length of this infrastructure.
Linkedtothisfactitrisestheproblemofthesafetyof
such structures and the safety of the marine
environment at risk of failure or damage. Statistical
data indicat
e that a significant threat to underwater
pipelines is the ships traffic especiallywith it the
riskofdamagebytheanchorsordirectlythehullhit.
Other dominant factors of damage underwater
infrastructure arefalling objects from oil rigs and
shipsduringcargoandsparepa
rtstransshipmentand
pipelines corrosion. The statistics of damage to
offshoresectorpipelinesaregatheredinthePARLOC
2001database.Dataarecollectedinyears1960‐2003
andconcernpipelinesintheNorthSea.Thedatabase
includes 1,567pipelines witha total length of 24837
km.
2 LITERATUREREVIEW
Risk of the offshore i
nfrastructure damageis very
important issue for companies operating the oil and
gas fields as well for the classification societies and
safety institutions which create rules and
recommendations for them. They can be found for
example in Det Norske Veritas or HSE
recommendations[1],[2],[3],[5].Moreover,thereare
scient
ific researches concerning safety and risk
assessmentinareaoftheriskforunderwaterpipeline
systems. Authors continue research contained in
Criteria of Accidental Damage by Ships Anchors of
Subsea Gas Pipeline in the Gdańsk Bay Area
K.Marcjan,R.Dzikowski&M.Bilewski
M
aritimeUniversityofSzczecin,Szczecin,Poland
ABSTRACT:Thispaperdiscussesissuesoftheaccidentalanchordamagetooffshoresubseapipelineasoneof
themostsignificantthreattounderwaterinfrastructure.Thedensityofvesseltrafficoverthepipelinebetween
platform Baltic Beta and Wladyslawowo power plant has been analyzed. In order to determine the most
common damages associated with heavy ship t
raffic, the authors used the risk model for underwater
infrastructure.Forthispurposeshipsanchorequipmenthasbeencategorizedandastheresultsthecriteriaof
damagetothepipelinehavebeendiscussed.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 3
September 2017
DOI:10.12716/1001.11.03.07
442
papers [6], [7] for systems situated in the Polish
economiczone.
Figure1.Underwater pipeline damage statistic. Data from
PARLOC2001database
DatabasePARLOC2001groupsthemostcommon
causes of damage to the: damage by anchors of
vessels passing above the pipeline, hit by the shipʹs
hull,corrosion,technicaldefects,defectsinmaterials,
natural hazards, structural defects, technical
maintenance, human error, operational problems,
others.Fig.1.
DNVGLclassificationsocietyobservedincreasing
amount of the lost and dragged anchors. In Fig. 2
thereisthestatisticoflostanchors.
Figure2.Anchorlostper100shipyear.DatafromDNVGL
Scenarios of the subsea pipelines system risk
assessment should take into consideration the
following factors: vessels passing the pipeline,
including oil rig support ships (supply vessels,
floating cranes, ships, surveillance and diving
vessels), merchant ships and ferries, fishing vessels.
Byassumingemergencysituations,thereshouldbe
consideredsituationsofemergencyanchors
dropping
or dragging (important data aretype and weight of
anchors) and bottom trawling (network type, trawl
thrust)aswellasthecharacteristicsofthepipeline:
thetype(steel,flexible),thedepthofthebasin,deep
depressions in the ground, pipeline diameter, wall
thicknessandpipelagging.Modelofrisk
assesement
is presented in Fig. 3. To analyse the damage
importantistocheckifthedredgedanchorsareable
tocatchthepipelinesystem,whatisanalysiedinthis
paper.
Figure3.Modeloftheriskanalysisforoffshorepipeline
3 OFFSHOREACTIVITIESINTHEPOLAND’S
ECONOMICZONE
The exploitation of underwater resources by Polish
companiestakesplaceinPolandʹseconomiczone.In
the complex process of subsea exploitation, the
extraction of oil and/or gas is oneof the last stages.
Startingfromthedevelopmentofageologicalmodel
of
productionsitesmakinguseofgeophysicalsurvey,
the operations include the assembly and fixing of
drilling and production platforms and underwater
systems of pipelines and networks, seaborne
transport of hydrocarbons to land,movement of
drilling rigs to new locations and periodical
reconstruction of existing wells.Given below are
upstream activities
related to the oil and gas
production and operation and maintenance of
existingwellslocatedinthePolisheconomiczone:
1 explorationisperformedby:
seismic reflection survey vessels Polar Duke
andSt.Barbarathatcarryout3Dseismicsurvey
withinthelicensedareaofexplorationinfields
B21and
B16(Fig.4),anddrillingofexploration
holes.
drilling holes for geophysical survey and
measurements,executedbyPetrobaltic,Lotos
Petrobalticrigs.
2 productionperformedbyvarioustypesofrigs:
jackupstationaryproductionrigs,
jackupmobiledrillingrigs,
jacketstationaryunmannedproductionrigs.
3 exploration
andexploitationwellsareestablished
inlicensedareas;exploitationwellsareusedfor
oil and gas extraction as well as injection of
depositwaterandseawaterfilteredtooptimizethe
production.
4 transfer of gas via an underwater pipeline to
Wladyslawowo.
Anchors/trawl/hull
empiricimpactmodel
Pipelinesystem
description
AISTraffic
information
VMS‐fishing
vesselstraffic
Information
Accidentsdatabase
Tolerablerisk
citeria
Shippingdata
analysis
(FEM)FiniteElementMethod
pipelinedamageevaluation
Pipelineis
threatened?
ON
Impactstudy
consequencemodel