Marine Survey & Cable Routing

Transcription

1 Marine Survey & Cable Routing Sub Optic 2004 Short Course Ron RAPP, Mark LAWRENCE, Dick BORWICK, Takuo KUWABARA

2 Topics Introduction/Objectives/Project Cycle Ron Rapp Desktop Study and Cable Route Study Mark Lawrence Routing & Cable Engineering General Guidelines Takuo Kuwabara Landing site selection Cable routing considerations Armor selection Burial Requirements Installation and Maintenance Considerations Dick Borwick Alter courses Laybacks Touchdowns and offsets Cable crossings Documentation/Charting, Tools, Databases, (GIS) Ron Rapp Summary/Questions All Introduction

3 Introduction & Objectives Course to focus on Marine Route Selection and Cable Engineering (not Surveying techniques) Intended audience are cable owners with some understanding of the route engineering Objectives of the Course: How route selection and cable selection evolves from the bid process to what is finally installed. How the route selection and engineering fits into the overall project. Importance and element of the Cable Route Study/ Desktop Study. General guidelines for selecting landings, routes, armor, burial Examples of impact of route engineering on Installers and Maintainers. Importance of documentation and use of common databases through the process Tools for route engineering Opportunity for discussion and questions with SCIG members Introduction

4 What is the SCIG? Informal forum of several major industry suppliers Emphasis on Installation and Maintenance Complementary to the ICPC Scope includes areas of mutual benefit for our customers and the industry as a whole SCIG Members Alcatel Submarine Networks Global Marine Systems Limited KDDI Submarine Cable Systems Tyco Telecommunications Introduction

5 SCIG Mission To develop cost-effective approaches and solutions to improve cable reliability and to communicate these to relevant international parties Introduction

6 Marine Project Cycle Proposal Desktop Study Route Survey Cable Engineering Recent Recent projects, projects, with with tight tight schedules, schedules, have have begun begun cable cable manufacturing manufacturing based based on on Desktop Desktop Study Study (or (or earlier) earlier) routing routing and and cable cable engineering. engineering. Route Route survey survey data data is is then then used used for for route route and and cable cable verification verification and and for for installation installation support support Permits & Marine Liaison Cable Manufacture & Integration Vessel Load Cable Manufacture & Integration More Recent Projects Traditional Model Client Route Working Group Meeting Client Client Approval Approval for for route route and and SLD SLD Installation Final Documentation Maintenance

7 Key elements for success The marine activities form a critical part of the overall project implementation, ensuring the provision of a reliable and secure submarine link. The key elements to ensure success are: A thorough Cable Route Study Accurate data acquisition during the Route Survey Detailed analysis of survey data leading to optimum route planning and cable engineering Effective installation and burial of the cable Introduction

8 Key elements for success Installers are able to address these key elements as follows: Cable Route Planning considerable experience in the planning of cable systems worldwide Route Survey data acquisition leading the cable survey industry standards through the introduction of seabed imagery and digital terrain modelling Route & cable engineering utilising specialist software such as: Makai Plan Use of the latest, state of the art, purpose built cable ships and cable ploughs Introduction

9 Desktop Study & Cable Route Study

10 Cable Route Study A detailed Cable Route Study (CRS) will be carried out, to allow a safe and economic route for the cable, to include the following: Visits to Landing Sites Local Authorities, Representatives of other industries (e.g. fishing, shipping, petrochemical) Identification of permits, licences and other regulatory items Investigation of environmental & cultural aspects Identification of all sources of risk to cable Produce recommendations for a secure cable route (provisional cable protection & burial) Desktop/Cable Route Study/

11 Cable Route Study The information within the CRS is derived from existing data sources and concentrates primarily on potential hazards. The study includes: Pre-Survey Route Position List (RPL) Seafloor Morphology and Geology Natural Hazards e.g. Seismic events, submarine volcanism Oceanography and Meteorology Human Activities e.g., mineral extraction, oil & gas, fishing Man-Made Hazards e.g. anchoring, dredging Other cables/pipelines/lease blocks Desktop/Cable Route Study/

12 Cable Route Study Seafloor Morphology & Geology Coastal areas Continental shelf Abyssal Plains Continental Slope Continental Rise Ocean Ridges Ocean Trenches Desktop/Cable Route Study/

13 Cable Route Study 5.5 C Average Winter Seabed Temperatures around the UK 16.5 C Average Summer Seabed Temperatures around the UK Desktop/Cable Route Study/

14 Cable Route Study Natural Hazards Earthquake activity around the Pacific/Asia/Philippines plate boundaries Caption? Desktop/Cable Route Study/

15 Human Activities External causes of cable faults in the Atlantic Suspensions 5% Cableship activity 1% Earthquake or sediment Others 18% 3% Anchor 18% Fish bite 2% Dredging/drilling/pipe installation1% Fishing Activity 52% Human Activities account for over 75% of cable faults Desktop/Cable Route Study/

16 Routing & Cable Engineering General Guidelines

17 General Guidelines Landing site selection Cable routing considerations Cable Protection Armor selection Burial General Guidelines

18 Decision of Cable Landing Station Consideration of Cable Landing Station Floor space for terminal equipment, facilities and office for maintenance staff, etc Connectivity to back haul network Access for construction and future maintenance Approach to the cable landing site Land cable route Electronic/magnetic interference General Guidelines

19 Cable Landing Site Selection Suitable for cable landing/installation operation cable laying ship can easily access to the beach access for beach works and usage of heavy machinery seabed topography, material and condition close parallels/crossing to other cables, pipelines Low risk of fishing activity, anchoring, dredging, mining Regulation, permission issues national park, coastal reserves, etc. General Guidelines

20 Cable Routing Considerations Avoid crossing of other cable/pipeline as far as possible Shortest possible cable route Avoid unnecessary alter courses Sea bottom sediment should preferably be sandy or muddy, but not rocky Avoid steep slopes (less than 20º for surface laying) and crossing steep slope Easier subsequent cable installation and removal of the existing cable Maximise the utilization of the available space General Guidelines

21 Some of the issues to be considered for Route Engineering Some specific areas no longer have suitable seabed How we can expand possible seabed for new cables? Developing reliable cable repair techniques for congested areas Cable route recycle New/Local agreement, guidelines General Guidelines

22 Selection of Cable Protection Cable protection certainty Armoring low protection, high certainty of availability increasing a chance of cable surviving for cable life Burying high protection, but reduced certainty of availability reducing certainty of burial protection by various seabed composition and sediment movement Increasing the armoring level at the route engineering stage where burial protection certainty is low General Guidelines

23 Armor Selection Factors of armor selection water depth for a cable recovery threat and hazard what burial possible burial depth (level of requirement and achievement) burial method, tool soil condition Type of armor armor wire (LWA, SA, DA, RA, etc.) metallic screen/strengthen jacket (LWP, LWS, SPA, etc.) armoring post cable manufacturing duct, articulated pipe, etc. General Guidelines

24 Installation & Maintenance Considerations [ What the Owners don t know about and the Surveyors don t care about!!! ]

25 Alter Courses Size of an Alter Course The frequency of A/Cs Layback Cable touchdown Run-ins/ Run outs the Touchdown Offset consideration Cable Crossings Close to Repeaters Close to Branching units Multiple crossings Other Useful hints Considerations

26 Size of an Alter Course Typical limits are: Maximum 15 for plough buried sections Maximum 15 for PLIB buried sections Maximum 25 in surface laid areas Considerations

27 The frequency of A/Cs In shallow water (less than 100m): A/C s should be minimum 250 metres apart In deeper water depths (100 to 1000m): A/C s should be minimum 300 metres apart In deep water (>1000m): A/C s should, where-ever possible be 2 x water depth apart Considerations

28 Layback Cable touchdown Layback Distance (kilometres) ,000 Depth of water (metres) 2,000 3,000 4,000 5,000 6,000 0km/hr [0kts] 2km/hr [1.08kts] 4km/hr [2.16kts] 6km/hr [3.24kts] 8km/hr [4.32kts] 10km/hr [5.40kts] 12km/hr [6.48kts] Calculated using generic LW cable Considerations

29 Run-ins / Run outs A sharp Alter Course just before entering and just after exiting a narrow cable corridor between two seabed features results in: Potential cutting of corners across the hazard Resulting in Damage = SYSTEM DOWNTIME = ADDITIONAL COST Significant period of slow laying to reduce cable layback and thus increase accuracy of touchdown Resulting in Longer duration of installation = ADDITONAL COST Considerations

30 Touchdown Offset consideration [Cutting corners] Modified route Original Route Considerations

31 Cable Crossings Close to repeaters Separation to be three times the depth of water This will ensure that the repeater can be recovered, without endangering the crossing cable Close to branching units Main Trunk Leg Separation to be three times the depth of water Branching Leg - Separation to be four times the depth of water This allows for a cutting drive, a holding drive and buoying off the cable Multi Crossing Points Help to reduce cable congestion and reduce the total number of crossings Multiple crossings can drastically reduce the length of sterilised or unrecoverable cable in deep water scenarios if a fault occurs. Considerations

32 Cable Crossings to Reduce Congestion SCIG Recommendations for Triple Crossing has been incorporated into the ICPC cable crossing recommendations (Issue 7 - May ) Triple Crossing Considerations

33 Other useful hints Be aware of Steep slopes for ploughing Don t have uneconomic distances for ploughing Don t have more A/Cs in shore ends than is really necessary Frequent Slack changes are unrealistic Beware of the optimum direction of lay. Don t have multiple RPL points Ensure armour change positions allow for adequate cable strength for a cable recovery Considerations

34 Summary There is more to planning a cable route than just finding a suitable geological and hydrographically friendly cable corridor. Remember that someone actually has to lay the cable Considerations

35 Documentation/Charting, Tools, Databases, GIS

36 Documentation/Charting, Tools, Databases, (GIS) Cable Engineering and Survey Documentation Straight Line Diagrams (SLD) Route Position Lists (RPL) Survey Charts (Bathymetry, Geomorphology) Obstruction Reports/Crossing Matrix Burial Feasibility Study (Cores/CPT data, Sub bottom Profile) Route Planning Tools Databases and Geographic Information System Cable database critical to determine cable crossings Documentation

37 Straight Line Diagram (SLD) Toyoashi BMH (+) DA-GP LWA-GP SPA LWA-GP SPA LW SPA LW SPA SPA LW SPA LW SPA LWA-GP DA-GP Piti BMH (-) The SLD is established during the preliminary route planning in the bid and proposal phase and usually becomes the contract baseline for the cable deliverables. The SLD is refined through the DTS and Route survey. It becomes the manufacturing drawing Documentation

38 Route Position Lists TGN Pacific Segment G2 Toyohashi, Japan to Piti, Guam Issue: 7 Engr: ADB/GRT/VAN Date: 06-Dec-01 Route Distance Cable Distance Cable Pos Latitude Longitude Depth Heading Course Between Total Slack Between Total Span Cable Comments Auto Label No. (m) Change (km) (km) (%) (km) (km) (km) Type Label Provisional landing 0 N E BMH;DA-GP Toyohashi; Japan DA-GP 1 N E AC DA-GP 2 N E Plowing Begins Plow Event DA-GP 3 N E AC DA-GP 4 N E AC DA-GP 5 N E AC DA-GP 6 N E Plow Up PLUP Slack Change DA-GP Crosses JIH Segs 1 and 2 7 N E Cable Crossing 62 deg DA-GP 8 N E Plow Down PLDN Slack Change DA-GP Bury The Route Position List forms the basis for all route planning, permit applications, cable crossings, installation planning and cable manufacturing Documentation

39 As Laid Chart Traditional NorthUP Documentation

40 Marine Chart Overview Chart outlines are established along the route Documentation

41 Route Planning Tools - MakaiPlan Allows you to load: Regional shoreline Bathymetric data Survey data as it becomes available. Create cable routes: Point and drag Entering precise coordinate points Reading an existing RPL Letting MakaiPlan automatically route you along a great circle route in a series of Rhumb lines Documentation

42 Route Planning Tools - MakaiPlan Computes the bottom profile along the selected route Profiles are displayed and slopes are computed Required cable length is computed based on specified bottom slack Allows zooming and panning along the route in both the plan and profile views Documentation

43 Route Planning Tools - MakaiPlan SLD and RPL generated from same data. Errors are minimized. An RPL can be edited, exported, reversed or split into separate cable lays. Documentation

44 GIS Based Charting Data is continuous over the route rather than cut into chart rectangles. User can zoom to area of interest. Web based viewers make data accessible to a wide array of users. Documentation

45 Documentation Summary The route survey charts/data will become the as-laid charts/data that follow the system through its life Key to the maintenance authority. A complete, accurate, and consistent specification for chart data and layering convention in the route survey contract deliverable is crucial. Agreement with client on as-laid charts (NorthUp, alignment) format must be established early. Documentation

46 Summary Reliable and cost effective Route and Cable Engineering is crucial to the project success and future maintenance needs. A complete and thorough Desktop Study is a fundamental building block of the project Client contracted DTS and Marine Survey should be to specification of the supply contractor to insure data compatibility If schedules requires that cable type decisions to be made prior to route survey completion, then risk must be understood and accepted. Landing site selection, safe and efficient routing, and cable protection guidelines provide for consistent engineering Route planning and engineering for efficient Installation and Maintenance of the system is critical Route Survey data formats for charts must be established early since they form the basis of the as laid final record

47 Marine Survey & Cable Routing Sub Optic 2004 Short Course Ron RAPP, Mark LAWRENCE, Dick BORWICK, Takuo KUWABARA