Benefits of Proper Route Engineering to Mitigate Risk During the Design Life of Submarine Cable Systems

Transcription

1 Benefits of Proper Route Engineering to Mitigate Risk During the Design Life of Submarine Cable Systems Simon Cooper TATA Communications International Gordon Lucas Alcatel-Lucent Submarine Networks Ron Rapp TE SubCom Graham Evans EGS Survey Group

2 Agenda Critical Infrastructure Consequence of Cable Outage Real Cost of Ownership Route Planning Tools and Risk Identification Physical and Political Routing Constraints Marine Route Survey Cable Protection and Installation Maintenance Considerations

3 Concept to Reality Key Phases Development of Business Model Definition of Key Project Milestones Project Concept & Initial Investors Feasibility Study & Initial Engineering Define Permitting Requirements Formation of Interim Management Team Pre Survey Desk Study Secure System Permits in Principle Supply Contract Processes Route Survey & Burial Assessment Marine Operations Permitting Route Survey Contract Process System Installation

4 Topics for A Submarine Cable Planning Discussion

5 Why are Submarine Cables important? International Commerce Freedom of Communication Information Sharing Lowest Cost Solution Sustainable and Footprint Lite

6 What do you want from your route? (Oh, and what don t you want?) Diversity versus Latency Market Coverage versus Permitting Complexity Risk & USP s versus Known & Me Too Big Enough versus Biggest Ever New Technology versus The Proven Local Factors versus Network Integration

7 The TGN Intra-Asia System TGN-Pacific (Japan Guam) is an existing system Singapore Vietnam Hong Kong Philippines Japan

8 TGN-IA s Resilient Architecture

9 Early Life Information

10 TGN-Intra Asia: The Re-Route

11 Total Cost of Ownership TCO translates to: What will you have to spend and when? A high quality Desk Top Survey High value $$ If it drives the survey PoW and Rt Eng pre-planning The Survey Who represents you? What are the goals and acceptable compromises? How to reduce the TCO? Cable Armour that may reduce repair volume: obvious value? Deep burial: can you afford not to? Deep water: who cares? Project Costs: Plan, Predict and Keep Under Control Future Costs: Replacement, Marine Ops, Reputation & Revenue

12 Route Planning Tools Use of a GIS based system is essential and facilitates the display of key information Existing in service and out of service cables Planned systems system deconfliction! Maritime boundaries, navigation charts and coastal data Sea bed assets associated with offshore energy Concession blocks Restricted areas such as marine parks, areas of SSI General seabed bathymetry and other survey data sets Marine Route Survey results

13 Risk Identification A thorough Cable Route Study (DTS) is crucial A comprehensive study of all potential threats: Fishing, anchoring, mineral extraction, slopes, seismic etc Fault histories of nearby cables and their status Landing point selection Influenced by risk and not by infrastructure or real estate Typical issues include crossing reefs in the surf zone, proximity to charted anchorages, high energy beaches Route Diversity from potential restoration cables Avoid areas of known seismic activity (fault histories) Political risk: permit lead times for repairs

14 Risk Mitigation It may not be possible to route away from all risks Engineer the system with appropriate protection In shallow water bury the cable or up-armour In deep water increase protection (LWP,DWP) Increase burial depth according to seabed type Deep burial in selected high risk areas Exploit the potential of available tools Increase near-shore protection Horizontal directional drilling (HDD) Articulated pipe and pinning

15 Physical Routing Constraints 15

16 Physical Routing Constraints Pattern of Single Fault Incidents Multiple Fault Incidents Single Faults widespread but manageable Multiple Faults in choke points and critical 16

17 Physical Routing Constraints Landing points Proximity to cable station and terrestrial infrastructure Established cable corridors usually preferred except when diversity is important Low energy, stable beach not prone to erosion Direct landing from a cable ship preferred (15m WD < 2km)depending on currents and seabed. Access for shore end team and equipment to land the cable Route perpendicular to beach (allows more cables, shortest distance to deepwater) Avoid anchorage, harbor, dredging, environmentally sensitive areas Shelf routing Lowest fishing and anchoring risk; avoid hydrocarbon lease blocks and dredging Short distance to deepwater to minimize armor, burial and risk. Avoid rocky, abrasive seabed Find route suitable for burial if external aggression is a risk Suitable distance from active cables, crossing near 90 deg; congestion is often an issue. Limit alter course angle to 15 deg in burial, economic distance between PLUP & PLDN. 17

18 Physical Routing Constraints 18

19 conference & convention Physical Routing Illustrated 19

20 Physical Routing Constraints (Cont) Deepwater routing Great circle for shortest cable length Look for smooth flat seabed away from slopes and seamounts, avoid steep slopes and side slopes Keep suitable distance (2 x WD min) from active cables; congestion often also in deep water Avoid crossings to extent possible, cable crossing angles > 45 deg, cross away from other cable repeaters Avoid abrasive seabed and currents, use of SPA cable is such area Prefer final splice and BU placement in deeper water away from burial (1500m ideal depth) Consider using out-of-service cable route Bottom slack 2.5 to 3% plus fill slack Limit A/C to 30 deg otherwise vessel must slow to reduce layback Consider repeater placements either side of deep trench Economic cable length between transitions Consider installation and future maintenance in your routing and cable engineering 20

21 Physical Routing Constraints Earthquake Resulting Severe 300 km Mud Flow 21

22 Physical Routing Constraints Special Problems Ensuring all pipelines are known and found Databases are not complete; must rely of surveys Meeting ICPC recommendations in congested areas Not possible in many locations Accuracy of cable databases, also with regard to repair bights Owners often reluctant to disclose 22

23 Political Routing Constraints 23

24 Political Routing Constraints Minimize the number of coastal state claims especially Territorial Sea (TS) transited by the route Consider disputed claims and need for permits in overlapping claims Investigate coastal state s interpretation of UNCLOS and regulation for survey and use of foreign flag vessels Minimize length in TS (and CZ, EEZ) Consider taxes on cable and repeaters) Consider coastal state regulations in TS, CZ, EEZ. What is strength of fishing unions and expected compensation both shallow and deepwater Feedback from fishing unions is important especially in shelf routing Minimize number of active hydrocarbon lease blocks crossed 24

25 Political Routing Constraints 25

26 The Route Survey Provides information required to confirm or amend the preliminary pre survey DTS route Defines and documents the final route Enables final cable engineering to be defined Provides the system installer with the data required to finalize installation procedures Identifies potential post installation/residual hazards including unmitigated risks from potential tectonic activity during the system design life

27 conference & convention Route Survey Offshore Vessel

28 Route Survey Data Sets Data is collected along a strip of seabed, typically 500m to 3 x water depth wide and includes: Bathymetric data seabed topography Sonar imagery data seabed surface features Sub-bottom profiling data shallow sub surface soil profile Burial assessment data mechanical properties of the seabed soils within the planned burial profile (typically 1m to 3m) Geophysical and soils data usually only collected where cable protection by burial is planned typically up to a maximum water depth of 1,000m; rarely up to 2,000m Only bathymetric data collected in deep water

29 Multibeam Bathymetry Bathymetry and colocated back-scatter data Digital data output can be rapidly processed and analysed Data used to develop seabed terrain model Resolution of multibeam systems is altitude dependant

30 High Resolution in Shallow Water

31 High Resolution in Shallow Water

32 Deep water data Philippine Trench maximum depth 10,400m

33 Side Scan Sonar Imagery Towed systems Depth range up to 3000m Provide images of seabed surface features Surface back-scatter intensity can be used as indicator of seabed hardness

34 Side Scan Sonar Imagery

35 Sub-bottom data

36 Burial Assessment Gravity coring Cone Penetrometer Tests measure Tip resistance Sleeve friction Resistivity Typically to 3m below seabed Used to predict and categorize cable plough burial performance

37 Short reporting leadtimes have led to: On-board data acquisition, processing & charting Telemetry of processed data to shore based offices Data output direct to route planning software (Makai) Final reporting typically office based

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41 Cable Protection The Threat All External Aggression Faults (%) 70% 60% 50% 40% 30% 20% 10% 0% Fishing Anchors Other Abrasion Tyco Data ASN Data Dredge Geological Crushing M. Kordahi, S. Shapiro, G. Lucas, Trends in submarine Cable System Faults, SubOptic 2007 Fishing and anchoring pose the greatest risk to cable security. Cable burial remains the most effective and economical method of protection against these threats. 41

42 Cable Protection Desktop Study Route Selection Survey, Seabed Assessment, Route Refinement Burial Feasibility Study Burial Operations Cable Awareness Program Elements of of cable protection span the full project cycle! 42

43 Burial Category: A: Cable burial to a target cover depth of m; B: Cable burial to a target cover depth greater than 0.4m but less than 0.8m; C: Cable burial to a target cover depth of less than 0.4m; D: Risk of uncontrolled cable burial to a cover depth of greater than 0.8m; E: Cable burial to a target cover depth of 1.5 m in water depths of m; F: Cable burial to a target cover depth of 3 m in water depths of less than 10 m; G: Cable burial to a target cover depth of 3 m. Cable Protection Burial Example Only Deeper burial may be required in many cases Risk Category: 1: No identified risk of damage to the burial equipment due to seabed conditions; 2: Possible risk of damage to burial equipment due to seabed conditions. Scale of possible damage to be repairable on the installation vessel using shipboard equipment; 3: High risk of damage to the burial equipment due to seabed conditions. Scale of possible damage in excess of category 2. Key Elements of the BFS Seabed description Core and CPT penetration depth Hazards such as slopes, rock, boulders, coral, sand waves, soft sediment, pock marks Cable or pipeline crossings Currents that may affect plow or ROV deployment or operations Results of the integrated survey and analyses form the Burial Feasibility Study BFS is a guideline to predict burial likelihood and plow risk along the route Where seabed not conducive to burial, consider uparmor only if warranted by risk of external aggression 43

44 Cable Protection Burial Towed cable plows remain the industry standard for cable burial. Sea Stallion 3 m Plow MD3 3 m Plow Improved capability allow deeper burial and in more challenging seabed. The burial will be dictated by plow operations and reasonable endeavors ROV for Jet burial guidelines. Sea Plow 7-1.5m Plow 44

45 Maintenance Considerations Effective maintenance solution to minimise outage Club (zone) vs Private Maintenance Speed of response Base location Transit speed Strategic spares onboard not in depot Vessel performance Weather capability Maintenance and training, outside work?

46 Maintenance Considerations Post repair burial performance Age and power of ROV Enhanced burial protection protection Permitting track record Speed of response Fault prioritisation Fibre vs shunt; isolated branches vs ring systems Transmission performance Repairs should not affect upgrade-ability

47 Maintenance Considerations Commercial aspects Direct Measures Of Quality (DMOQs or SLAs) Pooling of joint kits and spare cables Tailored contracts vs standard terms Additional Services Fisheries Liaison Spare plant testing Shallow water repairs Land cable repairs

48 2010 conference & convention The 7th International Conference & Convention on Undersea Telecommunications Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May