HydroDigger Excavation Services - Forside...HydroDigger and pump remote control boxes are mounted on...

O:\06UTLEIE\MASKINER\FISHER OFFSHORE\DIVERSE OG HYDRODIGGER\Hydrodigger Avd. 300\Hydrodigger info fra UK\General Hydrodigger project rev01.doc

0 2010-12-07 For Information to Client IJC NIL Rev Date Description Prepared Approved

HydroDigger Excavation Services

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Contents Page

1 Contacts .................................................................................................................... 3 2 Introduction .............................................................................................................. 4 3 Overview of HydroDigger Equipment .................................................................... 4

3.1 HydroDigger System ............................................................................................... 4 3.2 Operating Envelope ................................................................................................. 5 3.3 The HydroDigger ...................................................................................................... 5 3.4 Deployment System (LARS) ................................................................................... 6 3.5 Main Hydraulic Power Pack .................................................................................... 9 3.6 Jetting Sub Assembly ............................................................................................. 9 3.7 Control Cabin ........................................................................................................... 9 3.8 Survey and Control Equipment ............................................................................ 10

4 Method Statement (Typical) .................................................................................. 13 4.1 Relevant Experience .............................................................................................. 13 4.2 Vessel Requirement and Services Required ....................................................... 14 4.3 Equipment Dimensions Typical Spread .............................................................. 14 4.4 Personnel ................................................................................................................ 15 4.5 Mobilisation ............................................................................................................ 15 4.6 Method for Pipeline Burial (Typical Application) ................................................ 16 4.7 Method Sketches for Pipeline Burial (Typical Application) ............................... 17 4.8 Commercial ............................................................................................................ 18 4.9 Project specific notes ............................................................................................ 19

5 Terms and Conditions ........................................................................................... 19

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1 Contacts Scan Tech AS Finnestadsvingen 23 Postboks 738 4004 Stavanger Phone number +47 51 54 54 00 Fax number +47 51 54 54 50 General Email [email protected] Web www.scan-tech.no

Project Contacts:

Nils Inge Lovra

Rental Manager

Ian Castle

Product Development & Compliance Advisor Tel

Direct

Mobile

Email

+47 51 54 54 00

+47 51 54 54 41

+47 51 911 88 246 [email protected]

Tel

Direct

Mobile

Email

+47 51 54 54 00

+47 51 54 54 14

+47 928 07 860 [email protected]

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2 Introduction The HydroDigger mass flow excavation system has been developed continuously over the last decade to produce the most robust, reliable and controllable seabed excavation system available today.

HydroDigger offers the following advantages over other dredging techniques:

• No physical contact with the seabed or seabed assets • No need to dispose of spoil • Real-time sonar imaging of the work site and progress • Continuously variable power • Utilisation from small, economic vessels • Effective on a wide range of substrates, including sand, rock dump and clays.

3 Overview of HydroDigger Equipment

3.1 HydroDigger System The HydroDigger is a variable power, remotely operated, subsea tool, which excavates by a process known as "Mass Flow Excavation" (MFE). A low pressure, high volume flow of water is generated by a propeller within the underwater unit and directed vertically downwards at the area to be excavated. When the water column meets the seabed it breaks up the soil surface and raises it into suspension. The suspension is dispersed into the surrounding water and carried from the site according to the prevailing current or tide. In still water conditions dispersal is more local and berms are formed around the excavation.

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A particular benefit of the M.F.E. technique is that excavation is carried out without any physical contact with the seabed and therefore structures within the soil such as valves or pipes may be uncovered without any risk of damage. Typically the tool is operated 3-5m above the seabed although this may be reduced in shallow water or to provide a more localised excavation. Another important advantage of the technique is the ability to completely remove all the soil from around and within complex shapes. Because of these attributes, the technique is now routinely used within the offshore industry for excavating live pipelines and damage-sensitive structures such as well heads and manifolds and in soils ranging from silt, sand and gravel to rock dump, drill cuttings and soft clays. The HydroDigger is a completely self contained and integrated system and is designed specifically for installation and operation from vessels equipped with dynamic positioning or accurate mooring capabilities. The spread typically consists of an underwater excavation unit, deployment system, power pack, control cabin, survey and control instrumentation.

3.2 Operating Envelope The HydroDigger is aligned with the vessel by means of one or two guide wires (depending on tool configuration) and as such the system uses the positioning system of the vessel to maintain station. The main limiting factor for the tool is movement in the vertical plane. The maximum swell acceptable is 3m, provided that the vessel is capable of maintaining location. Useful work time is usually limited by the abilities of the vessel rather than the HydroDigger.

3.3 The HydroDigger The HydroDigger consists of a robust vertical tubular housing in which a heavy-duty propeller is mounted. The propeller is directly driven by a powerful, reliable hydraulic motor, which is powered from a deck-mounted hydraulic power unit. The propeller generates a broad, high volume, relatively low velocity water column that excavates the seabed material and disperses it laterally. When the tool is moved over the seabed it forms a trench with a berm on either side. Raising and lowering the tool within its operational envelope (between 2 and 15 metres above the seabed) increases or decreases the area of the excavation. The shape, depth and rate of excavation produced by the HydroDigger depend on a combination of variables:

• Altitude of the tool above the seabed • Excavation power • Speed and direction of the tool over the work area • Seabed material being excavated

Using the sonar image for reference the HydroDigger operator is able to adjust these parameters to provide the required excavation profile.

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3.4 Deployment System (LARS) The HydroDigger is deployed from a purpose built over side handling system, which can be fitted to any vessel with sufficient deck space. The system requires 8m of vessel side free from obstruction if sea fastened directly to the deck. Alternatively, the system can be mounted on beams to clear vessel bulwarks. The HydroDigger is deployed on a main lift wire with one or two independent one tonne clump weights set 7m apart. The tool is fitted with outrigger arms, which slide on the guide wires. The purpose of the guide wires is to maintain the orientation of the tool with that of the vessel. This allows the HydroDigger operator to have a reliable reference for the sonar display in relation to the work area. Once the HydroDigger is deployed it mirrors the movement of the surface vessel very closely in all planes for most practical purposes. For some applications the use of a crane may be preferred. For instance, those jobs that require HydroDigger deployment adjacent to infrastructure, such as platform J-tube excavation, are better served with a crane to provide sufficient stand-off of the vessel. Scan Tech are able to offer cranes for this purpose or we can work with the vessel crane depending on specification.

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Scan Tech’s new Launch and Recovery System (LARS)

HydroDigger with Compact Crane Based Launch and Recovery System

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Scan Tech’s new HD5 XL (above left) alongside a standard HydroDigger

Standard HydroDigger

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3.5 Main Hydraulic Power Pack The HydroDigger is powered by a deck mounted hydraulic power pack. Power is infinitely variable and is directly controlled by the operator from the control cabin. Electric power packs are preferred for ease of maintenance but diesel packs are available for those vessels where power is at a premium.

3.6 Jetting Sub Assembly Where hard ground is expected, the HydroDigger may be fitted with a water-jetting sub assembly which directs a 3” jet of water at approximately 30 bar and up 6000 litres per minute directly at the seabed from the centre of the HydroDigger water column. Jetting is carried out simultaneously with HydroDigger excavation and has proved most effective in firm to stiff clays encountered in the Gulf of Mexico. The motive power for the jet is provided from a deck mounted six-stage centrifugal pump powered by a 650 HP diesel engine.

3.7 Control Cabin A control cabin can be provided to operate the HydroDigger. The cabin is fitted with sonar processors, camera controls, monitors and video equipment. The HydroDigger and pump remote control boxes are mounted on the operator’s desk, which allows one man to vary excavation power instantly whilst referencing the seabed beneath the tool in real time on the sonar display. One end of the cabin is fitted as a workshop and spares store. On some systems mainly where space is a premium on the vessel we operate without a control cabin, in which case the control and sonar equipment are set up in a suitable air-conditioned space aboard the vessel.

Vessel Navigation Screen Inside Control Cabin

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3.8 Survey and Control Equipment The HydroDigger is usually fitted with dual real-time sonar, which enables the operator to view the seabed beneath the tool in two planes, allowing the operator to visualise the seabed in three dimensions. The sonar allows the operator to work regardless of the amount of debris generated. The sonar system used on HydroDigger has recently been upgraded to the Imaginex Delta-T. This new system gives the same degree of visibility and control as previous systems but has a significant advantage. The system is PC controlled from the control cabin allowing the data to be continuously recorded throughout the excavation process if required. This data can them be stored to CD or DVD for future reference and post-processing. This saves a lot of video cassettes and makes future access of the recorded data far quicker and easier. If necessary the data collected can be post-processed to provide three dimensional colour renderings of the seabed. Imagenex have worked closely with Scan Tech in developing the software that operates the sonar. This has resulted in a special software filter which removes much of the ‘noise’ that was present on the old system. The differences in clarity between the old sonar system and the new Delta-T system can be seen in the screen shots shown on the following pages. In addition the post processed 3D images show far greater detail with accurate measurement facilities. Two SIT cameras and lights will be fitted to the HydroDigger. Where underwater visibility allows the two cameras provide alternative views of the excavation area beneath the tool. These are useful for identifying and following recognisable seafloor objects such as pipelines or structures. As well as providing better perspective the two cameras provide a degree of redundancy should one fail. The signals from these instruments are brought to the surface through an armoured electrical umbilical and displayed on monitors in the control cabin. Monitors are also mounted within the support vessel bridge, in view of the DP or anchor winch operator. This shared view of operations improves communications and understanding between the HydroDigger operator and the vessel’s navigation crew. This is crucial to safe and efficient execution of excavation projects.

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Above: Typical Delta-T Sonar image during Pipeline Excavation – Red sections

show profile along trench and the green sections the cross-section

Above: Typical old Sonar image during Pipeline Excavation

Top of Pipe

Top of Pipe

Bottom of Trench

Bottom of Trench

Bottom of Trench

Direction of Travel

Forward End of Trench

Forward End of Trench

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Above: 3D Post Processed image of Pipeline on Seabed from Imaginex Delta-T

sonar of a North Sea Pipeline showing Debris around It.

Above: 3D Sonar Image of Seabed Preparation for Habitat Installation, Tune Field produced from old sonar systems

Debris

Seabed

Pipe

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4 Method Statement (Typical)

4.1 Relevant Experience

HydroDigger has been used extensively over the years for both pre and post-lay pipeline trenching operations. In addition to this the system is routinely employed for pipeline de-burial work trench clearance, free-span correction, pipeline crossing correction, de-commissioning work and sand wave levelling etc. Scan Tech operates 5 separate HydroDigger spreads, currently located in Mexico, Singapore, USA, Africa and the North Sea, although more HD Spreads are under construction at present to meet demand.

Scan Tech is registered with Achilles (ID number 13815) and our quality and HSE credentials can be examined here along with our performance feedback. The group has successfully completed over 70 HydroDigger projects in remote, hostile environments around the world. Each project is managed to the same high quality and HSE standards demanded in the Norwegian North Sea and UK.

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4.2 Vessel Requirement and Services Required

The work will be performed from a client-supplied vessel that can provide the following minimum capabilities:

• DP vessel with the ability to follow an accurate path at speeds down to 1m/min

• Craneage to mobilise Scan Tech equipment in port • Rigging/welding to install HydroDigger system and test sea fastenings • Deck space for Scan Tech equipment • Accommodation for 6 HydroDigger personnel • Services as follows:

• Stable 220-240V 16 Amp electrical supply • Stable 440V 350 Amp 3 phase electrical supply • 2 x Stable 440V 63 Amp 3 phase electrical supply • Seawater supply for cooling

• Business communications – phone, fax & email • Fuel and lubes appropriate to the equipment in use (Jetting unit etc).

Example deck layout can be prepared.

4.3 Equipment Dimensions Typical Spread

Item Description Required / Option

Length (mm)

Width (mm)

Height (mm)

Weight (kg)

1 HydroDigger R Ø1760 Ø1760 1750 4600

2 Main Hydraulic Power Pack R 1900 1700 1896 4000

3 Hydraulic Hose Reel R 2550 2500 2650 6000

4 Handling System (LARS) R 4110 2900 3500 8400

5 Control Cabin R 4946 2430 2600 5500

6 Main Water Jetting Pump O 6100 2400 2600 15000

7 Water Hose Reel O 3000 3000 3400 5500

8 Submersible Pump O 800 800 1500 500

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4.4 Personnel

Scan Tech selects experienced marine crew for HydroDigger projects. We have a core team of job superintendents and technicians that have worked extensively with the equipment, often in remote locations. The crew work to the highest standards of quality and safety, and communicate fully with vessel crew from riggers to the client rep. For 24 hour operation the following personnel will be required:

• 1 x Superintendent • 1 x Shift Supervisor • 4 x Technicians

(Total 6 personnel)

4.5 Mobilisation

• Prior to mobilisation, a deck plan will be agreed. The deck plan will take into consideration: • The location and clearance of permanent vessel equipment and

superstructure • The likely location of additional job-specific equipment • Access to power, air & water services • Access to hatches, walkways etc.

• A full site-specific risk assessment will be performed prior to commencement of work and toolbox chats will be organised on deck by the supervising staff involving all personnel involved in the mobilisation.

• On arrival of HydroDigger at the vessel, the equipment will be positioned

according to the deck plan drawings.

• The signal from the dual sonar mounted on the HydroDigger will be relayed via the control cabin to a monitor at the navigation control on the vessel bridge. This allows the DP/anchor winch operator to view in real time the position of the HydroDigger relative to seabed assets and to communicate more efficiently with the HydroDigger operator.

• Sea-fastening will be conducted in accordance with vessel or client

specifications. • After completing mobilisation and prior to sailing, 3rd party inspection and

testing of the sea fastening arrangements will be conducted.

• A short launch and test of the equipment will be conducted prior to sailing to location.

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4.6 Method for Pipeline Burial (Typical Application)

(To be read in conjunction with Method Sketches 4.7) Primary Requirements.

• A Dynamic Positioning Vessel capable of maintaining a small footprint and moving at a constant speed as low as 1m/min. DP2 or winch system.

• An experienced marine crew capable of accurate barge positioning. • An Experienced Survey Team. • Dual Sonar System. • DVD/Video Recording.

Prior to commencing HydroDigger activities: -

• Meet with Client to establish instructions for Start and End points of the trench and Transition Profiles.

• Work with Survey and place marks on the navigation screen to mark the Start and End of each Transition and also mark the pipeline at 50Mtr intervals between the two transitions.

Method:

• Position vessel at the start point of the transition and move the vessel 10Mtrs away from the pipeline and any other subsea assets. Deploy the HydroDigger as per the Launch Procedure

• Relocate vessel back to the start point and locate pipeline with the sonar. • Position the HydroDigger so the centre of the tool is approximately 0.5Mtrs to

the side of the pipeline. • Activate the HydroDigger at low power and adjust according to soil strength. • Instruct the DP Operator to begin moving the vessel along the pipeline at a

rate of approximately 3 to 5M/min or as dictated by the excavation rate and trench profile for 50Mtrs.

• Excavate the transition by starting at low power and increasing the power of the tool to dig a trench that matches the desired transition profile.

• At the first 50Mtr mark, stop the vessel and reduce the power of the digger. The tool should then be repositioned onto the opposite side of the pipeline.

• Continue trenching along the opposite side of the pipeline until the next mark is reached. Digging with this method ensures that the pipeline is lowered in an even manner into the trench and prevents the pipeline rolling down into it and placing torsional strain on the pipeline.

• Continue digging along the pipeline, swapping sides every 50Mtrs until the required length of pipeline is trenched including the end transition.

• Return down the length of the pipeline in the opposite direction in the same manner. However this time the opposite side of the pipeline that has not yet been trenched should be dug.

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• Upon returning to the original start point, the tool should be relocated so that it is over the centre of the pipe. The vessel should then proceed along the trenched pipeline at a slightly faster rate of around 6M/min. The tool should be set for low power to wash away any backfill and the pipe should be surveyed to ensure it is at the correct depth.

• Fixes should be taken every 50 or 100Mtrs as agreed with the client. The depth of the top of the pipe below the natural seabed should be recorded and Video/DVD footage of each fix point should also be taken.

• If there are any points that are not at the required depth these can be corrected at the same time on this pass.

• The client is required to sign a completion certificate upon satisfactory completion of the survey.

N.B. Full client supplied engineering procedures will be agreed prior to work commencing.

4.7 Method Sketches for Pipeline Burial (Typical Application) To follow upon client enquiry,

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4.8 Commercial HydroDigger Rates – North Sea Area

Item Description Unit Rate NOK

1 Equipment Mobilisation in Stavanger only (includes

demob charge in Stavanger only) Lump sum TBA,-

2 Transport to each way, 3 large road lorries

Alternative Mob sites may be considered Lump sum

TBA,-

3 Personnel Mob-demob ex Aberdeen / Stavanger Lump sum TBA,-

4 HydroDigger Equipment Day Rate - Working (Inclusive

of dual Sonar system) Per day TBA,-

5 HydroDigger Equipment Day Rate - Normal Standby Per day TBA,-

6 HydroDigger Equipment Day Rate - *Special Standby

(Unmanned without Personnel) Offshore/Onshore Per Day TBA,-

7 Jetting System including Pump, submersible pump,

4” Hose reel etc Per Day TBA,-

8 Personnel Charge - 6 man crew (24hr crew),

comprising:

1 x Superintendent

1 x Shift Supervisor

4 x Technicians/Operators

Per day TBA,-

9 Crew Change - one per man per 28 days Per man TBA,-

10

Travel and subsistence expenses for project meetings

and during personnel mob/demob out with Aberdeen /

Stavanger

Cost + 15%

Should an urgent Personnel Mobilisation be required (<3weeks), Cost + 15% will be charged.

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4.9 Project specific notes To follow upon Client enquiry.

5 Terms and Conditions 1. HydroDigger Equipment day rates are payable Ex Scan Tech works until return

to Scan Tech’s works. 2. Personnel day rates, accommodation and subsistence are to Client account

from departure from Stavanger until return to Stavanger unless alternative arrangements have been agreed. A 10% charge will apply to accommodation and subsistence costs.

3. A minimum of 10 days written notice is required prior to mobilisation. 4. Scan Tech reserve the right to change out crew at Client’s expense on a 28 day

rotation. 5. Any part day is charged as a whole day at the higher of the applicable day

rates. 6. Each working day includes up to 2 hours routine maintenance. 7. Downtime is subtracted from the working day rate on an hourly pro-rata basis. 8. Fuel, lubricants, hydraulic oils and communications from the vessel are to

Client account. 9. Sea fastenings, steelworks, craneage at dockside and reinstatement of vessel

are to Client account. 10. Prices are in NOK. 11. All rates and prices exclude VAT, local sales taxes, withholding taxes and

import / export duties etc. 12. This proposal is made subject to availability of equipment and the signing of a

mutually acceptable contract. 13. This proposal will remain valid for a period of 120 days from submission. 14. A minimum rental period applies to all rates.

HydroDigger Excavation Services - Forside...HydroDigger and pump remote control boxes are mounted on...

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